Abstract: The transmission of torsional vibrations from a rotating driving shaft, at the output of an internal combustion engine, to a driven shaft, at the input of a manual transmission, are reduced or eliminated by employing a normally-engaged, oil-cooled wet clutch to interconnect the two shafts, the clutch being controlled to introduce a desired amount of slippage. Slipping the wet clutch to a relatively small extent allows the necessary torque to be transmitted, but any torque fluctuations in the driving shaft will be effectively absorbed and prevented from causing torsional vibrations in the drivetrain.

Abstract: A variable speed fan drive, operated in response to the sensed coolant temperature in an internal combustion engine for a vehicle, blows a controlled amount of air through the engine's radiator to maintain the coolant temperature in a desired narrow operating range. The air pulled in by the fan also cools the refrigerant flowing through the condenser of the vehicle's air conditioning system, the condenser being positioned in front of the coolant radiator. If insufficient condenser cooling occurs, even though the coolant may be adequately cooled, the refrigerant temperature rises and causes the compressor discharge pressure in the air conditioning system to increase. That pressure is monitored or sensed and if it exceeds a predetermined maximum allowable level the normal operation of the control system is overriden and the fan is driven at its maximum speed to maximize the air blown through the condenser and radiator, thereby decreasing the refrigerant temperature and thus the discharge pressure.

Abstract: When additional heat exchangers, such as oil coolers and turbocharged air coolers, are mounted in front of or within the normal coolant heat exchanger or radiator of an internal combustion engine, a variable speed fan drive may be employed to blow air through all of the heat exchangers to cool the various fluids flowing through those heat exchangers. Since the different fluids usually have different desired operating temperature ranges for optimum engine performance, controlling the variable speed fan drive only in response to the temperature of the engine coolant can result in overheating of at least one of the other fluids. This is avoided by temperature sensing the different fluids and effectively determining which one of them has the highest relative temperature in its operating range. The fan drive is then controlled in response to the sensed temperature of that particular fluid. In this way, all of the fluids will be maintained within their desired operating temperature ranges.

Abstract: A smooth, optimum engagement of a pressure-operated actuator, such as a brake or clutch, is obtained by producing a pulse width modulated signal, having a gradually changing duty cycle, which is then used to control a three-way on/off solenoid valve to which is supplied pressurized fluid such as air. The solenoid valve is rapidly switched between pressure in and exhaust out in accordance with the changing duty cycle in order to develop a gradually increasing fluid pressure for application to the actuator.

Abstract: The operating temperature of an internal combustion engine is maintained within desired limits by employing a single coolant temperature sensor for controlling and coordinating the operation of three different temperature control devices for the engine coolant. When the sensed coolant temperature is in a relatively low range a flow control valve controls the amount of coolant diverted from the engine jacket to a radiator to dissipate heat absorbed by the coolant from the engine. If the coolant temperature exceeds that low range, even though the control valve is fully open and all of the coolant is circulated through the radiator, the sensor then effects the opening of radiator shutters to cause ram air to impinge on the radiator to increase the cooling of the coolant.

Abstract: A control system for a power shifted transmission includes an electrical signal processing system, incorporating a digital processor, which provides output signals to regulate operation of the directional clutch and the range clutches through a plurality of spool valves. A hydraulic stabilizer is connected to a common line supplying the directional clutch, to provide a predetermined amount of fluid with each change in direction, with the remainder of the fluid being provided through a forward-reverse modulating valve. A neutral bleed valve is connected to reduce the measured amount of fluid in the stabilizer when the clutch is being shifted from the neutral position, instead of a full directional change. To improve range shifts, the directional clutch is slipped while the range change is made, and the directional clutch is then re-applied. A horsepower indicator provides the vehicle operator with an instantaneous indication of the vehicle operating efficiency.