621H, 623H and 627H Wheel Tractor-Scrapers Power Train Caterpillar

Note: Before performing any of the operational checks, verify that all of the fluids are at the appropriate levels.

1. Shift the transmission shift lever into any gear except NEUTRAL. Attempt to start the engine. The engine should not start.

2. Shift the transmission shift lever into the NEUTRAL position. Start the front engine. Start the rear engine (if equipped). Run the machine in all FORWARD gears. Run the machine in all REVERSE gears.

3. When both of the tractor wheels are turning at the same speed, depress the differential lock pedal.

4. While the machine is traveling in any gear, engage the transmission hold control. The current transmission speed should be maintained until the transmission hold control is deactivated.

5. If your machine has a rear engine, verify that the front transmission and the rear transmission are synchronized. Start the tractor engine. Start the scraper engine. Make sure that the parking brake is applied. Walk to the rear of the machine. Verify that the transmission synchronization light is not on. If the transmission synchronization light is on, the transmissions are not synchronized.

If any of the previous machine operations are not functioning properly, refer to this Systems Operations, Testing and Adjusting, "Power Train Troubleshooting".