GB2392663A

GB2392663A - Wear pad arrangements for telescopic limb

Info

Publication number: GB2392663A
Application number: GB0220643A
Authority: GB
Inventors: Richard Paul Barnard; Andrew Richard Ellis
Original assignee: Fermec International Ltd
Current assignee: Fermec International Ltd
Priority date: 2002-09-05
Filing date: 2002-09-05
Publication date: 2004-03-10
Anticipated expiration: 2022-09-05
Also published as: GB2392663B; GB0220643D0

Abstract

A telescopically extensible limb, such as a stabilizer leg or a dipper arm for an excavator vehicle, has an outer part (12) and an inner part (16) which is slidable relative thereto and wear pads (21-24) disposed therebetween to provide packing, guide the inner part (16) as it slides and prevent rattle and excessive wear of the parts. Adjustment as the pads (21-24) wear is provided for in that the inner part (16) has at least one sloping abutment face and the wear pad (21-24) adjacent thereto is wedge shaped, having a tapered portion which opposes the sloping abutment face. At least one of these wedge shaped pads (21, 22) is slidingly displaceable to maintain contact with the sloping abutment face and with an opposing surface of the other part (12) of the limb by means of an adjustment member, such as a bolt (25, 26) which extends through the outer part (12) and is adjustable relative thereto. In other examples the sloping abutment face may be on the outer part of the limb and/or the outer part may be slidable relative to a fixed inner part.

Description

- P650926GB

WEAR PAD ARRANGEMENTS FOR TELESCOPIC LIMB

The present invention relates to a telescopic limb, which may be, for example, a stabilizer leg for a vehicle, such as an excavator, or part of a stabilizing frame for such a vehicle, or a dipper arm of an excavator vehicle. More particularly, the invention concerns an adjustable wear pad arrangement for any of these or other types of telescopic limb.

A telescopic limb comprises an outer part and an inner part, at least one of which is slidable relative to the other, and a wear pad disposed therebetween. Conventionally, the outer part is a fixed upper housing and the inner part is slidable therein to project from a lower end thereof. The purpose of the wear pad, of which there is generally more than one, is to provide packing, to guide the inner part as it moves relative to the outer housing and to prevent rattle which exacerbates wear on the parts and decreases efficiency of operation.

In prior art telescopic limbs, the wear pads are accessible

via apertures in the outer part, which apertures, in use, are closed by bolt on plates. After prolonged operation of the limb, when the pads become worn and the inner part is no

longer a close sliding fit (i.e. it has become loose and rattling), the plates can be removed and additional packing or shims inserted behind one or more of the wear pads, or the wear pads can be replaced.

GB 2327216 discloses a stabilizer leg having an adjustable wear pad which is threadedly engaged through an aperture in the outer part of the limb. Its clearance relative to the inner part can then be adjusted by rotation, using a tool inserted into an external socket of the wear pad.

An object of the present invention is to provide an adjustable wear pad arrangement which is applicable to any form of telescopic limb and does not involve direct threaded engagement between the wear pads and either part of the limb.

According to the invention a telescopically extensible limb as referred to above is characterized in that at least one of the outer part and the inner part has a sloping abutment face and the wear pad is wedge shaped, having a tapered portion which opposes the sloping abutment face, and is slidingly displaceable to maintain contact with said abutment face and with an opposing surface of the other part of the limb by means of an adjustment member which extends through the outer part and is adjustable relative thereto.

There may be two adjustment members provided for slidably displacing the wear pad. Such respective adjustments members are preferably located adjacent upper and lower ends of the wear pad.

Conveniently, the or each adjustment member comprises a bolt which threadedly engages through the outer part.

The outer part may be substantially rectangular in section and the wear pad disposed inside one corner thereof.

The inner part may be polygonal in cross-section.

