| 摘要 |
A hydraulic system (20) including hydraulic units (22, 24, 26, 28) serving as wheel motors and pumps is disclosed. The hydraulic units (22, 24, 26, 28) include stationary members (52, 53) supporting cylinders with piston assemblies (60, 62) reciprocating therein. The piston assemblies (60, 62) have bodies (84) and follower assemblies (82) which follow lobes (50) on a rotary cam (48). The piston assemblies serve both as pistons and as timing valves for controlling the flow of fluids. The piston assemblies (60, 62) may have either undercuts (88, 90, 91) or internal passages (306, 308) in their bodies. The follower assemblies have compliant springs (354, 355) elastically positioning rollers (350) between arms of a yoke (344) to allow lateral movement of these rollers relative to the arm of the supporting yokes. Sealing mechanisms (358) are provided which seal between the rotary cam (48) and the stationary member (52) to form an annular scavenge chamber. At least one sealing mechanism (358) has a non-rotating annular intermediate member (360) which pilots relative to the rotary cam (48). A static seal (380) accommodates radial movement between the stationary and intermediate members. A dynamic seal (384), preferably a ferrofluidic seal, is interposed between the intermediate member (360) and the rotary cam (48). |
