HOSE 5P1267 - Caterpillar

Illustration 1 g03564657
Secondary Steering System 914K (1) Steering cylinders (2) HMU (3) Pressure sensor (4) Steering valve (5) Secondary steering motor (6) Check valve (7) Steering pump (8) Hydraulic tank
Illustration 2 g03649809
Secondary steering 910K (1) Steering Cylinders (2) HMU (3) Pressure Sensor (4) Steering valve (5) Secondary steering unit (6) Check valve (7) Steering pump (8) Hydraulic tank (9) Priority valveIf the machine is moving and the engine shuts down, oil pressure for the steering system is lost. The optional secondary steering system will provide the flow that is needed for steering. The electric drive motor and the attached hydraulic pump are located beneath the hydraulic oil tank. The secondary steering system operates if the pressure in the steering line is lost. When the oil pressure in the steering lines drops below the preset level, pressure sensor (3) sends a signal to machine ECM. The ECM activates secondary steering motor relay. The secondary steering enable relay activates the secondary steering unit. The electric motor rotates and the pump starts to pump oil. The hydraulic oil is drawn from the hydraulic tank (8) to the secondary steering pump (7). The Oil flows through the steering valve (4), and into the HMU. The HMU (2) sends oil to the steering cylinders (1). Check valve (6) inside steering valve (5) closes the passage to the main steering pump allowing hydraulic oil to flow only from the secondary steering pump to the steering HMU (2) .Note: For the 910K the hydraulic fluid also passes through a priority valve (9) before oil passes through the steering valve (4) and on into the steering HMU (2).