Abstract: An inching device for a grinding mill which allows selective rotation of the mill at reduced speed for mill alignment, maintenance and the like. The device is comprised of a hydraulic motor having an output drive shaft and a disc type brake assembly operably associated with the output shaft. The entire inching device is mountable to the end of a shaft included in the mill drive train. Preferably, this mounting is at an overhanging end area of a high speed shaft included in a drive train speed reducer and is effected by a coupler structure which accommodates selective inching device installation and removal. This coupler structure also comprises the sole support for the inching device. Torque arms fixedly secured to the hydraulic motor and brake assembly extend radially outward of the output shaft generally parallel and coextensive with each other to be affixed by a common retaining member to some rigid structure adjacent the mill.