DESCRIPTION

TECHNICAL FIELD

The present invention relates to a wire saw having a saw wire drive sheave for driving an endless saw wire, a motor for driving the drive sheave, and a stand for carrying the motor, the stand rising from a base and forming therewith a stand assembly, and the motor and the drive sheave being displaceable along the stand as the saw wire is cutting, a plurality of saw wire sheaves mounted to form a storage for the saw wire, the storage including at least one displaceable sheave and at least one fixed sheave, and the wire saw having two swivel sheaves carried by the stand assembly, one for guiding the saw wire at a position between the drive sheave and an object to be sawed, and the other for guiding the saw wire at a position between the object to be sawed and the saw wire storage.

It also relates to a method of rebuilding a wall saw having a rotary saw blade, a motor for driving the saw blade, and a stand, along which the motor and the saw blade are displaceable as the saw blade is cutting, said method including substituting a saw wire drive sheave for the saw blade, providing a plurality of saw wire sheaves and mounting them at least indirectly on the stand to form a storage including at least one displaceable sheave and at least one fixed sheave for a movable endless saw wire driven by the drive sheave, and providing two swivel sheaves, one for guiding the saw wire at a position between the drive sheave and an object to be sawed, and the other for guiding the saw wire at a position between the object to be sawed and the saw wire storage.

In the present context, a sheave is a wheel with a groove along its edge for holding a saw wire, and a saw wire uses diamond-impregnated beads on a cable.

BACKGROUND ART

Construction machinery is used in renovating, reconstructing and extending buildings, for example. Wall saws are used for cutting and extending openings for doors, windows and light wells, etc., corrective work on facades, partition walls and garden walls, etc., and controlled demolition of concrete. Wall saws and similar construction machinery have a prime mover, such as a motor, and a rotary tool driven by the motor. In a wall saw, the tool is a circular saw blade equipped with cutting diamonds. Generally, heavy duty wall saws are driven hydraulically, see US 6,955,167 B2, US 2006/0201492 Al, US 2007/0163492 Al, and US 5,887,579, for example. However, hydraulic wall saws are comparatively heavy and not easy to set up, and comparatively low-weight electric wall saws, such as the one disclosed in US 2006/0189258 Al, for example, have been introduced on the market.

For certain tasks, wire saws are preferable over wall saws. As an example, they can make a cut much thinner than a blade-based saw is capable of. They can also cut through much thicker objects than a blade based saw is capable of, since the maximum depth of the cut is set by the radial distance between the periphery of the saw blade and its hub.

For some construction contractors it would be advantageous to have a single machine, which by dismounting some components from one version of the machine and installing other components from an accessory kit easily could be converted to another version, e.g. a wall saw into a wire saw and the other way round.

An example of a wire saw is disclosed in DE 298 05 157 Ul. It can be described in the wording of the preamble of the appended claim 1. However, it is designed to be just a wire saw, and it is neither intended nor suitable for conversion into a wall saw. In addition, the saw wire storage is a separate unit that is built on a separate base, not the one of the displaceable motor.

Another example of a wire saw is disclosed in DE 298 05 457 Ul, where the motor for rotating the drive sheave for the saw wire appears to be fixed to a stand and not displaceable therealong. The wire saw has a saw wire storage with two sheave groups of five sheaves, for example, of which one group is fixed and the other is displaceable by means of an hydraulic actuator keep the saw wire tensioned and accommodate an increased length of saw wire in the storage as the sawing proceeds.

