SHIM 2706944 - Caterpillar

Shift from SECOND gear to THIRD
When the transmission control is moved from SECOND gear to THIRD, an upshift will occur when the output shaft of the transmission achieves the correct rpm. The Power Train ECM activates upshift solenoid (31). The Power Train ECM also deactivates lockup clutch solenoid (29). Upshift solenoid (31) sends pump oil to rotary actuator (32). This causes the rotor of the rotary actuator and of rotary selector spool (36) to move in a clockwise direction from position 2 to position 3. When rotary selector spool (36) achieves position 3, the transmission gear switch that is connected to the rotary selector spool sends an electrical signal to the Power Train ECM. The signal informs the Power Train ECM that the shift has been made. Upshift solenoid (31) is deactivated and lockup clutch solenoid (29) is activated. Movement of the rotor in rotary actuator (32) and in rotary selector spool (36) stops.For information on the results of activating and deactivating the lockup clutch solenoid, refer to the power train Systems Operation, "Lockup Clutch and Synchronizing Valve (Torque Converter)".Position 3 of rotary selector spool (36) sends pilot oil to selector piston (45) and to selector piston (44). Rotary selector spool 36 drains the pilot oil at selector piston (39) and at selector piston (50). Selector piston (39) moves against the load piston body. This drains the oil that is between selector piston (39) and load piston (40). Selector piston (50) moves against the load piston body. This drains the oil that is between selector piston (50) and load piston (49) .Load piston (40) and modulation reduction valve (41) now move toward selector piston (39). Load piston (49) and modulation reduction valve (48) now move toward selector piston (50). The pump oil that is flowing to the No. 2 clutch is stopped by modulation reduction valve (41). The clutch oil that is in the No. 2 clutch is drained. Pump oil that is flowing to the No. 5 clutch is stopped by modulation reduction valve (48). The clutch oil in the No. 5 clutch and in the No. 2 is drained. The No. 2 clutch and the No. 5 clutch are released.The pilot oil that is flowing to selector piston (45) causes selector piston (45) and load piston (46) to move to the right. The pilot oil that is flowing to selector piston (44) causes selector piston (44) and load piston (43) to move to the left. The force of the springs causes modulation reduction valve (47) to move to the right. The force of the springs causes modulation reduction valve (42) to move to the left. Pump oil now goes around modulation reduction valve (47) and the No. 1 clutch begins to fill. The clutch oil also