PLATE AS- 4781750 - Caterpillar

Service Brake
All wheels of the wheel tractor-scraper are equipped with air brakes. The air brakes are actuated by air pressure when the service brake pedal (1) is pushed by the operator. The braking force increases as the pedal pressure is increased.
Illustration 1 g00677093The service brakes on wheel tractor-scrapers are designed to stop the machine. When you are using the retarder, the service brakes should not be used repeatedly in order to slow the machine. Parking Brake
All four wheels of the wheel tractor-scraper are equipped with spring applied parking brakes. The parking brakes and service brakes use the same brake actuator to activate the brakes.
Illustration 2 g00667001Pull the parking brake control (2) outward. This will release the air pressure and the springs will be allowed to apply the parking brakes. The air pressure must be above 621 kPa (90 psi) in order to disengage the parking brakes.If the brake air pressure drops below 517 35 kPa (75 5 psi), the following events will occur:
The action alarm will sound.
The action lamp will sound.
The brake air pressure indicator will flash.If the brake air pressure drops below 379 34 kPa (55 5 psi), the parking brakes will engage automatically.Note: When the parking brakes have been engaged automatically, the parking brake control must be reset manually. When the air pressure in the system has returned to the normal operating pressure, the knob must be pulled upward into the ENGAGED position. Next, push down on the parking brake control in order to disengage the parking brakes.When the parking brake is engaged and the transmission control is moved out of the NEUTRAL position, the action alarm will sound and the action lamp will flash.Retarder (If Equipped)
Illustration 3 g00667002The retarder is a fluid coupling that is mounted at the engine flywheel housing. Engage the retarder (3) in order to slow the machine ground speed. The transmission must be in gear in order to drive the retarder impeller. Use the retarder on a downgrade to prevent engine overspeed.Use the retarder to help to stop the machine. The retarder will not completely stop the machine and the retarder will not hold the machine stationary.Note: Use the retarder at least one time during each work day to keep the seals lubricated.Retarding on a Downgrade
The speed selection is very important because a lower speed increases the effective force of the retarder. Generally, the speed that is used to negotiate an empty machine on an upgrade should be used for driving a loaded machine on a downgrade of the same slope. Readjust the speed after a trial run.Before you approach a downgrade, slow the machine. Anticipate the need to use the retarder. Move the retarder control lever in order to engage. The retarder will usually engage in less than four seconds. Allow the transmission to downshift to the necessary lower speed. Engage the transmission hold.Select the proper transmission speed that will allow the retarder to maintain a safe ground speed with little use of the service brakes.To ensure maximum