In EP 0 904 907, it has been proposed to rebuild a wall saw to a wire saw. However, although a considerable number of sheaves are used, the wire saw with its saw wire storage takes up a great deal of space. The wire saw has a guide rail extending along a bed, e.g. a floor. At the end of the section of the guide rail facing away from the object to be sawed, a single wire storage roller is provided, by means of which the wire length extending from the drive wheel to the object to be sawed can be shortened by inclusion into the guide path of the saw wire. The wire storage roller is displaceable along the rear third of the guide rail and can be either secured in a plurality of predetermined positions therealong or mounted on an additional rail frame that can be fixed to the guide rail by clamping. A characteristic feature of this wire saw is that when the sawing starts, the wire storage roller is not included in the guide path of the saw wire. Thus, when the sawing has proceeded so far that a further displacement of the drive roller to keep the saw wire tensioned is impossible, the sawing has to be interrupted and the saw wire rethreaded to include also the wire storage roller in its path. In fact when rethreading also another roller, close to the drive wheel, is included in the wire path according to Fig. 1 and 2. Rethreading the cutting wire is a dirty manual job. A single storage roller is used in the rear or outer end of the guide rail. Using a single roller is of course to keep rethreading reasonably simple. The maximum amount of wire is stored when the drive wheel has moved to the outer end of the guide rail. Two loops of wire are then formed, one around the drive wheel and one around the wire storage roller. Using only two loops makes it necessary to use a longer guide rail, i.e. a longer machine, as compared to machines using three or more loops. The latter machines can be shorter or lower for the same sawing capacity or have a bigger capacity, or both. Further rethreading is difficult to make automatic - partly or fully.

SUMMARY OF THE INVENTION

One object of the present invention is to provide a wire saw, which is compact and in addition to performing its function as wire saw can be rebuilt easily to a wall saw, and the other way round.

In a wire saw of the kind referred to in the first paragraph above, this object is achieved in accordance with the invention in that said at least one displaceable sheave is directly or indirectly attached to the stand and displaceable in an essentially axial direction of the stand for adjusting a length of saw wire in the storage, and the saw wire wraps all of the sheaves of the storage during all sawing operations, so that the wire never is transferred to wrap another sheave and thereby increase the length of saw wire in the storage. Rethreading is thereby avoided. Moving the at least one displaceable sheave can relatively simply be made partly or fully automatic.

Such a wire saw is compact and in addition to performing its function as wire saw can be rebuilt easily to a wall saw, and the other way round.

Preferably, said at least one displaceable sheave is one of a pair of sheaves mounted side by side and together displaceable in an essentially axial direction of the stand, said at least one fixed sheave is one of two other sheaves that are at least indirectly connected to the base, and said displaceable pair of sheaves is located essentially above the two fixed sheaves. This means that three loops of wire are used. Thereby, the height of the wire saw necessary for creating a sufficiently large saw wire storage may be reduced, which is an important advantage. Alternatively a bigger wire storage could be used.

If desired, said at least one displaceable sheave may be fixed at least indirectly to the motor and thereby indirectly to the stand for travelling with the motor along the stand. Thereby, the sawing may be continued for an extended period of time without interruption. With many conventional wire saws, the sawing must be interrupted when the motor has arrived at the end of the stand, then the motor must be returned to its starting point and the at least one displaceable sheave must be displaced toward the end of the stand to tension the slack of the saw wire, whereafter the sawing can be continued. Usually this has to be repeated more than once. If said at least one displaceable storage sheave is fixed at least indirectly to the motor for travelling therewith along the stand, the travelling speed of the motor will be reduced to about a third of the normal one to maintain the desired tension in the saw wire by accumulating in the storage the additional wire length created by the saw wire cutting through the object to be sawed.

Suitably, the displacement of the motor together with the drive sheave and said at least one displaceable sheave along the stand is controlled by the tension in the saw wire.

In an alternative but less preferred embodiment, said at least one displaceable sheave is one of a pair of sheaves mounted side by side and together displaceable in an essentially axial direction of the stand, said at least one fixed sheave is one of at least two other sheaves that are at least indirectly connected to the stand at an upper position thereof, and said displaceable pair of sheaves is located essentially below the at least two fixed sheaves. Also this embodiment reduces the height of the wire saw.

Preferably, said at least one displaceable sheave is manually displaceable for attachment in an arbitrary position along the stand.

It is preferred that said at least one displaceable the sheave is mounted on a shaft carried by an arm, which is pivotally and at least indirectly attached to the stand adjustably in a direction along the stand for adjusting a length of saw wire in the storage, and which is biased toward a neutral position, so as to reduce possible tension variations in the saw wire. The expression "at least indirectly" shall be interpreted to include the alternatives of attachment to the stand for manual displacement along the stand and attachment to the motor for travelling therewith along the stand.

