Patent Application
20120119567
This disclosure relates generally to chain for a track work machine and, more particularly, to a cartridge assembly for coupling links disposed on opposite sides of the chain together.
Track work machines utilize articulating track chains for propelling the work machines over the terrain during operation. Such track chains operate in extremely adverse environments in which track joints may be exposed to various abrasive mixtures of water, dirt, sand, rock and/or chemical elements and to wide temperature ranges varying from high heat in deserts and extreme cold in arctic regions. Consequently, seals are placed in the track joints and must be maintained to ensure that the seal will effectively exclude contaminants and retain lubricant during use.
Typical track chain designs include a track pin either rotatably or fixed to a pair of chain links or two pairs of chain links and have a bushing rotatably positioned between the links and about the track pin. These designs have included a variety of seal configurations and positions such as against an inside face of the link or against the track bushing. Some typical cartridge assemblies include a bushing with a pair of bearing members positioned adjacent each end face of the bushing. The bearing members and the bushing are retained by a pair of collars that are press fit or welded to the ends of the track pin. Seal grooves are positioned in each end of the bearing members and the collars in which a seal arrangement may be placed. The seal arrangements push against the end faces of the bushing and the end faces of the bearings. However, despite the use of two seals at either end of the bushing, keeping the seal areas free from contaminants and the positioning of the seals remains problematic. Therefore, improved designs are needed.
In one aspect, a cartridge for a track chain for a track undercarriage is disclosed. The cartridge includes a bushing including two opposing ends. Each end of the bushing includes an annular seal pocket. Each pocket accommodates a seal.
In another aspect, a cartridge for a track chain is disclosed. The cartridge includes a pin that passes axially through a bushing. The bushing includes two opposing ends and a cylindrical outer surface extending between the two opposing ends. Each end of the bushing may include an annular seal pocket for accommodating a seal and an annular step groove for coupling each end of the bushing to an inner track link. The bushing may be axially disposed between two inserts and the seals are track seals that each engages one of the inserts. The inserts are axially disposed between two collars. The collars may be coupled to the pin. The collars may each include annular seal pockets. By moving the seal pockets from the inserts or bearings to the bushing, wider inserts may be employed for improved insert retention.
In yet another aspect, a method of replacing an existing cartridge of an existing link subassembly of a track chain is disclosed. The method includes detaching ends of the track chain at a master link. The method further includes removing the existing cartridge from the existing link subassembly that includes two pairs of inner and outer links. The method further includes providing a new cartridge for the link subassembly. The new cartridge includes a pin that passes axially through a bushing. The bushing includes two opposing ends and a cylindrical outer surface extending between the two ends. Each end of the bushing may include an annular seal pocket for accommodating seals and an annular step groove for coupling each end of the bushing to an inner track link. The bushing may be axially disposed between two inserts and the seals are track seals that each engages one of the inserts. The method also includes press fitting the cartridge between the two pairs of inner and outer track links.
In any one or more of the aspects described above, the bushing may include annular step grooves for coupling each end of the bushing to an inner track link. In any one or more of the aspects described above, the bushing may be disposed between two inserts or bearings. In combination with any one or more of the aspects described above, the seals disposed at the ends of the bushings may be track seals that each may engage one of the inserts. In any one or more of the aspects described above, each insert may be disposed between a collar and a bushing and the two collars may be coupled to the pin that extends axially through the bushing. The collars may each include annular seal pockets. In combination with any one or more of the aspects described above, a thrust ring may be disposed between each annular seal pocket of each collar and the pin. In combination with any one or more of the aspects described above, each collar may be disposed between the pin and an outer link. In combination with any one or more of the aspects described above, each insert or bearing may be disposed between the pin and an inner link.
The assembly 30 illustrated in
Thrust rings 34, 35 may be disposed between the collars 31, 32 and inserts 25, 26. Additional annular seal pockets 36, 37 may be formed by the collars 31, 32, the thrust rings 34, 35 and the inserts 25, 26. As will be apparent to those skilled in the art, the annular seal pockets 36, 37 could be formed entirely by the collars 31, 32 or they could be formed entirely by the bearings or inserts 25, 26. Other designs will also be apparent to those skilled in the art. The annular seal pockets 36, 37 also accommodate seals 38, 39 which, in the embodiments illustrated, may be track seals. Of course, other types of seals will be apparent to those skilled in the art. Additional wear resistant layers or tips 41, 42 may be provided on the seals 38, 39 for engaging the inserts 25, 26 respectively. The interior 44 of the pin 33 may be sealed with plug assemblies shown generally at 45, 46.
Thus, the outer links 12, 14 ride on the collars 31, 32 which are secured to the pin 33. The inner links 11, 13 ride on the inserts 25, 26 (or bearings 25, 26). The bushing 10 may be coupled to the inner links 11, 13 by the annular step grooves 47, 48. As illustrated in
Still referring to
The inner and outer links 11, 12, 13, 14 may include main body portions 51, 52, 53, 54 as well as shoe abutment surfaces 55, 56, 57, 58. Each link 11, 12, 13, 14 may also include a rail surface 61, 62, 63, 64.
The cartridge assembly 30 illustrated in
The thickness of the bushing 10 has been increased over prior art bushings to provide for thicker inserts 25, 26, 125, 225 for improved insert retention. Also contributing to insert retention is the placement of the seal pockets 17, 18 in the bushing 10 as opposed to the inserts 25, 26.
An engagement between the cartridge assembly 30 and an idler 81 is illustrated in
Cartridge assemblies for track chains of track undercarriages are shown and described. The disclosed design provides stronger bushings, improved insert (bearing) retention, wider inserts and improved annular seal designs which reduce dirt and contamination and therefore premature wear of the seals. A bushing design is also disclosed with annular seal pockets disposed at each end of the bushing. The improved bushing design also includes annular step grooves or annular steps for coupling each end of the bushing to the inner track link. The geometry of the inserts or bearings disposed at either end of the bushing may be varied to improve insert retention. Thrust rings may be included between the outer collars and the inner inserts or thrust rings may be formed from the collars and/or inserts themselves. A second or outer annular seal pocket may be formed by the insert, collar and thrust ring.
To replace existing prior art cartridges with the disclosed cartridges, the chain may be detached at the master link prior to removal of an existing cartridge in need of replacement. The new cartridge, which includes a pin passing axially through an improved bushing with outer annular seal pockets, two insert and two collars may be press fitted through the inner and outer links.
