GB1579508A - Recoil device for track-type vehicle undercarriage - Google Patents

Description

(54) RECOIL DEVICE FOR TRACK-TYPE VEHICLE UNDERCARRIAGE (71) We, CATERPILLAR TRACTOR CO., a corporation organized and existing under the laws of the State of California, United States of America, of 100 N. E. Adams Street, Peoria, Illinois 61629, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- Conventional track roller frames of tracklaying vehicles are structurally connected to an associated idler through a mechanical arrangement which allows the idler to recoil in response to loads which deform the track.

The idler is held in position by an adjustable preloaded coil spring which acts against a shaft and yoke arrangement. Accumulated debris between the track roller frame and yoke often restrict the function of these conventional recoil devices. Also, the recoiling idler slides on a portion of the roller frame in metal-to-metal contact therewith resulting in a wear problem.

In view of the above, it would be advantageous to provide a recoil device for a track-type vehicle undercarriage which avoids the debris accumulation problems of the prior art and also avoids the sliding metal-tometal wear contact and which overcomes the problems associated with the prior art.

According to the present invention a track-laying vehicle undercarriage has a track idler with a recoil device comprising a housing; first recoil means operably connected for relative movement with the housing in response to movement of the idler; second recoil means operably connected for relative movement with the housing in response to movement of the first recoil means; third recoil means operably connected for movement in response to movement of the second recoil means; and a wear sleeve removably mounted in the housing in wear receiving engagement with the first recoil means.

An example of an undercarriage constructed in accordance with the invention is illustrated in the accompanying drawings, in which: Figure 1 is a partial side elevation; Figure 2 is a partial plan view; Figure 3 is a section taken on the line III-III in Figure 2; and, Figure 4 is an exploded partial side elevational view.

Referring now to Figure 1, a track-laying vehicle undercarriage is generally designated 10 and includes a support frame 12 connected to the vehicle (not shown) through a pivot shaft, one end of which is shown at 14. A sprocket 16 is connected to drive a track 18 in the well known manner. Also, an idler 20 and rollers 22 are provided for supporting and guiding track 18 as is well known.

Recoil means generally designated 24, 26 and 28 are operably connected to move in response to movement of idler 20 as hereinafter described in greater detail.

Figure 2 graphically illustrates the recoil device including a housing portion 30 of support frame 12. The first recoil means 24 comprises a pair of pistons 32 having their one end 34 connected to opposite sides 36, 38 of idler 20 and having their other end 40 movably mounted in housing 30. In this manner, the first recoil means 24 is operably connected for relative movement with housing 30 in response to movement of idler 20.

The second recoil means 26 comprises a piston 42 fluidly connected, via conduits 44, to move in response to movement of pistons 32.

The third recoil means 28 comprises a resilient member, such as coil spring 46, connected to be compressed in response to movement of piston 42.

In FIG. 3, it can be seen that a first fluid retaining chamber means is generally designated 48 and includes a pair of chambers 50 formed in housing 30. The pair of chambers 50 receive the first recoil means or the pair of pistons 32.

A second fluid retaining chamber means generally designated 52 comprises a main chamber 54 which is formed in housing 30 and receives the second recoil means or piston 42. Conduits 44 fluidly connect the pair of chambers 50 with the main chamber 54.

Referring now to FIG. 4, only one of the pair of chambers 50 will be discussed in detail since each of the pair is a duplication of the other.

Housing 30 of support frame 12 is preferably of fabricated steel and includes chamber 50 for retaining fluid 56, preferably thirty weight oil, and for slidably receiving piston 32 therein. Chamber 50 preferably has a circular cross-section defined by annular peripheral wall 62 and is open at first end 58 and closed at second end 60 to form a cylindrical chamber. It is preferred that a passage 84 is provided through annular wall 86 for venting chamber 50 Main chamber 54 is also formed in housing 30 and is preferably centrally displaced between and slightly to the rear of chambers 50 as illustrated in the Figures. Chamber 54 preferably has a circular cross-section defined by annular peripheral wall 64 and is closed at first end 66 and open at second end 68 to form a cylindrical chamber.

