Draft gear assemblies for cushioning buff and draft shocks encountered during make-up and operation of a railway vehicle are well known in the art to include a housing having a closed end and an open end, a compressible member disposed within the closed end and a friction mechanism disposed within the open end. Lately, various railroads and operators of railway vehicles have been seeking both the increased loading of the railway vehicles and capability of the draft gear assembly to withstand higher dynamic impact loads.
Prior to the conception and design of the present invention, efforts have been made to eliminate the draft gear housing in order to increase the loading capacity of the railway vehicle. U.S. Pat. No. 6,446,820 issued to Barker et al. discloses one type of such effort, wherein the draft gear assembly which has a yoke, a coupler follower, a rear follower, a front resilient member and a back resilient member. The yoke has top and bottom stops. The coupler follower is biased against the yoke top and bottom stops. The draft gear assembly also includes a center rod that extends through the yoke, through the back resilient member and through the rear follower. The rear end of the center rod is threaded and receives a threaded fastener to retain the rear follower and the back resilient member. However, it has been found that during repetitive use the center rod is not sufficient to maintain axial alignment of the back resilient member resulting in loss of lateral stability of pads and plates and further resulting in decreased performance and decreased reliability of the draft gear assembly. It has been further found that this draft gear assembly does not resist overcompression of the back resilient member further resulting in decreased reliability and increased maintenance costs.
Therefore, there is a continuing need for a lighter and reliable draft gear assembly capable of absorbing high dynamic impact loads.