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Title:
PIVOTING AXLE LIFTING SYSTEM
Document Type and Number:
WIPO Patent Application WO/2016/101046
Kind Code:
A1
Abstract:
An axle lifting system for use with the truck, and a method of using the system, may include a displacement mechanism that can be attached to the chassis of a truck so that a free end is positionable relative to a fixed end. The system may also include a lever arm having a proximal end pivotably attached the free end of the displacement mechanism and a distal end attachable to an axle to be lifted. A shackle is configured to depend from the chassis and has a pivot connection with the lever arm at a position between the ends of the lever arm. Expansion of the displacement mechanism causes the free end of the displacement mechanism to move the proximal end of the lever arm, which causes the distal end of the lever arm to push up on an axle of the truck to lift the axle from contact with the ground.

Inventors:
PRESEZNIAK FLAVIO AUGUSTO (BR)
ANDRUSCZEWICZ LUIS WOLSKI (JP)
Application Number:
PCT/BR2014/000457
Publication Date:
June 30, 2016
Filing Date:
December 26, 2014
Export Citation:
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Assignee:
VOLVO DO BRASIL VEÍCULOS LTDA (BR)
International Classes:
B62D61/12
Foreign References:
US5090495A1992-02-25
US20070222169A12007-09-27
US5403031A1995-04-04
US4634141A1987-01-06
US7434821B22008-10-14
Attorney, Agent or Firm:
ASPEBY, Magnus (Centro, -906 Rio de Janeiro - RJ, BR)
Download PDF:
Claims:
CLAIMS

1. An axle lifting system comprising:

a displacement mechanism comprising a first end and a second end, wherein the first end is configured to be attached to the chassis of a truck and the second end is selectively positionable relative to the first end;

a lever arm having a proximal end and a distal end, the proximal end pivotably

attached relative to the second end of the displacement mechanism, the distal end configured to be engaged with an axle of the truck; and

a shackle having a first pivot between the shackle and the lever arm, the first pivot at a position between the proximal end and the distal end, and a second pivot, the second pivot configured to allow the shackle to pivot relative to the chassis of the truck,

wherein expansion of the displacement mechanism is configured to cause the distal end of the lever arm to push up on an axle of the truck to lift the axle from contact with the ground.

2. The axle lifting system according to claim 1, wherein the displacement mechanism comprises an axis along which the second end translates, wherein the displacement mechanism is configured to be attached to the chassis with the axis vertically oriented.

3. The axle lifting system according to 1, further comprising a first joint member, the first joint member providing a pivotable connection between the proximal end of the lever arm and the second end of the displacement mechanism.

4. The axle lifting system according to claim 3, comprising a second joint member, the second joint member configured to provide a pivotable connection between the distal end of the lever arm and the axle.

5. A method of lifting an axle of a truck, the method comprising the steps of:

providing a displacement mechanism comprising a first end and a second end, wherein the first end is configured to be attached to the chassis of a truck and the second end is selectively positionable relative to the first end; a lever arm having a proximal end and a distal end, the proximal end pivotably attached relative to the second end of the displacement mechanism; and a shackle configured to be pivotably mounted to the chassis of the truck and being pivotably connected to the lever arm at a position between the proximal end and the distal end; and

expanding the distance between the first end and the second end of the displacement mechanism, wherein expansion causes the proximal end of the lever arm to move in a first direction which causes the distal end of the lever arm to move in a second direction to lift an axle of the truck from wheel contact with the ground,

6. The method according to claim 5, wherein the displacement mechanism comprises an axis along which the second end translates, wherein the displacement mechanism is configured to be attached to the chassis with the axis vertically oriented.

