COVER 2172543 - Caterpillar

Illustration 1 g00903402
Steering components locations
(AA) Outlet port to the combination valve
(BB) Inlet port from the combination valve
(CC) Outlet port to the steering cylinders for a right turn
(DD) Load sensing signal port
(EE) Outlet port to the steering cylinders for a left turn
(FF) Line to steering cylinder for a right turn
(GG) Line to steering cylinder for a left turn The steering circuit is composed of the following components:
The hydraulic tank
The hydraulic and steering pump with the pressure and flow compensator valve
The accumulator
The steering metering pump
The left and right steering cylindersHydraulic oil for the steering circuit is supplied by the hydraulic and steering pump. The steering priority valve gives the steering function priority over the available hydraulic pump flow. The priority valve senses pressure in the steering circuit.Typically, the requirements of the oil flow for the steering circuit are significantly less than the available hydraulic pump flow. This means that oil flow to other implement circuits will not be interrupted when the steering is operated. The steering metering pump provides oil flow to the steering cylinders. This depends on the direction and the rotation of the steering wheel.Oil Flow of the Steering Hydraulic System
Illustration 2 g01000422
Steering system in the HOLD position
(1) Steering metering pump
(2) Gerotor
(3) Steering cylinders
(4) Rotary sleeve
(5) Line relief valves with anticavitation valves
(6) Check valve for supply oil
(7) Anticavitation check valve
(8) Hydraulic and steering pump
(9) Hydraulic tank
(10) Signal purge valve
(11) Signal relief valve
(12) Signal resolver valve
(13) Steering priority valve
(14) Pressure compensator valve
(15) Flow compensator valve
(16) Implement relief valve
(17) Steering relief valve
(18) Combination valve In the HOLD position, the top envelope of priority valve (13) is activated. This allows oil to flow to both the steering and to the implements. The supply oil is blocked at the implement valves. The supply oil is also blocked at the steering metering pump (1). The signal oil that is coming from combination valve (18) flows through an internal orifice of sleeve (4) in the steering metering pump and back to tank (9).Signal oil pressure flows from priority valve (13) to signal resolver valve (12). Flow compensator valve (15) is in the metering position due to signal oil from the signal resolver. Hydraulic and steering pump (8) will be in low pressure standby. Signal oil pressure is approximately 345 kPa (50 psi).
Illustration 3 g01000444
Steering system during a right turn
(1) Steering metering pump
(2) Gerotor
(3) Steering cylinders
(4) Rotary sleeve
(5) Line relief valves with anticavitation valves
(8) Hydraulic and steering pump
(9) Hydraulic tank
(13) Steering priority valve
(14) Pressure compensator valve
(15) Flow compensator valve
(18) Combination valve When the steering wheel is turned to the right, sleeve (4) is rotated in order to make the bottom envelope active. At the same time, gerotor (2) pumps oil to cylinders (3). The oil is supplied to steering metering pump (1) through the center envelope in priority valve (13). The signal pressure flows from the steering metering pump and priority valve (13) to the signal resolver valve (12). This oil provides the signal to flow compensator valve (15). The hydraulic and steering pump will upstroke in order