HANDLE-GRAB 3112471 - Caterpillar

Illustration 1 g01445052
992K Wheel Loader
See auxiliary view (Z) for 854K Wheel Dozer.
(1) Steering cylinders
(2) Shuttle valve
(3) Relief valve
(4) Diverter valve
(5) High pressure screen
(6) Steering pump
(7) Filter bypass switch (case drain)
(8) Case drain filter
(9) Hydraulic oil tank
(10) Selector and pressure control valve (secondary steering)
(11) Pressure reducing valve (secondary pilot supply)
(12) Steering control valve
(13) Crossover relief valve
Illustration 2 g01445053
854K Wheel Dozer
Auxiliary view (Z)
( 4) Diverter valve
(5) High pressure screen
(6) Steering pump
(8) Case drain filter
(9) Hydraulic oil tank The steering pump supplies high pressure oil for the steering system. The steering pump can also supply supplemental pilot oil for the pilot oil system.During normal operation, steering pump (6) withdraws oil from hydraulic oil tank (9). High pressure oil then flows through high pressure screen (5) (if equipped). High pressure oil then travels through one of four routes.In the first route, oil is sent to control valve spool (12). The control valve spool sends oil flow to steering cylinders (1).In the second route, the oil is sent to selector and pressure control valve (10) (if equipped). The selector and pressure control valve has a pressure switch that monitors the steering oil pressure. If steering oil pressure drops, an indicator in the cab alerts the operator of the problem.In the third route, the oil travels to diverter valve (4). The oil pressure keeps diverter valve (4) shifted downward. When the diverter valve is shifted downward, oil from the secondary oil pump is sent back to the hydraulic oil tank.In the fourth route, the oil flows to relief valve (3) and pressure reducing valve (11). Pressure reducing valve (11) is responsible for lowering high pressure oil to pilot oil pressure. The pressure reducing valve allows the steering pump to supply supplemental pilot oil if the pilot oil pump fails during operation.Oil exiting the case drain flows through filter (8). All the machines have VIMS and a filter bypass switch (7) that alerts the operator that the filter is clogged.When the operator moves the pilot control valve, pilot oil shifts steering control valve (12). When steering control valve (12) shifts, high pressure oil from the steering pump flows to steering cylinders (1). This allows the machine to articulate.When the control valve spool (12) is in the NEUTRAL position and if an outside force tries to steer the machine an increase in pressure will open crossover relief valve (13). The crossover relief valve prevents the pressure in the steering cylinders from exceeding specifications.Shuttle valve (2) allows high pressure oil to travel through a load sensing line. The load sensing line travels back to steering pump (6).