Abstract: The invention concerns an arrangement for controlling a hydraulic rock drilling device. The arrangement includes a pressure ratio valve that is used for adjusting the relation between the pressures in the pressure channel leading to the percussion device and/or another actuator, such as a shank stabilizer, and the pressure channel leading to the feed mechanism. The pressure ratio valve is arranged to keep the relation between the pressures of the actuator and the feed mechanism constant over the normal drilling range.

Abstract: A control system for a heavy duty hydraulic hammer reduces blank firing of the hammer. The control system provides a reduced flow of hydraulic fluid to the hammer for a selected period of time upon actuation of the hammer and then provides full hydraulic flow increasing the frequency of impacts to full rated values.

Abstract: The invention provides an impacting device capable of , crushing or drilling work with reduced noise or vibration, with high crushing efficiency, high energy efficiency, increased output and prolonged durability A super magnetostrictive material (1) is arranged in the center of an exciting coil (4) to which a pulse voltage is applied, a rod (12) is arranged in tight contact with the front end of the super magnetostrictive material (1), a reaction-receiving plate (3) is provided in tight contact with the other end of the super magnetostrictive material (1), and a power unit (6) is provided for repeatedly applying a pulse voltage to the exciting coil (4).

Abstract: The present invention provides a device for breaking up a paved surface which attaches to a host transport, such as a skid steer or backhoe, having a hydraulic power supply and preferably comprises a closed hydraulic system which includes a regenerative and concentric type double hydraulic cylinder arrangement adjustably supported within a vertical frame. The cylinder is operably attached to a weight such that when fluid is pumped into a first chamber, a piston drives a rod, thereby lifting a weight while at the same time, the piston forces hydraulic fluid from a second chamber to the host. The piston separates the first chamber from the second chamber within the cylinder. Upon reaching a prescribed height, a valve is opened, allowing fluid to flow from the first chamber into the second chamber, thereby allowing the weight to drop rapidly under the influence of gravity.

Abstract: A drilling tool, the drill head (16) of which can be connected either to a drill (10) or a casing string (28), is also fitted with an automatic direction reversing mechanism (64) which is designed so that the driven part (14) of the drill head (60) executes backward and forward movements of less than 90°, but preferably 20° to 30°. In this way the drill head can also strike the casing string when sinking it.

Abstract: A damper pressure control apparatus for a hydraulic rock drill is automatically adjustable of damper pressure to be applied to a damping piston depending upon a thrust of a rock drill body and makes damping function and floating function effective even when thrust of hydraulic rock drill is varied. The damper control apparatus is thus provided damper pressure control means for controlling the damper pressure (DPpr) to be applied to a damping piston (16, 17) from a hydraulic pressure source (21) based on the frontward thrust (F1) acting on the hydraulic rock drill body 1.

Abstract: A drive tool having a top portion which is engageable with a drive source and a lower portion engageable with a fastener. The drive tool includes an axial load assist mechanism configured to urge the lower portion and upper portion of the tool away from each other (i.e. relative movement) such that a generally axial force is applied to the fastener engaged with the lower portion of the tool. As a result, the amount of upper body axial force an operator must apply to the drive tool to install the fastener is reduced.

Abstract: A hydraulic pump assembly (10) for powering a hydraulic torque wrench (24) is air-powered and has hydro-pneumatic control circuitry (39) which continues operation of an air motor (18) which drives the hydraulic pump (16) for a post-advance period after an advance actuator (55) is deactuated. Operation of the pump (16) is continued for a period sufficient to retract a double-acting torque wrench (24), to permit subsequent advances of the wrench (24) within the post-advance period without restarting the pump (16) or to permit a single acting wrench to be moved from one fastener to the next within the post-advance period without restarting the pump (16). Operation of the pump (16) is terminated when the post-advance period expires if the advance actuator (55) is not reactuated, so as to conserve energy and avoid unnecessary heating of the hydraulic fluid.

Abstract: An impact boring tool according to the invention suitable for using with a directional boring machine has a tubular housing and a head mounted at a front end of the housing. The head preferably includes a chisel configured for breaking loose rocks and stones encountered in soil. A striker is disposed within the housing for delivering an impact force to the head, either directly or through one or more intervening parts. A trigger mechanism causes the striker to deliver an impact to the head and chisel only when an external force exerted on the impact tool in its lengthwise direction exceeds a predetermined level. This predetermined level generally coincides with a maximum effective amount of pushing or pulling force for moving the tool through the ground exerted by an external device such as a directional boring machine.

