MOBILE WORK UNIT WITH RAISABLE AND LOWERABLE SUPPORT LEGS

Abstract: A mobile work unit (1) having raisable and lowerable support legs (4, 4'), which adjacent to one end portion are arranged pivotally attached to the work unit (1), and which during a pivoting movement can take up contact with a below located ground plane (6) under influence from an associated piston cylinder (5, 5'). According to the invention, at least one support leg (4, 4') is arranged supporting a linkshaped member (8), pivotally attached to the support leg (4, 4') and extending in a crosswisely extending relationship to the length direction of extension for the support leg (4, 4'). Associated piston cylinder (5, 5') for the operation of the support leg (4, 4') is arranged pivotally attached with a first end portion at the work unit (1), and with the second end portion pivotally attached adjacent to a first end portion of the linkshaped member (8). Opposed end portion of the linkshaped member (8) is attached to a movement transferring means (9), during the pivoting movement of the linkshaped member (8) between two alternative restricting positions being arranged to cause a movement for a vehicle wheel (2, 2', 3, 3') located adjacent to the support leg (4, 4') in substantially the opposed direction in relation to the direction of travel for the support leg (4, 4'), said wheel preferably being located with the wheel center in front of the front portion of the work unit (1) or behind its rear portion. The movement transferring means (9) is advantageously a longitudinally extending member (9), rigidly connected to the linkshaped member (8), arranged supporting a drive motor (7) and/or a vehicle wheel (2, 2', 3, 3') adjacent to the opposed end portion.

Description: MOBILE WORK UNIT WITH RAISABLE AND LOWERABLE SUPPORT LEGS The present invention relates to a mobile work unit with raisable and lowerable support legs, for example wheel supported mobile excavators, which, when working, are arranged with lowered support legs. It is desirable to locate the wheel axles of the work unit in such positions in relation to the vehicle body that maximum stability is achived during transport movements, and with regard to the portion where a movable work device is attached, e.g. an excavator jib with associated bucket, it is of particular importance that adjacently located pair of wheels are arranged in such a position that the risk for a forward tilting movement is eliminated. However, for such units, having pivotally attached support legs, which by means of a pivoting movement can be moved into a supporting contact position against a ground plane, it has previously not been considered possible to locate the wheels in a forward position in relation to the points of attachment for the support legs against the unit. Such a location is obviously most desirable, since the stability of the work unit thereby can be considerably improved. However, this requires that the vertical position of the wheels can be changed when the support legs are raised/lowered. The object of the present invention is to disclose a work unit having the wheels located in a forward and/or rear position in relation to the vehicle body, and also how the support legs can be raised/lowered in relation to the ground plane with a simultaneous movement of adjacent wheels in the opposed direction, said operation being performed as an automatic operation when the support legs are raised/lowered. The present invention also facilitates a simple driving and steering arrangement for the work unit for travel between different work locations, as well as other advantages, which are disclosed in the following descriptive part of the specification. The mobile work unit according to the present invention is arranged with raisable and lowerable support legs, which adjacent to one end portion are arranged pivotally attached to the work unit, and which during a pivoting movement take up contact with the opposed end portion against a below located ground plane under influence from an associated piston cylinder, and it is mainly characterised in that at least one support leg is arranged supporting a linkshaped member, pivotally attached to the support legand extending in a crosswisely extending relationship to the longitudinal direction of the support leg, and that associated piston cylinder for operating the support leg is pivotally attached with a first end portion against the work unit, the other end portion being pivotally attached adjacent to a first end portion of the linkshaped member, the opposed end portion of said linkshaped member being attached to a movement transferring means, which when the l nkshaped member is pivoted between to alternative restricting positions causes a movement in substantially opposed direction in relation to the support leg for a vehicle wheel located adjacent to the support leg, the wheel