CONTROL DEVICE FOR A HYDRAULIC MOTOR

摘要

A control device (20) for controlling a speed of a hydraulic motor (22) includes a housing (26) defining a first void (28). A speed valve (30) is disposed within the first void (28) and is moveable between a first speed valve position (98) and a second speed valve position (100). The first void (28) includes a speed valve pressure chamber (42) disposed at one end of the speed valve (30). A speed valve spring (44) is disposed at another end of the speed valve (30). The housing (26) further defines a speed change port (94) and a speed change passage (96) interconnecting the speed change port (94) and the speed change pressure chamber for directing a pressurized fluid directly into the speed valve pressure chamber (42) to exert a pressure force on the speed valve (30) and bias against the speed valve spring (44) to move the speed valve (30) between the first speed valve position (98) and the second speed valve position (100).