IDLER WHEEL ASSEMBLY FOR A TRACK-LAYING VEHICLE

Abstract: An idler wheel assembly (20) for a track-laying vehicle (10) has a hub member (30) and a plurality of replaceable wear segments (50,52) positioned around the circumference of the hub (30). A plurality of U-shaped grooves (42,44) in the circumferential surface of the hub (30) receive resilient means (46,48). The wear segments (50,52) also fit within the grooves (42,44) and hold the resilient means (46,48) in place. A plurality of clamping members (54) encircle the hub (30), overlap the wear segments (50,52), and clamp the resilient means (46,48) between the wear segments (50,52) and the grooves (42,44) as they are secured to the hub (30). The wear segments (50,52) are therefore resiliently isolated from the idler hub (30).

Description: This invention relates to an idler wheel assembly for a vehicle and having a plurality of individual replaceable wear segments which cooperate to form a continuous tread surface with the wear segments being resiliently isolated from a hub of the idler wheel. Earthmoving and construction vehicles which utilize self-laying endless track chain assemblies for support and propulsion generally include one or more idler wheels for guiding and supporting portions of the track chain. Since the track chains include metal connecting links, which contact metal tread portions of the idler wheel during the track guiding function, considerable noise and vibration is generated by the metal to metal contact of the moving components. One type of idler wheel having a plurality of replaceable rim segments and elastomeric cushioning means disposed between the rim segments and a flange of the wheel is disclosed in US. Re. 30,039. In that patent specification, elastomeric strips and disposed between each rim segment and the flange of the wheel. The segments are secured to the wheel flange by screw threaded fasteners. A clearance is provided between the bottom of the rim segments and the wheel flange. Although this arrangement functions to cushion the noise and vibrations from mating track components, the threaded fasteners could possibly work loose when the elastomeric strips compress and the clamping force of the fasteners is reduced. Another type of cushioned wheel for track-laying vehicles is disclosed in US-A-3,606,497 In that disclosure, the entire outer surface of the wheel is covered with a layer of elastomeric material, such as rubber. Although this arrangement would appear to cushion the mating track components sufficiently, the elastomeric material is subject to rapid wear and deterioration. It is also subject to being torn from the wheel by impact with various foreign objects. According to the present invention, an idler wheel assembly for a track-laying vehicle comprises a circular hub having first and second side portions and a circumferential surface portion, the surface portion having a central support surface, first and second contact surfaces, and first and second U-shaped circumferential grooves, each positioned between a respective one of the contact surfaces and the central support surface; a plurality of first wear segments positioned within the first groove, and a plurality of second wear segments positioned within the second groove; resilient means located within the grooves and positioned between the hub and the wear segments; a plurality of clamping members, the clamping members encircling the hub, contacting the wear segments and compressing the resilient means; and means for securing the clamping members to the central support surface of the hub. Track-laying vehicles generate considerably noise and vibration from the interaction of various moving track components. Some of these components are the track idler wheel and the track links which are guided and supported by the idler wheel. The noise is irritating to the machine operator, other workers in close proximity, and anyone else who is close to the work site. The subject invention provides a reduced noise level wheel assembly by isolating the idler wheel treads from the wheel hub with resilient rings. The invention also reduces impact forces so noise radiating from the track is less. In the accompanying drawings:- Fig. 1 is a diagrammatic side elevation of a vehicle incorporating an idler wheel assembly according to the present invention; Fig. 2 is an enlarged diagrammatic view of a portion of the idler wheel assembly with several of the components in exploded position; and, Fig. 3 is an enlarged diagrammatic plan view of the idler wheel assembly with portions in section. As shown in the drawings, a track-laying vehicle 10 includes an engine 12, an operator's station 14, a main frame 16, a powered sprocket 18, and front and rear idler wheel assemblies 20 and 22. The main frame 16 supports a subframe 24, which in turn supports the idler wheel assemblies 20 and 22, as well as a plurality of guide roller assemblies 26. An endless track 28 is driven by the sprocket 18 and encircles the idler wheel assemblies 20,22 and the roller assemblies 26. The idler wheel assemblies 20 and 22 are substantially similar and, therefore, only the front idler assembly 20 will be described in detail. With particular reference to Figures 2 and 3, the idler wheel assembly 20, which supports and guides the endless track includes a circular hub or body 30, which has first and second side portions 32 and 34, a central circumferential support surface portion 36, and first and second circumferential contact, or clamping, surfaces 38 and 40. The wheel assembly 20 further includes first and second circumferential "U" shaped grooves or cavities 42 and 44, with one cavity positioned between each of the contact surfaces 38,40 and the central support surface 36. First and second formed resilient rings 46 and 48 are located within the first and second cavities 42 and 44 respectively. The rings 46 and 48 are preferably formed of natural rubber and have a pre-formed shape which conforms substantially to the shape of the first and second cavities 42 and 44. The ring 46 is held within the cavity 42 by a plurality of hardened metal wear segments 50, and the ring 48 is held within the cavity 44 by a plurality of similar hardened metal wear segments 52. A plurality of arcuate shaped clamping plates 54 encircle the hub 30 and contact the wear segments 50 and 52. The clamping plates 54 are secured to the hub by a plurality of threaded fasteners 56 which penetrate through bores 58 in each plate 54 and engage threaded apertures 60 in the hub surface 36. As the fasteners 56 are tightly engaged with the apertures 60, the plates 54 engage the wear segments 50 and 52 and these segments compress the rubber rings 46 and 48 between the segments 50,52 and the hub cavities 42 and 44. Each of the wear segments 50,52 has a cross-sectional configuration which is substantially similar to the combined cross-sectional configuration of one of the cavities 42,44 and one of the adjacent contact surfaces 38,40. When the wear segments 50 are secured in place in the hub cavity 42, they form a first continuous hardened tread surface 62. Likewise, the wear segments 52 form a second continuous hardened tread surface 64. As the track 28 runs around these tread surfaces 62,64, the resilient rings 46,48 are slightly compressed between the wear segments 50,52 and the hub 30. As is evident from Fig. 3, each of the clamping plates 54 overlaps a portion of one of the wear segments 50 and a portion of one of the wear segments 52. With particular reference to Fig. 2, it can be seen that the wear surfaces 62,64 of the wear segments 50,52 have an arcuate shape. Likewise, the external surfaces of the clamping plates 54 also have an arcuate shape. The arcuate angle of the wear segments 50,52 and the clamping plates is approximately 45°. Industrial Applicability The subject idler wheel assembly 20 is particularly useful with earthmoving and construction vehicles and specifically, track-laying vehicles, such as the vehicle 10. Power from the engine 12 is transmitted to the sprocket 18 which rotates and drives the endless track 28. The track 28 travels around the idlers 20 and 22 and the guide roller assemblies 26. As the metal track 28 contacts the metal wear segments 50,52, noise and vibration are generated. Because the segments 50,52 are isolated from the wheel hub 30 by the resilient rings 46,48, the noise and vibration are not transferred into the wheel hub 30, where is could be amplified. Because the noise level produced by contact between the idler wheel assembly 20 and the track 28 is lower, the vehicle can operate closer to workers and occupied buildings without being objectionable. Also, because the vibrations are damped, the life of the track 28 and vehicle components are prolonged.

