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Title:
PULL-PULL SHIFTER ASSEMBLY
Document Type and Number:
WIPO Patent Application WO/2015/090370
Kind Code:
A1
Abstract:
The present invention provides a pull-pull shifter assembly comprising: - a shift lever (2) mounted in a housing to be pivotable in a select direction between at least two shift gate positions and, in each shift gate position, from a neutral position in a shift direction, select and shift directions being perpendicular to each other, - a shift pulley (4; 104, 105) coupled to the shift lever so that movements of the shift lever in shift direction are transferred to corresponding rotations of the shift pulley, a shift cable (6) being routed around and fixed to the shift pulley to transmit rotations of the shift pulley to corresponding displacements of the shift cable, - a select pulley (14; 114, 115) coupled to the shift lever so that movements of the shift lever in select direction are transferred to corresponding rotations of the select pulley, a select cable (16) being routed around and fixed to the select pulley to transmit rotations of the select pulley to corresponding displacements of the select cable, characterized in that the shift pulley (4; 104) and the select pulley (14; 14) are rotatably mounted in the housing such that their axes of rotation are parallel and in that the shift lever (2) is coupled to the shift pulley (14; 114, 115) and to the select pulley (14; 114, 115), respectively, by a respective mechanical linkage.

Inventors:
SKOGWARD KENNETH (SE)
BERGNER JONAS (SE)
LINDEKULL MARTIN (SE)
Application Number:
PCT/EP2013/076955
Publication Date:
June 25, 2015
Filing Date:
December 17, 2013
Export Citation:
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Assignee:
KONGSBERG AUTOMOTIVE AB (SE)
International Classes:
F16H59/04; F16H61/36
Foreign References:
US20120118094A12012-05-17
US20120118094A12012-05-17
DE19544837A11996-06-20
US6093892A2000-07-25
Attorney, Agent or Firm:
AHME, Johannes et al. (Beselerstraße 4, Hamburg, DE)
Download PDF:
Claims:
Claims

1. Pull-pull shifter assembly comprising: a shift lever (2) mounted in a housing to be pivotable in a select direction between at least two shift gate posi¬ tions and, in each shift gate position, from a neutral po¬ sition in a shift direction, select and shift directions being perpendicular to each other, a shift pulley (4; 104, 105) coupled to the shift lever so that movements of the shift lever in shift direction are transferred to corresponding rotations of the shift pul¬ ley, a shift cable (6) being routed around and fixed to the shift pulley to transmit rotations of the shift pulley to corresponding displacements of the shift cable, a select pulley (14; 114, 115) coupled to the shift lever so that movements of the shift lever in select direction are transferred to corresponding rotations of the select pulley, a select cable (16) being routed around and fixed to the select pulley to transmit rotations of the select pulley to corresponding displacements of the select cable, characterized in that the shift pulley (4; 104) and the select pulley (14; 114) are rotatably mounted in the housing such that their axes of rotation are parallel and the shift lever (2) is coupled to the shift pulley (14; 114, 115) and to the select pulley (14; 114, 115), respec¬ tively, by a respective mechanical linkage.

2. Pull-pull shifter assembly according to claim 1, charac¬ terized in that the shift pulley (4) and the select pulley (14) are coaxially mounted in parallel horizontal planes in the housing below the shift lever (2) so that their axes of rotation extend vertically, parallel to the gen¬ eral direction of the shift lever.

3. Pull-pull shifter assembly according to claim 2, charac¬ terized in that the mechanical linkage coupling the shift lever (2) to the select pulley (14) comprises a select pin (8) extending from the shift lever at the level of its pivotal bearing in the housing and extending perpendicular to the shift lever and to the shift direction, the outer end of the select pin (8) being received in an aperture (9b) of a select lever arm (9) which is rotatably mounted in the housing with an axis of rotation parallel to a plane in which the select pin (8) moves during a shift lever select movement but displaced from that plane so that a pivotal movement of the shift lever in select di¬ rection is transferred via the select pin (8) to the se¬ lect lever arm (9) to cause its rotation around its axis of rotation (99), which rotation is in turn transferred by a select pulley drive pin (10) which is disposed at a lower end portion of the select lever arm (9) and which is received in an oblong aperture (15) of the select pulley (14) at a distance of the axis of rotation of the select pulley so that the longitudinal displacement of the select pulley drive pin (10) accompanying the rotation of the se¬ lect lever arm (9) is transferred to a rotational movement of the select pulley (14) .

4. Pull-pull shifter assembly according to claim 2 or 3, characterized in that the mechanical linkage coupling the shift lever (2) to the shift pulley (4) comprises a shift pin (18) extending from the shift lever (2) at the level of its pivotal bearing in the housing and extending perpendicular to the shift lever and to the select direction, an outer end of the shift pin (18) being received in an oblong aperture (19b) of a shift lever arm (19) which is rotatably mounted in the housing with an axis of rotation (199) parallel to a plane in which the shift pin (18) moves during a shift movement but displaced from that plane so that a pivotal movement of the shift lever in shift direction is transferred via the shift pin (18) to the shift lever arm (19) to cause its rotation around its axis of rotation (199), which rotation in turn is transferred by a shift pulley drive pin (20) which is disposed at a lower end portion of the shift lever arm (19) and which is received in an oblong aperture (5) of the shift pulley (4) at a distance of its axis of rotation so that the longitudinal displacement of the shift pulley drive pin (20) accompanying the rotation of the shift lever arm is transferred to a rotational movement of the shift pul¬ ley (4) .

5. Pull-pull shifter assembly according to claim 3, charac¬ terized in that the mechanical linkage coupling the shift lever to the shift pulley comprises a shift arm (30) which forms an extension of the shift lever (2) beyond its piv¬ otal bearing in downward direction which carries a fork member (32) with an elongated cavity (34) at its lower end which disposed with its elongation perpendicular to the shift direction and which is arranged to receive a shift pulley drive stud (36) mounted to the shift pulley (4) at a distance with respect to its axis of rotation such that there is engagement between the elongated cavity (34) and the shift pulley drive stud (36) in shift direction such that shift movements of the shift lever cause correspond¬ ing movements of the shift arm (30) which are transferred via the fork member (32) and the shift pulley drive stud (36) to corresponding rotational movements of the shift pulley ( 4 ) .

6. Pull-pull shifter assembly according to claim 5, charac¬ terized in that the shift pulley (4) is disposed above the select pulley (14) and comprises a cut out segment or an arcuate elongated opening through which the select pulley drive pin (10) extends to be received in the oblong aper¬ ture of the select pulley (14) .

7. Pull-pull shifter assembly according to any of claims 1 to 4, characterized in that the select pulley (14) is dis¬ posed above the shift pulley (4) and comprises a cut out segment or an arcuate elongated opening through which the shift pulley drive pin (20) extends to be received in the oblong aperture of the shift pulley (4) .

8. Pull-pull shifter assembly according to claim 1, charac¬ terized in that there are two subsequent shift pulleys (104, 105) with parallel and horizontal axes of rotation which are displaced in horizontal direction, the shift ca¬ ble (6) being fixed to at least one of the shift pulleys and routed around them such that the vertical distance be¬ tween shift cable portions extending from the shift pul¬ leys is less than the diameter of any of the shift pulleys (104, 105), and in that there are two subsequent select pulleys (114, 115) with horizontal and parallel axes of rotation which are displaced in horizontal direction, the select cable (16) being fixed to at least one of the se¬ lect pulleys and routed around them such that the vertical distance between the select cable portions extending from the select pulleys is less than the diameter of any of the select pulleys (114, 115).

