U-BOLT 1717575 - Caterpillar

Illustration 1 g00853705
Secondary Steering Control Valve in the primary Position
(1) Pressure reducing valve. (2) Inlet from the steering pump. (3) Steering cylinder crossover relief valve. (4) Inlet from the secondary steering pump. (5) Outlet to the hydraulic oil tank for the steering system. (6) Secondary steering relief valve. (7) Diverter valve. (8) Pilot port. (9) Spool. (10) Shuttle valve. (11) Springs. (12) Retainer. (13) Pilot oil port. (14) Return oil passage. (15) Port for left turns. (16) Passage of the supply oil. (17) Port for right turns. (18) Return passage. (19) Primary steering relief valve.
Illustration 2 g00853708
Typical example of the steering control valve
Note: The secondary steering control valve is located on the left inner frame behind the cab.Standard steering control valves and secondary steering control valves consist of the same basic components. Additionally, standard steering control valves and secondary steering control valves have the same basic functions, unless there is a loss of primary pump flow.Reference: For additional information about the operation of primary steering control valves, refer to the Service Manual module Systems Operation, "Steering Control Valve" for the machine that is being serviced.Although the basic components of a standard steering control valve and of a secondary steering control valve are the same, secondary steering control valves contain the following additional components:
Inlet (4) for the secondary steering pump
Secondary steering pump relief valve (6)
Diverter valve (7)
Load check valve (not shown)If the primary steering pump fails, diverter valve (7) 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 operator moves the STIC steering control lever in order to make a right turn, pilot oil flows from the pilot control valve through the right neutralizer valve. The oil then flows through the quad check valves and to pilot oil port (13). Pilot oil flows past retainer (12). The oil flow acts against spool (9). The force of the oil overcomes springs (11). This causes spool (9) to move to the left.When spool (9) moves to the left, oil in passage (16) flows past spool (9). The oil then flows into port (17) for right turns. The oil then flows through the lines to the head end of the left steering cylinder. The oil in port (17) then flows through the lines to the rod end of the right steering cylinder.Secondary steering relief valve (6) limits the secondary steering system pressure to 14000 700 kPa (2050 100 psi).