The hydraulic drive provides for rapid approach of the toolslide to the workpiece, working feed and rapid return upward. High-output gear pump 1 is used for rapid traverse. Variable-displacement piston pump 2 is used for the working feed. The working cycle is controlled by valve spool 3 which is shifted automatically or by hand using lever 4. In the position shown, pumps 1 and 2 deliver fluid through a groove of valve spool 3 and through rapid traverse valve 5 to the upper end of power cylinder 6. At this, the lower end of cylinder 6 is connected to the delivery line of pump 1.• The rod of piston 7 is rigidly attached to toolslide 8. Owing to the action of the fluid, piston 7 and toolslide 8 travel rapidly downward. When cam dog a reaches valve 5, the valve member is shifted, switching the system over to the working feed. The rate of feed of the toolslide is varied by changing the output of variable-displacement piston pump 2. At the end of the working stroke, toolslide 8 runs up against positive stop d. Owing to the increase in pressure in the system, valve 9 is opened and through it fluid is discharged to the tank. At the same time, valve member 10 shifts downward, connecting the lower end of spool 3 through pipeline 11 to gear pump 1. This shifts spool 3 upward and fluid is delivered by gear pump 1 to the lower end of working cylinder 6. At this, the upper end of the cylinder is connected to the tank. Piston 7 and toolslide 8 are rapidly withdrawn upward. Relief valve 12 prevents the toolslide from moving down unintentionally due to its weight.
$4191$CHP,Dr$