9. Pull-pull shifter assembly according to claim 8, charac¬ terized in that the mechanical linkage for select move¬ ments comprises a select pin (108) extending from the shift lever at the level of its pivotal bearing in the housing and extending perpendicular to the shift lever and to the shift direction, the outer end of the select pin comprising a ball portion being received in a ball joint

(110) in the upper end of a select rod (109), the lower end of the select rod (109) being coupled to one of the select pulleys (114, 115) to which the select cable (16) is fixed, wherein the select rod (109) is coupled to the one of the select pulleys (114, 115) via a ball joint

(111) at a distance from its horizontal axis of rotation so that movements of the shift lever (2) in select direc¬ tion are transferred via a pivotal movement of the select pin (108) to displacements of the select rod (109) and further to a rotational movement of the one of the select pulleys (114, 115) to which it is coupled.

10. Pull-pull shifter assembly according to claim 8 or 9, characterized in that the mechanical linkage for shift movements comprises a shift pin (118) extending from the shift lever (2) at the level of its pivotal bearing in the housing and extending perpendicular to the shift lever and to the select direction, the outer end of the shift pin (118) comprising a ball portion which is received in a ball joint (120) at an upper end of a shift rod (119), wherein the lower end of the shift rod is rotatably con¬ nected to one of the shift pulleys (104, 105) to which the shift cable (6) is fixed, wherein this rotatable connec¬ tion is at a distance to the axis of rotation of the shift pulley to which the shift rod (119) is connected, such that shift movements of the shift lever are transferred via pivotal movements of the shift pin (118) to displace¬ ments of the shift rod (119) and further to rotations of the one of the shift pulleys (104, 105) to which the shift rod (119) is connected.

11. Pull-pull shifter according to any of the claims 8 to 10, characterized in that the shift pulley (104) and the se¬ lect pulley (114) are coaxially mounted on a horizontal shaft to be rotatable around this shaft, and in that the further shift pulley (105) and the further select pulley (115) are coaxially mounted on a further shaft to be ro¬ tatable around this further shaft, the further shaft being displaced from the shaft in the direction of the shift ca¬ ble portions (6) and select cable portions (16) extending away from the shift pulley (104) and select pulley (114) .

12. Pull-pull shifter according to claim 11, characterized in that the shaft and the further shaft are disposed on a vertical level relative to each other such that the upper shift cable portion of the shift cable being routed around shift pulley (104) is deflected downwards by the further shift pulley (105) such that it extends from the further shift pulley (105) at a lower vertical level than from the shift pulley (104), and such that the upper select cable portion extending from the select pulley (114) is deflected downwards by the further select pulley (115) to a lower vertical level than the upper select cable portion extending from the select pulley (114) .

13. Pull-pull shifter assembly according to claim 12, charac¬ terized in that the select rod (109) is coupling the se¬ lect pin (108) to the select pulley (114) at a distance from its axis of rotation, and that the shift rod (119) couples the shift pin (118) to the further shift pulley (105) . Shift tower for pull-pull cable assemblies for effecting shift and select movements of a shift shaft (302) of a gearbox of a vehicle, comprising transmission means capa¬ ble of converting movements of the shift cable (6) into rotational movements of the shift shaft (302) around its longitudinal axis, and movements of the select cable (16) into displacements of the shift shaft (302) along its lon¬ gitudinal axis, characterized in that the transmission means comprise: a shift pulley (304) and a select pulley (314), the shift cable (306) being routed around and fixed to the shift pulley (314), the select cable routed around and fixed to the select pulley (314), the shift pulley (304) and the select pulley (306) being mounted in a housing (300) adja¬ cent to each other with their rotational axes parallel to each other, a carriage (330) mounted in the housing to be moveable in a first direction parallel to the longitudinal direction of the shift shaft (302), and in a second direction per¬ pendicular to the first direction, a shift lever (301) with one of its ends being connected to the shift shaft (302) and extending in a direction perpendicular to the longitudinal direction of the shift shaft, the other end of the shift lever being coupled to the carriage (330) such that movement of the carriage in the first direction are transferred by the shift lever (301) to cause select movements of the shift shaft (302) along its longitudinal axis, and that movement of the car¬ riage in the second direction are transferred by the shift lever to cause rotational shift movements of the shift shaft (302) around its longitudinal axis, a coupler (340) being connected on the one hand to the shift cable (6) to follow movements of the shift cable in the second direction, and being engaged on the other hand with the carriage (330) to cause movements of the carriage in the second direction in response to shift cable (6) movements in the second direction, and a linkage pivotably (350) mounted with its central postion in the housing and coupled with one of its ends to the se¬ lect pulley (314) at a distance from the rotational axis of the select pulley, and being coupled with its opposite end to the carriage (330) such that rotational movements of the select pulley (314) are transferred via pivotal movements of the linkage (350) to movements of the car¬ riage (330) in the first direction which are transferred via the shift lever (301) to shift shaft (302) select movements along its longitudinal axis.

15. Shift tower according to claim 14, characterized in that the coupler (340) comprises a coupling member (340) fixed to the shift cable (6) and at least one leg extending therefrom, which leg is received in an elongated slot (332) extending in the carriage (330) in the first direc¬ tion so that movements of the coupler (340) in the second direction are transferred by the leg of the coupler (340) to the carriage (330) .

16. Shift tower according to claim 14 or 15, characterized in that the linkage (340) comprises pins at its opposite ends, one end pin being received in an elongated slot in the select pulley (314) spaced apart from its rotational axis, the other end pin being received in an elongated slot (334) extending in the carriage (330) in the second direction so that the carriage, when the linkage (340) with its end pin received in the elongated slot (334) pivots with an associated movement in the first direction, follows such movement in the first direction.

17. Shift tower according to any of claims 14 to 16, charac¬ terized in that an inertia wheel (360) is mounted within the housing with its rotational axis being oriented paral¬ lel to the rotational axis of the shift and select pulleys (304, 314), the inertia wheel being coupled to the shift pulley (304) such that rotation of the shift pulley re¬ sults in rotation of the inertia wheel (360) .

18. Shift tower according to claim 17, characterized in that the inertia wheel (360) comprises a gear wheel (362) dis¬ posed coaxially on the inertia wheel and projecting form one side thereof, and in that the shift pulley comprises an inwardly facing gear wheel portion (305) close to its outer circumference which is arranged to mesh with the gear wheel (362) of the inertia wheel 360) .

19. Shift tower according to claim 18, characterized in that the inertia wheel (360) having the major part of its mass in a peripheral ring portion which is connected by spokes to the central hub of the wheel.

20. Automatic length adjuster for a cable assembly having a conduit (50, 50') and a cable (52) slidably disposed therein, comprising a housing part (60) fixed in axial direction with respect to a conduit portion (50) extending from one end of the housing part and having a cylindrical cavity (62) at the opposite end, and a cylindrical member (70) to be received in the cylindrical cavity (62) and be¬ ing fixed in axial direction with respect to a conduit portion (50') extending from an end of the cylindrical member opposite to the end received in this cylindrical cavity, wherein the cylindrical member is rotatably and slidably moveable in axial direction with respect to the housing part, wherein the cylindrical member and the hous¬ ing part cooperate via a series of steps of increasing depth and projections formed respectively in their engag¬ ing surfaces, the projection being arranged to be in abut¬ ment with any of the steps to hold the cylindrical member and the housing apart at a distance in axial direction de¬ fined by the respective step, wherein the series of steps defines a series of increasing longitudinal extensions of the cooperating cylindrical member (70) and housing part (60), and wherein a spring (80) is biasing the cylindrical member and the housing part to rotate relative to each other to increase the longitudinal extension to compensate slack in the cable assembly, characterized in that in the cavity of the housing part the series of steps are defined by at least two coaxial, circumferentially extend¬ ing winding stairs (64, 66, 68), each comprising a series of planar step surfaces, each pair of adjacent step sur¬ faces being interconnected by an inclined surface, and in that the end portion of the cylindrical member to be re¬ ceived in the cavity is provided with at least two comple¬ mentary coaxial, circumferentially extending winding (74, 76, 78) stairs defining complementary planar step surfaces and interconnecting inclined surfaces, such that the num¬ ber of step surfaces and inclined surfaces of the coaxial, circumferentially extending winding stairs (64, 66, 68) of the housing part being in abutment with step surfaces and inclined surfaces of the circumferentially extending wind¬ ing stairs (74, 76, 78) of the cylindrical member is at a maximum when the housing part (60) and the cylindrical member (70) have the state shortest longitudinal exten¬ sion, and such that the number of the step and inclined surfaces of the coaxial, circumferentially extending wind- ing stairs (64, 66, 68) in abutment with step and inclined surfaces of the complementary coaxial, circumferentially extending winding stairs (74, 76, 78) is decreasing with increasing longitudinal extension of housing part and cylindrical member upon rotation of the housing part relative to the cylindrical member.

