Fastening Plate for Sprocket Segments

This invention relates generally to sprocket teeth segments for track-type machines and more particularly to a fastening plate for securing the sprocket teeth segments to the machine.

Earthmoving and construction type machines, which have endless self-laying track chain assemblies for support and propulsion, generally utilize a sprocket wheel to engage and drive the track chain. Several different types of sprocket wheels have been used in the past. These include a single wheel member having a plurality of integral teeth, hub members which accommodate a plurality of separate individual teeth, and a circular support member for supporting multiple segments, with each segment having several teeth. Each segment is generally connected to the circular support member by a plurality of threaded fasteners and cooperating threaded nuts.

One type of drive sprocket having a plurality of separate individual teeth connected to a hub portion is disclosed in U.S. Pat. No. 2,365,544, issued to H. D. Geyer et al. on Dec. 19, 1944. In this patent, the teeth are fulcrumed to the hub portion somewhere near the middle of the teeth so the teeth can rotate in either direction about the fulcrum. Resilient means are provided to return the teeth to their original no load position. This arrangement is intended to make the teeth self-adjusting to accommodate variations in the track chain.

Another type of sprocket wheel, having a plurality of segments with several teeth on each segment, is shown in U.S. Pat. No. 4,511,186, issued to T. Sasamoto on Apr. 16, 1985. In this patent, the teeth segments are connected to an outer tube by a plurality of threaded bolts and nuts.

Each of the above-noted sprocket assemblies provides replaceable drive teeth, either individually or in segments. However, the teeth are secured to a support member so that they are intended to deflect, or by bolts and nuts which may allow deflection of the segments under heavy loads.

The present invention is directed to overcoming one or more of the problems, as set forth above.

In one aspect of the present invention, a fastening plate for connecting a multi-toothed sprocket segment to a support member includes an arcuate shaped metal bar having a substantially flat planar surface. The planar surface is adapted to contact the sprocket segments when the segments are installed on the support member. The metal bar has a plurality of threaded or non-threaded through holes which are used in conjunction with threaded fasteners to connect the sprocket segments to the support member.

In self-laying track-type machines utilizing endless track assemblies, the driving power from the machine is transferred to the endless track assemblies by multiple toothed sprocket wheels. In large size machines the torque applied to the sprocket teeth can be of large magnitude. It is advantageous to make the sprocket wheels from a plurality of individual segments, with each segment having a plurality of teeth and being bolted to a support member. Ideally, each segment would have as few teeth as possible, such as four or five teeth. However, to prevent the segments from slipping under high forces, some segments require as many as nine teeth and nine bolt and nut assemblies.

The subject invention utilizes threaded or non-threaded fastening plates to secure the sprocket segments to the support member. The fastening plates provide increased clamping surface area to resist torque forces and reduce tangential slippage of the individual sprocket segments. If non-threaded fastening plates are used, conventional threaded fasteners and nuts are used to secure the fastening plates and sprocket segments together.

FIG. 1 is a diagrammatic side elevational view of a work machine incorporating the subject invention;

FIG. 2 is an enlarged diagrammatic side elevational view of a sprocket assembly incorporating the subject invention; and

FIG. 3 is an enlarged diagrammatic sectional view, taken generally along lines 3--3 of FIG. 2.

Referring to the drawings, a work machine 10, such as a self-laying track-type machine 10, has a power drive system 12, a drive sprocket assembly 14, first and second idler wheels 16,18, and an endless track chain assembly 20 which encircles the sprocket assembly 14 and the idler wheels 16,18. The sprocket assembly 14 is adapted to transfer power from the machine 10 to the track assembly 20.

The sprocket assembly 14 includes a circular support hub 22 which has a flange portion 24. The flange portion 24 defines a plurality of first apertures 26. The sprocket assembly 14 further includes a plurality of arcuate shaped teeth segments 28, a plurality of fastening plates 30, and a plurality of threaded fasteners 32. The teeth segments 28 are adapted to engage and encircle the flange portion 24 and form a sprocket wheel 34. Each teeth segment 28 has a plurality of teeth 36 and defines a plurality of second apertures 38. Although each segment 28 is illustrated with five teeth, the number of teeth 36 on each segment 28 can vary between two and up to one-half the number of teeth on the sprocket wheel 34. Adjacent segments 38 may also have a different number of teeth 36, such as four teeth 36 on one or more segments 38 and five teeth 36 on one or more other segments 38.

The fastening plates 30 and the threaded fasteners 32 are adapted to connect the multi-toothed sprocket segments 28 to the flange portion 24 of the support hub 22. Each fastening plate 30 includes an elongated arcuate shaped metal bar 40 which has a plurality of threaded through holes 42 and a substantially flat planar surface 44. In the installed condition of the segments 28 and the fastening plates 30 on the support hub 22, the planar surface 44 of each metal bar 40 is adapted to contact the segments 28.

The teeth segments 28 are arranged in a circular pattern around the support hub 22 and a joint 46 is formed at the juncture between adjacent segments 28. Preferably, each of the fastening plates 30 spans one of the joints 46 and is therefore in contact with a portion of two adjacent segments 28. In the installed condition, each of the threaded through holes 42 aligns with one of the first apertures 26 in the support member 22 and with one of the second apertures 38 in the segments 28. A threaded fastener 32 then penetrates the first and second apertures 26,38 and engages the threaded holes 42 to securely connect the segments 28 to the support member 22. Because of the additional surface contact provided by the fastening plates 30, the potential for tangential slippage of the teeth segments 28 under load is greatly reduced.

The subject fastening plates 30 are particularly useful for securely connecting a plurality of teeth segments 28 to a support member 22 for forming a sprocket wheel 34. The segments 28 are connected to the support member 22 by a plurality of threaded fasteners 32 which engage threaded holes 42 in the fastener plates 30 to clamp the segments 28 between the flange portion 24 and the fastening plates 30. In some applications, the holes 42 will not be threaded and threaded fasteners 32 and conventional nuts will connect the segments 28 and the fastening plates 30 to the support member 22. The flat planar surfaces 44 of the fastening plates 30 provide additional surface area to reduce the potential for tangential slippage of the segment 28 under load. The potential for slippage is also reduced because each of the fastening plates 30 spans a joint 46 between adjacent teeth segments 28, and is therefore in contact with a portion of at least two adjacent segments 28.

Other aspects, objects and advantages of this invention can be obtained from a study of the drawings, the disclosure, and the appended claims.