Claims: An idler wheel assembly (20) for a track-laying vehicle (10), the assembly comprising a circular hub (30) having first and second side portions (32,34) and a circumferential surface portion, the surface portion having a central support surface (36), first and second contact surfaces (38,40), and first and second U-shaped circumferential grooves (42,44), each positioned between a respective one of the contact surfaces (38,40) and the central support surface (36); a plurality of first wear segments (50) positioned within the first groove (42), and a plurality of second wear segments (52) positioned within the second groove (44); resilient means (46,48) located within the grooves (42,44) and positioned between the hub (30) and the wear segments (50,52); a plurality of clamping members (54), the clamping members (54) encircling the hub (30), contacting the wear segments (50,52) and compressing the resilient means (46,48); and means (56,60) for securing the clamping members (54) to the central support surface (36) of the hub (30). An assembly according to claim 1, wherein the resilient means includes first and second ring members (46,48) having a pre-formed shape which conforms substantially to the first and second U-shaped grooves (42,44) and the first and second contact surfaces (38,40) respectively. An assembly according to claim 1 or claim 2, wherein each of the wear segments (50,52) has a cross-sectional configuration which is substantially similar to the combined cross-sectional configuration of a respective one of the grooves (42, 44) and the adjacent contact surfaces (38,40). An assembly according to any one of the preceding claims, wherein each of the clamping members (54) overlaps a portion of a first wear segment (50) and a portion of a second wear segment (52). An assembly according to any one of the preceding claims, wherein the plurality of first wear segments (50) forms a first continuous circular tread surface (62) and the plurality of second wear segments (52) form a second continuous circular tread surface (64). An assembly according to any one of the preceding claims, wherein each of the clamping members (54) has a plurality of through bores (58) and the securing means (56,60) includes a plurality of screw-threaded apertures (60) in the central support surface (36) and a plurality of screw-threaded fasteners (56), the fasteners (56) penetrating the through bores (58) and engaging the apertures (60). An assembly according to any one of the preceding claims, wherein the resilient means (46,48) includes first and second rings (46,48) of natural rubber. An assembly according to any one of the preceding claims, wherein each of the clamping members (54) has an external arcuate surface portion bounded by an angle of substantially 45°. An assembly according to any one of the preceding claims, wherein each of the first and second wear segments (50,52) includes a hardened wear surface (62,64). An assembly according to claim 9, wherein the wear surface (62,64) of each wear segment (50,52) has an arcuate shape bounded by an angle of substantially 45°.

Inventors: OERTLEY, THOMAS EARL
Applicants: CATERPILLAR INC.
Application year: 1989
Main classification: B62D55
IPC codes: B62D55