Hydraulic pumps on mobile equipment generally are driven by an engine either through a drive box mounted to the engine's flywheel, through a power takeoff (PTO) from the vehicle's geared transmission, or even through the engine's own belt drive. In all of these cases, the pump runs whenever the engine does, whether hydraulic power is needed or not. This condition not only causes unnecessary wear on the pump, but increases fuel consumption.
To eliminate this drain on fuel and pump life, a clutch can be installed between the pump and its mechanical power source. The clutch is normally inactive, to prevent the hydraulic pump from rotating. However, when hydraulic power is called for, actuating the clutch allows the pump to power the hydraulic system. These clutches can be actuated electrically, pneumatically, hydraulically, or mechanically, or by a combination of these methods.
Electromagnetic clutches from Ogura Industrial Corp., Somerset, N.J., provide quick and easy engagement and disengagement of hydraulic pumps and other attachments driven by a gas or diesel engine. Maximum torque ratings are 100 to 1500 lb-ft. Large bearings and a one-piece bi-directional spring help the clutch withstand heavy vibration. Multiple disk units are also available for mounting inside gearboxes in an oil bath environment and can generate torque in excess of 12,000 lb-ft.