Preferably, the arm is resiliently and at least indirectly connected to the stand by a coupling including at least one elastic rubber element, which upon rotation of an inner coupling member in relation to a coaxial outer coupling member becomes elastically squeezed between to two coupling members and tries to move them back to a starting position.

In a preferred embodiment, the two coupling members have a basically square cross section, the inner member is rotated 45° in relation to the outer member, and an elastic element is provided in each one of four spaces formed between the two coupling members.

To permit the use of a comparatively long saw wire while maintaining the compact design of the saw wire storage, it is preferred that a pair of the storage sheaves is mounted side by side on the arm, and two other storage sheaves are at least indirectly connected to the base at a distance from said pair and at an angle to each other and to a rotation plane of the sheave pair.

To make it possible for the storage to accommodate a a greater length of saw wire, it is also preferred that said at least one displaceable sheave is displaceable along a major portion of the length of the stand. This major portion may be either an upper or a lower portion of the stand.

Another but related object is to provide a method of rebuilding a wall saw to a compact wire saw, and the other way round.

In a method of the kind referred to in the second paragraph above, this object is achieved in accordance with the invention in that said method is characterized by: - providing a base from which the stand rises upward to form a stand assembly,

- mounting the two swivel sheaves on the base,

- attaching the at least one displaceable sheave directly or indirectly to the stand to be displaceable in an essentially axial direction of the stand for adjusting a length of saw wire in the storage, and - mounting the other sheaves of the storage such that the saw wire wraps all of the sheaves of the storage during all sawing operations, so that the wire never is transferred to wrap another sheave and thereby increase the length of saw wire in the storage.

Thereby, the resulting wire saw will be compact and in addition to performing its function as wire saw in a satisfactory manner, it can be rebuilt easily to a wall saw, and the other way round.

Suitably, the at least one sheave is mounted on a shaft carried by an arm, and the arm is attached to the stand pivotally and adjustably in a direction along the stand for adjusting a length of saw wire in the storage, and the arm is biased toward a neutral position, so as to reduce possible tension variations in the saw wire.

Preferably, the biasing of the arm is carried out by means of an elastic coupling. Thereby, it will be less sensitive to disturbances in a dust-laden environment during sawing.

To permit the use of a comparatively long saw wire while maintaining the compact design of the saw wire storage, it is preferred to mount a pair of the storage sheaves side by side on the arm, and to mount two other storage sheaves on the stand assembly at a distance from said pair and at an angle to each other and to a rotation plane of the sheave pair. Further features characterizing the invention and what is obtained thereby will be obvious from the detailed description below and the appended drawings.

BRIEF DESCRIPTION OF THE DRAWINGS In the following, the invention will be described in more detail with reference to preferred embodiments and the appended drawings.

Fig. 1 is a front view of a preferred embodiment of a wall saw rebuilt to a wire saw in accordance with the present invention and having a saw wire storage with at least one displaceable sheave located above at least one fixed sheave.

Fig. 2 is a perspective view of the wire saw of Fig. 1 with the saw wire removed for greater clarity, but provided with transportation wheels and saw wire shields and viewed at an angle from below.

Fig. 3 is a perspective view of a top portion of the wire saw of Fig. 1 with the saw wire removed for greater clarity, but viewed at an angle from above and behind.

Fig. 4 is a simplified side view of an elastic mounting of a sheave carrying pivotal arm attached at the top of the stand of the wire saw.

Fig. 5 is a front view of second preferred embodiment of a wall saw rebuilt to a wire saw in accordance with the present invention and having a saw wire storage with at least one displaceable sheave located below at least one fixed sheave.

MODE(S) FOR CARRYING OUT THE INVENTION

The wire saw shown in Figs. 1-4 is rebuilt from a wall saw. Suitable wall saws are WS 440

HF, shown at http://ap.husqvarnacp.com/nodel552. aspx?nid=66037&pid=10381, and WS

463, shown at http://ca-eng.husqvarnacp.com/nodel552. aspx?nid=5597&pid= 10394, for example. WS 440 HF has an electric motor, while the motor of WS 463 is a hydraulic one.