center preferably being located in front of the forward portion or behind the rear portion of the work unit. As a further characteristic feature can be stated, that the movement transferring means comprises of a longitudinally extending member, rigidly connected to the linkshaped member, at the opposed end portion arranged to support a drive motor and/or a vehicle wheel. A number of embodiments of a work unit according to the present invention are more fully described below with reference to the example of an embodiment of a work unit shown in the enclosed drawings, in which: Fig. 1 is a sche atical plan view of an excavator having four wheels viewed from above, and with the wheel pair arranged by the support legs located adjacent to the excavator jib in a forward position in relation to the excavator body; Fig. 2 is a side view of a corner portion of the excavator and a front wheel, with the support leg in a lowered position; Fig. 3 is a side view corresponding to Fig. 2, but with the wheel lowered into a contact position against the ground plane, the support leg being located in a raised position; and Fig. 4 is a view from above of the corner portion shown in Figs. 2 and 3. With reference to Fig. 1, a work unit is schematically indicated as an excavator, denominated as a complete unit as 1, having two front wheels, 2 and 2 ' respectively, and two rear wheels, 3 and 3 ' respectively. Two groups of pairs of support legs 4, 4 ' are also shown, pivotally attached 5 adjacent to the corner portions of the excavator 1, arranged to performing a pivoting movement in the vertical plane towards/away from a ground plane 6 when associated hydraulically operated piston cylinders 5, 5 ' are operated. Such a work unit is of a previously known type, but according to the present invention, the front wheel pair 2, 2 ' is 10. located in front of the excavator 1, and the piston cylinders 5, 5 ' are utilized for a further purpose, namely to raise/lower the wheels 2, 2 ' in relation to adjacently located support legs 4 when same are moved towards/away from the ground plane 6. In this embodiment, the front wheels 2, 2 ' may also advantageously be arranged connected to an 5 individual hydraulic motor 7 for each wheel 2, 2 ' , which independently of each other can be driven in alternative rotary directions when associated valve means are influenced. An example of an embodiment, intended to disclose how the piston 0 cylinders 5 moving the forward support legs 4 also can be used to raise/lower the front wheels 2, 2 ' in relation to the ground plane 6, is shown more in detail in Figs. 2 - 4. Fig. 2 shows a support leg 4 in a lowered position, and adjacently located wheel 2 in a lifted position in relation to the ground plane 6. Said figure shows, that the piston 5 cylinder 5 is pivotally attached adjacent to one end portion against the work unit 1, and that the opposed end portion (the piston rod) is pivotally attached against the outer portion of a linkshaped member 8, which is pivotally attached at its central portion against the support leg 4. A longitudinally extending member 9 extends from the opposed end 0 portion of the linkshaped member 8, supporting a hydraulic motor 7 at the free end portion, which is attached to the wheel 2. In this shown embodiment, the linkshaped member 8 and the longitudinally extending member 9 are internally rigidly joined together, whereby a predermined angular relationship therebetween is maintained. By influencing a valve means associated with the piston cylinder 5, the piston rod of the piston cylinder 5 can be moved in direction towards the work unit 1. During a first movement, the linkshaped member 8 is pivoted in direction towards the position shown in Fig. 3, while the longitudinally extending member 9 performs a corresponding pivoting movement in direction towards the ground plane 6, whereby the wheel 2 takes up contact with the ground plane 6. During the continued movement of the piston rod, the support leg 4 is pivoted/l fted in direction away from the ground plane, and if the linkshaped member 8 has not initially been pivoted to the position shown in Fig. 3, this is performed as a final movement. The work unit can now be moved to a suitable point of location for continued work, and this is advantageously performed by influencing a 2-way valve, which interrupts the oil supply to the piston cylinders 5, 5 ' , and transfers the supply of oil under pressure to the drive motors 7 of the front wheels 2, 2 " . Hereby can the same operating device/valve utilized for raising/lowering the forward and the rear support legs 4, 4 ' respectively also be used for steering the left and right hydraulic motor 7 respect vely. When the work unit 1 has been moved to location, the piston cylinders 5, 5 ' are again influenced in σrdep tσ lower the support legs 4, 4 ' . During a preliminary stage of this movement, the linkshaped