21. Automatic length adjuster according to claim 20, characterized in that each of the at least two coaxial, circum- ferentially extending winding stairs (64, 66, 68, 74, 76, 78) extends circumferentially by more than 270°, in par¬ ticular up to 360°.

22. Automatic length adjuster according to claim 20 or 21, characterized in that there are three coaxial, circumfer- entially extending winding stairs (64, 66, 68) in the cavity (62) of the housing part (60), and three complementary coaxial, circumferentially extending winding stairs (74, 76, 78) provided on the cylindrical member.

Description:
Pull-pull shifter assembly

The present invention relates to a pull-pull shifter assembly comprising: a shift lever mounted in a housing to be pivotable in a select direction between at least two shift gate posi ¬ tions and, in each shift gate position, from a neutral posi ¬ tion forward and backward in a shift direction, select and shift directions being perpendicular to each other; a shift pulley coupled to the shift lever so that movements of the shift lever in shift direction are transferred to correspond ¬ ing rotations of the shift pulley, a shift cable being routed around and fixed to the shift pulley to transmit rotations of the shift pulley to corresponding displacements of the shift cable; and a select pulley coupled to the shift lever so that movements of the shift lever in select direction are trans ¬ ferred to corresponding rotations of the select pulley, a se ¬ lect cable being routed around and fixed to the select pulley to transmit rotations of the select pulley to corresponding displacements of the select cable.

A traditional shifter assembly for a manual transmission of a vehicle typically comprises a shift lever which is displace- able in a shift direction (forwards and backwards from a rest position, the shift direction normally being parallel to the longitudinal direction and driving direction of the vehicle) , and which is displaceable in a select direction between two or more shift gate positions (the select direction being to the left and right, perpendicular to the longitudinal direction and driving direction of the vehicle) .

In a traditional push-pull cable the movements of the shift lever and the cable transferring the control commands of the shift lever to a shift shaft of a gearbox the resulting move ¬ ments are as follows: movement of the shift lever forward results in pulling the shift cable; movement of the shift lever backwards results in pushing the shift cable; movement of the shift lever to the left results in pulling the select cable; and movement of the shift lever to the right results in pushing the select cable.

The cables are in turn connected to a shift tower which trans ¬ lates the movement of the cables into a rotation of a shift shaft around its longitudinal axis (corresponding to a shift movement of the shift shaft) and into a longitudinal displace ¬ ment of the shift shaft along its longitudinal axis (corre ¬ sponding to a select movement of the shift shaft) . The shift shaft is in turn selectively engageable with shift forks which engages/disengages the various gears of the transmission.

A problem associated with such traditional shifter assemblies is that the cables must be capable of transferring a pushing force. This implies high requirements on the structural rigid ¬ ity of the cables. A cable, more particularly the inner cable element which is enveloped by a cable sleeve, has to be rather stiff such that it does not bend when pushing forces are transferred through the inner cable element.

It is also known in the field to utilize so called pull-pull shifter assemblies, i.e. a shifter assembly that actuates the shift tower solely by pulling cables. This requires two cable portions for each of the select and the shift directions (the two cable portions needed for each direction can in fact be ¬ long to one cable which is routed around a pulley and con ¬ nected thereto such that rotational movement of the pulley in forward and backward directions result in a pulling action of one of the two cable portions, respectively; alternatively two separate cable portions individually connected to the respec ¬ tive pulley can be used) . However, due to the lower require ¬ ments on the structural rigidity, the cables needed in a pull- pull shifter assembly will still be cheaper than cables needed in traditional push-pull shifter assemblies.

U.S. 2012/118,094 Al discloses a pull-pull shifter assembly according to the preamble of claim 1. The shifter assembly has a shift lever which is mounted to be pivotable in a select di ¬ rection between at least two shift gate positions and, at each shift gate position, from a neutral position in a shift direc ¬ tion perpendicular to the select direction. The shift lever is directly and fixedly connected to a shift pulley so that mov ¬ ing the shift lever forward or backward in shift direction di ¬ rectly rotates the shift pulley to make a corresponding rota ¬ tional movement in forward or backward direction. A shift ca ¬ ble is routed around and fixed to the shift pulley to transmit rotational movements thereof to corresponding displacements of the shift cable. There is furthermore a select pulley with a corresponding select cable to transmit rotations of the select pulley into corresponding displacements of the select cable. The shift lever comprises a select arm projecting at a right angle therefrom and extending into an elongated slot formed in the select pulley such that upward and downward pivotal move ¬ ment of the select arm caused by tilting of the shift lever in the left or right direction is transferred to corresponding rotational movements of the select pulley. This arrangement requires that the shift pulley is following the tilting move ¬ ment of the shift lever if the latter performs a select move- ment . Therefore, the rotational axis of the shift pulley can not be stationary within the housing but has to accommodate the tilting select movements of the shift lever which requires a complicated bearing structure. Furthermore, there is a risk that the shift cable which is guided around the circumference of the shift pulley in a circumferential groove thereof be ¬ comes dislodged from the shift pulley when the latter is per ¬ forming a tilting movement with the shift lever. Such removal of the shift cable assembly from the shift pulley would render the shifter assembly inoperative.

It is an object of the present invention to provide a pull- pull shifter assembly which allows for a compact design and a reliable operation of the shifter assembly.

This object is achieved by the pull-pull shifter assembly com ¬ prising the features of claim 1. Preferred embodiments of the invention are set out in the dependent claims.

According to the present invention the shift pulley and the select pulley are rotatably mounted in the housing such that their axes of rotation are fixed and parallel. Furthermore, the shift lever is coupled to the shift pulley and to the se ¬ lect pulley, respectively, by a respective mechanical linkage.

Due to the mounting of the shift pulley and the select pulley with fixed rotational axis in the housing the bearing struc ¬ ture for the pulleys is much simpler since no tilting move ¬ ments have to be performed by the pulleys but only purely ro ¬ tational movements. Mounting the shift pulley and the select pulley with parallel axes of rotation allows for a compact de ¬ sign since shift pulley and select pulley can be mounted adja ¬ cent and parallel to each other. Furthermore, the purely rota ¬ tional movements of the shift and the select pulleys ensure a reliable operation since no critical pivotal movements of the pulleys have to be performed.

A mechanical shift linkage for transmitting shift movements of the shift lever to the shift pulley, and a mechanical select linkage to transfer select movements of the shift lever to the select pulley allow for a reliable and safe operation of the shifter assembly.