Of course, it is within the skill of an ordinary craftsman to rebuild also other wall saws by using the teachings of the present invention.

A wall saw has a rotary saw blade, a motor carriage 25 holds a motor 3 for driving the saw blade, and a stand 4, along which the motor 3 and the saw blade are displaceable as the saw blade is cutting. If desired, the motor 3 both rotates the saw blade and displaces itself along the stand, which has a longitudinal rack, but it is also possible to use a one motor for the rotation of the saw blade and another one for the displacement along the stand. On rebuilding the wall saw to a wire saw, a saw wire drive sheave 2 is substituted for the saw blade. The stand 4 is mounted to rise from a base 5 and forms therewith a stand assembly 6. The base 5 is plane and has a plurality of leveling screws 7, in the shown embodiment four, for supporting the base 5 on an uneven floor or other uneven substructure. As illustrated in Fig. 2, the base 5 at its rear side is provided with a pair of transportation wheels 8 for moving the wire saw to another location. When the base 5 is supported by the leveling screws 7, the wheels 8 are lifted from contact with the floor or other substructure.

To form a storage 9 for a movable endless saw wire 1 driven by the drive sheave 2, in Figs. 1-3 a plurality of saw wire sheaves 10, 11, 12, 13 are provided mounted at least indirectly on the stand assembly 6. The storage 9 includes at least one displaceable sheave 10, 11 and at least one fixed sheave 12, 13. Fig. 3 shows how the motor 3 with drive wheel 2 is fastened to the motor carriage 25. This carriage has 4 rollers, two hidden, for rolling along the stand 4. A clamping carriage 24 holds the at least one displaceable sheave 10, 11 in a biased or non biased way, as will be described. The clamping carriage can be locked in different locations along the stand 4. As shown the carriage 24 contacts a dove tail-shaped grove so that it will not fall off the stand when undamped. An important feature is that the two carriages 24, 25 do not interfere with each over. Therefore both carriages can take use of the full free length of the stand 4. It is possible to use a liftaid for lifting the clamping carriage 24 to a new higher position along the stand 4. A permanently attached gas spring could be used as lift aid. It is significantly easier to include such a helping feature into this design than into a rethread design as ace. to EP 0 904 907. This is another important advantage. Further, two swivel sheaves 14, 15 are provided, one 14 for guiding the saw wire 1 at a position between the drive sheave 2 and an object to be sawed, not shown, and the other 15 for guiding the saw wire 1 at a position between the object to be sawed and the saw wire storage 9. Of course, when the base 5 is supported by the leveling screws 7, the swivel sheaves 14, 15 have no contact with the floor or other substructure. The object to be sawed may be located beside, below or above the wire saw, e.g. part of a wall, a floor or a ceiling, respectively. The wire saw is of course suitably fastened not to move under the forces of the saw wire. Further it is designed to have a vertical stand 4, which is normally preferable as space is usually more limited in a horizontal direction. However the wire saw could of course be adapted to have a horizontal stand instead, i.e. a lie down configuration.

The at least one displaceable sheave 10 is directly or indirectly attached to the stand 4 and displaceable in an essentially axial direction of the stand 4 for adjusting a length of saw wire 1 in the storage 9. The saw wire 1 always wraps all of the storage sheaves 10, 11, 12, 13 during all sawing operations and no rethreading to include additional sheaves is necessary. Thus, the wire 1 never is transferred to wrap another sheave and thereby increase the length of saw wire 1 in the storage 9. Such a wire saw is compact and in addition to performing its function as wire saw it can be rebuilt easily to a wall saw, and the other way round.

Preferably, the at least one displaceable sheave 10 is manually displaceable for attachment in an arbitrary position along the stand 4, and is one of a pair of sheaves 10, 11, which are mounted side by side and together displaceable in an essentially axial direction of the stand 4. The at least one fixed sheave 12 is one of two other sheaves 12, 13 that are at least indirectly connected to the base 5, and said displaceable pair of sheaves 10, 11 is located essentially above the two fixed sheaves 12, 13. Thereby, the height of the wire saw necessary for creating a sufficiently large saw wire storage may be reduced, which is an important advantage.

