Steering system with secondary steering means

Claim 2

In a vehicular steering system having; a source of fluid under pressure, steering motor means, primary control valve means, fluid communication means for communicating said pressure source with said primary control valve means, and for communicating said primary control valve means with said steering motor means, steering mechanism means for actuating said primary control valve means to control the flow of pressure fluid to and from said steering motor means, the improvement comprising; secondary steering means for providing a supply of pressure fluid for operating said steering motor means in the event of failure of said source of fluid under pressure to supply said steering motors, said secondary steering means including accumulator means supplied by said source for storing fluid under pressure for selective passage to said steering motor means, secondary control valve means for controlling fluid flow from said source to said accumulator means and from said accumulator means to said steering motor means, said secondary control valve means operative for automatically permitting fluid flow from said source to said accumulator means while concurrently blocking flow from said accumulator means to said steering motor means when the pressure of said source is above a first predetermined value, said secondary control valve means being further operative for communicating flow from said accumulator means to said steering motor means while concurrently blocking flow from said source to said steering motor means when the pressure of said source is below said first predetermined value, said steering mechanism means including mechanical linkage means directly connected to said secondary control valve means and to said primary control valve means for actuating said secondary control valve means concurrently with said primary control valve means to provide immediate mechanical control of fluid flow from said accumulator means to said steering motor means when the pressure of said source drops below said first predetermined value.

Claim 3

The invention of claim 1 wherein said steering motor means include a pair of double acting hydraulic fluid jacks.

Claim 4

In a vehicular steering system having; a source of fluid under pressure, steering motor means, primary control valve means, fluid communication means for communicating said pressure source with said primary control valve means, and for communicating said primary control valve means with said steering motor means, steering mechanism means for actuating said primary control valve means to control the flow of pressuRe fluid to and from said steering motor means, the improvement comprising; secondary steering means for providing a supply of pressure fluid for operating said steering motor means in the event of failure of said source of fluid under pressure to supply said steering motors, said secondary steering means including accumulator means supplied by said source for storing fluid under pressure for selective passage to said steering motor means, secondary control valve means for controlling fluid flow from said source to said accumulator means and from said accumulator means to said steering motor means, said secondary control valve means operative for automatically permitting fluid flow from said source to said accumulator means while concurrently blocking flow from said accumulator means to said steering motor means when the pressure of said source is above a first predetermined value, said secondary control valve means being further operative for communicating flow from said accumulator means to said steering motor means while concurrently blocking flow from said source to said steering motor means when the pressure of said source is below said first predetermined value, said steering mechanism means including mechanical linkage means directly connected to said secondary control valve means for actuating said secondary control valve means concurrently with said primary control valve means, said secondary control valve means including; a valve body having bore means including first, second and third annuli, a valve spool disposed within said bore means, first communication means for connecting said source with said first annulus, second communication means, for connecting said first annulus with said third annulus, third communication means for connecting said third annulus with said accumulator means, fourth communication means for connecting said second annulus with said steering motor means.

Claim 5

In a vehicular steering system having; a source of fluid under pressure, steering motor means, primary control valve means, fluid communication means for communicating said pressure source with said primary control valve means, and for communicating said primary control valve means with said steering motor means, steering mechanism means for actuating said primary control valve means to control the flow of pressuRe fluid to and from said steering motor means, the improvement comprising; secondary steering means for providing a supply of pressure fluid for operating said steering motor means in the event of failure of said source of fluid under pressure to supply said steering motors, said secondary steering means including accumulator means supplied by said source for storing fluid under pressure for selective passage to said steering motor means, secondary control valve means for controlling fluid flow from said source to said accumulator means and from said accumulator means to said steering motor means, said secondary control valve means operative for automatically permitting fluid flow from said source to said accumulator means while concurrently blocking flow from said accumulator means to said steering motor means when the pressure of said source is above a first predetermined value, said secondary control valve means being further operative for communicating flow from said accumulator means to said steering motor means while concurrently blocking flow from said source to said steering motor means when the pressure of said source is below said first predetermined value, said steering mechanism means including mechanical linkage means directly connected to said secondary control valve means for actuating said secondary control valve means concurrently with said primary control valve means, said secondary control valve means including; a valve body having bore means including first, second and third annuli, a valve spool disposed within said bore means, first communication means for connecting said source with said first annulus, second communication means, for connecting said first annulus with said third annulus, third communication means for connecting said third annulus with said accumulator means, fourth communication means for connecting said second annulus with said steering motor means.

Claim 6

The invention of claim 3 wherein said valve spool includes a plurality of spaced apart lands, said valve spool movable within said bore means to a first position wherein a land thereof blocks fluid communication between said second and third annuli while communication exists between said first and second annuli.

Claim 7

The invention of claim 4 wherein said valve spool is further movable within said bore means to a second position wherein a land blocks communication between said first and second annuli and wherein another of said lands blocks communication between said second and third annuli.

Claim 8

The invention of claim 5 further including spring means for constantly urging said valve spool away from said first position and toward said second position.

Claim 9

The invention of claim 3 wherein said seocnd communication means include one-way check valve means for preventing fluid flow from said third annulus to said first annulus.

Claim 10

The invention of claim 3 wherein said mechanical linkage means include a stem member received within said bore means of said secondary control valve body and directly selectively engaging a first portion of said valve spool upon manipulation of said steering mechanism means.

Claim 11

The invention of claim 8 wherein said steering mechanism means is manipulatable in a first direction and in a second direction opposite to said first direction, and wherein manipulation of said steering mechanism means in either of said first or second directions will move said valve spool away from said second position and toward said first position when said valve spool is in said second position.

Claim 12

The invention of claim 9 wherein said valve spool, when in said first position, will be unaffected by manipulation of said steering mechanism means in either said first or second directions.