In a preferred embodiment the shift pulley and the select pul ¬ ley are coaxially mounted in parallel horizontal planes in the housing below the shift lever so that their axes of rotation extend vertically, parallel to the general direction of the shift lever (the shift lever may slightly deviate from a strictly vertical orientation due to shift and select move ¬ ments) . This embodiment permits a very compact design since the shift and select pulleys are mounted on top of each other below the shift lever. Furthermore, the design of this embodi ¬ ment is very compact since the two cable portions of the se ¬ lect cable extending from the select pulley, and the two shift cable portions extending from the shift pulley are on the same vertical level, and the cable portions of the shift cable and the select cable can be vertically at a close distance which is determined by the vertical distance between the shift pul ¬ ley and the select pulley being disposed on top of each other. This arrangement is less space consuming than an arrangement in which the shift and select pulleys are disposed with their axes of rotation in horizontal direction because in the latter arrangements the vertical upper cable portions of the shift and select cable, respectively, have to be deflected down ¬ wardly by corresponding further pulleys in order to reduce the vertical extension needed to accommodate the shift and select cables . In a preferred embodiment the mechanical linkage coupling the shift lever to the select pulley comprises a select pin ex ¬ tending from the shift lever at the level of its pivotal bear ¬ ing in the housing and extending perpendicular to the shift lever and to the shift direction. The end of the select pin remote from the shift lever is received in an aperture of a select lever arm which is rotatably mounted in the housing with an axis of rotation parallel to a plane in which the se ¬ lect pin moves during a shift lever select movement but dis ¬ placed from that plane; this arrangement implies that a piv ¬ otal movement of the shift lever in select direction, which is accompanied by a pivotal vertical movement of the select pin, is transferred to the select lever arm to cause its rotation around its axis of rotation, this rotation of the select lever arm causing a select pulley drive pin to move which is fixed at a lower end portion to the select lever arm and which is received in an oblong aperture of the select pulley at a dis ¬ tance of the axis of rotation of the select pulley. Therefore, a rotation of the select lever arm is accompanied by a longi ¬ tudinal displacement of the select pulley drive pin in the ob ¬ long aperture of the select pulley which oblong aperture is oriented so that the rotation of the select lever arm is transferred by the select pulley drive pin to a rotational movement of the select pulley.

In a preferred embodiment the mechanical linkage coupling the shift lever to the shift pulley corresponds to the above- described mechanical linkage coupling the shift lever to the select pulley.

In an alternative embodiment, the mechanical linkage coupling the shift lever to the shift pulley comprises a shift arm which forms an extension of the shift lever beyond its pivotal bearing in downward direction, which shift arm carries a fork member with an elongated cavity at its lower end which is dis- posed with its elongation perpendicular to the shift direction and which is arranged to receive a shift pulley drive stud mounted to the shift pulley at a distance with respect to its axis of rotation such that there is engagement between the elongated cavity and the shift pulley drive stud in shift di ¬ rection such that shift movements of the shift lever cause corresponding movements of the shift arm which are transferred via the fork member and the shift pulley drive stud to corre ¬ sponding rotational movements of the shift pulley. On the other hand, movements of the shift lever along the select di ¬ rection are not transferred to the shift pulley, since the shift pulley drive stud can slide along the elongated cavity when the shift lever is moved in select direction.

In a preferred embodiment the shift pulley is disposed verti ¬ cally above the select pulley and comprises a cut out segment or an arcuate elongated opening through which the select pul ¬ ley drive pin extends to be received in the oblong aperture of the select pulley, the cut out segment or the arcuate opening being shaped such that it allow shift rotational movements of the shift pulley with the select pulley drive pin at rest. In an alternative arrangement the select pulley is disposed ver ¬ tically above the shift pulley and comprises a cut out segment or an arcuate elongated opening through which the shift pulley drive pin extends to be received in the oblong aperture of the shift pulley, the cut out segment or the arcuate opening being shaped to allow rotational select movements of the select pul ¬ ley while the shift pulley drive pin is addressed. These ar ¬ rangements of the shift and select pulleys vertically on top of each other allows for a compact design of the pull-pull shifter assembly.

In a preferred embodiment the shift pulley and the select pul ¬ ley are rotatably mounted in the housing for rotation around a horizontal axis and are disposed below the shift lever, wherein the horizontal rotational axis extends perpendicular to the general direction of the shift lever and to the shift direction. Because of this vertical orientation of the pulleys each of the pulleys is associated with a further pulley which has an axis of rotation parallel to but displaced from the horizontal rotational axis of the first shift pulley and the first select pulley. The further shift pulley is arranged such that the shift cable being routed around the first shift pul ¬ ley is further routed around the further shift pulley to guide the vertically upper portion of the shift cable downward again to decrease the vertical distance between the upper portion and the lower portion of the shift cable, and the second se ¬ lect pulley is arranged such that the select cable being routed around the first select pulley is further routed around the further select pulley to guide the vertically upper por ¬ tion of the select cable downwards to decrease the vertical distance between the vertically upper and vertically lower portions of the select cable.

In a preferred embodiment the mechanical linkage for select movements comprises a select pin extending from the shift lever at the level of its pivotal bearing in the housing and extending perpendicular to the shift lever and to the shift direction, the outer end of the select pin comprising a ball portion being received in a ball joint at the upper end of a select rod, the lower end of the select rod being coupled to one of the select pulleys to which the select cable is fixed, wherein this coupling comprises via a ball joint at a distance from the horizontal axis of rotation of the pulley so that movements of the shift lever in select direction are trans ¬ ferred via a pivotal movement of the select pin to displace ¬ ments of the select rod and further by the select rod to a ro ¬ tational movement of the one of the select pulleys. In a preferred embodiment the mechanical linkage for shift movements comprises a shift pin extending from the shift lever at the level of its pivotal bearing in the housing and extend ¬ ing perpendicular to the shift lever and to the select direc ¬ tion, the outer end of the shift pin comprising a ball portion which is received in a ball joint at an upper end of a shift rod. The lower end of the shift rod is rotatably connected to one of the shift pulleys to which the shift cable is fixed, wherein this connection is disposed at a distance of the re ¬ spective axis of rotation, such that shift movements of the shift lever are transferred via pivotal movements of the shift pin to the shift rod and thereby further to the one of the shift pulleys to transfer shift lever shift movements to cor ¬ responding rotational movements of the one of the shift pul ¬ leys .

In a preferred embodiment the shift pulley and the select pul ¬ ley are coaxially mounted on a horizontal shaft for rotation around this shaft. Likewise, the further shift pulley and the further select pulley are coaxially mounted on a further shaft for rotation around this further shaft, wherein the further shaft is displaced from the shaft in the direction of the shift cable portions and the select cable portions extending away from the shift pulley and the select pulley.

Preferably the shaft and the further shaft are disposed on a vertical level relative to each other such that the upper shift cable portion of the shift cable being routed around the shift pulley is deflected downwards by the further shift pul ¬ ley such that it extends from the further shift pulley at a lower vertical level than from the shift pulley, and such that the upper select cable portion extending away from the select pulley is deflected downwards by the further select pulley to a lower vertical level than the upper select cable portion ex ¬ tending from the select pulley. In such arrangement the select rod is preferable coupling the select pin to the select pulley at a distance from its axis of rotation, and the shift rod couples the shift pin to the fur ¬ ther shift pulley. In this case the select cable is fixed to the select pulley, and the shift cable is fixed to the further shift pulley so that rotations of the respective pulley are transferred to displacements of the respective cables.

In a pull-pull shifter system it is necessary to translate the longitudinal movements of the select and shift cables into a displacement of a shift shaft of the gearbox along its own longitudinal axis (select movement) and into a rotation of the shift shaft around its longitudinal axis (shift movement) to execute the change of gear desired by the operator. This is achieved by a so-called shift tower which is mounted to the gearbox and coupled to the shift and select cables on the one hand and to the shift shaft on the other hand. DE 195 44 837 Al discloses a shift tower for performing the above-described function. It includes a first lever which is at its center point pivotally coupled to the gearbox or another stationary structure. The select cables are connected to the opposite end portions of this first lever such that a pull actuation in one of the select cables results in the rotation of the first lever in a first direction, while a pull actuation in the other of the select cables results in a rotation in the oppo ¬ site direction. At the center portion the first lever carries a downwardly extending rod which has a ball formed on its lower end. The rod and the ball extend into a slot formed in a second lever which is mounted with its center portion to the shift shaft and which extends perpendicular to the first lever and to the shift shaft. The shift cables are connected to the opposite two ends of the second lever. In this manner a rota ¬ tion of the first lever effected by the select cables is transferred via the downwardly extending rod and the ball re- ceived in the second lever into a movement of the second lever and the shift shaft connected thereto in the longitudinal di ¬ rection of the shift shaft (select movement), whereas a rota ¬ tion of the second lever results in a corresponding rotation of the shift shaft around its longitudinal axis (shift move ¬ ment) . It is a disadvantage of this shift tower that it re ¬ quires a lot of space for accommodating the spaced apart and perpendicularly oriented levers.

