POSITIONAL VARIABLE ORIFICE PIN FOR HYDRAULIC PRESSURE CONTROL IN A DRAFT GEAR

摘要

A draft gear assembly (10) including a housing (12) having an open front and closed rear portions (14). A compressible cushioning element (18) is positioned within the rear portion with a seating arrangement abutting one end thereof adjacent the open front portion. A friction cushioning element (42) is provided in the open front portion of the housing. A spring release mechanism (76) continuously urges the friction cushioning element outwardly from the compressible cushioning element thereby releasing such friction cushioning element after compression of such draft gear assembly. A compressible cushioning element includes a hydraulic cylinder (102) having a slidable piston (122) to define a high pressure chamber and a low pressure chamber. A positional variable metering assembly is disposed within the piston to increase the reaction fluid pressure in the low pressure chamber for increasing the shock absorbing capacity of such draft gear assembly during operational buff conditions and to reduce the reaction fluid in the low pressure chamber pressure for meeting the requirements of the drop hammer test.