Case Corporation

Jimmie D Clifford

Guy T Stoever

Disclosed is a modulating hydraulic circuit for controlling a clutch such as the clutch on a power takeoff (PTO) shaft. The circuit includes a throttling valve having (a) an inlet port for receiving hydraulic fluid from a source, and (b) a discharge port connected to the clutch. The discharge port is also connected to an accumulator which is at an accumulator pressure. The discharge port and the clutch are at a pressure generally proportional to the accumulator pressure. As accumlator pressure rises at a controlled rate, the clutch is progressively engaged. Optionally, the circuit includes a brake control valve for 'softly' disengaging a PTO shaft brake as the accumulator pressure rises. A method for controlling the clutch includes flowing hydraulic fluid through hydraulic lines to a throttling valve connected to an accumulator and to the clutch, increasing pressure in the lines and progressively engaging the clutch.

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Naperville, IL, United States of America

Jimmie D Clifford