Operation of the Caterpillar Compression Brake
- Before descending a long grade or a steep grade, test the Caterpillar compression brake in order to ensure proper operation.
- Never exceed a safe control speed.
- Do not use the Caterpillar compression brake when the vehicle is attached to two trailers.
- Do not use the Caterpillar compression brake when an empty trailer is pulled on wet pavement or slippery pavement. This is particularly important if the vehicle has a single drive axle.
- Do not shift gears without using the clutch when the Caterpillar compression brake switch is in the ON position. Do not make a double clutch when the Caterpillar compression brake is activated. Power train damage may occur.
The Caterpillar compression brake will not operate during the following conditions. The following conditions will temporarily interrupt the operation of the Caterpillar compression brake.
- The temperature of the engine coolant is below 70 °C (158 °F).
- The engine speed is below 1400 rpm and the vehicle speed is below 24 km/h (15 mph). If low braking speed is desired, choose a transmission gear that will maintain the engine rpm above 1400 rpm.
- On downgrades, do not coast while the clutch pedal is depressed.
- Do not coast with the transmission in NEUTRAL.
- If no engine power is needed, disengage the cruise control.
- Select the correct gear that does not allow the engine speed (rpm) to exceed 2600 rpm.
- Use the Caterpillar compression brake in order to control the speed of the vehicle.
- Occasionally, when heavy loads or steep grades are encountered, it may be necessary to descend using a gear that is lower than the gear that is used to ascend. Maximum braking power occurs over 2200 rpm. Care should be taken at the top of a hill in order to ensure that the vehicle is in the proper gear for optimum braking.
Controls for the Caterpillar Compression Brake
ON/OFF Switch - This switch activates the system for the Caterpillar compression brake.
Progressive Braking Switch - This switch allows various settings for different conditions.
LOW Setting - This setting will provide approximately one-third of the total available braking horsepower. This setting is typically used on flat roads when light loads are hauled.
MED Setting - This setting will provide approximately two-thirds of the total available braking horsepower. This setting is typically used when the LOW setting is not adequate in order to provide the desired braking horsepower.
HIGH Setting - This setting will provide full braking horsepower. This setting is typically used on downhill grades or the setting is used when heavy loads are involved. Use this setting only when there is good traction.
In addition to the switch controls that were previously discussed, other switches are available. A control switch exists for the Caterpillar compression brake that is activated by the position of the clutch pedal. There is also a switch that is activated by the position of the accelerator pedal.
The Caterpillar compression brake operates similarly in vehicles with automatic transmissions and in vehicles with manual transmissions. However, some vehicles are equipped with autoshift transmissions. In this situation, the Caterpillar compression brake may actuate in order to help the transmission make an upshift. This feature is controlled automatically through the transmission control module. This automatic control can happen even if the Caterpillar compression brake switch is in the OFF position.