Switching device for variable speed gears in machine tools

In a machine tool having a plurality of sliding gear blocks and associated switching bars, a switching device for variable speed gears comprising:

• motor means;
• a shaft driven by said motor means;
• a main drive shaft;
• a switching bar movable in response to rotation of said main drive shaft;
• a plurality of gears intermeshing to form a gear train mechanically linking said motor drive shaft with said main drive shaft, said gear train and said motor means being adapted for switching through individual gear stages;
• a shock absorbing element disposed within said gear train intermediate said shaft driven by said motor means and said switching bar;
• a plurality of rotatable, individually adjustable cam discs mounted in sequence axially along said main drive shaft;
• a plurality of switches, each one of said switches being actuable by rotation of an associated one of said cam discs;
• a disc with markings attached to a free end of said main drive shaft and adapted to indicate the engaged gear stage of said variable speed gears;
• and
• a window disposed in a common housing surrounding said switching device and adjacent said free end of said main drive shaft, said window being adapted for viewing said disc with markings.

In machine tools having a plurality of sliding gear blocks and associated switching bars, a switching device for variable speed gears, said switching device comprising:

• a gear drive housing;
• a bearing housing rigidly mounted on said gear drive housing, said bearing housing comprising a bushing, a flange and a support plate;
• an electric servomotor rigidly mounted on said support plate, said servomotor having a drive shaft;
• a main drive shaft journaled in said rigid bushing in spaced, axially parallel relationship with respect to said servomotor drive shaft;
• a gear rack mounted to one of said switching bars;
• gear train means coupling said servomotor drive shaft, said main drive shaft and switching bar for linear movement of said switching bar in response to rotation of said servomotor drive shaft;
• a plurality of independently rotatably adjustable cam discs on said main drive shaft and rotatable therewith;
• a plurality of switches mounted to said flange, each of said switches being actuable by one of said cam discs;
• and
• elastic shock absorbing means disposed within said gear train intermediate said servomotor drive shaft and said switching bar to absorb any sudden shocks occasioned by operation of the switching device without affecting the distance moved by said switching bar in response to rotation of said servomotor drive shaft.