Abstract: A method and an arrangement for controlling rock drilling on the basis of a pressure acting in a pressure conduit of a rotation motor of a drill rod. In the method, the pressure acting in the pressure fluid conduit of the rotation motor is measured during the rotation when the drill bit does not touch the rock to be drilled, and the control is carried out thereafter on the basis of the difference between the pressure value measured during the drilling and the idle pressure value. In the arrangement, the rock drilling machine comprises a control unit that measures the pressure acting in the pressure fluid conduit of the rotation motor when the drill rod is rotated so that it does not touch the rock to be drilled and stores it in the memory and controls the rock drilling machine during the drilling on the basis of the difference between the pressure value measured during the drilling and the idle pressure.

Abstract: A closed loop control system for a core drilling mechanism automatically controls the penetration rate, the weight on the drill bit, and the torque load applied to the drill string, and maintains all three at or below preselected maximum values. The closed loop control system incorporates a controller that receives sensed information and generates corresponding control signals to control the penetration rate and thus the weight on the drill bit and the torque load through a servo valve in a hydraulic drive circuit. One or more sensors are provided to sense the penetration rate of the drill bit, and are coupled with the controller. Similarly, sensors are provided to determine the weight on the drill bit and the torque load applied to the drill string.

Abstract: The rock drill (9) includes a reversible rotary motor (10) and a percussion unit (11) with a percussion valve (17). Rotary unit and Percussion unit (11) are operated via separate valves (39, 46) in a control unit (34). The percussion frequency of the percussion unit (11) is coupled to the rotation rate of the rotary motor (10) in such a way that the percussion unit (11) stops automatically when the rotary motor (10) comes to a standstill. The coupling is achieved by employing a fluid driven assembly without a mechanical clutch between the rotary motor (10) and the percussion valve (17). When disassembling the drill rods a jammed thread can be shaken loose with the percussion unit (11) be manually bypassing the fluid coupling. The same is also possible in case the drill rods becomes jammed in the drill bore. With the described embodiment a simple, space-saving and cost-effective construction is achieved which is versatile in application.

Abstract: When a start SW 3 is pressed, a one-shot multivibrator circuit 15 turns on and releases a pulse. The pulse is transmitted to a self-hold circuit 16 which in turn stays in self-hold mode and releases an H level output continuously until it is reset. This cause a transistor 17 to turn on and actuate a ram downward movement relay R1. When the ram arrives at the lower limit of its movement, a lower LS 4 is opened causing a self-hold circuit 21 to produce an H level signal in accordance with an output of a one-shot multivibrator 18. The H level signal from the self-hold circuit 21 is delayed by a delay circuit 22 and turns on a transistor 23. As the result, a ram upward movement relay R2 is actuated. Because of the function of the one-shot multivibrator circuit 15, the ram will not restart when the start SW 3 is continuously depressed. The delay circuit 22 contributes to the longer operational life of a directional valve switching mechanism.

Abstract: The system and method for use with a drawworks having a rotatable drum on which a line is wound, wherein the drawworks and the line are used for facilitating movement of a load suspended on the line, includes a drawworks control system for monitoring and controlling the drawworks. A brake arrangement is connected to the rotatable drum for limiting the rotation of the rotatable drum and at least one electrical motor is connected to the rotatable drum for driving the rotatable drum. A load signal representative of the load on the line is produced and a calculated torque value based on the load signal and electrical motor capacity is provided. The drawworks control system provides a signal representative of the calculated torque value to the electrical motor wherein pre-torquing is generated in the electrical motor in response to the signal.

Abstract: A drilling device comprises a drive motor (22), which sets a tool (36) in rotation, and a feed motor (14) which axially displaces the tool. Load sensors (12, 18, 20, 24) detect not only the tool feedrate (V) but also at least two of the three parameters, tool feed force (F), tool torque (M) and tool speed (U). An evaluation and control unit (70) evaluates the above-mentioned parameters and via control units (38, 42) activates the drive motor (22) and the feed motor (14) in such a way that the tool feed force (F) and the tool speed (U) or the tool torque (M) assume values at which the tool feedrate (V) for a specific ground hardness (H) is maximized.

Abstract: A percussion piston for use in a drilling apparatus includes a drill bit and at least three tubular parts which increase in diameter in a direction extending from the drill bit toward a rear end of the piston. The piston further includes flanges positioned between the tubular parts and a first corresponding delivery space at the rear end of the piston. At least two additional corresponding delivery spaces are positioned between the first corresponding delivery space and the drill bit. Channels allow the transport of pressurized hydraulic fluid to and from the first and additional corresponding delivery spaces such that an energy pulse produced by impact of the piston on the drill bit is almost completely absorbed by the drilled object.

