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US 4,354,351 AGranted
Load sensing steering
AssigneeCaterpillar Tractor Co.
InventorJoseph E. Dezelan
Life of this patent
Estimating the term…
Abstract
Fluid in the relatively long lines (22, 24) between a control valve (16) and a fluid actuator (14) can become overly viscous in cold weather. Herein, fluid is circulated through such lines (22, 24), at least during cold weather, even when the fluid actuator (14) is not being used. This flowing is discontinued in response to shifting of the control valve (16) to a position where it motivates the actuator (14) and in response to pressure in the circulating path (20) exceeding a selected level.
Claims5
In a fluid circuit (10) having a pressurized fluid source (12);
- a fluid actuator (14);
- a directional control valve (16 or 16") selectively positionable in first and second positions, and being connected to receive pressurized fluid from said source (12);
- fluid directing means (20 or 20") for directing fluid from the valve (16 or 16") to the actuator (14) in response to positioning of the control valve (16 or 16") in said second position;
- and flowing means (26,26' or 26") for flowing pressurized fluid into and for venting that fluid from said fluid directing means (20 or 20");
- the improvement comprising:
- logic means (34,34' or 34") for preventing operation of said flowing means (26,26' or 26") in response to both (a) positioning of said valve (16) in said second position and (b) the pressure of the fluid in said fluid directing means (20 or 20") exceeding a preselected magnitude.
3 more elements
A steering circuit (10) comprising:
- a pressurized fluid source (12);
- a steering motor (14);
- a directional control steering valve (16 or 16") selectively positionable between a first position at which fluid is blocked from communication with said steering motor (14) and a second position at which fluid is in communication with said steering motor (14) and being connected to receive pressurized fluid from said source (12);
- fluid directing means (20 or 20") for directing fluid from said steering valve (16 or 16") to said steering motor (14);
- flowing means (26,26' or 26") for flowing pressurized fluid into and for venting said fluid from said fluid directing means (20 or 20");
- and
- logic means (34,34' or 34") for preventing operation of said flowing means (26,26' or 26") in response to both (a) positioning of said steering valve (16 or 16") in said second position and (b) the pressure of the fluid in said fluid directing means (20 or 20") exceeding a selected value.
4 more elements
Dependencies are inferred from the claim text.