7. A truck comprising:

a chassis having a pair of longitudinal frame rails; at least three axles supported below the chassis, the at least three axles including a front axle, an intermediate axle and a trailing axle, wherein each axle supports at least one wheel on each end thereof; and

an axle lifting system, the axle lifting system comprising:

a displacement mechanism having at least a contracted state and an expanded state, comprising a first end and a second end, wherein the first end is attached to the chassis of the truck and wherein the second end is selectively positionable relative to the first end according to the state of the displacement mechanism; a lever arm having a proximal end and a distal end, the proximal end pivotably

attached to the second end of the displacement mechanism and the distal end attached to one of the intermediate axle and the trailing axle; and

a shackle pivotably mounted to the chassis and pivotably connected to the lever arm at a position between the proximal end and the distal end;

wherein the expanded state of the displacement mechanism causes the second distal end of the lever arm to push upwardly upon the axle of the truck to lift the axle from contact with the ground.

8. The truck according to claim 7, wherein the lever arm is connected to the trailing axle.

9. The truck according to claim 7, wherein the lever arm is connected to the intermediate axle.

10. The truck according to claim 7, wherein the displacement mechanism has an axis along which the second end translates, wherein the displacement mechanism is attached to the chassis with the longitudinal axis vertically oriented.

11. The truck according to claim 7, comprising a first pivot joint member providing a pivotable connection between the proximal end of the lever arm and the second end of the displacement mechanism.

12. The truck according to 11, comprising a second pivot joint member providing a pivotable connection between the distal end of the lever arm and one of the intermediate axle and trailing axle.

Description:
PIVOTING AXLE LIFTING SYSTEM

FIELD OF INVENTION

[0001] This disclosure relates to axle lifting systems for a multi-axle commercial truck or trailer.

BACKGROUND

[0002] Driving characteristics of heavy trucks vary substantially depending upon the weight of the load. Trucks with a full load benefit from high spring rate suspensions and the support of three or more axles to help distribute and balance the weight of the cargo, improving the traction and handling of the truck. These advantages can become disadvantages when a truck is driven empty. When the truck is empty, the down force on each wheel is relatively lower, reducing traction. The reduction in down force, coupled with a suspension spring rate tuned for heavy loads, is believed to causes uneven and premature wear of the tires.

[0003] The search for handling improvements for empty trucks and for cost savings by reducing the rate of tire wear has resulted in trucks equipped with at least one axle that can be selectively raised from contact with the road. Raised wheels are no longer subject to friction wear, which improves tire life. Also, the relative down-force on the wheels remaining in ground contact increases, enhancing traction.

[0004] There remains a need for improved axle lifting systems.

SUMMARY

[0005] The present disclosure is directed to an axle lifting system. The axle lifting system may have a displacement mechanism that acts on a lever arm to lift or lower an axle. A first, fixed end of the displacement mechanism is configured to be attached to the chassis of a truck and a second, movable end is selectively positionable relative to the first end. The system may include a lever arm having a proximal end pivotably attached to the second end of the displacement mechanism and a distal end configured to be pivotably attached to an axle of the truck. The system may further include a shackle pivotably attached to the lever arm at a position between the proximal end and the distal end, providing a fulcrum for the lever arm.

The shackle is mountable on a chassis or frame of the truck at a second pivot, the second pivot configured to allow the shackle to pivot or swing relative to the chassis of the truck.

Expansion of the displacement mechanism acts on the lever arm to cause the second distal end of the lever arm to push up on an axle of the truck to lift the axle from contact with the ground.

[0006] Embodiments of the axle lifting system may also include the displacement mechanism having an axis along which the second end translates, wherein the displacement mechanism is configured to be attached to the chassis with the axis oriented vertical or perpendicular to a longitudinal axis of the chassis.