In practical embodiments of the invention there will probably be several wear pads disposed between the inner and outer parts. At least one, often two of these pads will be adjustable. The others may be fixed or nonadjustable. They may be arranged inside respective corners of the outer part, where the outer part is rectangular. However, other arrangements are possible, including inside each of four sides of a substantially rectangular outer part. The arrangement may depend on the cross-sectional shape of the inner part, which may be, for example, octagonal or hexagonal, or rhomboid, or trapezoid, or rectangular but offset about 45 relative to the outer part, when it is rectangular. Also wear pads may be arranged above each other at the same location

- 4 around the inner and outer parts. This will depend on the size of the telescopic limb to which they are mounted.

The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of a stabilizer leg in accordance with the invention; Fig. 2 is a greatly enlarged plan view of the stabilizer leg of Fig. 1, omitting its support foot and central hydraulic cylinder; Fig. 3 is a fragmentary perspective view of a support frame in accordance with the invention; Fig. 4 is a perspective view of a telescopic excavator dipper arm in accordance with the invention; and Fig. 5 is a further view of the dipper arm of Fig. 4 with a bucket and its operating cylinder attached thereto.

Referring firstly to Figs. 1 and 2, a first embodiment of the invention comprises a telescopic stabilizer leg 10, as may be used with an excavator or other earth moving vehicle, or a vehicle provided with an overhead working platform or the like, and which may form part, together with another similar

- 5 - leg, of a stabilizing frame for such a vehicle, such a frame 30 being shown in Fig. 3.

The leg 10 comprises an outer part in the form of a housing 12 inside which an inner part in the form of hollow element 16 is telescopically slidable by means of a hydraulic 18, which is mounted internally of the leg 10. The outer housing 12 is uppermost. It is substantially rectangular in section and is formed from a U-section profile having its open side closed by a wall 14. The inner element 16 is substantially octagonal in section, and carries a foot 20 at its lower end. It is slidable out and in of the lower end of the housing 12 under the action of the ram of the cylinder 18. The cylinder 18 is mounted on a pin (not shown) which extends between bosses 28 provided near the top of the outer housing 12.

At the lower end of the outer housing 12, four wear pads 21, 22, 23, 24 are positioned between the housing 12 and the inner element 16, as best shown in Fig 2. These pads are retained within the housing 12 by a peripheral inwardly extending flange at the base of the housing, through which the inner element 16 extends with a narrow clearance. In crosssection, the pads 21, 22, 23, 24 are irregular hexagons of generally tapering form and having three abutment surfaces. The pads are disposed inside the corners of the outer housing 12. Two of the pads 21, 22, disposed in adjacent corners, are adjustable by means of bolts 25, 26, which extend through the

- 6 - outer housing 12 and respective external supporting bosses 35, 36, and are threadedly engaged therewith. By tightening the bolts 25, 26, i. e. screwing them inwardly of the limb, the pads 21, 22 are slidingly displaceable towards each other with abutment surfaces of their tapering portions in sliding contact with a sloping surface of the octagonal inner element 16 and with an opposing surface of the outer housing 12, respectively. Locknuts 39 are provided on the bosses 35, 36 to secure the bolts 25, 26 once they have been adjusted.

The other two of the pads 23, 24 have a surface which is maintained in contact with a sloping surface of the inner element 16 by pressure on the latter from the adjustable pads 21, 22.

The pads 21, 22 are elongate and two bolts 25, 26 act on each of them, one near the upper end of each pad, one near the lower end, as shown in Fig. 1. This optimizes surface contact between the tapering portion of each pad 21, 22 and the inner and outer parts 16, 12 of the limb 10.

The pads 21, 22 are not required to tightly clamp the inner element 16 They are merely required to maintain contact with both inner and outer parts so as to permit sliding of the former without excess play. In this respect the pads 21-24

are made of low friction material, such as nylon, but nevertheless become worn where they abut the inner part, necessitating periodic inward adjustment of the bolts 25, 26.

Additional guide pads 31-34 are provided inside each side of the outer housing 12, at a spacing well above the adjustable pad arrangement 21-24.

