TUBE 1638104 - Caterpillar

Steering Hydraulic System for the Two-Wheel Steer
Illustration 1 g01102718
(1) Front steering cylinder (2) Metering pump (3) Pump (4) Load signal (5) Hydraulic tank (6) Check valve (7) Check valve (8) Priority valve (9) Load signal (10) Pump pressure (11) Tank lineThe steering system is a closed center system. The steering system is part of the load sensing, pressure compensated hydraulic system. The components that follow are components for the standard two-wheel steering system. Front steering cylinder (1), steering metering pump (2), priority valve (8), hydraulic pump (3) and Hydraulic tank (5). Pump (3) is common to both the steering and implement systems.The following components are involved in the operation of the steering system and the implement system.
Load signal oil (9) that flows to the backhoe control valve
Tank line (11)
Pump pressure oil (10) that flows to the backhoe control valve
Load signal oil (4) that flows from the backhoe control valveHydraulic tank (5) provides oil for both the steering and implement hydraulic systems. If you operate the machine, oil flows from the hydraulic tank to the hydraulic pump. The oil then flows into the priority valve (8). The priority valve is part of the bank valves for the loader. The oil that is not used by the steering system flows to the bank valve for the loader.The bank valves for the loader are located under the cab floor. The bank valves are located on the right frame rail. The priority valve contains a spool and a relief valve which limits the signal pressure.The steering metering pump (2) is located behind a panel in the operator station. The metering pump is connected to the steering column. Oil flows from the priority valve (8) into the metering pump through an inlet check valve (7) .When the steering wheel is not turning, oil constantly flows from the metering pump back to the hydraulic tank through the advanced signal passage in the priority valve. This oil flow prevents the priority spool from completely blocking oil flow to the metering pump. This improves the response of the steering particularly in cold weather. When the wheel is turned, the oil flows through the steering metering pump to the steering cylinder.The inlet check valve (7) in the steering metering pump prevents steering kickback in the event of external forces. In the control section of the metering pump, there is another check valve. The check valve (6) is between the pump supply and the ports for the return oil.The two check valves allow steering capability when the engine is not running. The check valve (16) allows oil to flow from the hydraulic tank. This oil flows to the inlet for the metering pump. The oil flows in order to recirculate between the metering pump and the steering cylinder.Front steering cylinder (1) is located on the front axle in front of the rear trunnion mount. The cylinder has one piston and the cylinder is double ended with two rod ends. When you turn the steering wheel, the metering pump