CASE-DIFFERENTIAL 4981036 - Caterpillar

Illustration 1 g03457900
(1) Chamber
(2) Check valve
(3) Spool
(4) Spring
(5) Adjustment screw
(6) Slug
(7) Port - oil supply
(8) Chamber
(9) Relief valve
(10) Torque converter inlet chamber The transmission hydraulic control relief valve is used in order to regulate the pressure to the main components in the transmission. The transmission hydraulic control relief valve also provides oil to the torque converter.Oil enters the relief valve at oil supply port (7). The pressure of the oil acts on spool (3). Spool (3) moves to the right when the pressure that is acting on the spool is greater than the force of spring (4). Oil flows to the chamber for the torque converter inlet (10). When spool (3) moves to the right, oil enters chamber (1) past check valve (2). Under normal operation, oil in port (7) seeps past spool (3) at chamber (8) to the torque converter. As the pressure of the oil to the torque converter rises, relief valve (9) allows the oil to escape to the sump. This action controls the inlet pressure of the oil in the torque converter.If the oil supply to the transmission hydraulic control relief valve is stopped, the oil in chamber (1) is trapped by check valve (2). This oil can escape slowly past slug (6) to the sump and allowing the spool to return to the left. This action prevents spool (3) from returning to the left before the torque converter has stopped rotating.Adjustment screw (5) alters the preload on spring (4) in order to adjust the relief pressure.