Abstract: A hydraulic drive system wherein differential pressures across flow control valves are controlled by pressure compensating valves to become the same value, i.e., a differential pressure .DELTA.PLS, and the differential pressure .DELTA.PLS is maintained at a target differential pressure .DELTA.PLSref by a pump displacement control system. For modifying the target differential pressure .DELTA.PLSref depending on change in rotational speed of an engine, a flow rate detecting valve is disposed intermediate between delivery lines of a fixed displacement hydraulic pump and a differential pressure .DELTA.Pp across a variable throttle of the flow rate detecting valve is introduced to a setting modifying unit to thereby modify the target differential pressure .DELTA.PLSref. The flow rate detecting valve changes an opening area of the variable throttle depending on the differential pressure .DELTA.Pp depending on the rotational speed of the engine.

Abstract: A brake booster operated, in particular, by a vacuum has an input member (32), into which an actuating force is introduced, and an output member (42) for emitting an increased force to a downstream subassembly, for example a master cylinder (12). Since each component of the brake booster (10) has a tolerance range, length tolerances necessarily occur along the actuating travel, and these have an undesirable influence on the characteristic of the brake booster and therefore have to be eliminated or at least reduced. In order to avoid a series of sensing disks (36) and distance disks (62) of different thickesses having to be kept ready for length compensation, it is proposed to calibrate the length of the input member (32) and/or of the output member (42) by the compressive forming of the latter to a desired length which is obtained from a comparison between an actual dimension and a desired dimension, and then to install said member in the brake booster (10).

Abstract: A method is provided for extending the system life of variable geometry components, including variable geometry rings, in an engine system by minimizing relative motion incurred from engine vibrations. Initially, the variable geometry rings are de-tuned from resonant engine vibrations. Damping is then introduced to absorb the impact from the relative motion incurred by engine vibrations and to minimize transmission of the relative motion through the variable geometry components.

Abstract: A method for controlling the displacement of a variable displacement hydraulic pump to produce a desired flow of fluid is disclosed. The method includes the steps of: determining that the machine is being operated in a digging cycle; determining a desired displacement of the pump, the desired pump displacement being less than the maximum pump displacement; and controlling the pump displacement to the desired pump displacement to produce a desired flow of fluid.

Abstract: The hydraulic control system disclosed herein employs a pair of combination poppet/spool valves to control the operation of a hydraulic cylinder driven from a bidirectional pump. Flow introduced through the source port of one valve lifts the poppet of the other valve on its way to one side of the cylinder which in turn opens a throttling port to modulate return flow from the other side of the cylinder.

Abstract: A hydraulic power steering gear assembly includes an assembly body defining a piston chamber having opposed chamber ends with plunger passages formed in the ends, a reciprocating piston and a chamber having opposed ends and a passage extending between the piston ends, a check valve at each end of the piston passage, and a plunger assembly in each plunger passage with each assembly including a spring frictionally holding assembly in the passage and a poppet extending into the chamber to unseat a ball valve as the piston is moved toward one end of the chamber.

Abstract: In a hydraulic pump (P) comprising at least one piston pump element whose ston (11) is oriented towards an eccentric (E) of a drive shaft (2), and being equipped between the eccentric (E) and a bearing ring (R) rotatable on the eccentric (E) with an eccentric slide bearing (G) having a bearing bush (B) fixed in the bearing ring (R), the bearing bush (B) and the bearing ring (R) each have molded and locally meshing stop portions (A1, A2) which positively fix the bearing bush (B) in the bearing ring (R) in rotational and axial direction. (FIG. 1).

Abstract: A control apparatus for a brake system having a housing with a first bore for retaining a spool valve and a second bore for retaining a selector valve. A cap separates the first bore into a first chamber and a second chamber. The first chamber has an inlet port connected to a source of fluid under pressure, a gear port for connected the source of fluid under pressure to a hydraulically operated device, a relief port connected to a reservoir and an outlet passage connected to a selector valve which communicates pressurized fluid through an outlet port to a brake booster. The second chamber is connected to the reservoir and the second bore. The a spool valve has a peripheral surface with first and second grooves separated by lands and an internal operational passage connecting the second groove to the outlet passage.