1. Field of the Invention
This invention relates to the art of slackless railcar connections such as couplers, drawbars, articulated connectors and the like having a gravity wedge component that functions to move downwardly so as to fill up the space created when the other parts of the slack-free system wear. More specifically, it is directed to an improved follower block which contains lubrication retention grooves for retaining and communicating a lubricant between the follower block and the coupler end in order to reduce the lateral coupling friction which could contribute to wheel lift and possible derailment.
2. Description of the Related Art
Slackless coupling systems are well known in the art wherein the principle object of these types of coupling systems is to hold the coupler member in such a way as to minimize longitudinal movement with respect to the car body. When the coupling system is first assembled, clearances between the components are minimal and there is virtually no slack or movement of the components longitudinal of the car. However, wear eventually develops through use (deemed free slack) and the cumulative effect is to magnify the longitudinal impact forces caused by free slack.
Slackless coupling systems have cured this problem by adding a gravity wedge between the follower block and the closed end of the pocket sill casting. The wedge tends to force the follower block away from the pocket casting end wall and firmly against the butt-end of the coupler member. When cars are being pushed, the longitudinal buff loads cause compression of the coupler member against the follower, wedge and pocket casting end wall. When cars are being pulled, the longitudinal draft loads tend to separate the coupler from the pocket casting. Upon separation, the gravity wedge descends to fill up the slack and once again, maintain contact between the coupler, follower, and pocket casting. Examples of slackless railcar connections are shown in U.S. Pat. Nos. 5,035,338; 4,700,853; and 4,593,829. Typical in such slackless systems, the mating faces of the follower block and gravity wedge, as well as the follower block and coupler are preferably curved to permit the coupler to pivot slightly both vertically and laterally. Since slack-free connections as those just described are usually under some longitudinal loading from the action of the gravity wedge under draft or buff loading, it is desirable to reduce the frictional resistance present during vertical and lateral angling. It has been found that under high longitudinal buff loading the frictional forces at the follower block/coupler interface might create lateral force components high enough to cause wheel lift. Wheel lift is a condition where the wheel of a railway truck is actually disengaged from the rail. This condition is especially pronounced when railcars are forced to undergo extreme cornering or curving conditions, as when being switched at low speed, within a rail yard. Under certain conditions, wheel lift can lead to a derailment.