CYLINDER GP-STICK 2426852 - Caterpillar

Table 1
Transmission Synchronization
Four-Speed Transmissions    
Tractor's Gear     Scraper's Gear    
Neutral     Neutral    
1     1    
2     1    
3     2    
4     2    
5     3    
6     3    
7     4    
8     4    
Table 2
Transmission Synchronization
Eight Speed Transmission    
Tractor's Gear     Scraper's Gear    
Neutral     Neutral    
1     1    
2     2    
3     3    
4     4    
5     5    
6     6    
7     7    
8     8    The scraper's power train ECM compares the front and rear gear information. The "Transmission Synchronization" tables show the relationship between the gear of the tractor's transmission and the gear of the scraper's transmission. Most of the time, the scraper's transmission and the tractor's transmission are in an "in sync" condition. During this time, the scraper's power train ECM keeps the transmission sync solenoid activated. The energized transmission sync solenoid allows engagement of the transmission clutches. The scraper's power train ECM decides that a shift of gears is required when the gear of the tractor's transmission no longer matches the gear of the scraper's transmission. At this time, the control deactivates the transmission sync solenoid. This action disengages the transmission clutches. In order to shift the scraper's transmission, the control activates the up solenoid or the down solenoid. Shifting the transmission rotates the actual gear switch and the control now receives the new rear gear information. When the proper relationship exists between the two transmissions, the control deactivates the shift solenoid. The transmissions are synchronized "in sync" at this time. The scraper's power train ECM de-energizes the up solenoid or the down solenoid. Then, the scraper's power train ECM energizes the transmission sync solenoid. The transmission sync solenoid is de-energized only when the transmission is shifting gears. This functionality allows the transmission to shift smoothly. Note: The tractor's power train ECM must operate correctly or the scraper's power train ECM will not operate correctly. When the operator moves the neutral/run switch to the NEUTRAL position, the scraper's power train ECM shifts the transmission to neutral. The transmission remains in neutral until the switch is moved to the RUN position. Then normal shifting resumes. Operation of The Shift Solenoids
The up solenoid and the down solenoid control the flow of oil within shift cylinder (5). When the scraper transmission control activates the up solenoid or the down solenoid, the pressure of the oil causes shift spool (3) to move. Shift spool (3) is connected to selector spool (4). The Shift spool (3) will move selector spool (4). The linkage also connects shift spool (3) to the rotor within transmission switch (6). When shift spool (3) moves selector spools (4), the rotor rotates within transmission switch (6). The signal now corresponds to the new position of shift spool (3).
Illustration 1 g00746833
Illustration 2 g00746836
When the scraper's power train ECM receives the correct signal from transmission