member 8 at each support leg 4 maintains a substantially unchanged position, but when the outer end portions of the support legs 4 take up contact with the ground plane 6, less force will be required to lift adjacently located wheels 2, 2 ' than required to lift the entire work unit 1 by means of the support legs 4, whereby the linkshaped member 8 performs a pivoting movement, which due to a corresponding movement of the associated longitudianlly extending member 9 causes associated wheels 2, 2 ' to be lifted in direction away from the ground plane 6. The resulting position taken up is shown in Fig. 3. In the above described embodiment, the four wheels 2, 2 ' , 3, 3 ' are arranged in a fixed and non-steerable position in relation to the work unit. As a result, a turning operation performed during movement results in a "skidding movement" of the rear and not driven wheels 3, 3 ' . For certain types of units, locating the working device in a suitable position makes it possible to move the center of gravity in such a way that the rear wheel 3, 3 ' do not carry an unnecessarily high load, but this obviously results i reduced stability. In order to reduce or eliminate the disadvantages caused when the work unit 1 is turned, the rear wheel pair 3, 3 ' of the above described embodiment may be replaced by one wheel only, located adjacent to the length axis of the work unit 1, freely pivotable in the horizontal plane. Such a wheel may advantageously be located in a position behind the work unit, joined with at least one of the rear support legs 4 ' in a fashion comparable to the front wheel pair 2, 2 ' , whereby the wheel will be raised/lowered in an opposed relationship to the- direction of movement for the rear support legs 4 ' . Such a wheel is further advantageously arranged freely rotatable in the horizontal plane, and when the driven wheels 2, 2 " are driven with a different rotary speed in relation to each other, or different rotary directions, the freely rotable wheel in the horizontal plane will thus take up a position of location adapted to the present turning movement. Hereby is the "skidding movement" avoided as previously discussed with reference to the embodiment including a pair of non-steerable rear wheels 3, 3 ' . It is also possible to accomplish a suspension- system for the wheels which as previously described are arranged movable- n relation to adjacent support legs 4, 4 " . When the support legs 4, 4 " are located in a raised position, the piston cylinders 5, 5 ' act as movement absorbing suspension means, but since the piston cylinders 5, 5 ' are operated by means of a hydraulic medium, the degree of compression possible for such a medium is obviously restricted. The piston cylinders 5, 5 " may therefore advantageously be connected to at least one hydraulic accumulator when the support legs 4, 4 ' have taken up a position moved away from the ground plane 6. Such a hydraulic accumulator can be of a previously known type, e.g. a container in which the oil under pressure is separated from nitrogen or other gas by means of a diaphragm. For larger and heavier work units 1, the rigid connection to the linkshaped member 8, formed by means of a fixed longitudinally extending member 9 directed away from the linkshaped member 8, may for example be replaced by a force transferring link, pivotally attached against the linkshaped member 8. The movement of such a force transferring link can be transferred to a crank pin, an excentrically mounted member or similar, arranged rotatably supported by a support leg 4, 4 ' , and carrying associated wheel 2, 2 ' , 3, 3 " . As a result, the rather long lever in the shown and described embodiment is avoided, which causes a relatively large application of force at the point of attachment between the linkshaped member 8 and the longitudinally extending member 9. In the described embodiment, only one wheel pair 2, 2 ' is arranged to be influenced during the movement of associated support legs 4, but it is obviously also possible to arrange both wheel pairs 2, 2 " , 3, 3 ' in a corresponding fashion. Furthermore, there are obviously a number of technical solutions for transferring the movement of each linkshaped member 8 to associated wheel 2, 2 ' , 3, 3 ' , and apart from rigid joints such as links, it is thus also possible to transfer the movement by means of chains, wires or similar, and also such modifications fall within the scope of the invention. It is further also obviously possible to arrange a wheel pair, or a single wheel supporting one end portion, manually turnable in the horizontal plane, in order to facilitate a steering operation for the work unit during a transfer movement. The present invention is thus in no way restricted to the example of an embodiment shown and described, but can be further modified within the scope of the inventive thought and the following claims.

