Abstract: A hydraulic circuit for use on a turning machine (10) having a quill (32) which is movable to an extended and retracted position for detecting, through pressure drop, when the quill (32) is fully retracted or extended and engaging a workpiece. The quill (32) is positioned by a hydraulic cylinder (40) which is operated from a hydraulic power supply (60). A pressure actuated switch (48) is connected to one of the operating ports on the hydraulic cylinder (40) and a orifice (70) is connected to the same port. By detecting when the pressure sensitive switch (48) is activated with respect to positioning of the hydraulic cylinder (40) proper functioning of the quill (32) can be determined. A timer (90) circuit is provided for determining that the pressure sensitive switch (48) changes position within a set time period after the hydraulic circuit is activated to change position of the quill (32).

Abstract: An improved machine tool has a chuck assembly which is actuated by a piston and cylinder type motor assembly. When a workpiece is to be gripped by the chuck assembly, high pressure fluid is directed to one chamber of the piston and cylinder motor and is exhausted from the opposite chamber. When the chuck assembly has gripped a workpiece, relative movement between the piston and cylinder is interrupted and fluid is no longer discharged from the motor. A pressure responsive switch assembly detects the reduction in the rate of the flow of fluid from the motor to provide a signal to indicate that a workpiece has been firmly gripped by the chuck assembly. After an initial machining operation in which relatively high forces are applied to the workpiece, such as during a rough cutting operation, the chucking forces applied to the workpiece are reduced prior to initiation of a finish cutting operation.

Abstract: A machine tool (10) utilizing two speed hydraulic indexing with direction control valves (86,88) which are energized to stop. A turret (12) is rotated during indexing by a hydraulic motor (36). An open loop control system is utilized to locate the turret (12) position before clamping. A plurality of cams (40,42,44,46,48,50) which trigger associated proximity switches (41,43,45,47,49,51) are used to provide control information to the electric control circuit (17) for turret indexing. A final position cam (50) which rotates at a multiple of the turret (12) indexing speed is provided for final positioning of the turret (12) at a desired work station. The final position cam (50) is adjustable so that the tool turret (12) will be accurately stopped at a selected work station. The final position cam (50) also provides information which is utilized for switching from a high speed indexing mode to a low speed indexing mode when the selected work station is approached.