A more advantageous arrangement for a shift tower would be:

A shift tower for pull-pull cable assemblies for effecting shift and select movements of a shift shaft of a gearbox of a vehicle, comprising transmission means capable of converting movements of the shift cable into rotational movements of the shift shaft around its longitudinal axis, and movements of the select cable into displacements of the shift shaft along its longitudinal axis, characterized in that the transmission means comprise: a shift pulley and a select pulley, the shift cable being routed around and fixed to the shift pulley, the select cable assembly routed around and fixed to the select pulley, the shift pulley and the select pulley being mounted in a housing adjacent to each other with their rotational axes parallel to each other, a carriage mounted in the housing to be moveable in a first direction parallel to the longitudinal direction of the shift shaft, and in a second direction perpendicular to the first direction, a shift lever with one of its ends being connected to the shift shaft and extending in a direction perpendicular to the longitudinal direction of the shift shaft, the other end of the shift lever being coupled to the carriage such that move ¬ ment of the carriage in the first direction cause select move ¬ ments of the shift shaft along its longitudinal axis, and that movement of the carriage in the second direction cause rota ¬ tional shift movements of the shift shaft around its longitu ¬ dinal axis, a coupler being connected on the one hand to the shift cable to follow movements of the shift cable in the second direc ¬ tion, and being engaged on the other hand with the carriage to cause movements of the carriage in the second direction in re ¬ sponse to shift cable movements in the second direction, and a linkage pivotally mounted in the housing and coupled with one of its ends to the select pulley at a distance from the rotational axis of the select pulley, and being coupled with its opposite end to the carriage such that rotational move ¬ ments of the select pulley are transferred via pivotal move ¬ ments of the linkage to movements of the carriage in the first direction which are transferred via the shift lever to shift shaft select movements along its longitudinal axis.

Such shift tower is preferably arranged such that the coupler comprises a coupling member fixed to the shift cable and at least one leg extending therefrom, which leg is received in an elongated slot extending in the carriage in the first direc ¬ tion so that movements of the coupler in the second direction are transferred by the leg of the coupler to the carriage, whereas the coupler permits movement of the carriage in the first direction by letting the leg slide along the elongated slot .

Such shift tower may further be arranged such that the linkage comprises pins at its opposite ends, one end pin being re ¬ ceived in an elongated slot in the select pulley spaced apart from its rotational axis, the other end pin being received in an elongated slot extending in the carriage in the second di ¬ rection so that the carriage, when the linkage with its end pin received in the carriage, pivots with an associated move ¬ ment in the first direction, follows such movement in the first direction.

Such shift tower is preferably arranged such that an inertia wheel is mounted within the housing with its rotational axis being oriented parallel to the rotational axis of the shift and select pulleys, the inertia wheel being coupled to the shift pulley such that rotation of the shift pulley results in rotation of the inertia wheel.

Such shift tower is preferably further arranged such that the inertia wheel comprises a gear wheel disposed coaxially on the inertia wheel and projecting form one side thereof, and in that the shift pulley comprises an inwardly facing gear wheel portion close to its outer circumference which is arranged to mash with the gear wheel of the inertia wheel.

Such shift tower is preferably further arranged such that the inertia wheel having the major part of its mass in a periph ¬ eral ring portion which is connected by spokes to the central hub of the wheel.

For a pull-pull shifter system a length adjuster for a cable assembly is preferably provided to take up any slack in the cable assembly. The cable assembly has a conduit and a cable slidably disposed therein. A length adjuster for such cable assembly is known from U.S. 6, 093, 892 Bl . This length adjuster has two components which are rotatable to each other, namely a housing part fixed in axial direction with respect to a conduit portion extending from one end of the housing part and having a cylindrical cavity at the opposite end. The second component is a cylindrical member to be received in the cylin ¬ drical cavity of the housing part. This cylindrical member is fixed in axial direction with respect to a conduit portion ex ¬ tending from an end of the cylindrical member opposite to the end received in the cylindrical cavity. The outer surface of the cylindrical member is provided with a series of steps of increasing depth (with respect to the end of the cylindrical member to be received in the housing part) . In the device de ¬ scribed in U.S. 6, 093, 892 Bl there are three such series of steps of increasing depth distributed around the circumference of the outer surface of the cylindrical member. The inner wall of the housing part is provided with three corresponding pro ¬ jections. In a given rotational state of the cylindrical mem ¬ ber with respect to the housing part each of the three projec ¬ tions rests on a given step of a corresponding depth in said series of steps. When the cylindrical member is rotated with respect to the housing part until each projection comes free from the current step the housing part is sliding further onto the cylindrical member until its projection come into abutment with the next deeper step in said series of steps. A spring is biasing the housing part and the cylindrical member for rota ¬ tion relative to each other such that the deepest step in said series of steps is reached which can be reached by taking up slack in the cable assembly. In this manner the length ad ¬ juster reduces its length when slack is present in the cable assembly to do so. A problem associated with this device is that the maximum area available for forming steps is re ¬ stricted by the outer circumference of the cylindrical member. If it is desired to provide an adjuster with a particular maximum stroke (difference between maximum effective length of the device and minimum effective length) one either has to re ¬ duce the number of steps (which reduces the capability of the device to makes fine adjustment steps) or one has to reduce the load bearing area, i.e. the area of each step. In other words the more steps are provided the less area the individual step has and the less load bearing area between projections and steps is available to absorb loads on the device. In view of this it would be desirable to have a length adjuster which allows for large number of steps while maintaining a large load bearing area between housing part and cylindrical member to absorb forces in the longitudinal direction. This is achieved by providing a cable length adjuster for use with the pull-pull shifter assembly according to the present invention:

An automatic length adjuster for a cable assembly having a conduit and a cable slidably disposed therein, comprising a housing part fixed in axial direction with respect to a conduit portion extending from one end of the housing part and having a cylindrical cavity at the opposite end, and a cylin ¬ drical member to be received in the cylindrical cavity and be ¬ ing fixed in axial direction with respect to a conduit portion extending from an end of the cylindrical member opposite to the end received in this cylindrical cavity, wherein the cy ¬ lindrical member is rotatably and slidably moveable in axial direction with respect to the housing part, wherein the cylindrical member and the housing part cooperate via a series of steps of increasing depth and projections formed respectively in their engaging surfaces, the projection being arranged to be in abutment with any of the steps to hold the cylindrical member and the housing apart at a distance in axial direction defined by the respective step, wherein the series of steps defines a series of increasing longitudinal extensions of the cooperating cylindrical member and housing part, and wherein a spring is biasing the cylindrical member and the housing part to rotate relative to each other to increase the longitudinal extension to compensate slack in the cable assembly, charac ¬ terized in that in the cavity of the housing part the series of steps are de ¬ fined by at least two coaxial, circumferentially extending winding stairs, each comprising a series of planar step surfaces, each pair of adjacent step surfaces being intercon ¬ nected by an inclined surface, and in that the end portion of the cylindrical member to be received in the cavity is pro ¬ vided with at least two complementary coaxial, circumferen- tially extending winding stairs defining complementary planar step surfaces and interconnecting inclined surfaces, such that the number of step surfaces and inclined surfaces of the coax ¬ ial, circumferentially extending winding stairs of the housing part being in abutment with step surfaces and inclined sur ¬ faces of the circumferentially extending winding stairs of the cylindrical member is at a maximum when the housing part and the cylindrical member have the state shortest longitudinal extension, and such that the number of the step and inclined surfaces of the coaxial, circumferentially extending winding stairs in abutment with step and inclined surfaces of the com ¬ plementary coaxial, circumferentially extending winding stairs is decreasing with increasing longitudinal extension of housing part and cylindrical member upon rotation of the housing part relative to the cylindrical member.

