Caterpillar Tractor Co.

Curtis E Chadwick, Iii

Karl A Nerstad

Gordon W Johnson

Franklin O Koch, Jr

Celius R Anderson

PCT No. PCT/US 79/00837 Sec. 371 Date Oct. 10, 1979 Sec. 102(e) Date Oct. 10, 1979 PCT Filed Oct. 10, 1979 Pneumatically operated control mechanisms (10-18) for vehicles have often been found to leak control fluid during start-up in extreme cold conditions until attaining normal operating temperature. It has been discovered that the problem lay in loss of resiliency of poppet valves (21) because of the exposure of the elastomer seals (24,26) to extremely cold ambient operating conditions. The problem has been solved by heating the incoming air. Reliable heating is accomplished under extreme cold conditions by use of a fluid heater (40) having an elongated heating member (41) and inner and outer sleeves (48,51) around the heating member to provide inner and outer annular spaces (49,52) through which the fluid to be heated flows in counter-current directions.

Fluid heater for pneumatic control mechanisms

A fluid pressure operated clutch which transmits torque from an engine output shaft to a transmission input shaft, including a rotatable flywheel connected to the output shaft, an adapter connected to the flywheel for rotation with the flywheel, the adapter having a first annular plate with a fluid passage near the inner periphery of the plate, and a centrifugal piston which defines with the adapter a fluid chamber supporting a rotatable torus of hydraulic fluid. The piston has a second annular plate, slideable with respect to the first plate, and a second fluid passage near the outer periphery of the second plate. The first and second plates, at their inner peripheries, provide a controlled clearance to vary the rate of hydraulic fluid into the first fluid chamber as the second plate slides. A centrifugal relief valve is connected to the piston and has a conical valve member removably seated on an outlet of the valve to drain fluid from the chamber through the second passage and the outlet when engine overspeed occurs. A clutch pack of friction plates responds to movement of the piston to engage and disengage the clutch.

Centrifugal clutch with an overspeed relief valve and clutch modulation

A clutch for coupling an engine to a transmission gearbox engages and disengages automatically in response to engine speed variation. Springs hold the clutch pressure plate retracted from the clutch discs at idling speeds. As engine speed increases, centrifugally generated fluid pressure in the clutch lubricant overcomes the spring force and applies a modulated engagement pressure to the discs. An internal valve continuously supplies an oil flow to lubricate and cool the clutch components and to charge the centrifugal pressure-generating means. Retraction of the pressure plate shifts the valve to reduce the oil flow while the clutch is disengaged. This reduces viscous drag within the clutch and thereby assures a more controlled disengagement. Retainer means stores some of the reduced oil flow to assure that ample fluid is available to the centrifugal pressure-generating mechanism when engagement commences.

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Edelstein, IL, United States of America

Curtis E Chadwick, Iii