LEVER 6Y2780 - Caterpillar

Illustration 1 g02626919
(1) Solenoid
(2) Ball
(3) Orifice
(4) Chamber
(5) Clutch Fill Port
(6) Control Spool
(7) Spring
(8) Oil Supply Port
(9) Drain Port Control of the torque converter lockup clutch is achieved by the use of a modulating valve that is controlled by a solenoid.Pressurized oil is supplied by the transmission pump to the modulating valve through oil supply port (8). Pilot pressure is allowed through control spool (6) to chamber (4). The oil in chamber (4) is allowed to drain to the sump through orifice (3) and drain port (9). When solenoid (1) is energized, ball (2) is forced against orifice (3). The pressure of the oil in chamber (4) increases. The increased pressure moves control spool (6) to the right against spring (7) and pressurized oil is allowed to flow to the torque converter lockup clutch through clutch fill port (5). The clutch then engages direct drive through the torque converter.When solenoid (1) is de-energized, the pressure of the oil in chamber (4) unseats ball (2). The oil in chamber (4) is allowed to drain to the sump through orifice (3) and drain port (9). As the pressure in chamber (4) drops, control spool (6) is moved back to the left by spring (7). As the control spool is returned to the left, the supply of oil from oil supply port (8) is blocked and the oil in the clutch is allowed to flow to the sump via drain port (9).