HUB ASSEM. 6S7803 - Caterpillar

Automatic Engine Speed Control (AEC)
The automatic engine speed control functions to automatically reduce engine speed when there is no hydraulic demand or when the hydraulic demand is very small. The purpose of the AEC system is to reduce fuel consumption and noise.The system will be inoperable while the governor control system backup switch is in the MAN position. (If the hydraulic oil is not at normal operating temperature, the AEC may respond slowly.)The AEC system operates in the following three levels, depending on the position of the AEC switch and the operation of the manual low idle switch. In any condition, the engine rpm will recover automatically to the engine speed dial setting upon the activation of any hydraulic function.Level One:
* AEC switch OFF* Manual AEC system not activated* Engine speed dial in a position from "5" to "10"The electronic controller automatically reduces engine speed by 100 rpm approximately three seconds after there has been no hydraulic demand.Level Two:
* AEC switch ON* Manual AEC system not activated* Engine speed dial in a position from "5" to "10"The AEC system in the electronic controller will automatically reduce the engine rpm to around 1300 rpm approximately three seconds after there has been no hydraulic demand.Level Three:
* AEC switch ON or OFF* Manual AEC system activated* Engine speed dial in a position from "3" to "10"Anytime the manual low idle switch is activated (the switch located in the right implement control lever), the engine speed is reduced to approximately 950 rpm. Pressing the switch again will allow the engine speed to return to the engine speed dial setting or approximately 1300 rpm (LEVEL 2) if the AEC switch is in the ON position, and there is no hydraulic demand. Automatic Engine Speed Control (AEC) Switch - The switch and the indicator are activated when the engine start switch is placed in the ON position. The switch position changes from OFF to ON and from ON to OFF each time the AEC switch is pushed.
Earlier machines
Later machines Manual Low Idle Switch - This switch reduces the engine speed to approximately 950 rpm from the engine speed dial setting or the AEC setting of 1300 rpm. If the switch is pressed again, the engine speed will return to the engine speed dial setting or the AEC setting of 1300 rpm, depending on whether there is hydraulic demand or not.Electronic Controller System Backup Switches
Located inside the rear of the right console. Governor Control System Backup Switch (1) - To gain access to the switch, open the access cover by sliding it backward.In normal condition, the switch must be in the AUT (normal) position. If a problem occurs in the electronic control system which controls the engine governor, move the switch to the MAN (backup) position. The electronic controller is disconnected from the governor actuator circuit and the engine speed can be controlled manually.When the switch is placed in the MAN position, an "A" appears in the first digit of the character display. The switch