CHASSIS AR 3358376 - Caterpillar

Illustration 1 g00648672
Secondary steering valve (1) Diverter spool (2) Outlet port to the tank (3) Passage (4) Spring (5) Steering control valve port (6) Passage (7) Restrictor (8) Check valve (9) Passage (10) Primary pump inlet (11) Check valve (12) Supplemental inlet from the tank (13) Spring (14) Reversing spool (15) Passage (16) Inlet or outlet port to the secondary steering pump (17) Inlet or outlet port to the secondary steering pump (18) PassageThe secondary steering valve contains two spools and two check valves.Diverter spool (1) connects the oil flow from the secondary steering pump to the tank when there is sufficient flow from the primary steering system in order to meet the requirement of the steering system. Diverter spool (1) connects the oil flow from the secondary steering pump to the steering system when the primary oil flow is below system requirements.Reversing spool (14) alters the secondary oil flow through the secondary steering valve in order to compensate for the reverse rotation of the secondary steering pump when the machine is reversing.Check valves (8, 11) regulate the oil flow between the primary steering system and the secondary steering system.With a running engine, oil from the primary steering pump flows into the secondary steering valve through port (10). The oil then passes through restrictor (7) and the oil unseats check valve (8), and the oil flows through port (5) to the steering control valve.The pressures that are developed on both sides of restrictor (7) are transmitted through passages (6, 9) to the chambers at either end of diverter spool (1) .The pressure drop across the restrictor ensures that the pressure at the left side of diverter spool (1) is higher than the pressure at