Abstract: A blasthole drill is provided with sensors for sensing the pressure (AP) applied to and through a drill bit to convey cuttings from the drill hole, the rate of rotation (N) of the drill bit, the torque (RT) required to rotate the bit, the force (FB) applied axially to the bit and the instantaneous vertical position (Y) of the bit. Output signals from the sensors are applied to a microprocessor-based controller which computes the penetration of the drill bit per revolution of the bit (P/R) and the rock specific fracture energy (Es). Using the sensed values and the computed values, the controller produces output signals to increment/decrement the force (FB) applied axially to the drill. The applied axial force is controlled such that the penetration of the bit per revolution remains substantially constant for a given range of values of the rock specific fracture energy but varies for different ranges of the rock specific fracture energy. The rate of rotation of the drill bit is controlled to a reference value.

Abstract: A fluid-assisted dust seal for a drill shaft includes a tubular housing, flexible seals spaced apart in the housing along its length in contact with a drill shaft therein, a fluid plenum between two adjacent seals in the housing, and a fluid inlet for admitting pressurized fluid into the plenum, to deflect the seals downwardly so as to cause fluid flow out the bottom of the seal and thereby limiting entry of dust into the housing.

Abstract: A drilling apparatus, having a drilling tower, tiltable for angle drilling, on a drilling platform with an aperture for a drill string, includes a dust seal holder that extends into the aperture in the platform, the dust seal holder being connected to the tower, so as to move up and down in the aperture in an arcuate path along with the drilling tower, as the tower is tilted for angle drilling, the dust seal holder being disconnected from the tower, so as to be not movable, as the tower is moved between a horizontal and vertical position.

Abstract: An apparatus includes a vehicular mainframe having a vehicular longitudinal axis and a substructure mounted on the mainframe. The substructure has a substructure longitudinal axis and is tiltable relative to the vehicular mainframe about the substructure longitudinal axis. The apparatus includes a tower and a tower support rigidly secured to the substructure. The substructure longitudinal axis is approximately the same vertical height as an upper surface of the vehicular mainframe.

Abstract: A closed loop hydraulic system for use in a rotary drilling apparatus includes an extendible-retractable feed cylinder and a valve for biasing the feed cylinder. A variable, reversible displacement pump is provided for pumping fluid from either of the first and second pump ports, including pumping fluid to the feed cylinder. A reservoir retains a supply of fluid for the system. A check valve is provided for supplying additional fluid to the pump in response to the feed cylinder being extended. An overcenter valve is connected to each of the first and second ports for controlling flow from the system in response to pressures received from the first and second ports when the feed cylinder is extended and retracted.

Abstract: A drill pipe transfer arm supports the bottom portion of a drill pipe and positions it in relationship to the drill string to permit angle drilling with a tilted drill tower. The transfer arm is uniquely suited to circular carousels and features a drill pipe conforming saddle which permits close-quarter operation with a packed carousel.

Abstract: A rock drill feed system moves a drill toward and away from a wall with a reciprocating hydraulic motor powered by pressurized fluid. The pressurized fluid is controlled by a movable control valve that has a first position obtained manually to move the drill inwardly to drill, a second position obtained automatically when the drill has completed drilling, and a third position obtained automatically when the drill has been completely withdrawn. The sensing of the location of the drill to position the control valve is accomplished by measuring the pressure and flow rate of the hydraulic fluid delivered to the motor with pressure responsive switches. When the pressure exceeds a preselected level and the flow rate drops below a preselected level, the two pressure switches close to produce a signal that moves the valve to another position.