Milling machine system

In a multiple-mode tracer valve for simultaneously controlling the operation of a plurality of motors in order to drive machine tool components along selected ones of three orthogonally related axes, said tracer valve including body, a first, second and third spool valve, a stylus having a central axis, a tip, and a dimension of length, first mounting means mounting said stylus at a first location spaced from said tip along its length, whereby said stylus can be shifted axially and also said tip can be deflected in any lateral direction relative to said axis, adjustment means for adjusting said first mounting means adjustably to determine the lowermost permissible position of the stylus, second mounting means coupling said stylus to said second and third spool valves at a second location along its length to shift the spools of said second and third spool valves along their respective axes by distances proportional to components of displacement of the stylus tip along said axes, and to permit free vertical movement of said stylus, the improvement comprising:

• said first spool valve comprising a cylindrical first sleeve and a cylindrical first spool slidably fitted in said sleeve, said spool and sleeve having a common axis, said axis being aligned with said axis of said stylus when said stylus is in a centralized position, said first sleeve and said first spool having grooves and lands to form a coordinating sector, a first directional control sector, and a second directional control sector, said spool valve being ported to supply and receive fluid to and from motors at regulated and directionally selected rates and to receive pressurized fluid, and to pass fluid to exhaust;
• and
• a transmission interposed between said first spool and said stylus, said transmission comprising a first conical surface in the end of said stylus adjacent to and opening toward said first spool, a ball resting on said first conical surface, a rod having a planar converter surface on its end facing said ball normal to said first axis, said rod being rigidly fixed to said spool, a converter plunger axially slidably mounted in said first spool surrounding said rod, a second conical surface opening toward said ball, converter means for shifting said converter plunger to a position where the ball can bear against said converter surface, or to a position where said ball bears against said second conical surface but not against said converter surface, and converter means to shift said converter plunger to a selected one of said positions.