If desired, in an embodiment not shown, said at least one displaceable sheave 10, 11 may be fixed at least indirectly to the motor 3 and thereby indirectly to the stand 4 for travelling with the motor 3 along the stand 4. This is best described by referring to Fig. 3. The motor with drive wheel 2 is carried by the motor carriage 25. Said at least one displaceable sheave 10, 11 is carried by the clamping carriage. By joining the two carriages 24 and 25 into one common carriage the sheaves 10, 11 and the drive wheel 2 will move together. This big carriage would probably some extra rollers to take the increased pulling loads when moving. Thereby, the sawing may be continued for an extended period of time without interruption. With conventional wire saws, the sawing must be interrupted when the motor 3 has arrived at the end of the stand 4, then the motor 3 must be returned to its starting point and the at least one displaceable sheave 10 must be displaced toward the end of the stand 4 to tension the slack of the saw wire 1, whereafter the sawing can be continued. In this context, these steps together are called a retake. Usually, the retake has to be made more than once. If said at least one displaceable storage sheave 10 is fixed at least indirectly to the motor 3 for travelling therewith along the stand 4, the travelling speed of the motor 3 will be reduced to about a third of the normal one to maintain the desired tension in the saw wire 1 by accumulating in the storage 9 the additional wire length created by the saw wire cutting through the object to be sawed.

In an alternative but less preferred embodiment shown in Fig. 5, said at least one displaceable sheave 10 is one of a pair of sheaves 10, 11 mounted side by side and together displaceable in an essentially axial direction of the stand 4, said at least one fixed sheave 12' is one of at least two other sheaves 12', 13', 13" that are at least indirectly connected to the stand 4 at an upper position thereof, and said displaceable pair of sheaves 10, 11 is located essentially below the at least two fixed sheaves 12', 13', 13". Also this embodiment reduces the height of the wire saw. All of the sheaves have a peripheral groove for the saw wire 1, and the saw wire contacting part of the groove is formed in a wear resistant material, such as rubber. The axially outer sides of the sheaves may be pressed sheet-metal. As illustrated in Figs. 1 and 3, at least one of the sheaves of the storage 9 is mounted on an arm 16, which is pivotally attached to the stand 4 adjustably in a direction along the stand for adjusting a length of saw wire 1 in the storage 9. The arm 16 is biased toward a neutral position, so as to reduce possible tension variations in the saw wire 1 during sawing. Such tensions may occur when the saw wire 1 comes into contact with an area of other density or hardness in the object to be sawed than surrounding areas, e.g. stones or reinforcement bars in concrete. The increase in saw wire length to be stored in the storage as the saw wire gradually is cutting through the object to be sawed is taken up by the displacement of the motor 3 along the stand 4.

In the preferred embodiment shown in Figs. 3 and 4, one end of the arm 16 is resiliently connected to the stand 4 by a coupling 17 including at least one elastic rubber element 18, which upon rotation of an inner coupling member 19 in relation to a coaxial surrounding outer coupling member 20 becomes elastically squeezed between to two coupling members and tries to move them back to a neutral starting position. Both of the two coupling members 19, 20 have a basically square cross section, the inner member 19 is rotated 45° in relation to the outer member 20, and an elastic rubber element 18 is provided in each one of four spaces formed between the two coupling members. In the preferred embodiment shown in Fig. 4 the arm 16 is fixed by screws 23 to an axial end of the inner member 19 of the coupling, but if desired it could alternatively be fixed to the outer member 20, dependent on which one of the two coupling members is attached to the stand 4. A suitable coupling is the rubber suspension unit of type DR-A, marketed by Rosta AG in Switzerland. Also in a dust-laden environment caused by sawing in concrete, for example, the rubber suspension unit requires no maintenance. The position of the coupling 17 along the stand 4 is adjustable to permit the saw wire 1 to extend around the object to be sawed. In the preferred embodiment shown in Fig. 3, the coupling 17 is mounted on the stand 4 by means of a clamping carriage 24 that is loosened and tightened manually. However, if desired, it is, of course, possible to attach the coupling 17 to the motor carriage 25 of the motor 3, so that the displacement of the motor 3 along the stand 4 causes the coupling 17, the arm 16, and said at least one sheave 10 carried thereby to be displaced as a unit.

