The United States of America As Represented by the Secretary of

Jerome A Gunn

Roger J Morrell

Richard J Wilson

Gerald D Gore

A square hole drill having a cutterhead configuration whose outline is in the form of a Reuleaux triangle and which also has a planetary gear drive. Two counter revolving motions are present in the drill at the same time. One is the pure rotary motion of the drill's cutterhead about its own shaft. The other is the circular motion of the cutterhead as a unit about a center line due to its eccentric mounting and drive. To achieve the opposite rotation of the unit as a whole compared to the rotation of the cutterhead about its own axis, a combined meshing planet gear and ring gear are used. The planet gear is directly connected to the cutterhead by a shaft rigidly attached to the gear's front side. At the rear side of the planet gear is the eccentrically mounted drive shaft. Surrounding the external teeth of the planet gear is a larger stationary ring gear with internal teeth to continuously engage the planet gear's teeth. As these teeth become engaged the planet gear rotates on its own shaft and also rotates, in a larger radius, counter to that direction around the ring gear. In the preferred embodiment the rotation about the planet gear's shaft was one third as fast as the planet gear's rotation around the ring gear. The composite effect of these two counter revolutions when considered with the shape of the cutterhead is that the cutting bits transcribe and cut out a square hole.

Square hole drill

A method and the apparatus for implementing the method to provide temporary ground support in a mine. After an auger or other type of hole has been bored in an underground mine, at least one inflatable bladder with a fluid conduit therethrough is inserted into the hole. Once the bladder is inflated it expands to fill the hole's diameter and to act as a plug. Thereafter, fluid is forced through the fluid conduit past the bladder and into the hole cavity to act in conjunction with the bladder as a ground support for the hole. Appropriate fluid valves, meters, and conduits are placed at the input to the fluid conduit to control and measure the fluid being forced into the bladder and the hole cavity. Quick connect-disconnect couplings are provided when two or more bladders are connected seriatim and placed within the hole.

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Saint Paul, MN, United States of America

Jerome A Gunn