Caterpillar Inc.

Susan E Bieker

Edward William Mate

Michael D Hudson

Dennis Ray Barber

John J Kaufman

Eric P Jakubiak

Moses Imo Akpan

Scott D Vollmer

A hydraulic fan circuit is provided. The hydraulic fan circuit includes a tank, a motor having a fluid inlet and a fluid outlet and a pump to draw fluid at a low pressure from the tank and discharge the fluid at elevated pressures to the motor via the fluid inlet. The hydraulic fan circuit further includes a directional control valve disposed between the fluid outlet of the motor and the tank. The directional control valve is operable to move between a flow blocking position and a flow passing position. Further, the directional control valve is configured to reduce a positive speed of the motor below a lowest positive speed attainable through control of pump output. Furthermore, the hydraulic fan circuit includes a pressure control circuit configured to provide a pilot fluid flow at varying pressure to move the directional control valve.

Hydraulic system having low speed operation

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Minooka, IL, United States of America

Susan E Bieker