ARM 0305069 - Caterpillar

Illustration 1 g00338932
Lockup Clutch And Synchronizing Valve (1) Synchronizing solenoid (2) Lockup clutch valve spool (3) Passage (4) Synchronizing valve spool (5) Inlet passage from pump (6) PassageThe lockup clutch and the synchronizing valve group is made up of synchronizing solenoid (1) , lockup clutch valve spool (2) and synchronizing valve spool (4) .Synchronizing solenoid (1) and synchronizing valve spool (4) work together in order to make sure that the tractor and scraper transmissions are in correct relation before the scraper transmission is engaged. When the scraper transmission is not in correct relation with the tractor transmission, synchronizing solenoid (1) does not permit the pump oil from passage (5) through the left end of synchronizing valve spool (4) . Pump oil goes through passage (6) to the right end of synchronizing valve spool (4) . This pushes spool (4) to the left. Pump oil now goes to the torque converter. Pump pressure is now less than the setting of the priority valve. This causes the priority valve to close. Pressure can not increase in the clutches and the scraper transmission does not engage.When both transmissions are in correct relation, synchronizing solenoid (1) permits pump oil to go from passage (5) through passage (3) to the spring chamber of synchronizing valve spool (4) . This pressure and the force of the spring holds synchronizing valve spool (4) to the right. The pump pressure can now increase to a normal setting. This causes the priority valve to open. Oil goes to the clutches and the scraper transmission engages.Machines without retarders do not have a lockup clutch. Lockup clutch valve spool (2) has no function on these machines. For the operation of the lockup clutch valve spool, refer to Systems Operation, SENR9064, "Retarder" in this module.For a further explanation of the synchronizing valve and the solenoid, refer to Systems Operation, SENR9064, "Transmission Electronic Control System" in this module.