Press fits are used across virtually all industries to couple together machine components. A component having a cylindrical outer diameter is typically pressed into a bore in a second component which includes a cylindrical inner diameter having an interference fit with the outer diameter of the first component. Press fitting the components creates a joint coupling them together. In many instances, the press fit between the components is intended to be permanent, and relatively strong forces are required to de-couple the components. Increasing the relative interference between the components can in some instances increase the “strength” of the press fit, however, there are limits to the practicability of this approach. In particular, too much interference between press fit components can result in galling of the materials' surfaces as they are pressed together, sometimes compromising the integrity of the joint, and certainly preventing re-assembly if the components are ever de-coupled. Various lubrication fluids, pre-heating techniques, and surface knurling strategies have been proposed as ways to enhance the strength of press fits. Nevertheless, certain machine environments are simply so rugged that still stronger press fits continue to be highly desirable.
Track-type machines such as those used in various earth moving, construction, mining and similar industries inherently operate in rugged environments, which can subject press fit joints in the machines to forces sufficient to affect their integrity. The ground engaging tracks of such machines must necessarily be relatively robust and capable of withstanding a wide variety of load types and wear. As such, the components and coupling hardware used in ground engaging tracks are typically manufactured and coupled together in a manner contemplated to provide as long a service life as possible. In certain instances, however, press fits between parts can be overcome by alternating loads on the track components, causing movement of one part relative to another. In extreme cases, movement of one of the parts relative to another part can cause failure of the joint. Moreover, even where failure does not ultimately occur, relative movement between the components can cause seals to become ineffective, lubricant to leak from the assembly, and contaminants to enter the joint. Over time, this phenomenon can also cause failure of the assembly or require expensive and undesired down time for repairs and maintenance.
In an attempt to reduce the tendency for certain track components to experience such failure and wear, engineers have developed a variety of means for increasing the relative strength of press fits used in the track environment. As alluded to above, increased interference between the parts can complicate manufacture and assembly. Leading chamfers and blends, relative hardness and finishes of the parts must also be relatively tightly controlled, and specialized lubricants used for differing amounts of press fit.
Still other strategies for reinforcing or enhancing press fits in machine track have also been proposed. Track pins used to couple together track links may be reinforced by the addition of snap rings, positive pin retention elements, etc. Both of these approaches add a positive stop to prevent a track link from “walking” off of a pin due to repeated alternating loads. U.S. Pat. No. 5,887,958 to Bissi et al. is directed to a track link assembly having positive pin retention. Although approaches such as that of Bissi et al. tend generally to be effective, they inherently require the use of extra parts, and can also mandate increased length and pin sizes, as well as requiring specialized tooling for assembly and manufacture.
The present disclosure is directed to one or more of the problems or shortcomings set forth above.