Claims: C L A I M S i. Mobile work unit (1) with rai sable and lowerable support legs (4, 4 ' ), which adjacent to one end portion are arranged pivotally attached to the work unit (1), and which during a pivoting movement take up contact with the opposed end portion against a below located ground plane (6) under influence from an associated piston cylinder (5, 5 ' ), c h a r a c t e r i s e d i n, that at least one support leg (4, 4 ' ) is arranged supporting a linkshaped member (8), pivotally attached to the support leg (4, 4 ' ) and extending in a crosswisely extending relationship to the longitudinal direction of the support leg (4, 4 ' ), and that associated piston cylinder (5, 5 ' ) for operating the support leg is pivotally attached with a first end portion against the work unit (1), the other end portion being pivotally attached adjacent to a first end portion of the linkshaped member (8), the opposed end portion of said linkshaped member (8) being attached to a movement transferring means (9), which when the linkshaped member (8) is pivoted between to alternative restricting positions causes a movement in substantially opposed direction in relation to the support leg (4, 4 ' ) for a vehicle wheel (2, 2 " , 3, 3 ' ) located adjacent to the support leg (4, 4 ' ), the wheel center preferably being located in front of the forward portion or behind the rear portion of the work unit (1). 2. Mobile work unit according to claim 1, c h a r a c t e r i s e d i n, that the movement transferring means (9) comprises of a longitudinally extending member (9), rigidly connected to the linkshaped member (8), at the opposed end portion arranged to support a drive motor (7) and/or a vehicle wheel (2, 2 ' , 3, 3 ' ). 3. Mobile work unit according to claim 1, c h a r a c t e r i s e d i n, that the movement transferring means (9) comprises of a link, chain, wire or similar, pivotally attached to the linkshaped member (8), arranged to transper a pivoting movement of the linkshaped member (8) into a movement for an adjacently located vehicle wheel (2, 2 ' , 3, 3 ' ), thus causing said wheel (2, 2 ' , 3, 3 ' ) to perform a substantially opposed movement in relation to the direction of movement for adjacently located support leg (4, 4 ' ). 4. Mobile work unit according to any one of claims 1 - 3, c h a - r a c t eri s e d i n, that the control members/valve means utilized to raise/Tower the front and rear support legs (4, 4 ' ) respectively of the work unit by means of a control valve means can be connected for individual control of two hydraulic motors (7), connected to a vehicle wheel (2, 2 ' , 3, 3 ' ) at left respectively right side of the work unit. 5. Mobile work unit according to any one of claims 1 - 4, c h a - r a c t e r i s e d n, that the piston cylinders (5, 5 " ) are arranged connected to at least one hydraulic accumulator when the piston cylinders (5, 5 ' ) take up the position in which the support legs (4, 4 ' ) are pivoted away from the ground plane (6). 6. Mobile work unit according to any one of claims 1 - 5, c h a - r a c t e r i s e d i n, that the work unit adjacent to one end portion is arranged with only one supporting vehicle wheel, freely turnable in the horizontal plane, and located in a position adjacent to the length axis of work unit. 7. Mobile work unit according to any one of " claims 1 - 5, c h a - r a c te r i s e d i n, that the work unit adjacent to one end portion is arranged with only one supporting vehicle wheel, manually steerable between desired rotary positions in the horizontal plane, and located in a position adjacent to the length axis of the work unit. 8. Mobile work unit according to any one of claims 6 and 7, c h a - r a c t e r i s e d i n, that the supporting vehicle wheel is arranged to perform an opposed movement in relation to the movement of adjacent support leg (4, 4 ' ) in direction towards/from the ground plane (6) by means of at least one connecting means (9) attached to at least one support leg (4, 4 ' ) via thereby arranged linkshaped member (8). 9. Mobile work unit according to any one of claims 1 - 8, c h a - r a c t e r i s e d i n, that one or a number of the vehicle wheels (2, 2 ' , 3, 3 ' ) located adjacently to the support legs (4, 4 ' ) and/or the drive motors (7) supporting the vehicle wheels (2, 2 " , 3, 3 ' ) are arranged joined with adjacent support leg (4, 4 ' ) by means of a crank pin, an excentrically supported member, or similar, arranged to support and guide the vehicle wheels (2, 2 " , 3, 3 ' ) in a curved movement during the movement of same in relation to the support legs (4, 4 ' ). 10. Mobile work unit according to any one of claims 1 - 9, c h a - r a c t e r i s e d i n, that a vehicle wheel (2, 2 " , 3, 3 ' ) joined to a support leg (4, 4 ' ) by means of a movement transferring means (9) and a linkshaped member (8) is arranged having a different angular orientation in the vertical plane than the length direction of extension for the support leg (4, 4 ' ).

Inventors: DAHLGREN BO, SVENSSON ULF, DAHLGREN, BO, SVENSSON, ULF
Applicants: SVENSSON ULF, SVENSSON, ULF
Application year: 1987
Main classification: E02F9
IPC codes: E02F9