Abstract: A spindle unit (A) for effecting a manufacturing or repair procedure includes a spindle assembly (2) having a spindle (12) that holds a tool (B), an electric motor (4), and a friction drive transmission (6) located between the spindle assembly and the motor. The transmission includes a sun roller (86) driven by the motor, an outer ring (110) coupled to the spindle, and a pair of support rollers (90) located between the sun roller and outer ring to position the outer ring eccentric to the sun roller and create a wedge gap (126) between the sun roller and the outer ring. The transmission also has a loading roller (96) located at the wedge gap such that it can displace laterally and lodge tightly in the wedge gap. The spindle rotates in bearings (14, 16), one of which is a single row tapered roller bearing that transfers thrust loads developed during the procedure.

Abstract: A spindle unit (A) for effecting a manufacturing or repair procedure includes a spindle assembly (2) having a spindle (12) that holds a tool (B), an electric motor (4), and a friction drive transmission (6) located between the spindle assembly and the motor. The transmission includes a sun roller (86) driven by the motor, an outer ring (110) coupled to the spindle, and a pair of support rollers (90) located between the sun roller and outer ring to position the outer ring eccentric to the sun roller and create a wedge gap (126) between the sun roller and the outer ring. The transmission also has a loading roller (96) located at the wedge gap such that it can displace laterally and lodge tightly in the wedge gap. The spindle rotates in bearings (14, 16), one of which is a single row tapered roller bearing that transfers thrust loads developed during the procedure.