Due to the coaxial arrangement of winding stairs, one of the winding stairs being located radially inside of the other, the abutment area of the cylindrical member against the housing part is substantially increased compared to the prior art. In the state of minimal longitudinal extension of the device all winding stairs are in complete abutment against each other to provide a maximum abutment area between the components to ab ¬ sorb loads. The abutment area is slowly decreasing when the cylindrical member is rotated against the housing part to in ¬ crease the longitudinal extension of the combined structure of housing part and cylindrical member.

A preferred length adjuster of this kind is arranged such that each of the at least two coaxial, circumferentially extending winding stairs extends circumferentially along more than 270°, in particular up to 360°.

Such an automatic length adjuster is preferably further arranged such that there are three coaxial, circumferentially extending winding stairs in the cavity of the housing part, and free complementary coaxial, circumferentially extending winding stairs provided on the cylindrical member. In this manner the abutment area between housing part and cylindrical member is further increased by the first circumferentially ex ¬ tending winding stairs.

The invention will now be described in further detail with reference to embodiments shown in the drawings in which:

Fig. 1 shows a schematical side view of a pull-pull shifter assembly according to a first embodiment;

Fig. 2 shows a perspective schematical view of the pull-pull shifter assembly according to the first embodiment;

Fig. 3 shows an exploded view of components of the pull-pull shifter assembly according to the first embodiment;

Fig. 4 shows a perspective view of a pull-pull shifter assem ¬ bly according to a second embodiment;

Fig. 5 shows a perspective view of the pull-pull shifter as ¬ sembly according to the second embodiment;

Fig. 6 shows a perspective view of the pull-pull shifter as ¬ sembly according to the second embodiment;

Fig. 7 shows a perspective partial view of the pull-pull shifter assembly according to the second embodiment; Fig. 8 shows a perspective schematical view of a pull-pull shifter assembly according to a third embodiment;

Fig. 9 shows a perspective schematical view of the pull-pull shifter assembly according to the third embodiment;

Fig. 10 shows a perspective schematical view of the pull-pull shifter assembly according to the third embodiment;

Fig. 11 shows a perspective view of a shift tower to be used with a pull-pull shifter assembly;

Fig. 12 shows a side view of the shift tower of Fig. 11;

Fig. 13 shows a top view of the shift tower of Fig. 11; and

Fig. 14 shows a perspective view of the shift tower of Fig. 11.

Fig. 15 shows an exploded view of a cable length adjuster which can be used in connection with the present invention;

Fig. 16 shows a side view of the housing part and the cylin ¬ drical member of the cable length adjuster of Fig. 15;

Fig. 17 shows a cross-sectional view of the cable length ad ¬ juster of Fig. 15 and 16;

Fig. 18 shows a perspective view of the cable length adjuster of Figs. 15 to 17 in an assembled state; and

Fig. 19 shows perspective views of the housing part and the cylindrical member with their cooperating surface structures. A first embodiment of the pull-pull shifter assembly will now be described with reference to Figs. 1 to 3. The shifter as ¬ sembly comprises a shift lever 2 which extends generally in vertical direction and which is mounted in a pivotal bearing which allows to pivot the shift lever in shift direction (in the plane of Fig. 1) and in a select direction between shift gates in a direction perpendicular thereto. In general, the shift direction corresponds to the longitudinal and driving direction of a vehicle, and the select direction is perpen ¬ dicular to the longitudinal axis of the vehicle.

It should be noted that in Figs. 1 to 3 the pivotal bearing of the shift lever 2 in which a ball mounted on its lower end portion is received, is not shown in Figs. 1 and 2 and only partially shown in Fig. 3.

A shift pulley 4 and a select pulley 14 are coaxially mounted below the shift lever with their axis of rotation being oriented vertically. Around the shift pulley 4 a shift cable is routed which is received in a groove that is extending circum- ferentially around the shift pulley 4. The shift cable 6 is further fixed to the shift pulley 4 such that any rotational movement is translated to a corresponding longitudinal dis ¬ placement of the two cable portions extending from the shift pulley 4. In a corresponding manner a select cable 16 is routed around a select pulley 14 and is received in a groove formed in its circumference. The select cable 10 is likewise fixed to the select pulley 14 such that rotational movements of the select pulley 14 are translated into corresponding lon ¬ gitudinal displacements of the two cable portions of the se ¬ lect cable 16 extending from the select pulley 14.

The shift lever 2 is coupled by respective mechanical linkages to the shift pulley 4 and to the select pulley 14, respec- tively, which mechanical linkages will now be described with reference to Figs. 1 to 3.

The mechanical linkage for transferring the select movements comprises a select lever arm 9. The select lever arm 9 has a bore 9a for receiving a shaft (not shown) which is fixed with respect to the shifter assembly housing and around which the select lever arm 9 can rotate, wherein the axis of rotation is indicated by reference numeral 99.

The ball portion at the lower end of the shift lever 2 carries a select pin 8 extending therefrom and into an oblong aperture 9b of the select lever arm 9 in which the select pin can slide. The aperture 9b and the select pin 8 are spaced apart from the rotational axis 99 of the select lever arm 9. Select movements of the shift lever 2 to the right hand side or to the left hand side cause an upward or downward movement, re ¬ spectively, of the outer end of select pin 8. Since the select lever arm 9 is mounted to be rotational around axis 99 spaced apart from select pin 8 and oblong aperture 9b, moving select pin 8 upwards or downwards causes a rotation of select lever arm 9 around rotational axis 99. On the lower end of select lever arm 9 a select drive pin 10 is disposed which is re ¬ ceived in an oblong aperture 15 (Fig. 3) of select pulley 14. In this manner a select movement of shift lever 2 is trans ¬ ferred via an upwards or downward movement of select pin 8 into a rotation of select lever arm 9 around its axis of rota ¬ tion 99 which is accompanied by a pivotal movement of select drive pin 10 which pivotal movement includes a translational movement component which in turn causes a rotational movement of select pulley 14.

The mechanical linkage for shift movements is formed in a cor ¬ responding manner, as can be seen in Fig. 3. It is noted that the ball in the lower end portion of the shift lever 2 is re- ceived in a bearing, but only one of the bearing members being shown in Fig. 3 and none of the bearing components in Figs. 1 and 2. Shift movements of the shift lever 2 result in pivotal upward and downward movements of a shift pin 18. This shift pin 18 is received in an oblong aperture 19a of a shift lever arm 19. Spaced apart from oblong aperture 19b is a bore 19a for receiving a shaft (not shown) fixed in the housing. Around this shaft shift lever arm 19 is rotatable around rotational axis 199. Since shift pin 18 and oblong aperture 19b receiving shift pin 18 are displaced from the rotational axis 199 of shift lever arm 19 pivotal vertical upward and downward move ¬ ments of shift pin 18 are translated into rotational movements of shift lever arm 19 around rotational axis 199. Rotational movements of shift lever arm 19 are accompanied by pivotal movements of shift pulley drive pin 20 mounted at the lower end of shift lever arm 19. This shift pulley drive pin 20 is received in oblong aperture 5 of shift pulley 4 and can slide therein. Rotational movements of the shift lever arm 19 thus result in rotational movements of shift pulley 4 around its vertical axis of rotation.

In the embodiment shown in Figs. 1 to 3 select pulley 14 is disposed above shift pulley 4. In principle this relative po ¬ sitioning of shift and select pulley could also be reversed such that the shift pulley would be disposed on top of the se ¬ lect pulley.

In the embodiment of Fig. 1 to 3 the upper select pulley 14 is not circular but has a cut out segment. This shape of the se ¬ lect pulley 14 provides for better access to the shift pulley 4 positioned below the select pulley 14. The select lever arm 19 is disposed such that it extends through the area of the cut out segment of the select pulley to an oblong aperture 5 formed in a protrusion on the outer circumference of shift pulley 4. If the roles of shift pulley and select pulley were reversed, i.e. the shift pulley would be disposed on top of the select pulley as indicated above, then the cut out segment would be formed in the shift pulley disposed on top of the se ¬ lect pulley, and the protrusion with the oblong aperture 5 would be formed on the shift pulley.