As stated above, chambers 50 and main chamber 54 retain oil 56 and those chambers are interconnected by conduit 44 for communicating oil 56 from closed end 60 of chamber 50 to closed end 66 of chamber 54.

A wear sleeve 70, preferably a fabricated steel tube, has an annular wall 86 and is inserted into cylindrical chamber 50 and retained therein by a steel retainer or snap ring 72 engaged in wall 62 of chamber 50.

Preferably, a pair of annular grooves 76 are formed in the inner annular surface 78 of wall 86. The grooves 76 are preferably spaced apart at some predetermined interval which is not deemed to be a critical distance.

Removal of retainer ring 72 facilitates removal of sleeve 70.

Annular bearing rings 88, preferably of some suitable synthetic dry lubricating material, such as polytetrafluoroethylene or the like, are retained in grooves 76 for slidably receiving piston 32. Alternatively, other lubricating material can be provided if desired.

Piston 32, as stated above, has its first end 34 connected to idler 20 at pin 80. Piston 32 extends into sleeve 70 so that its outer peripheral surface 82 is in sliding contact with bearings 88. Second end 40 of piston 32 is in contact with oil 56 adjacent closed end 60 of chamber 50. An annular sealing "0" ring 90 of a suitable well known material is preferably carried by second end 40 of piston 32 for sealing oil 56 in chamber 50. Also an annular sealing "0" ring 92 is in sealing engagement between piston 32 and chamber 50 adjacent second chamber end 58. Preferably, seal 92 is retained in position by a removable retainer ring 94.

Conduit 44 extends from closed end 60 through wall 62 of chamber 50 and through wall 86 of sleeve 70 to closed end 66 of chamber 54.

Piston 42 is slidingly received in chamber 54. Piston 42 includes a first end 98 adjacent closed end 66 of chamber 54. First end 98 preferably carries a suitable well known "0" ring type seal 99 mounted thereon and retained in place by retainer ring 100. A second end 102 of piston 42 is adjacent open end 68 of chamber 54 and preferably also carries a sealing "0" ring type seal 103 mounted thereon and retained in place by retainer ring 104.

It is also preferred that a pair of spaced annular grooves 106 are provided in piston 42 for retaining a pair of bearing rings 108, similar to rings 88 as stated above for limiting wear of piston 42 sliding in cylinder 54.

Oil 56 preferably fills chambers 50 and 54 and their interconnecting conduit 44 so that movement of piston 32 toward second chamber end 60 will displace oil 56 from chamber 50 to chamber 54 causing expansion of chamber 54 and the resultant movement of piston 42 in response thereto.

Piston 42 is permitted to move in response to displacement of oil 56 into expanding chamber 54 since second end 102 is connected to a pressure plate 110 which is urged against third recoil means 28 comprising coil spring 46. The spring is preferably retained in position due to a compressive preload acting on plate 110 and due to a retaining nub 112 mounted on plate 110 and extending partially within coil spring 46.

Preferably, a well known annular threaded member 114 is provided for threaded engagement at mating threads 116 of housing 30.

Threaded member 114 permits an adjustable preload to be exerted on plate 110 and coil spring 46.

In operation, with the members assembled as stated above, a rearward movement of idler 20, as viewed in the Figures, causes a responsive movement of pistons 32 toward ends 60 of chambers 50. As a result, oil 56 is displaced as chambers 50 decrease in volume thus displacing the oil from ends 60 of chambers 50 through conduits 44 to end 66 of chamber 54. The displaced oil 56 causes a corresponding increase in volume of chamber 54 and a responsive moving piston 42 toward second end 68.

Piston 42 acts directly on plate 110 which moves in response movement of piston 42 causing compression of spring 46.

Due to the sliding engagement between pistons 32 and rings 88, metal-to-metal contact between relatively movable parts is avoided. Similarly, the sliding engagement between piston 42 and rings 108 avoids metal-to-metal contact between relatively moving parts.

The foregoing has described a recoil device which substantially avoids the previously known debris accumulation problems and the sliding metal-to-metal wear contact of the prior art.

