Abstract: A rock drill having a hydraulic system for controlling a striking, rotating and advancing movements of a drilling rod. The advancing or forward feeding conduit for a feed actuator is provided with a relief valve which is responsive to the pressure in the positive rotating conduit for a rotary actuator so that the pressure in the forward feeding conduit is relieved to weaken the advancing force when the load on the rotary actuator is increased. A further relief valve is also provided for relieving the pressure in the striker conduit to weaken the striking force. A switching valve is provided between the advancing and retreating conduits for the feed actuator so that the direction of movement of the feed actuator is automatically changed when there is an abrupt decrease in the pressure in the striker conduit.

Abstract: A control system for a hydraulic percussion rock drill and feed mechanism including a single constant power hydraulic pump for supplying pressure fluid to operate the feed mechanism, drill stem rotation motor, and the percussion hammer. The drill feed, rotation and percussion functions are controlled by individual manually actuated pressure compensated valves. Fluid pressure to the feed mechanism is controllable at one of two selectable pressures and is automatically reduced if fluid pressure to the drill stem rotation motor exceeds a predetermined limit. The drill percussion blow intensity and frequency is controlled by a mechanism responsive to a fluid pressure signal which is automatically operated to provide for a high blow frequency and low blow intensity operating mode when the drill is retracted away from the workface. The constant power hydraulic pump is provided with a control which will adjust the pump output to a partial displacement setting when the drill is being retracted away from the workface.

Abstract: A drilled hole end adjusting arrangement for a drilling machine or the like mounted on a boom structure in which the positions of the drilling machine are located such that ends of drilled holes are in a predetermined plane by positioning the boom structure in a rectangular coordinate plane established immediately in front of a working face. The depths to which the holes are drilled are caused to be such that the ends are in a plane parallel to the rectangular coordinate plane by supplying numerical instructions to the boom structure so that the positioning is carried out with high accuracy and the controls for the boom structure can be quickly programmed.

Abstract: This invention relates to an overload protection apparatus for hydraulic multi-function equipment. It is applicable to equipment sharing a common pressure and return line and in which functional operation of the equipment is interrelated such as to expose certain elements to overpressure conditions. The system includes an overload or overstress valve having a manifold to which the power lines of all of the actuators, except the principal actuator which responds to an overstress condition, are connected. These connections are directed through check valves so that fluid within the lines will be directed only to the overstress valve. A pilot valve connected to the power side of the principal cylinder controls a pressure actuated control valve in the manifold to control and open a passage to the reservoir.

Abstract: A rock drill assembly and more particularly a rock drill assembly having improved fluid power means therefor.

Abstract: An arrangement for controlling the drilling functions of a full profile rock drill in which the speed of rotation of the cutting head and the feed force of the cutting head are controlled so that the rate of penetration of the drill bit reaches its optimum rate as a function of the feed force. The full profile of drilling apparatus has a part of the cutting head in which cutters are freely rotatable. The change of the rate of penetration of the cutting head into the rock is measured during the drilling operation, and the drilling functions are controlled on the basis of the measured results so that the cutting head feed force is either increased or decreased.

Abstract: Method and apparatus for forming piles in the earth with a pile hammer rig having a crane, a hoisting drum carried by the crane, a driving mechanism for driving the drum through a clutch assembly, a braking assembly for the drum, a hoisting rope leading from the drum for lifting a drop-weight, an automatic sensor for sensing the top of the drop-weight stroke for disengaging the clutch mechanism, a second automatic sensor for sensing the bottom of the drop-weight stroke for engaging the drum braking assembly, and in one form of the invention an automatic sensor for sensing the rotation of the hoisting drum for disengaging the braking assembly and engaging the clutch assembly.