In order to most expeditiously manufacture the dual system of the above-identified application, it is proposed to utilize power steering gear assemblies of the type having a piston and a cylinder with an output gear engaged with a rack on the piston and a valve responsive to the steering shaft, as shown, for example, in my previous patent, Sheppard US. Pat. No. 3,092,083, issued June 4, 1963. Theoretically, two power steering gears as shown by this patent could be incorporated at opposite sides of the steering linkage to steer the vehicle. However, it would be much more expensive and perhaps prohibitably so to utilize two complete power steering units of this type. Further, the problem of synchronization between the integral valves of the two units would add substantial cost to the overall system. This high cost of converting to a fail-safe system is one of the most important factors facing the Government and private ofiicials and thus the solving of this problem is considered to be the primary thrust of the present inventive effort.
8 Claims, 2 Drawing Figures 1 POWER STEERING GEAR ASSEMBLY The present invention relates to power steering of vehicles, and more particularly, to a power steering gear assembly particularly adapted for use as a slave unit in dual power steering systems.
It is still another object of the present invention to provide a steering gear assembly having a hollow piston with check valve means at each end and lateral bleed ports to effect release of hydraulic pressure buildup from the rack and output pinion enclosure BRIEF SUMMARY OF THE INVENTION The power steering gear assembly of the present in vention includes a cylinder housing, a reciprocating piston defining alternate power and exhaust chambers at the ends of the piston, and means for bleeding the output gear enclosure through the hollow interior of the piston and automatically out through the exhaust or softside of said piston. This bleed means includes a cap at each end of the piston that houses oppositely directed check valve means to resist the escape of fluid during the power stroke and to allow retroflow of. exhaust fluid during exhaust of that chamber. The valve means communicates with the hollow interior of the piston and thence through lateral port means to the area of the rack and the output gear enclosure.
The advantages of this power steering gear assembly can now be noted briefly. Due to normal leakage past the sealing rings at the ends of the piston, in prior art devices, it was inevitable that pressure would build up in the area of the output gear, thereby necessitating a seal around the shaft of the output gear that would withstand the constant high pressure. With the present arrangement, only a low pressure seal must be provided around the output shaft since during each power stroke the high pressure fluid that leaks around the piston rings is exhausted through the lateral port means, through the hollow interior of the cylinder and then by lifting the check valve from its seat out through the exhaust side of the piston. The output gear seal must thus withstand only the nonpressurized hydraulic fluid. Even under high frequency repeated turning action of the vehicle, there is no chance that pressure can build v up in the area of the output gear since on each stroke the enclosure is directly communicated to the soft side of the piston.
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This part is also known as Ford F150 Pickup Power Strg Assembly.