Manual displacement control

摘要

A manual displacement control is provided for varying the displacement of a hydraulic pump. The pump has a tiltable swashplate and is used in a hydraulic system which includes a control valve having an axially movable spool for metering control fluid to modulate the swashplate position. A displacement control linkage has a non-linear coupling element and a resilient override spring serially connected between the input lever and the valve spool. A torsional centering spring is connected between the input lever and the override spring to generate a feedback force which opposes a control force applied thereto and urges the input lever to a position representative of the no flow position of the pump swashplate. An adjustable connection is provided for centering the valve spool while maintaining a corresponding neutral position of the input lever and swashplate during assembly of the displacement control.