Abstract: A power assisted vehicle steering system of the speed responsive kind has a ram 6 fluid flow to chambers 4 and 5 of which from a pump 9 is directed by an open center steering valve 1. Communication between the chambers 4 and 5 is permissible through a by-pass valve 13 adjustable by a solenoid 17 in response to vehicle speed to open such communication as speed increases (and thereby decrease power assistance) and vice versa. The valve 13 has a spool 22 which is spring loaded relative to a control spindle 18 of the solenoid. Adjustment of the spool 22 in response to speed variations opens or closes by-pass ports 14 and 15 to opposite ends of a restrictor 32 which provides such fluid flow communication.A spring loaded spool 41 in the valve 13 is responsive through chambers 39 and 40 to fluid pressure at opposite sides of the restrictor 32. When the fluid pressure differential across the restrictor 32 exceeds a predetermined differential, the spool 41 is displaced to direct fluid pressure to spool chamber 55.

Abstract: A vehicle power assisted steering system comprises a hydraulic pump 24 having a constant volume output communicating with an open center power assistance valve 40 which is adjustable from a neutral condition in response to a steering input torque during a steering maneuver to control fluid flow from the pump to opposed chambers of a ram 18b providing power assistance to assist the steering maneuver. A by-pass valve 25 communicates between the outlet of the pump 24 and a fluid reservoir 21 and is responsive to vehicle speed to increasingly open communication between the pump 24 and the reservoir 21 as vehicle speed increases and conversely. The valve 40 has valve members displaceable from a neutral condition in response to a steering input torque to direct hydraulic fluid to actuate the ram 18b for power assistance. In the neutral condition of the valve members, they provide intercommunication between the pump 24, the chambers 18a of the ram and the reservoir 21.

Abstract: An hydraulic fluid actuated power assisted steering system has an open center valve 4 adjustable in response to a steering input to control fluid flow to a power assistance ram 6. A by-pass valve 8 communicates between a pressure line 3 and a return line 7 of the valve 4. The by-pass valve has a control port 11 which is adjustable by a valve member 9 spring biased at 10 to normally open the control port 11 so that fluid flow from line 3 to line 7 by way of port 11 alleviates the generation of noise in the valve 4 and back pressure in the line 3. The valve member 9 is responsive to a predetermined fluid pressure differential developing between the line 3 and 7 when the valve 4 is operated so that the member 9 is displaced to close port 11 and direct greater fluid flow from pump 2 to the ram 6.

Abstract: A vehicle steering system with power assistance means comprises an output component 4 displaceable relative to a housing 1 for that component and in response to a steering input for effecting a steering maneuver. The housing 1 is mounted for displacement relative to a frame part 9 of the vehicle. An hydraulic servo motor 13 is provided for assisting displacement of the output component 4 and reacting between the output component 4 and the vehicle frame part 9. An hydraulic pump 44 supplies working fluid to the servo motor 13 and a control valve 20 controls the supply of working fluid to the servo motor 13 in response to relative displacement between the housing 1 and the frame part 9 as a reaction to a steering maneuver and that response controls the servo motor 13 to assist the maneuver.

Abstract: A power assisted vehicle steering system, gear or a power assistance means for a vehicle steering gear comprises a housing 1 for a rack bar 4 which is displaceable in response to a steering input. The rack bar housing is resiliently mounted in a bracket 10 bolted to a frame 9 of the vehicle and is longitudinally displaceable relative to the bracket 10 as a reaction from displacement of the rack bar 4. Longitudinal displacement of the housing 3 adjusts a spool valve 20 on the bracket 10. Adjustment of the valve 20 controls a ram 13 which reacts between the bracket 10 and the rack bar 4 to provide power assistance to the intended displacement of the rack bar 4.The valve 20 can be incorporated as part of the ram 13. The ram 13 can be replaced by an alternative servo motor such as an electric motor and an alternative form of control such as an electrical switch to load cell can be provided for the valve 20.

Abstract: In a power assisted rack and pinion vehicle steering mechanism, a rack and a pinion engage within a housing. The pinion is mounted on a pinion shaft which is journalled in bearings in a cage. A lever is fixed to the cage and projects from the cage through the housing. The lever has a part-spherical seating portion which engages a part-spherical seat in the housing. Spring means biases the rack into engagement wiht the pinion, and through the cage biases the part-spherical seating portion of the lever into engagement with the seat on the housing. Steering torque imparted on the pinion moves the rack axially and causes a reaction on the pinion which rotates the cage about the center of the part-spherical seating portion. This rocks the lever to actuate power assistance means.

