Retard switch
My neighbor just bought a new 2013 Fleetwood Expedition 40X with a 360HP Cummings and Allison transmission on a Freightliner chassis. We were talking about the "Retard" button and he said the owners m...
Forum Discussion
CAUTION: Observe the following cautions when driving a vehicle equipped with a retarder:
• THE RETARDER WORKS ONLY WHEN THE ENGINE IS AT CLOSED THROTTLE.
• OBSERVE TRANSMISSION AND ENGINE TEMPERATURE LIMITS AT ALL TIMES. Select the lowest possible transmission range to increase the cooling system capacity and total retardation available.
• In the event of OVERHEATING, DECREASE THE USE OF THE RETARDER; USE THE SERVICE BRAKES TO SLOW THE VEHICLE.
• OBSERVE THE RETARDER/SUMP “OVERTEMP” LIGHT to be sure it responds properly to retarder temperature.
NOTE: The transmission retarder is configured as either a low, medium, or high capacity retarder. Retarder capacity configuration is determined by the vehicle OEM. Allison Transmission requires vehicle OEM approval before a service outlet increases the retarder capacity at customer request. This vehicle qualification is to make sure existing vehicle drivelines, differentials, axles, and cooling system are designed for the additional retarder torque generated in a higher capacity retarder configuration. Additionally, WTEC III Controls will require a retarder charging spring change and possibly an ECU re-calibration as well. Allison 4th Generation retarder requires only a TCM re-calibration with the OEM approval for a higher capacity retarder. Cost incurred to modify retarder capacity is the responsibility of the customer.
NOTE: Allison 4th Generation and WTEC III retarder activation, response, and driver requested retarder amount are characteristically similar but not identical. Refer to the Types of Retarder Control Table in this section to see how retarder modulation request (RMR) can be changed if desired to increase or decrease retarder percentage apply. These controls are also OEM determined and installed. Cost incurred to modify a RMR is the responsibility of the customer.
NOTE: Transmission fluid level must be set correctly for highest retarder effectiveness. As much as 2 liters (2 quarts) too high or too low can reduce retarder effectiveness and increase transmission temperature.
• THE RETARDER WORKS ONLY WHEN THE ENGINE IS AT CLOSED THROTTLE.
• OBSERVE TRANSMISSION AND ENGINE TEMPERATURE LIMITS AT ALL TIMES. Select the lowest possible transmission range to increase the cooling system capacity and total retardation available.
• In the event of OVERHEATING, DECREASE THE USE OF THE RETARDER; USE THE SERVICE BRAKES TO SLOW THE VEHICLE.
• OBSERVE THE RETARDER/SUMP “OVERTEMP” LIGHT to be sure it responds properly to retarder temperature.
NOTE: The transmission retarder is configured as either a low, medium, or high capacity retarder. Retarder capacity configuration is determined by the vehicle OEM. Allison Transmission requires vehicle OEM approval before a service outlet increases the retarder capacity at customer request. This vehicle qualification is to make sure existing vehicle drivelines, differentials, axles, and cooling system are designed for the additional retarder torque generated in a higher capacity retarder configuration. Additionally, WTEC III Controls will require a retarder charging spring change and possibly an ECU re-calibration as well. Allison 4th Generation retarder requires only a TCM re-calibration with the OEM approval for a higher capacity retarder. Cost incurred to modify retarder capacity is the responsibility of the customer.
NOTE: Allison 4th Generation and WTEC III retarder activation, response, and driver requested retarder amount are characteristically similar but not identical. Refer to the Types of Retarder Control Table in this section to see how retarder modulation request (RMR) can be changed if desired to increase or decrease retarder percentage apply. These controls are also OEM determined and installed. Cost incurred to modify a RMR is the responsibility of the customer.
NOTE: Transmission fluid level must be set correctly for highest retarder effectiveness. As much as 2 liters (2 quarts) too high or too low can reduce retarder effectiveness and increase transmission temperature.
