CYLINDER 0025777 - Caterpillar

Steering pump (2) is an axial piston pump with overcenter capability. The steering pilot valve controls the output of the steering pump. The steering pump controls the speed and the direction of the steering motor. The pump is mounted on the upper right of the torque converter housing.The steering pump head also contains the charge pump relief valve, the pressure compensator valve, and the crossover relief and makeup valves. The charge pump relief valve maintains the oil pressure in the charge circuit after the oil has been filtered and after the oil has been cooled. The pressure compensator valve limits the maximum pressure in both sides of the steering loop. The crossover relief and makeup valves are designed to open in order to protect the steering loop from pressure spikes. The makeup portion of these valves supplies oil to the low pressure side of the loop when oil is needed.Cold Start Valve
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Cold start valve (3) protects the charge system against high pressures when the machine is first started and the hydraulic oil is cold. The higher viscosity of cold oil can cause system pressures to increase. Oil that passes over the cold start valve is returned to the suction port of the charge pump. The cold start valve is located on the right hand side of steering pump (2) .Charge Pump
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Charge pump (4) is integrally mounted on the rear of steering pump (2), which is mounted on the upper right of the torque converter housing. The charge pump is a positive displacement type pump which provides pilot oil for the implement control valve and charge oil for the steering closed loop.Case Drain Filter
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Case drain filter (5) stops debris in the oil that flows from the pump case drain back to the tank in order to prevent damage to the hydraulic system components. The case drain filter is located behind the access door on the right side of the machine.Hydraulic Tank
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Hydraulic tank (6) is located at the rear of the machine on the right side. The hydraulic tank is a reservoir that contains the hydraulic oil.Remote Pressure Taps
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Remote pressure taps (7) provide convenient testing of the system conditions. Remote pressure taps (7) are located behind the access door on the left side of the machine.ReferenceRefer to Testing and Adjusting, "Pressure Taps" in this manual for more information on the remote pressure taps.Steering and Transmission Control
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Steering and transmission control (8) is located inside the cab to the left of the operator's seat. When the operator demands a turn, the steering and transmission control sends a signal to the power train Electronic Control Module (ECM). The power train ECM then sends a signal to the steering pump control. The steering pump control valve then allows charge oil to act upon the control piston. The linkage from the control piston moves the steering pump swashplate, which determines the output of the steering pump.Steering Motor
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The cab has been removed for the overhead photo.Steering motor (9) is