Abstract: A power assisted vehicle steering mechanism having a rack and pinion assembly, the pinion being mounted to be displaceable by reaction with the rack on the application of steering torque, including a lever mounted for pivotal movement in response to displacement of the pinion, movement of said lever actuating both an hydraulic valve for directing hydraulic fluid to augment steering torque and electrical sensor means for energizing a motor which drives a pump to supply hydraulic fluid to said valve.

Abstract: Power assistance mechanism for a rack and pinion steering gear assembly and an assembly which includes such mechanism includes a main rack and pinion steering gear 1 mounted on which is an auxiliary rack and pinion unit 9. The unit 9 includes an auxiliary rack bar 11, the rack of which engages with an auxiliary pinion in an auxiliary housing 10. The auxiliary pinion is rotatable by an electric motor 23 in the housing 10 to drive the auxiliary rack bar 11. The housing 10 is bolted through brackets 14 to the housing 2a of the main gear 1 while the auxiliary rack bar is coupled through a bracket 16 to the rack bar of the main gear 1. The electric motor 23 is controlled by a switch 27 in the steering input 7 to the pinion of the main steering gear 1 so that when the main rack bar is driven by rotation of the main pinion, the switch 27 is actuated to energize the electric motor and drive the auxiliary rack bar 11 in a sense appropriate to assist the displacement of the main rack bar.

Abstract: A rotary valve assembly and a method of assembling such a valve has a sleeve 5 and a rotor 3 relative rotation between which from a neutral condition adjusts the valve. The sleeve and rotor are biased to the neutral condition by an encircling C-spring reacting on pins corresponding to projections 11a and 12 relatively rotatable with the sleeve 5 and rotor 3 respectively. For setting-up the valve in its neutral condition the sleeve and rotor are mounted in a jig 15 with the projection 11a of the jig engaging in a recess 27 of an adjustable component in the form of a second C-spring 24 which is intitially rotatable on the sleeve 5. The sleeve 5 is rotated relative to the spring 24 and projections 11a and 12 to determine the neutral condition by the characteristics of fluid applied through valve ports E, S, P.sub.1, P.sub.2. The spring 24 is now welded or otherwise secured to the sleeve 5.

Abstract: A road vehicle power assisted steering system comprises a power assisted steering gear assembly (1) in which power assistance to the displacement of an output member of the steering gear (1) is provided by an electric motor in response to a steering gear torque applied to the input member (2). Motorcon also of the electric motor are capable of being switched from a power supply (10), to a resistive load and are controlled by control means (11) in response to the steering torque so that any kinetic energy of the displaceable components of the steering gear (1) may be dissipated by the resistive load to which the coils are switched by the control means when the steering torque falls below a predetermined value.

Abstract: A power assisted vehicle steering mechanism having a rack and pinion assembly, including a pinion shaft adapted at one end to receive a steering wheel, a pinion on the steering shaft engaging a rack connected to effect steering of the vehicle, a bearing for the pinion shaft located between the pinion and said one end, said bearing permitting angular play of the pinion shaft, the pinion shaft having a portion thereof connected to transmit angular movement of the pinion shaft due to steering torque to a power assistance means to augment steering torque.

Abstract: A power assisted vehicle steering system has a rack and pinion steering gear 6 incorporating a servo motor 6a controlled by a valve 22. A fluid pressure supply line 3 to the valve 22 includes a throttle or regulating valve 5 which is adjustable by a stepping motor 30 that is speed responsive to increase incrementally the restriction by the valve 5 to fluid flow to the valve 22 as vehicle speed increases. A flow control valve 7 is responsive to fluid pressure in the line 3 upstream of the valve 5 and to fluid pressure in the line 3 downstream of the valve 5 so that a pressure differential across the valve 5 is sensed by spool 9 which is displaced to open the supply line 3 upstream of the valve 5 and a reservoir 1. This latter opening reduces the supply of pressure fluid available for actuating the servo motor 6a and the available power assistance as the vehicle speed increases.

Abstract: A rack and pinion steering gear assembly has a rack bar 5 displaceable through a cylindrical bush 7 secured by a pin 38 in a rack bar housing 11. A flexible concertina-type bellows 21 is provided between the housing 11 and a tie rod on the end of the rack bar. The bush 7 has an annular recess 42 which is in constant communication by way of longitudinal grooves 39 in the surface of the bush with the interior of the bellows 21. The recess 42 coincides with an aperture 43 in the housing wall 11 within which is snap fitted a tubular plug 44 through which the bellows 21 breathes by way of the recess 42 and grooves 39. The bellows 21 can breathe through the plug 44 to atmosphere (preferably by way of a filter) or by way of a pipe to the interior of bellows located at the opposite end of the rack bar. The bush 7 can partly define a pressure chamber 23 of a piston and cylinder unit for power assisted steering.

