AIR DRYER GP 1941986 - Caterpillar

Illustration 1 g00465115
Location of the priority valve (group)The priority valve is mounted on the lower left side of the bevel gear case.
Illustration 2 g00462174
Components of the priority valve (group) (1) Torque converter inlet relief valve (1A) Relief valve spool (2) Passage to torque converter (3) Passage to bevel gear case (4) Relief valve spring (5) Relief valve adjustment (6) Priority valve adjustment (7) Priority valve spring (8) Priority valve (8A) Priority valve spool (9) Passage from torque converter and lubrication section of the pump (10) Slug chamber (11) Supply chamber (12) SlugThe priority valve (group) contains priority valve (8) and torque converter inlet relief valve (1) .The priority valve makes sure that oil pressure is first available for steering, braking, and transmission control. As the next priority, the priority valve supplies oil to the torque converter and lubrication for the steering clutches, lubrication for the brakes, and lubrication for the transmission.
Illustration 3 g00462176
(1) Torque converter inlet relief valve (5) Relief valve adjustment (6) Priority valve adjustment (8) Priority valve (13) Solenoid valveValve Operation
The priority valve setting is determined when solenoid valve (13) selects oil from either inlet (9) or drain (3) in order to supply oil to chamber (11) .Oil from section (A) of the power train oil pump enters inlet passage (9) in the priority valve. The oil goes from inlet passage (9) through a hole in spool assembly (8A). The oil then goes into chamber (10) between the slug and the poppet.When the oil pressure in chamber (10) becomes higher than the priority valve setting in the current mode of operation, spool assembly (8A) moves. The spool assembly moves toward adjusting screw (6) and this allows pressure oil flow to outlet passage (2) .The pressure oil goes from outlet passage (2) to the torque converter. The oil then goes through the oil cooler. From the oil cooler, the oil goes to the steering clutches and brakes in order to provide lubrication. The oil also provides part of the lubrication for the transmission.The priority valve has two modes of operation: normal mode and priority mode.Normal Mode
In the normal mode, flows for the torque converter and the lubrication are separate. The steering clutches, the brakes, and the transmission do not have priority.For the normal mode, the solenoid is ON and inlet (9) is selected.In the normal mode, inlet pressure in chamber (11) acts on more of the spool area around slug (12). This causes spool assembly (8A) to move toward adjusting screw (6). This allows oil from the torque converter and lubrication section of the pump to pass through the priority valve to the torque converter.Priority Mode
In the priority mode, oil flow to the torque converter and the lubrication system have priority in order to maintain pressure for steering, braking, and transmission control.For priority mode, solenoid (13) is OFF and drain (3) is selected.In priority mode, the pressure in supply chamber (11) is drained. This release of pressure causes the inlet pressure in slug chamber (10) to move spool assembly (8A).