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Exhaust brakes should not be used as a primary or service brake.
Auxiliary engine braking devices are approved for use on the 3176 Engine.Compression Brake
Operation (Jacobs Brake)
Compression brakes should not be used as a primary or service brake.Do not allow the engine to exceed 2300 rpm. However, engines equipped with a compression brake should not normally be operated above 2100 rpm.
The compression brake is an engine attachment that converts a diesel engine into an air compressor. Its function is to slow the vehicle and reduce brake wear.Operating Controls-Compression Brake
The compression brake controls may include a dash mounted module or an ON/OFF switch and a three position switch with "LO," "MED" and "HI" depending on how many cylinders of braking desired. Refer to the OEM vehicle manual for the type of operating controls that your vehicle is equipped with.Some applications are equipped with a multi-position switch to provide variable retarding capability. Operators should become familiar with the controls on their vehicles.The 3176 ECM monitors the clutch, brake, throttle position and engine rpm to determine when the compression brake can operate. It may take up to two seconds before compression brake activates.Since the compression brake is most effective at rated engine speed, gear selection is very important. Gearing down the vehicle, within the limits of rated engine speed, makes the engine brake a more effective retarder. Maximum retarding occurs at higher engine speeds.However, a compression brake equipped engine should not be operated above 2100 rpm.Cruise Control (If Equipped) OFF
With the Cruise Control (CC) in the OFF position the compression brake will function like any vehicle and engine that is not equipped with Cruise Control (CC).Cruise Control (If Equipped) ON
The driver must apply the service brake approximately two seconds and then release the service brake pedal. If the retarder "LATCH" mode has been programmed, the retarder will continue to slow the vehicle. To release or deactivate the retarder, the clutch or throttle foot pedal must be depressed or the engine rpm drop to 950 rpm.When using "COAST" mode, the compression brake should activate within two seconds after the brake pedal is applied and remain on as long as the brake pedal is applied. At the time the brake pedal is applied, the Cruise Control (CC) will deactivate.For information on adjustment to compression brake slave piston lash, refer to the Maintenance Schedule for Engine Valve Lash.Refer to the Truck Engine Application and Installation Guide, LEBT8121 April, 1988 for more information. Refer to the Systems Operation Test and Adjust in the Service Manual or to Jacobs Brake Troubleshooting Manual, SENR4251 for information regarding this auxiliary braking system.