Fluidlexikon

Operating modes of drives

Drives have not only a driving function, they also provide braking (e.g. deceleration or lowering braking). In addition, the direction of rotation can also be reversed. The combination of these possibilities yields, transferred to Cartesian co-ordinates, three variants: single quadrant operation, two quadrant operation and four quadrant operation (Figure B 14).

Single quadrant operation of a drive occurs if the direction of rotation and the torque are the same (1st quadrant). On hydrostatic displacement machines this situation represents normal pump/motor operation.

With two quadrant operation either the direction of the torque remains the same and the direction of rotation changes (2nd and 3rd quadrant) or the direction of rotation remains the same with a changing direction of torque (driving and braking, 3rd and 4th quadrant). Example:hydraulic pump that becomes a motor due to the pull from the load.

With four quadrant operation the drive operates with changing direction of rotation and changing direction of torque. Example: secondary control of a hydraulic motor.

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Figure B 14: Operating modes of drives