Abstract: This invention relates to a chuck assembly for a drill box of a mine drill for releasably securing a mining tool including a working end and a depending rod-like member for roof bolting and roof and face drilling operations and a method of using the chuck assembly. The drill box includes a source of rotary power and a drive member operatively connected to the source of rotary power to rotatably drive the chuck assembly. The chuck assembly includes a spindle, a collet closer and a collet. The spindle is operatively connected to the drive member and has a sleeve of a cylindrical shape including a threaded collar end and a bottom end and an opening extending a selected distance from the collar end to the bottom end. The collet closer includes an annular housing having an aperture threaded for threadingly engaging the threaded collar end of the spindle.

Abstract: A mining apparatus for the mechanized breaking-down of mineral raw materials, particularly coal, in underground mining operation includes at least one endless chain and chain wheels for the endless chain. A main drived is provided for one of the chain wheels and an auxiliary drive is provided for the other chain wheel. The main drive and the auxiliary drive each has a transmission unit including main transmission stage, initial transmission stage, coupling and drive motor. A superposed motor in the form of a controllable electric motor having small power acts in connection with a worm gear transmission on the superposed input of the superposed transmission unit. Synchronous running of the main drive and the auxiliary drive or the drive motors thereof is achieved by a unilateral drive control. This results in a uniform power and load input independently of the wear of the chain and chain wheels.