Fig. 3 shows a second embodiment of the invention in the form of a stabilizing frame 30. This comprises two stabilizer legs 40, 50, each very similar to that just described, having their respective outer parts 42, 52, connected by upper and lower cross-pieces 37, 38. The telescopically slidable inner parts are not shown here, but their arrangement and function and the provision of respective sets of wear pads, including adjustable pads, is just as already described for Figs. 1 and 2. The final illustrated embodiment is a telescopic dipper arm 60 for an excavator vehicle, as shown in Figs. 4 and 5. This again comprises an outer housing 44 of substantially rectangular section, inside which an inner hollow element 46 of octagonal section is telescopically slidable by means of an internally mounted hydraulic cylinder (not shown). Bosses 41, 43 are provided at the lower end of the inner part 46 for pivotal attachment of an excavator bucket 45, which is shown in Fig. 5. A bracket 47 is provided on the outer housing 44

- 8 for attachment of an external cylinder 48, as shown in Fig. 5, for operation of the bucket 45.

Inside the lower end of the outer housing 44, an arrangement of eight wear pads are mounted, two inside each corner region of the housing, one above the other with a spacer or support plate therebetween. A peripheral flange 49 and one of two support plates 59 retaining the pads at the base of the housing 44 are visible and similar support plates (not shown) preventing upward sliding of the pads during movement of the arm are provided. Two pads are used in each corner because the dipper arm 60 is larger and longer than the previous stabilizer leg 10, and a greater pad area is preferred for sliding contact of the inner element 46 during its operation.

As in the earlier leg embodiments, the pads at two adjacent corners are adjustable by means of two bolts each through the outer housing 44. Bosses 54 for threadedly receiving these bolts are clearly shown for one pair of pads.

A flange 56 is provided for protection of the bolts and their mounting bosses 54 from impact damage. The pairs of pads at the other two corners are non-adjustable and are kept in sliding contact with the inner part 46 by pressure from the adjustable pads.

- 9 - Additional guide pads may be provided higher up the dipper arm 60 between the inner element 46 and the outer housing 44.

The invention is not limited to specific details of the foregoing embodiments. Many variations in the mounting positions and details of the adjustable and non-adjustable wear pads are possible. For example, all the pads, or only one may be adjustable, or any number, as required. Also such an arrangement is applicable to any type of telescopic limb, the section shapes of the inner and outer parts may vary from those described. Use of bolts for adjustment is not essential and socket head screws or other similar items could be used instead. Also, in place of each locknut several washers could be provided with a washer removed at each adjustment to define the tightened bolt position.

Claims

- 10 CLAIMS

A telescopically extensible limb comprising an outer part and an inner part, at least one of which is slidable relative to the other, and a wear pad disposed therebetween, characterized in that at least one of the outer part and the inner part has a sloping abutment face and the wear pad is wedge shaped, having a tapered portion which opposes the sloping abutment face, and is slidingly displaceable to maintain contact with said abutment face and with an opposing surface of the other part of the limb by means of an adjustment member which extends through the outer part and is adjustable relative thereto.
2. A limb according to claim 1 wherein two adjustment members are provided for slidably displacing the wear pad.
3. A limb according to claim 2 wherein the respective adjustments members are located adjacent upper and lower ends of the wear pad.
- 11 A limb according to claim 1, 2 or 3 wherein the or each adjustment member comprises a bolt which threadedly engages through the outer part.
5. A limb according to any preceding claim wherein the outer part is substantially rectangular in section and the wear pad is disposed inside one corner thereof.
6. A limb according to any preceding claim wherein the inner part is polygonal in cross-section.
7. A limb according to any preceding claim including at least one further wear pad disposed between the outer and inner parts.
8. A limb according to claim 5 including a further wear pad disposed inside an opposing corner of the outer part to the first wear pad.
9. A limb according to claim 8 wherein the further wear pad is fixed in position.
10. A limb according to claim 8 wherein the further wear pad is not slidingly displaceable.
11. A limb according to claim 5 and 7 wherein a further, slidingly displaceable wear pad is disposed inside an adjacent corner of the outer part.
12. A telescopic stabilizer leg substantially as hereinbefore described with reference to and as illustrated by Figs. 1 and 2 of the accompanying drawings.
13. A stabilizer frame incorporating two extensible limbs as claimed in any preceding claim.
14. An excavator dipper arm substantially as hereinbefore described with reference to and as illustrated by Figs. 4 and 5 of the accompanying drawings.