WHAT WE CLAIM IS: 1. A track-laying vehicle undercarriage having a track idler with a recoil device which comprises a housing; first recoil means operably connected for relative movement with the housing in response to movement of the idler; second recoil means operably connected for relative movement with the housing in response to movement of the first recoil means; third recoil means operably connected for movement in response to movement of the second recoil means; and a wear sleeve removably mounted in the housing in wear receiving engagement with the first recoil means.

2. An undercarriage according to claim 1, further comprising first and second fluid retaining chambers in the housing for receiving respectively the first and second recoil means.

3. An undercarriage according to claim 2, wherein the first fluid chamber is in fluid communication with the second fluid chamber.

4. An undercarriage according to claim 2 or claim 3, wherein the first fluid retaining chamber slidably receives the first recoil means; and the second fluid retaining chamber slidably receives the second recoil means; and the arrangement is such that, in use, fluid is displaced from the first chamber by the first recoil means into the second chamber for moving the second recoil means.

5. An undercarriage according to claim 4, wherein the first recoil means comprises a pair of pistons connected at one end to opposite sides of the idler and mounted at the other end within the housing; the second recoil means comprises a piston which moves in response to movement of the first recoil means; and the third recoil means comprises a resilient member connected to be compressed in response to movement of the second recoil means.

6. An undercarriage according to claim 4 or claim 5, wherein the sleeve is mounted in the first chamber for slidably receiving the first recoil means, the sleeve including an inner annular surface having an annular groove therein and a bearing mounted in the groove for contact with the first recoil means.

7. An undercarriage according to claim 6, wherein the bearing is formed of a lubricating material.

8. An undercarriage according to any one of claims 1 to 4, wherein the wear sleeve carries a lubricating bearing.

9. An undercarriage according to any one of claims 1 to 4 or 8, further comprising adjustable means in the housing for preloading the third recoil means.

10. An undercarriage according to claim 1, substantially as described with reference to the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (10)

**WARNING** start of CLMS field may overlap end of DESC **. metal-to-metal contact between relatively moving parts. The foregoing has described a recoil device which substantially avoids the previously known debris accumulation problems and the sliding metal-to-metal wear contact of the prior art. WHAT WE CLAIM IS:

1. A track-laying vehicle undercarriage having a track idler with a recoil device which comprises a housing; first recoil means operably connected for relative movement with the housing in response to movement of the idler; second recoil means operably connected for relative movement with the housing in response to movement of the first recoil means; third recoil means operably connected for movement in response to movement of the second recoil means; and a wear sleeve removably mounted in the housing in wear receiving engagement with the first recoil means.

2. An undercarriage according to claim 1, further comprising first and second fluid retaining chambers in the housing for receiving respectively the first and second recoil means.

3. An undercarriage according to claim 2, wherein the first fluid chamber is in fluid communication with the second fluid chamber.

4. An undercarriage according to claim 2 or claim 3, wherein the first fluid retaining chamber slidably receives the first recoil means; and the second fluid retaining chamber slidably receives the second recoil means; and the arrangement is such that, in use, fluid is displaced from the first chamber by the first recoil means into the second chamber for moving the second recoil means.

5. An undercarriage according to claim 4, wherein the first recoil means comprises a pair of pistons connected at one end to opposite sides of the idler and mounted at the other end within the housing; the second recoil means comprises a piston which moves in response to movement of the first recoil means; and the third recoil means comprises a resilient member connected to be compressed in response to movement of the second recoil means.

6. An undercarriage according to claim 4 or claim 5, wherein the sleeve is mounted in the first chamber for slidably receiving the first recoil means, the sleeve including an inner annular surface having an annular groove therein and a bearing mounted in the groove for contact with the first recoil means.

7. An undercarriage according to claim 6, wherein the bearing is formed of a lubricating material.

8. An undercarriage according to any one of claims 1 to 4, wherein the wear sleeve carries a lubricating bearing.

9. An undercarriage according to any one of claims 1 to 4 or 8, further comprising adjustable means in the housing for preloading the third recoil means.

10. An undercarriage according to claim 1, substantially as described with reference to the accompanying drawings.