[0007] The present disclosure includes a method of lifting an axle of a truck. The method includes the step of providing an axle lifting system having a displacement mechanism comprising a first end and a second end, wherein the first end is configured to be attached to the chassis of a truck and the second end is selectively positionable relative to the first end. The system may also include a lever arm having a proximal end and a distal end, the proximal end pivotably attached to the second end of the displacement mechanism, the distal end being pivotably attached to an axle to be lifted. The system also includes a shackle pivotably attached to the lever arm at a position between the proximal end and the distal end, the shackle being mountable at a second pivot to the chassis of the truck. The method may further include the step of increasing the distance between the first end and the second end of the displacement mechanism such that the proximal end of the lever arm is moved in a first direction, causing the distal end of the lever arm to move in a second direction to push on an axle of the truck to lift the axle from contact with the ground.

[0008] Embodiments of the method may have the displacement mechanism comprising an axis along which the second end translates, wherein the displacement mechanism is configured to be attached to the chassis with the axis vertically oriented.

[0009] The present disclosure also includes a truck. The truck may have a chassis comprising a pair of longitudinal frame rails. The truck may have at least three axles supported below the chassis, the at least three axles including at least a front axle, an intermediate axle, and a trailing axle, wherein each axle supports at least one wheel on each end thereof. The truck may also include an axle lifting system. The axle lifting system can have a displacement mechanism comprising a first end and a second end, wherein the first end is configured to be attached to the chassis of the truck and the second end is selectively positionable relative to the first end. The system may also include a lever arm having a first, proximal end and a second, distal end, the proximal end being pivotably attached relative to the second end of the - displacement mechanism. The system can include a shackle being attached to the lever arm at a first pivot, the first pivot at a position on the lever arm between the proximal end and the distal end, the shackle being mounted to the chassis at a second pivot, the second pivot configured to allow the shackle to swing relative to the chassis of the truck. Expansion of the displacement mechanism acts on the proximal end of the lever arm to cause the distal end of the lever arm to push upwardly upon an axle of the truck to lift the axle from contact with the ground.

[0010] In some embodiments of the truck the lifted axle is the trailing axle. In some other embodiments, the lifted axle is the intermediate axle. In further embodiments, the lifted axle is a driven axle. The displacement mechanism may comprise an operational axis along which the second end translates, wherein the displacement mechanism is configured to be attached to the chassis with the operational axis vertically oriented.

[0011] These and other aspects of the present invention will become apparent to those skilled in the art after a reading of the following description of the illustrative embodiments, read in conjunction with the drawings. It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention as claimed.

BRIEF DISCRETION OF THE DRAWINGS

[0012] Fig. 1 shows a truck with one set of rear wheels in a raised position in accordance with the system of the present disclosure.

[0013] Fig. 2 shows a top perspective view of a lift system of the present disclosure.

[0014] Fig. 3 shows a side view of the lift system of Fig. 2 in an axle lowered position.

[0015] Fig. 4 shows the lift system of Fig. 3 in an axle raised position.

DETAILED DESCRIPTION

[0016] Exemplary embodiments of this disclosure are described below and illustrated in the accompanying figures, in which like numerals refer to like parts throughout the several views. The embodiments described provide examples and should not be interpreted as limiting the scope of the invention. Other embodiments, and modifications and improvements of the described embodiments, will occur to those skilled in the art and all such other embodiments, modifications and improvements are within the scope of the present invention. Features from one embodiment or aspect may be combined with features from any other embodiment or aspect in any appropriate combination. For example, any individual or collective features of method aspects or embodiments may be applied to apparatus, product or component aspects or embodiments and vice versa.

[0017] Fig. 1 shows one embodiment of a truck 1 equipped with an axle lifting system 100 of the present disclosure. The truck 1 includes at least three axles: a front axle 10, an

intermediate axle 20, and a trailing axle 30. The trailing axle 30 is illustrated in a first, raised position. In some embodiments, the axle lifting system 100 can be applied to lift the intermediate axle 20 instead. In some embodiments it would be possible to include an axle lifting system 100 on each of the intermediate axle 20 and the trailing axle 30, providing the truck 1 with the ability to selectively raise either of the intermediate axle 20 or the trailing axle 30. At least one of the intermediate axle 20 and the trailing axle 30 is a driven axle. When the lifted axle is a driven axle, a clutch can be provided, as known in the art, to disengage the driven axle from its drive shaft when in the raised position.

