D343 REAR ENGINE FOR 666 AND 657 SCRAPERS Driving The Machine Caterpillar

Driving The Machine

See the topic, DRIVING THE TRACTOR, in the Tractor Operation and Maintenance Instructions for additional instructions.

The scraper power shift transmission is controlled by means of electrically actuated hydraulic power. As the controls of the tractor torque divider and range transmissions are actuated an electrical current is sent through the wiring circuit to the scraper transmissions.

The electrical current actuates a hydraulic valve which supplies oil to a hydraulic cylinder. This cylinder positions the scraper transmission controls in exactly the same position as the tractor transmission controls.

1-Scraper transmission control switch. 2-Transmission synchronization light.

A red light (2), on the instrument panel of the operator's compartment, is on (glows) when the transmissions are not in synchronization.

The unit should not be operated without the scraper engine running.

When the unit is being moved or operated, using only the tractor engine for power and the scraper engine running, the scraper engine transmission can be locked in neutral position by scraper transmission control switch (1) located at the right side of the tractor instrument panel.

The speeds of the tractor engine and scraper engine are controlled by individual accelerator pedals. The tractor engine accelerator pedal (3) and the scraper engine accelerator pedal (4) are closely located so they may be operated together or separately. A mechanical linkage to the governor is provided for the tractor engine while an air valve and rotochamber provide governor linkage to the scraper engine.

For better machine control when making a sharp turn, operate the rear engine at low idle. Operating the rear engine at low idle eliminates first, the possibility of machine jackknifing, second, undue strain on scraper gooseneck assembly, and third, side scuffing of prime mover tires.

CONTROLS (657 Tractor Illustrated)
3-Tractor engine accelerator pedal. 4-Scraper engine accelerator pedal.

A warning system is provided to notify the operator that unsafe operating conditions exists in the scraper engine or transmission. The warning horn, located on the draft frame will sound when engine coolant temperature, engine oil pressure, transmission oil pressure or torque converter oil temperature reaches a point unsafe for continued operation.

A No-Spin type differential is used in the scraper power train. This differential is designed to deliver equal amounts of torque to each wheel when their speeds are equal. When a speed difference occurs, torque is transferred to the wheel which rotates more slowly. The axle to the wheel with the better traction will turn no slower than the bevel gear.