The other, free end of the arm 16 has shaft, on which at least one of the sheaves of the storage 9 is carried in bearings. In the preferred embodiment shown in Fig. 1, a pair 10, 11 of the storage sheaves is mounted side by side on the arm 16. The other two sheaves 12, 13 of the storage 9 are mounted on the base 5 at a distance from said pair and at an angle to each other and to a rotation plane of the sheave pair. The saw wire 1 runs from the object to be sawed (not shown) around the left hand swivel sheave 14 in Fig. 1, up and around the drive sheave 2, down and around the bottom sheave 12 that is closest to the stand 4, up and around the top sheave 10 that is closest to the stand 4, down and around the other bottom sheave 13, up and around the other top sheave 11, down and around the right hand swivel sheave 15, and then back around the object to be sawed. Of course, it is possible, if desired, to expand the storage by using three or more top sheaves and a corresponding number of bottom sheaves. The arm 16 is shown as mounted in a slightly upward sloping position. Thereby, the normal tension in the saw wire during normal operating conditions will pull down the free end of the arm 16 against the torsion force in the elastic coupling 17 to a generally horizontal position.

To protect operators in case of a possible break of the saw wire 1, a plurality of shields is provided as shown in Fig. 2. Each of the swivel sheaves 14, 15 is provided with a channel- shaped shield 14', 15', respectively, where the saw wire 1 follows the periphery of the sheave. The upper periphery of the drive sheave 2 is covered by a hood 2', the saw wire portion extending from the swivel sheave 14 to the drive sheave 2 is covered by a channel- shaped shield 21 open toward a vertical center plane of the saw, and on three vertical sides the storage is covered by a shield 22 that is open toward the vertical center plane of the saw.

In the preferred embodiment shown in Figs. 1-3, the motor 3 with its drive sheave 2 and the top sheave pair 10, 11 are shown in their positions at the end of a sawing operation, when the saw wire storage 9 is full. At the beginning of a sawing operation, a large length of the saw wire 1 is drawn out of the storage 9 and wrapped around the object to be sawed, and the motor 3 and the top sheave pair 10, 11 are at their lowermost positions. During sawing, the motor 3 rises to the top of the stand 4. Then the sawing is interrupted, the motor 3 is returned to its lowermost position, the clamping arrangement holding the coupling 17, the arm 16 and the top sheave pair 10, 11 is loosened, displaced upward along the stand 4 to tighten the saw wire, and then tightened again. Then the sawing is started again. In this context, these steps together are called a retake. If necessary, these steps are repeated until the sawing through is completed.

The saw wire 1 always wraps all of the storage sheaves 10, 11, 12, 13, and no rethreading to include additional sheaves is necessary. Then, preferably, at least one 10 of the storage sheaves 10, 11, 12, 13 is displaceable along a major portion of the length the stand 4. The major portion is either an upper portion or a lower portion of the stand 4. Further, the at least one storage sheave 10 is either manually displaceable for attachment in an arbitrary position along the stand 4 as shown in Figs. 1-3 or, in an embodiment not shown, fixed at least indirectly to the motor 3 for travelling therewith along the stand 4. When the at least one storage sheave 10 is manually displaceable for attachment in an arbitrary position along the stand 4, the motor 3 and the clamp mounting of the at least one sheave 10 are located on opposed longitudinal sides of the stand 4 as is best shown in Fig. 3. Thereby, they do not interfere with each other upon independent displacement of them along the stand 4. When, in an embodiment not shown, the at least one storage sheave 10 is fixed at least indirectly to the motor 3 for travelling therewith along the stand 4, e.g. the clamping carriage 24 may be devoid of its clamping ability and incorporated in the motor carriage 25, the travelling speed will be reduced to a third of the normal one to maintain the desired tension in the saw wire 1 by accumulating in the storage 9 the additional wire length created by the saw wire 1 cutting through the object to be sawed. If desired, this reduced displacement of the motor 3 may be accomplished with a separate motor or actuator, not shown. Then, equipment, not shown, may be provided for sensing the tension in the saw wire 1 caused by the rotation of the drive sheave 2 and for controlling the displacement of the motor 3 together with the drive sheave 2 and said at least one storage sheave 10 along the stand 4 in response to the sensed tension. When the at least one storage sheave 10 is carried on an arm fixed at least indirectly to the motor 3, the arm may be pivotally biased like arm 16 or it may be fixed.

