Image Number 2 for United States Patent #4946014.
A retarder adapted for use on a vehicle comprises: a blower connected to a crankshaft of the vehicle; a clutch provided between the blower and the crankshaft for selectively disconnecting the blower from the crankshaft; a speed change mechanism including a plurality of shafts, gears and bearings and provided between the crankshaft and the blower; an oil pump driven by energy transmitted from the clutch and the blower for supplying lubrication oil to the speed change mechanism; a sensor for detecting the pressure of the lubrication oil supplied to the elements of the speed change mechanism; and a control unit for allowing the clutch to disconnect the blower from the crankshaft when the lubrication oil pressure detected by the sensor is below a certain value. The blower consumes energy of the engine which is transmitted from the crankshaft, thereby applying a brake force to the engine. When trouble, such as a seize-up of the bearings, occurs in the speed change mechanism, the rotation of the shafts of the speed change mechanism is decelerated. Thereupon, the oil pressure from the oil pump drops since the pump is driven by energy derived from the speed change mechanism. An excessive brake force is not applied to the crankshaft since the trouble is detected by the control unit and then the blower is disconnected from the crankshaft promptly.