A second embodiment of the pull-pull shifter assembly is now described with reference to Figs. 4 to 7. The mechanical link ¬ age for transferring select movements of the shift lever 2 are transferred via pivotal movements of select pin 8 to rota ¬ tional movement of the select lever arm 9 around its axis of rotation 99. This is accompanied by a pivotal movement of the select pulley drive pin 10 which is extending through an opening in shift pulley 4 and which is received in an oblong aperture in select pulley 14 and which drives select pulley 14 to rotate around its vertical axis of rotation. This corresponds to the mechanism of the select linkage of the first embodiment and will not be further described here.

As can be seen in Figs. 4 to 7 the opening in the shift pulley 4 through which the select pulley drive pin 10 extends is an oblong curved opening to allow shift pulley 4 to rotate while select lever arm 9 is at rest. Also, since the oblong curved aperture in the shift pulley 4 has a width that is larger than the diameter of the select pulley drive pin 10, select lever arm 9 may rotate around its axis of rotation 99 which is ac ¬ companied by a pivotal movement of the select pulley drive pin 10 while shift pulley 4 is at rest.

The mechanical linkage for transmitting shift movements of the shift lever 2 comprises a shift arm 30 which forms an exten ¬ sion of the shift lever 2 beyond its pivotal bearing in down ¬ ward direction. At its lower end this shift arm 30 carries a fork member 32 which defines an elongated cavity 34 between the two fork legs. In this elongated cavity 34 of the fork member 32 a shift pulley drive stud 36 (see Fig. 5) is re ¬ ceived which is mounted to the shift pulley 4 at a distance with respect to its axis of rotation. The elongated cavity 34 is disposed with its elongation perpendicular to the shift direction. Therefore, there is engagement between the elongated cavity 34 and the shift pulley drive stud 36 in shift direc ¬ tion. In this manner, shift movements of the shift lever 2 cause corresponding pivotal movements of the shift arm 30 which are transferred via the fork member 32 to the shift pul ¬ ley drive stud 36 which are thus transferred to corresponding rotational movements of the shift pulley 4. During this move ¬ ment shift pulley drive stud 36 is sliding in the elongated cavity in the direction its elongated. The shift movements of the fork member 32 are indicated in Fig. 5 by the double ar ¬ row .

A third embodiment of the pull-pull shifter assembly will now be described with reference to Figs. 8 to 10. Please note that in the Figures of this as of the previous embodiment the outer surface of the housing of the bearing for the ball of the shift lever 2 is shown through which the drive and select pins are extending to the outside.

In this embodiment the shift pulley 104 and the select pulley 114 are mounted for rotation around a horizontal axis. In this embodiment the shift pulley 104 is accompanied by a further shift pulley 105 which serves to deflect the upper portion of the shift cable 6 vertically downward so that the vertical distance between the upper and lower shift cable portions is reduced. In a corresponding manner select pulley 114 is accompanied by a further select pulley 115.

The mechanical linkage coupling the shift lever 2 to the se ¬ lect pulley 114 comprises a select pin 108 extending from the shift lever at the lever of its pivotal bearing and extending perpendicular to the shift lever 2 and to the shift direction. The outer end of the select pin 108 comprises a ball portion received in a ball joint 110 at the upper end of a select rod 109. The lower end of the select rod 109 is coupled to the se ¬ lect pulley 114 via a ball joint 111 which is located at a distance to the horizontal axis of rotation of the select pul ¬ ley. In this manner select movements of the shift lever 2 are transferred via a pivotal movement of the select pin 108 to a displacement of select rod 109 which in turn causes a rota ¬ tional movement of the select pulley 114.

The mechanical linkage coupling the shift lever 2 to the shift pulley 104 comprises a shift pin 118 which extends from the shift lever 2 at the level of its pivotal bearing and which extends perpendicular to the shift lever 2 and to the select direction. The outer end of the shift pin 118 comprises a ball portion which is received in a ball joint 120 at an upper end of a shift rod 119. The lower end of the shift rod 119 is ro- tatably connected to the further shift pulley 105 at a dis ¬ tance of its horizontal axis of rotation. In this manner shift movements of the shift lever 2 are transferred via pivotal movements of the shift pin 118 to the shift rod 119 which is in turn displaced vertically so that its lower end rotatably coupled to the shift pulley 105 causes a rotational movement of shift pulley 105. Shift pulley 105 is also connected to shift cable 6. This connection of the cables to the pulleys is indicated in the drawings by pins through which the respective cables extend and which are fixed to the cables. These pins are illustrated in the Figs, as being received in complemen ¬ tary grooves in the outer circumference of the pulleys so that any rotational movement of a pulley is translated into a cor ¬ responding displacement of the respective cable.

In Figs. 8 to 10 the shift cable 6 is shown to be fixed to both shift pulleys 104, 105, and select cable 16 is shown to be fixed to both select pulleys 114, 115 by respective pins. In principle it is sufficient if the respective cable is fixed to the one of the two pulleys which is coupled by its mechani ¬ cal linkage to the shift lever so that shift lever movements which are translated into pulley rotations are safely trans ¬ mitted to the respective cable.

In principle the shift rod 119 could also be coupled to the first shift pulley 104.

In the following an embodiment of a shifter tower is described with reference to Figs. 11 to 14, which shift tower can be used in connection with the pull-pull shifter assembly of the invention. Such shift tower is used to translate the longitu ¬ dinal movements of the select and shift cables into a dis ¬ placement of a shift shaft of the gearbox along its longitudi ¬ nal axis (select movement) and into a rotation of the shift shaft around its longitudinal axis (shift movement) .

The shift tower shown in Figs. 11 to 14 has a housing 300 (see Fig. 11) in which a shift pulley 304 and a select pulley 314 are mounted for rotation around horizontal axis of rotation. A shift cable 6 is routed around shift pulley 304 and fixed by pins received in complementary grooves in the circumference of the shift wheel 304 such that any displacement of the shift cable 306 results in a corresponding rotational movement of shift pulley 304. Select cable 16 is in a corresponding manner routed around select pulley 314 and connected thereto such that any movement of the select cable 316 in longitudinal di ¬ rection results in a corresponding rotational movement of se ¬ lect pulley 314.

A carriage 330 is mounted in the housing to be moveable in a first direction parallel to the longitudinal direction of the shift shaft (the first direction is the vertical direction in Figs. 11, 12 and 14) and in a second direction. The second di ¬ rection is perpendicular to the first direction and is oriented horizontal in Figs. 11, 12 and 14.

The carriage 330 is coupled by a shift lever 301 (Figs. 12 and 13) to a shift shaft 302 (Figs. 12 and 13) . A movement of the carriage 330 in the first direction (parallel to the longitu ¬ dinal direction of shift shaft 302) is transferred by shift lever 301 to a select movement of the shift shaft 302 in di ¬ rection of its longitudinal axis. A horizontal movement of the carriage 330 in the second direction causes a turning movement of shift lever 301 around the axis of rotation of shift shaft 302, and thus causes a shift movement of the shift shaft. For this purpose shift lever 301 has to be coupled to the carriage 330 such that it allows a rotational movement of the shift arm 301 at the connection point to the carriage 330.

In order to transfer rotational movements of the select pulley to movements of the carriage 330 in the first direction (ver ¬ tical in Figs. 11, 12 and 14) there is a linkage 350 pivotably mounted in the housing (see Fig. 12) . This linkage is coupled with one of its ends to the select pulley 314 at a point spaced apart from the rotational axis of the select pulley 314. The opposite end of the linkage 350 carries a pin that is received in an elongated slot 334 extending in the second di ¬ rection. Please note that this slot 334 is not throughgoing and therefore visible in the view of Fig. 12, but not visible in the view of Fig. 14. When linkage 350 performs a pivotal movement around its central bearing in response to rotational movement of select pulley 314 the opposite end of the linkage 350 received in slot 334 performs a movement in the first, vertical direction accompanied by a movement in horizontal di ¬ rection which causes a sliding of the pin at the end of the linkage 350 received in the slot 334. The vertical component of the pivotal movement of the linkage 350 is thus translated into a vertical movement of carriage 330 in the first direc ¬ tion. This movement of the carriage in the first (vertical in Figs. 11, 12 and 14) direction is transferred via shift arm 301 to a select movement of shift shaft 302 in the direction of its longitudinal axis.