Abstract: A steering system has annular pressure responsive electric components, such as piezo-electric transducers, mounted between thrust and restraining faces respectively, the transducers respond to a mechanical load applied to them by generating or determining electrical signals which are proportional to the load, the signals are supplied to a comparator by way of electrical connections. The transducers are arranged in pairs on the axially opposed faces of a bearing, so that in response to an axial thrust applied to the bearing by an input shaft of a steering gear incorporated in the system, the signals provided by the transducers will change from a predetermined comparative condition, one signal increasing in response to the increased compressive load on one transducer, the other signal decreasing in response to a decrease in compressive load on the other transducer in the pair.

Abstract: A rack and pinion gear and a method of assembling such a gear. The gear has a rack bar 1 the rack 4 of which is biased into engagement with the pinion 6 by a spring loaded support 7 which slidably (or rolling) engages a bearing surface 8 of the rack bar. The bearing surface has a central region 9 parallel to the rack axis and tapering end regions 10 and 11 which reduce the thickness of the rack bar from the central region 9. The length C of the region 9 corresponds to 1 to 1.5 revolutions of the pinion 6 while the operative length A of the rack corresponds to at least three revolutions of the pinion. The pinion rotates about an eccentric axis 14 which varies the rack bar tightness. To determine the position of maximum tightness in which the spring loading of the support 7 is to be adjusted, the pinion is rotated from a central position on the rack 4 clockwise and counter-clockwise to displace the rack bar in each instance through a distance corresponding to 0.

Abstract: A power assisted steering system of the rack and pinion type with a "centre take-off" 7 has its rack bar 1 carrying a piston 17 at one end thereof. The rack bar 1 forms with the piston opposed pressurized faces 20 and 21 which present pressurized areas in the ratio 1:2. Valve means 22 controllable by rotational input to the pinion 4 directs fluid at the same pressure to both piston chambers 18 and 19 to assist in displacement of the piston rod 1 in a sense to contract the piston chamber 18 or directs fluid to the piston chamber 18 and exhausts the piston chamber 19 to assist in displacement of the piston rod 1 in a sense to contract the piston chamber 19--the power assistance to displacement of the piston rod being substantially the same in both senses of direction.

Abstract: A power assistance steering system for a vehicle, particularly a heavy vehicle, having a first power assistance subsystem known per se and a second power assistance subsystem including a fluid pump for directing fluid pressure selectively to a movement assistance device to assist steering and a prime mover for driving the pump in accordance with signals generated by a sensor responsive to steering.

Abstract: A vehicle control system has a system part 5 with a pump 6 feeding an open centre valve 4 which controls power assistance for vehicle steering. A second system part 11 has a pump 16 feeding an accumulator 13 and a closed centre valve 10 which controls operation of a clutch or brake booster 2. The pumps 6 and 16 are simultaneously driven by a motor 18. A by-pass valve 21 in conduit 20 is responsive through a pressure transducer 22 and an electrical control unit 19 to pressure in the accumulator 13 so that when the accumulator pressure attains a predetermined value the by-pass valve 21 opens communication between the output from pump 16 and a reservoir 7 to relieve the load on the motor 18. A pressure regulating valve 23 is provided in the steering system part 5.

Abstract: In a sealing arrangement for a rotary fluid pressure control valve, such as a power steering control valve, a resilient sealing ring is located in a ring groove for sealing engagement with an outer cylindrical member. Frictional losses and a tendency for the sealing assembly to jam are reduced by equalization of the fluid pressure on opposite faces of the sealing ring. This is achieved by virtue of a tapered ring cross-sectional profile and other ring profiles disclosed herein, or by provision of a relieved zone in the ring groove for transmission of fluid pressure.

Abstract: A power assistance steering system 10 for a vehicle comprises steering gear 12 having an internal hydraulic ram supplied with hydraulic fluid by a pump 14 from a reservoir 16 via a solenoid valve 18 controlled by a micro-processor 20 which also controls an electric motor 22 for driving pump 14. Steering input torque is sensed by a torque sensor 36 and steering direction is sensed by a direction switch 34. Output signals from these devices are fed to micro-processor 20 which controls solenoid valve 18 and pump motor 22 accordingly, varying the motor speed in accordance with the pressure requirements of the steering ram as sensed by the torque sensor. In a further embodiment the pump is driven at a constant speed and a proportional control valve 74 is controlled by a micro-processor 78 to vary the fluid pressure supply.