The power output from the ISM engine is controlled by an accelerator governor within the ECM. As with all Cummins electronic engines there are two distinct types of accelerator governor, each providing unique characteristics that affect the manner in which the engine responds to operator input. The two types of accelerator governor available in the ISM are:
With the Automotive Governor, the power output is determined by the position of the accelerator pedal. As is the case with a standard automobile governor, the accelerator pedal must be fully depressed for the operator to command full power output. Under normal operating conditions the operator will change the accelerator pedal position to vary the power output and thereby control vehicle speed.
Variable Speed (VS) Governor
Sometimes referred to as an 'all speed' governor, the variable speed accelerator governor controls engine speed based on accelerator pedal position. With this type of governor, the operator controls vehicle speed by maintaining a constant accelerator pedal position. By fully depressing the accelerator pedal with a variable speed governor, the operator commands the maximum engine speed available.
The choice between the Automotive type accelerator and the Variable Speed type accelerator governor should be based on vehicle configuration and operator preference. The Automotive type is most commonly used on Cummins engines.
To provide additional flexibility, some vehicles are equipped with a cab switch that allows the operator to switch from one type to other in response to changing circumstances and preference.
The Accelerator feature group is also very accommodating for specialty applications. The control system supports the installation of a remote accelerator pedal and can even deactivate the accelerator pedal under desired conditions (example: school bus door open).
Child Link List