Two speed grinding machine

Claim 1

A grinding machine comprising: a spindle; a grinding wheel mounted on said spindle; and a dual motor drive means connected with said spindle operable to rotate said spindle at a selected one of two speeds; said drive means comprising: a base member; an output shaft rotatably supported on said base member; means drivingly connecting said output shaft with said spindle; a high speed motor mounted on said base member; a low speed motor mounted on said base member; a high speed input drive member nonrotatably fixed to said output shaft; a high speed power drive member fixed to the shaft of said high speed motor and drivingly engaged with said high speed input drive member; a low speed input drive member rotatably mounted on said output shaft; a low speed power drive member fixed to the shaft of said low speed motor and drivingly engaged with said low speed input drive member; and a clutch means connected between the low speed input drive member and said output shaft operable to drivingly engage said low speed input drive member with said output shaft when said low speed motor is energized and said high speed motor is deenergized to cause said output shaft to be driven by said low speed motor, said clutch means being operable to disengage said low speed input drive member from said output shaft to permit free rotation between said output shaft and low speed input drive member when said high speed motor is energized and said low speed motor is deenergized, said clutch means being connected between said low speed input drive member and said output shaft such that said output shaft is driven in the same direction by both said high speed and low speed motors.