Abstract: An apparatus (10) for turning steerable wheels of a vehicle comprises a housing (14) that defines a fluid chamber (24). A rack bar (26) extends longitudinally through the housing (14) and is connectable with the steerable wheels of the vehicle. The rack bar (26) is movable relative to the housing (14) for turning the steerable wheels. A piston assembly (34) is fixedly attached to the rack bar (26) and sealingly engages the housing (14). The piston assembly (34) divides the fluid chamber (24) into first and second chamber portions (40 and 42). A fluid source (80) directs fluid toward one of the first and second chamber portions (40 or 42) for creating a differential pressure between the first and second chamber portions (40 and 42). The piston assembly (34) and the rack bar (26) move relative to the housing (14) in response to the differential pressure. The piston assembly (34) includes structure (132) for dampening fluid pulsations emanating from the fluid source (80).

Abstract: An apparatus (10) for turning steerable wheels of a vehicle comprises a housing (14) that defines a fluid chamber (24). A rack bar (26) extends longitudinally through the housing (14) and is connectable with the steerable wheels of the vehicle. The rack bar (26) is movable relative to the housing (14) for turning the steerable wheels. A piston assembly (34) is fixedly attached to the rack bar (26) and sealingly engages the housing (14). The piston assembly (34) divides the fluid chamber (24) into first and second chamber portions (40 and 42). A fluid source (80) directs fluid toward one of the first and second chamber portions (40 or 42) for creating a differential pressure between the first and second chamber portions (40 and 42). The piston assembly (34) and the rack bar (26) move relative to the housing (14) in response to the differential pressure. The piston assembly (34) includes structure (132) for dampening fluid pulsations emanating from the fluid source (80).

Abstract: A hydraulic power assist rack and pinion steering system (12) for a vehicle includes a housing (14) in which a rack (10) is movable along an axis (16) to effect turning movement of steerable wheels of the vehicle. The rack (10) comprises a first rack part (50) having an elongate body portion (56) and an end portion formed as a first piston portion (58), and a second rack (80) part having an elongate body portion (86) and an end portion formed as a second piston portion (88). The first piston portion (58) of the first rack part (50) is joined to the second piston portion (88) of the second rack part (80) to form a piston (22). The body portion (56) of the first rack part (50) extends axially away from the piston (22) in a first direction (110). The body portion (86) of the second rack part (80) extends axially away from the piston (22) in a second direction (112) opposite the first direction (110).

Abstract: A method and apparatus is disclosed for nullifying electrical offsets present in an output signal from a torsion sensing device. The apparatus includes a detection circuit for outputting an electrical signal when a change between a no applied torque condition and an applied torque condition occurs in a member whose torsion is being monitored. A sample and hold circuit measures the output signal from the torsion sensing device, the sample and hold circuit being triggered in response to the detection circuit. A differencing circuit subtracts the output of the sample and hold circuit from a "zero torque" reference value and outputs an electrical signal having a value indicative of the difference therebetween. An offset compensating circuit is electrically connected to the output of the differencing circuit and to the torsion sensing device and outputs a modified torsion sensing signal having a value that varies as a function of the applied torque offset by the value of the output of the differencing circuit.

Abstract: An auxiliary drive circuit is disclosed for an electric, power assist steering system including an actuatable switching device which, when actuated, provides an auxiliary electrical path between a source of electrical energy and a mechanically actuatable reversing switch assembly for applying electrical power to energize an electric assist motor. The actuatable switching device in the auxiliary drive circuit is electrically connected in parallel to an actuatable switching device in a main drive circuit. A detector circuit monitors the operation of the main drive circuit and the output signal from a torque sensor. Upon detection of applied steering torque greater than a predetermined value and that the main drive circuit is not operating, the detector circuit outputs an electrical signal indicative thereof. A latching element latches the output of the detector circuit to actuate the actuatable switching device in the auxiliary drive circuit.

Abstract: A power assist steering system in which electrical power to drive the electric assist motor is selectively provided from either the alternator or the battery depending upon the vehicle speed and applied steering torque. An electronic control unit controls the output voltage from the alternator by controlling current through the alternator field coil.

Abstract: An improved method and apparatus for sensing relative movement between a pair of members includes a pair of parts which cooperate to provide an electrical signal upon relative movement between the members. One of these parts may be a Hall effect device and the other part may be a pair of magnets. In order to accurately position the Hall effect device and the magnets relative to each, they are mounted on a substrate or base. The portion of the substrate upon which the magnets are disposed is connected with one of the members. The Hall effect device is disposed on a portion of the substrate which is connected with the other member. Once the substrate has been connected with the two members, it is separated to enable the members to be easily moved relative to each other.