In order to transfer shift movements of the shift cable 306 to movements of carriage 330 in the second direction (horizontal in Figs. 11, 12 and 14) there is a coupler 340 fixed on shift cable 306 such it follows shift movements of the shift cable 306. Coupler 340 is engaged with carriage 330 in such a manner that movements of the coupler 340 in the second direction are transferred and thus translated into corresponding movements of the carriage 330, whereas carriage 330 is freely moveable in the first, vertical direction with respect to coupler 340. Such engagement may for example be achieved by providing the coupler 340 with two legs extending towards the carriage 330, each of the legs being received in one of two longitudinal slots 332 formed in carriage 330. These legs thus transfer movements of the coupler 340 in the second direction to corre ¬ sponding movements of the carriage 330 in the second direc ¬ tion, wherein the engagement of the legs in the elongated slots 332 of the carriage 330 permit the carriage to move in the first (vertical) direction independently of the coupler 340.

In order to provide a more realistic feeling in the pull-pull shifter assembly when carrying out a shift command with the shift lever 2 the shift tower is provided with an inertia wheel 360 mounted in the housing 300 with its rotational axis being oriented parallel to the rotational axis of the shift and select pulleys 304, 314. The inertia wheel 360 is coupled to shift pulley 304 such that rotation of the shift pulley 304 is transmitted into a rotation of the inertia wheel 360. This coupling is achieved in this embodiment by a gear wheel 362 disposed coaxially on the inertia wheel 360 and projecting from the side thereof facing the shift pulley 304. The shift pulley 304 comprises an inwardly facing gear wheel portion 305 (see Fig. 14) close to its outer circumference which is ar ¬ ranged to mash with the gear wheel 362 of the inertia wheel 360 such that a rotational movement of shift pulley 304 is transmitted into rotational movement of inertia wheel 360. The gear transmission ratio of numbers of rotations of inertia wheel 360 to numbers of rotations of shift pulley 304 is lar ¬ ger than 1.

The inertia wheel has the major part of its mass in a periph ¬ eral ring portion which is connected by spokes to the central hub of the wheel.

The effect achieved by the inertia wheel is a smoother engage ¬ ment in disengagement of the gears. Due to the presence of the inertia wheel the force to be exerted by the driver on the shift lever is increased during the first movement phase of the shift lever. In this movement phase the increased force is stored by the inertia wheel by its increasing kinetic energy. This kinetic energy of the inertia wheel is then utilized in the last movement phase of the shift lever when the actual shifting with the meshing of the gear teeth occurs. The increased force at the end of the shifting process when meshing the gears is then partially taken from the inertia wheel so that the driver does not feel a substantial force increase needed at the end of the shifting movement. In other words, force peaks caused by the actual shifting in the gearbox are removed, and the shifting movement to be achieved by the driver by shifting the shift lever is smoother.

A cable length adjuster which can be used for the cable assemblies in connection with a present invention will now be described with reference to Figs. 15 to 19. The cable length ad- juster comprises two engaging main components, namely a hous ¬ ing part 60 and a cylindrical member 70. The housing part 60 is axially fixed with respect to a conduit portion 50 of the cable assembly, and the cylindrical member 70 is axially fixed with respect to a conduit portion 50' of the cable assembly extending therefrom. In the conduit portions 50, 50' a cable 52 is slidably disposed.

The housing part 60 has a cylindrical cavity (see Fig. 15) adapted to receive an end portion of cylindrical member 70. The cavity 62 is provided with the following step structures. There are three coaxial winding stairs or helical stairs 64, 66, 68 (see Fig. 19), each winding stairs comprising a sequence of planar step surfaces and intermediate inclined sur ¬ faces with an inclined surface between each adjacent two pla ¬ nar step surfaces. In Fig. 19 the reference numerals 64, 66 and 68 point to the uppermost step surface of each of the winding stairs. The opposite end portion of the cylindrical member 70 is provided with three coaxial, circumferentially extending winding stairs 74, 76 and 78, each winding stairs comprising a sequence of planar step surfaces and an interme ¬ diate inclined surface inbetween adjacent two planar step sur ¬ faces. Again, the reference numerals 74, 76, and 78 point in each case to the uppermost step surface of each of the circum- ferentially extending winding stairs. The size of the planar step surfaces is the same for all winding stairs. Likewise, the size and angle of inclination are the same for all in ¬ clined surfaces of the winding stairs.

When cylindrical member 70 is inserted into the cavity 62 of housing part 60 there are three pairs of cooperating circum- ferentially extending winding stairs, namely the outer pair of circumferentially extending winding stairs 64, 74, the intermediate winding stairs 66, 68 and the radially inner circum- ferentially winding stairs 68, 78. Each pair of cooperating winding stairs cooperates in such a manner that a number of planar step surfaces and of intermediate inclined surfaces come into abutment with each other. The arrangement is such that when all step and inclined surfaces of each pair of coop ¬ erating winding stairs are in abutment with the complementary step and inclined surfaces of the cooperating winding stairs, the cylindrical member is inserted into the cavity 62 of the housing part 60 as deep as possible; in other words in this state the assembly of housing part 60 and cylindrical member 70 has its shortest axial extension.

From this state of shortest axial extension the circumferen- tially extending winding stairs can now "climb up" their cooperating complementary winding stairs from step surface to step surface which is accompanied by a relative rotation between the housing part 60 and the cylindrical member 70. When rotat ¬ ing in this manner the axial extension of the assembly of the housing part 60 and the cylindrical member 70 increases step by step, wherein the step size of axial length extension corresponds to the axial distance between two adjacent planar step surfaces.

In the state of the lowest axial extension of the cable length adjuster all step surfaces of each pair of cooperating circumferential winding stairs are in abutment against corresponding step surfaces which corresponds to a maximal contact area be ¬ tween the housing part and the cylindrical member to absorb loads in axial direction. The further the housing part and the cylindrical member are rotated relative to each other, and the further each pair of cooperating circumferential winding stairs is climbing up with respect to each other the lower is the number of step surfaces in abutment with each other; in the extreme case of maximal axial extension of the cable ad ¬ juster only the uppermost step surface of each circumferential winding stairs is in abutment with the uppermost step surface of the cooperating circumferential winding stairs.

As can be seen in Fig. 15 and 18 a helical spring 80 is acting between the housing part 60 and the cylindrical member 70. This spring exerts a bias force or rather a bias torque that is trying to turn housing part 60 and cylindrical member 70 relative to each other. This bias torque is directed such that the cable length adjuster assumes the maximal axial extension state available. In other words the pairs of cooperating circumferential pairs 64 - 74, 66 - 76, and 68 - 78 are climb ¬ ing upwards relative to each other by this rotational bias un ¬ til any slack or free play in the conduits 50, 50' is absorbed by the increased axial extension of the cable length adjuster.

By disposing two or more, in the present embodiment three, circumferential winding stairs coaxially nested, i.e. having an radial direction inner winding stairs, intermediate winding stairs and outer winding stairs to cooperate with complemen ¬ tary coaxial winding stairs, the number of steps surfaces in abutment to each other is high since three pairs of cooperat ¬ ing circumferential winding stairs contribute to the total abutment area between the housing part and the cylindrical member which provides for a large surface area in abutment with each other to absorb axial loads acting between the hous ¬ ing part 60 and the cylindrical member 70. On the other hand by using two or more coopering pairs of circumferential wind ¬ ing stairs the step size can be rather low, i.e. axial adjust ¬ ments can be performed in fine axial steps.