Working speed control, function

G07.16-3144-79

General points about power take-off

The electronic working speed control takes place as soon as a power take-off is switched in. To do this up to three power take-offs can be parameterized differently according to the vehicle equipment. This means that different regulation specifications can be set for each power take-off.

Along with a range of other parameters it is possible,  for example, to set the entry requirements such as "parking brake tightened" or "transmission in neutral" or the rpm range (minimum engine speed, maximum engine speed) as well as a torque limitation.

It is furthermore possible to set the working speed during operation of a power take-off via the accelerator pedal or the keys on the multifunction steering wheel individually to an engine speed between 550 rpm and 750 rpm or to raise it via the idle speed switch to a parameterizable value.

Control of the working speed

Upon switching on a power take-off its parameters are active for the working speed control in the control unit (CPC) drive control (A3).

The drive control (CPC) control unit (A3) passes on the parameters via the drive CAN (CAN 4) to the engine management (MCM) control unit (A4).

Upon receipt of the appropriate information and while taking account of the current operating state of the engine, the engine management (MCM) control unit (A4) calculates the start of actuation of the fuel injectors for cylinders 1 to 6 (Y608 to Y613) now required as well as the necessary period of actuation (injection quantity) and ensures that the fuel is injected at the correct point in time and in the correct quantities into the respective combustion chamber through appropriate actuation of the quantity control valve (Y642) and the fuel injectors for cylinders 1 to 6 (Y608 to Y613).

 The working speed is only regulated if the appropriate power take-off is fully engaged.

Changing the working speed

Depending on the equipment installed and the parameterization of the power take-off functions, it is possible to change the working speed during operation of a power take-off via the accelerator pedal or further operating options such  as a cruise control switch individually to an engine speed between 550 rpm and 750 rpm or to increase it to a parameterized value via a switch, provided the speed does not exceed the maximum working speed or drop below the minimum working speed.

Changing the working speed using the accelerator pedal

If the accelerator pedal is actuated and therefore the position of the accelerator pedal sensor (B44) altered then the drive control (CPC) control unit (A3) alters the control specifications for the working speed and transmits these via the drive CAN (CAN 4) to the engine management (MCM) control unit (A4). In doing so, it takes account of prescribed parameters in the drive control (CPC) control unit (A3), as well as the current engine speed.

The engine management (MCM) control unit (A4) increases the working speed through appropriate actuation of the injection quantity to the desired value and holds this constant.

Changing the working speed using a switch

One special task in controlling the working speed is taken on by the switch installed by ABH. This allows one to switch on the constant engine speed facility which means that the engine management (MCM) control unit (A4) sets a single engine speed which has been parameterized and keeps this constant, independently of the loading conditions.

Changing the working speed over further operating options

The additional operating components installed by the ABH, such  as a cruise control switch, transmit the desired working speed to the drive control (CPC) control unit (A3). The drive control (CPC) control unit (A3) compares the desired working speed with the current one, the max. permissible as well as the min. permissible working speed (if these were parameterized), adapts the control specification and transmits this to the engine management (MCM) control unit (A4).

The engine management (MCM) control unit (A4) alters the working speed through appropriate actuation of the injection quantity to the desired value and holds this constant.