GEAR-DIFFERENTIAL 3925536 - Caterpillar

Illustration 1 g01129799
Steering Control Valve with Secondary Steering in the NEUTRAL Position
(1) Pressure reducing valve
(2) Inlet from the steering pump
(3) Steering crossover relief valve for the steering cylinders
(4) Inlet from the secondary steering pump
(5) Outlet to the hydraulic tank
(6) Diverter valve
(7) Secondary steering relief valve
(8) Pilot port
(9) Spool
(10) Port for the shuttle valve
(11) Springs
(12) Retainer
(13) Pilot oil port
(14) Return oil passage
(15) Port for right turns
(16) Passage for the supply oil
(17) Port for left turns
(18) Return passage
Illustration 2 g01125336
Location of the Steering Control Valve with Secondary Steering
Illustration 3 g01129658
Steering Control Valve with Secondary Steering
The steering control valve is located on the left side of the machine beneath the cab. The steering control valve is located under the access door on the left side of the cab platform.Note: Standard steering control valves and standard steering control valves with secondary steering consist of the same basic components. Additionally, standard steering control valves and standard steering control valves with secondary steering have the same basic function, unless there is a loss of primary pump flow.Reference: For information about the operation of a standard steering control valve, refer to Systems Operation, "Steering Control Valve" for the machine that is being serviced.A standard steering control valve and a steering control valve with secondary steering have the same basic components. Steering control valves with secondary steering contain additional components that follow:
Inlet (4) for the secondary steering pump
Diverter valve (6)
Secondary steering pump relief valve (7)If the primary steering pump fails, diverter valve (6) sends oil from the secondary steering pump. The oil is then pumped into oil passage (16). This will continue to occur when the machine is moving forward or backward.When the engine is running, oil flows from the hydraulic tank to the steering pump. The oil then flows into the steering control valve with secondary steering through port (2).When the STIC steering control lever or the steering wheel is in the CENTER position, the flow of pilot oil to either end of spool (9) stops. Similarly, if a steering neutralizer valve for a left turn or the steering neutralizer valve for a right turn is actuated, the flow of pilot oil to either end of spool (9) stops.When no pilot oil is acting on either end of spool (9), centering springs (11) return spool (9) to the NEUTRAL position. As the spool returns to the NEUTRAL position, the pilot oil that had been acting on an end of spool (9) is forced across an orifice and back to the hydraulic tank.When spool (9) is in the CENTER position, oil in port (2) is blocked at oil passage (16). This causes oil in the steering cylinder lines to be blocked in port (15) and in port (17).The shuttle valve in port (10) senses the load on the cylinder. The shuttle valve then directs the signal oil to flow back to the steering pump. This causes the pump to destroke. When this occurs, there is only enough oil in order to compensate for leaks.Note: If the machine is moving