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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 3406B PEEC Engine.Compression Brake
Operation (Jacobs Brake or Pacific Brake)
The Jacobs Engine Brake should not be used as a primary or service brake. Do not allow the engine to exceed 2300 rpm. However, engines equipped with a Jacobs Engine Brake should not normally be operated above 2100 rpm.
The Jacobs Engine 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 Jacobs Engine Brake controls may include a dash mounted module or an ON/OFF switch and a three position switch with "Lo" 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.The PEEC ECM monitors the clutch, brake, throttle position and engine rpm to determine when the Jacobs Brake can operate. It may take up to two seconds before Jacobs Brake activates.Since the Jacobs Engine Brake is most effective at rated engine rpm, gear selection is very important. Gearing down the vehicle, within the limits of rated engine rpm, makes the engine brake a more effective retarder. Maximum retarding occurs at higher engine rpm.Cruise Control (If Equipped) OFF
With the Cruis Control (CC) in the OFF position the Jacobs Engine 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 Jacobs 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 Jacobs Brake slave piston lash, refer to PM Level 2-Engine Valve Lash. Refer to Jacobs Brake Troubleshooting Manual, Form SENR4251 for information regarding this auxiliary braking system.There are differences in exhaust braking devices from those with little or no leakage when activated to those with a great deal of leakage.Sliding Gate Type (Williams Blue Ox)
This type of exhaust brake allows minimal leakage and must have a relief orifice to limit the maximum exhaust manifold back pressure to 50 psi (345 kPa) at maximum engine braking rpm. Flapper Type (Pacific)
With this type of exhaust brake, there is usually leakage around the movable plate. To obtain 50 psi (345 kPa) or 70 psi (485 kPa) performance level braking, a small hole would likely be required. The maximum permissible exhaust back pressure at maximum engine braking rpm is measured at the 1/4 NPT hole in the exhaust