[0018] Fig. 2 illustrates a top perspective view of the axle lifting system 100 in connection with a driven trailing axle 30. Fig. 3 illustrates the axle lifting system 100 and axle 30 of Fig. 2 in the lowered position and Fig. 4 illustrates the axle lifting system and axle in the raised position. In the lowered position of Fig. 3, the axle lifting system 100 is configured to position the wheels of the trailing axle 30 in substantially continuous contact with the road, ground or other support surface. In the lowered position, it is possible for the wheels to leave contact with the ground occasionally due to suspension movement over significant bumps or dips. In the raised position shown in Fig. 4, the axle lifting system 100 is configured to position the wheels of the trailing axle 30 out of contact with the road, ground or other support surface.

[0019] The axle lifting system 100 includes a displacement mechanism 110, for example, an air spring having an inflatable bellows as illustrated in Figures 3 and 4. The displacement mechanism can also take the form of various other motion cylinders capable of selectively expanding or contracting in length. Alternative examples of displacement mechanisms include pneumatic pistons, hydraulic fluid based actuators or linear motors. The displacement mechanism 110 has a first end 114, such as a top plate of an air bellows, and a second end 118, such as the bottom plate of an air bellows. The second end 118 of the displacement mechanism is selectively positionable relative to the first end. According to the illustrated embodiment, the second end is positionable by inflating (expanding) and deflating

(contracting) the air spring bellows.

[0020] An air spring, for example having a bellows or a piston/cylinder arrangement, requires communication with a source of compressed air through at least one valve. When the air spring is inflated with air, the distance between the top plate and the bottom plate increases. When air is vented from the inflatable air spring, the distance between the top plate and the bottom plate decreases. The spring can be inflated by any known means, mechanical or otherwise, in response to a generated signal, for example the press of a button in the cabin of the truck 1.

[0021] In one embodiment, the first end 114 of the displacement mechanism 110 is attached to a chassis 7 of the truck 1. As shown in Figure 2, the first end 114 may be attached to the chassis 7 by brackets 2 mounted to the longitudinal frame rails 5. The first end 114 may be fixedly attached to the chassis 7 or may be attached so that the first end 114 is capable of pivotal movement relative to the chassis. Most chassis have two longitudinal rails 5, and the displacement mechanism 110 may be attached to either one or both of the longitudinal rails 5. The displacement mechanism 110 may be attached to additional or pre-existing cross members or other structural members of the chassis of truck 1. The first end 114 may be attached to the chassis 7 by fasteners such as bolts, screws, or rivets. Alternatively, attachment may be provided by welding, in addition to or in place of fasteners.

[0022] In one embodiment, the displacement mechanism 110 is positioned vertically below a plane defined by the pair of longitudinal rails 5. The displacement mechanism 110 is configured to expand and contract along an expansion axis 122 of the displacement mechanism 110. The expansion axis 122 may be vertically oriented, which is defined here as perpendicular to a frame rail 5 longitudinal direction within reasonable manufacturing and assembly tolerances. The expansion axis 122 may also be mounted at alternative, slight non- vertical angles, about 20 degrees or less, off the vertical orientation. In some embodiments, the expansion axis 122 will have an angle that varies with respect to the longitudinal axis as the displacement mechanism 110 expands and contracts by providing an additional degree of freedom, such as a rotational joint, between the chassis mounting structure and the top 114 of the displacement mechanism 110. Translation of the second end 118 along a vertically oriented expansion axis 122 can provide packaging benefits if the displacement mechanism 110 is able to sufficiently handle any resulting offset between the top 114 and the bottom 118 thereof throughout the operating expansion length of the displacement mechanism 110. For example, when using a bellows type air spring, a relatively large diameter bellows is advantageous to meet the load demands of the axle lifting system 100. For example, a suitable air bellows may be upwards of 60 cm or more in diameter. These large diameter bellows would be more likely to interfere with other components if the displacement mechanism 110 were positioned non-vertically.

