Spring lock knob assembly

A control knob assembly for mounting on an end portion of a rotatable shaft and comprising:

• a bushing rotatably disposed to encircle the end portion of the shaft and having first interlocking means for transmitting rotary motion to the shaft;
• a non-rotatable race disposed adjacent an end portion of the bushing, the race including an annular end wall extended outwardly of the bushing end portion and an attached outer cylindrical wall disposed in spaced encircling relationship with the bushing end portion;
• windingly operated spring means annularly disposed between the bushing end portion and the cylindrical wall of the race for exerting radial pressure and releaseably locking the bushing to the non-rotatable race to prevent rotation of the bushing in either angular direction, the windingly operated spring means including an axially aligned pair of oppositely wound coil springs having respective portions disposed for engagement with the bushing end portion;
• a knob shell supported rotatably about the bushing and having second interlocking means for transmitting rotary motion thereto;
• release means axially aligned with a portion of the knob shell and disposed in engagement with the windingly operated spring means for controllably unlocking the bushing from the nonrotatable race in response to an axial force applied to the shell;
• and
• axially operated spring means disposed between the knob shell and the bushing for resiliently positioning the shell with respect to the bushing.