SHAFT-IDLER GEAR 4N1235 - Caterpillar

An optional hydraulic retarder is available with the CX31 transmission. The retarder acts as a secondary braking system that is activated by electrical inputs from the transmission controller. The retarder will only be enabled in the following conditions: if the torque converter is locked up, fuel is not requested by the governor, fuel is not requested by the cruise control and fuel is not requested by the throttle. The vehicle manufacturer selects the retarder controller and the location for the retarder controller at the operator station. The following three types of controllers are most commonly used: floor mounted pedal, column mounted hand lever and dash mounted set of switches. The pedal and lever determine the degree of retarding from 0 to 100 percent based on the movement of the pedal or the movement of the lever. The retarder switches are preprogrammed in order to provide off, low, medium, or a high percentage of retarding.
There are the following three modes of operation: Coast, Latch and Manual. The automatic Coast and Latch modes require the Cruise Control and the retarder controls be in the ON position. When programmed to Coast, the retarder is enabled only while the service brakes are being applied. The retarder will be applied to the preprogrammed setting selected (low, medium or high). The retarder disengages when the operator's foot is removed from the service brake. When programmed to Latch, the retarder stays on during and after the service brakes have been applied to the preprogrammed level selected. The retarder will remain in Latch mode until a request for engine fuel is active from the following: governor, cruise control and throttle. Manual Mode does not require the Cruise Control switch to be in the ON position. In the Manual Mode, the retarder will activate anytime the retarder switch is ON and a request for engine fuel is not present.
The retarder will not engage while the ABS is active. If the ABS becomes active while the retarder is active, the retarder will disengage.
The transmission retarder will not engage while a compression brake or an exhaust brake is operating. Should a compression brake or exhaust brake begin operation while the retarder is active, the retarder will disengage.
If the engine speed is turning faster than 2,600 rpm, the retarder will not engage. If the retarder is engaged and the engine speeds reach or exceed 2,600 rpm, the retarder will continue to function in order to help the operator reduce speed. The engine is protected against over speeding by the shift logic. However, there are conditions when the control logic is used to protect the hardware.
The retarder takes about one second before the transmission detects the performance of the retarder. Operators need to anticipate this delay in order to prevent the unnecessary use of the service brakes.
If the retarder has a lever that is not returned to the off position and the operator steps on the throttle, the accelerator pedal will disengage the retarder. The retarder will not engage again until