[0023] The second end 118 of the displacement mechanism 110 is configured for selective positioning relative to the first end 114, which is fixed to the chassis 7. The second end 118 includes at least one first joint member 126. The at least one first joint member 126 provides a relative pivotable connection between the second end 118 and a proximal end 134 of a respective lever arm 130. Additional joints may be added between the second end 118 and the lever arm 130 to provide at least one additional degree of freedom if required based on the orientation and restraints of the displacement mechanism 110. For example, the lever arm 130 may be considered as pivoting around a fixed point. As such, the proximal end 134 is displaced both vertically and horizontally as the lever arm 130 pivots. The additional degree of freedom may allow the second end 118 of the displacement mechanism 110 to be displaced along a horizontal direction.

[0024] As seen in Fig. 2, the illustrated embodiment of the axle lifting system 100 includes a single displacement mechanism 110 attached between a pair of lever arms 130, each lever arm associated with one of the longitudinal rails 5, and each associated with a position near the ends of the trailing axle 30. In alternative embodiments, the axle lifting system 100 may comprise a separate displacement mechanism 110 respectively associated with each lever arm 130. In these alternative embodiments, an axle lifting system 100 may be employed on each side of the truck 1.

[0025] Each lever arm 130 includes a proximal end 134 and a distal end 138. As described above, the proximal end 134 is pivotably attached to the second end 118 of the displacement mechanism 110 at a first joint member 126, which is attached to the second end 118 of displacement mechanism 110. The distal end 138 is pivotably attached to a liftable axle by way of a respective second joint member 142. The second joint member 142 is mounted on the trailing axle 30. The pivotable connection between each lever arm 130 and the respective first and second joint members 126, 142 may be provided by pins, ball joints or any other known connectors that allow the lever arm 130 to pivot about an axis substantially parallel to the axle to be lifted.

[0026] Each lever arm 130 is further supported by a shackle 150 which hangs from the chassis 7 on a bracket 32. The shackle 150 is attached to the lever arm 130 at a position between the proximal and distal ends 134, 138. As used herein, the term shackle refers to a swinging or pivoting member that controls the movement of another element within the system. The shackle 150 provides a fulcrum for the lever arm 130, allowing the displacement mechanism 100 to apply a force through the lever arm.

[0027] The shackle also allows some translation of the lever arm 130. The shackle 150 has a first pivot 154 to allow the shackle 150 to swing relative to the chassis 7, and a second pivot 146 to allow the shackle 150 to pivot relative to the lever arm. In the embodiment shown in Figs. 2-4, the second pivot 146 supports the lever arm 130 at a position about at the midpoint of the lever arm 130. Alternatively, the second pivot 146 may be positioned closer to the proximal end 134 or closer to the distal end 138, depending on the relative desired travel of, and forces on, the proximal end 134 and distal end 138 within the scope of this disclosure.

[0028] The shackle 150 is hung directly or indirectly from the chassis of truck 1. As shown in the embodiments of Figs. 2-4, the shackle 150 may be hung indirectly from a longitudinal rail 5 by using a second frame bracket 32.

[0029] By comparing Fig. 3, showing the lowered position of trailing axle 30, with Fig. 4, showing the raised position of trailing axle 30, the function of the axle lifting system 100 is shown. In the axle lowered position, referring now to Fig. 3, the displacement mechanism 110 is shown in a relatively contracted state. In the lowered position, the weight of the trailing axle 30 (including wheels, suspension and optional drive differential) will force down the distal end 138 of lever arm 130, causing a lifting of the proximal end 134 of the lever arm, thereby pushing the second end 118 of the displacement mechanism toward the first end 114. With the displacement mechanism 110 contracted (e.g., an air bellows deflated), the displacement mechanism 110 will provide minimal resistance in opposition to the load- carrying force applied by the trailing axle 30.