Fig. 5 shows a second preferred embodiment of a wall saw rebuilt to a wire saw in accordance with the present invention. In view of the great similarities with the first embodiment described above with reference to Figs. 1-4, identical reference numbers will be used for identical components, and components changed or added in Fig. 5 will be marked with a prime or a double prime symbol. The main difference between the second embodiment shown in Fig. 5 and the first embodiment shown in Figs. 1-4 is that the saw wire storage 9 has the at least one displaceable sheave 10, 11 located below instead of above at least one fixed sheave 12', 13', 13". In most other respects they have a similar design and offer similar advantages.

More precisely the displaceable pair 10, 11 of sheaves is carried by a lower arm 16' ' mounted to a second displaceable clamping carriage 24' . This carriage 24' is movable along the stand 4 and is clamped in a suitable position, as described in the first embodiment for the corresponding first clamping carriage 24. The first clamping carriage 24 is permanently locked in an upper position of the stand 4 and is holding the fixed sheaves 12', 13', 13" via an upper arm 16'. In a first variant of the second embodiment the upper arm 16' is fixed, and not biased. Instead the lower arm 16" is biased to tension the at least two and preferably four parts of the wire entering and leaving the displaceable sheaves 10, 11. In a second variant instead the lower arm 16" is fixed and the upper arm 16' is biased to tension the at least four and preferably six parts of the wire entering and leaving the fixed sheaves. So in the second variant more wire parts are tensioned than in the first variant. On the other hand this probably requires a stronger tensioning arrangement. In a third variant both the upper arm 16' and the lower arm 16" is biased. This however seems a bit complicated. Further, the storage 9 includes a sheave 12 fixed to the base 5 of the stand assembly 6 as in the first embodiment. From the swivel sheave 15 the saw wire 1 extends upward, wraps the first fixed top sheave 13", then downward to wrap the displaceable sheave 11, upwards to wrap the second fixed top sheave 13', downwards to wrap the other displaceable sheave 10, upwards to wrap the third fixed top sheave 12', downwards to wrap the sheave 12 that is fixed to the base 5, and finally upwards to wrap the drive sheave 2. In this way the wire is pulled from the swivel sheave 15 taking use of biasing feature of the storage 9, and this is a preferred way of operation. However it is also possible to draw the wire from swivel sheave 14, thanks to a special bearing arrangement of drive sheave 2. This double direction of rotation feature brings advantages under special occasions.

All three variants of the second embodiment has an advantage in common compared to the first embodiment. When the clamping of the second clamping carriage 24' is released the weight of the carriage and the displaceable sheaves 10, 11 will help to move the carriage 24' in the required direction downwards. In the first embodiment instead the first clamping carriage 24 should be moved upwards against the weight. This is an important advantage when the clamping to the stand 4 is released and a retake as defined above is made. This advantage is additional to the possibility of accommodating a longer saw wire 1 in the storage 9 of Fig. 5 thanks to the increased number of sheaves.

INDUSTRIAL APPLICABILITY

Construction machinery is used in renovating, reconstructing and extending buildings, for example. Wall saws and wire saws are used for cutting and extending openings for doors, windows and light wells, etc., corrective work on facades, partition walls and garden walls, etc., and controlled demolition of concrete. For certain tasks, wire saws are preferable over wall saws.