[0030] Where an air spring with a bellows is used, it will be understood by one skilled in the art that "deflated" is not meant to indicate complete evacuation of the bellows, but is meant to indicate the air pressure in the bellows is insufficient to lift the axle to a position in which the wheels are not in ground contact. Even in the relatively deflated state, positive pressure may remain in the air bellows. This relatively minimal positive pressure may assist the truck suspension system by providing a damping force to oppose changes in the distance between the trailing axle 30 and the truck chassis. The minimal positive pressure may also help prevent damage to the air bellows itself.

[0031] Lifting the trailing axle 30 from the lowered position to the raised position involves expanding of displacement mechanism 110, that is, selectively positioning the second end 118 of the displacement device relatively farther from the first end 114. In one embodiment, this process can be triggered by the truck operator using, for example, an actuator or button within or about the cabin. In the embodiment illustrated, activation of the axle lifting system 100 will inflate the air bellows using air from a source of compressed air. As the pressure within the inflatable air bellows increases, the distance between the first end 114 and the second end 118 increases. According to the embodiment shown in Figs. 3 and 4, the result of increasing the distance between the first end 114 and the second end 118 is a downward movement of the proximal end 134 of lever arm 130. As the proximal end 134 is pressed down, the lever arm 130 will pivot about second pivot 146 and force the distal end 138 to move upward. The distal end 138, in connection with second joint member 142, will push the trailing axle 30 upward into the raised position. To maintain the trailing axle 30 in the raised position, the position of the second end 118 will be substantially held constant by the air spring, providing a steady downward force on the proximal end 134 of the lever arm 130, resulting in a steady upward force on the trailing axle 30. Selection of the displacement mechanism 110 may affect the ability to maintain a constant position of the second end 118.

For example, a pressurized air bellows may allow more bounce than an actuator with a rigid piston.

[0032] Any number of known indicators may be used to determine when the axle lifting system 100 has reached a raised position. These include position sensors associated with the displacement mechanism 110, monitoring the distance between the first and second ends 114, 118 of the displacement mechanism 110 or associated with the trailing axle 30, measuring the position of the trailing axle 30 relative to the chassis 7. Where an air bellows is used, lifting may controlled to terminate at a predetermined internal pressure. This predetermined pressure can be equal to the pressure of the compressed air source, be set by a mechanical valve or determined by an electronic sensor.

[0033] When using an air bellows, the axle lifting system 100 may return from the raised position to the lowered position by releasing air pressure from the air bellows. This pressure release can be triggered by a button within the cabin of the truck. The pressure release can be facilitated by any known means, for example, a mechanical valve. As the pressure within the air bellows is released, the trailing axle 30 will be lowered back down to its original ground contact position.

[0034] The axle lifting system 100 of the present disclosure has advantageous characteristics when used to lift a driven trailing axle 30. The axle lifting system 100 provides improved axle clearance, having the displacement mechanism 110 offset longitudinally, relative to the longitudinal rail 5, from the trailing axle 30. For example, the offset provides room for a relatively large diameter air spring bellows that may be useful to provide sufficient forces to lift the trailing axle 30, even when equipped with the additional components for driving, such as a differential. The use of pivoting lever arms 130 also act as a force multiplier compared to prior art systems with fixed arms, thereby reducing the maximum pressures necessary to provide the required lifting forces. The axle lifting system 100 may also provide simpler maintenance and easier installation because the complete system is at the back of the truck.

[0035] Although the above disclosure has been presented in the context of exemplary embodiments, it is to be understood that modifications and variations may be utilized without departing from the spirit and scope of the invention, as those skilled in the art will readily understand. Such modifications and variations are considered to be within the purview and scope of the appended claims and their equivalents.