Abstract: When a start SW 3 is pressed, a one-shot multivibrator circuit 15 turns on and releases a pulse. The pulse is transmitted to a self-hold circuit 16 which in turn stays in self-hold mode and releases an H level output continuously until it is reset. This cause a transistor 17 to turn on and actuate a ram downward movement relay R1. When the ram arrives at the lower limit of its movement, a lower LS 4 is opened causing a self-hold circuit 21 to produce an H level signal in accordance with an output of a one-shot multivibrator 18. The H level signal from the self-hold circuit 21 is delayed by a delay circuit 22 and turns on a transistor 23. As the result, a ram upward movement relay R2 is actuated. Because of the function of the one-shot multivibrator circuit 15, the ram will not restart when the start SW 3 is continuously depressed. The delay circuit 22 contributes to the longer operational life of a directional valve switching mechanism.

Abstract: An arrangement for limiting the swing angle of a boom for a rock drilling unit when the boom is being lifted and lowered. In the arrangement, a control member is coupled to the boom, turning therewith. The control member includes a slot which receives a movable dowel pin. The dowel pin is coupled to control a relief valve so that when the boom is being lifted or lowered, and when it tends to turn outside a predetermined widest permissible swing angle, the control member controls the relief valve so that it lets hydraulic fluid into the swing cylinder for turning the boom in a reverse direction.

Abstract: An arrangement is provided for a telescope feeder of a rock-drilling machine, having two telescopic portions, between which is connected an extension cylinder so that the rock-drilling machine moves along one telescopic portion. The extension cylinder comprises a separate adjusting piston, which is mounted movably around the piston rod so that it can move irrespective of the piston of the extension cylinder. Three cylinder spaces are thus formed inside the extension cylinder and to each cylinder space is connected a separate channel for pressure medium, so that the adjusting piston can be displaced to a desired position.

Abstract: A hydraulic tool having a ram or other working element propelled by pressurized fluid. The tool has a lever which is squeezed to develop fluid force in a pump. The fluid circuitry automatically operates the ram selectively at any one of three operating speeds and hence at three different magnitudes of force relative to the input speed of the lever as it is squeezed. The circuitry includes a principal supply subcircuit in which fluid flows directly from the pump to the ram, thereby establishing a normal speed mode of operation. A high speed subcircuit and a low speed subcircuit each operated by respective pressure responsive valves direct fluid ejected as the ram piston and pump piston advance to the respective rear sides of the ram piston and pump piston.

Abstract: A manually operable tool, such as a hammer drill, for drilling and/or removing material in at least one of brittle material and low ductile material, has a continuously rotatable chuck (8) and a motor driven striking mechanism (1) for transmitting impulse-like blows to a tool bit (9) held in the chuck (8). The tool includes members (5) for transmitting impulse-like blows composed of superimposed axially-directed blows and torsional blows to the tool bit (9) in the chuck for forming drilling blows. Further, an adaptor can be provided for attachment to the hammer drill containing the members (5) for affording the superimposed blows.

Abstract: A hydraulic pump assembly for powering a hydraulic torque wrench is air-powered and has hydro-pneumatic control circuitry which continues operation of an air motor which drives the hydraulic pump for a post-advance period after an advance actuator is deactuated. Operation of the pump is continued for a period sufficient to retract a double-acting torque wrench, to permit subsequent advances of the wrench within the post-advance period without restarting the pump or to permit a single acting wrench to be moved from one fastener to the next within the post-advance period without restarting the pump. Operation of the pump is terminated when the post-advance period expires if the advance actuator is not reactuated, so as to conserve energy and avoid unnecessary heating of the hydraulic fluid.

Abstract: Arrangement in a hydraulically operated rock drilling equipment comprising a feed motor (3), a percussion device (2), and a hydraulic pump (1) for feeding hydraulic fluid to the feed motor (3) and the percussion device (2). The arrangement comprises a pressure control valve (17) connected to be controlled on the basis of the control signal of the feed regulation valve (8) when starting the drilling so that when the value of the control signal is below a predetermined switching value, the pressure relief valve (18) is connected to the percussion pressure line (13) of the percussion device (2), and when the control signal exceeds the switching value, the pressure control valve (17) disconnects the pressure relief valve (18) from the percussion pressure line (13) and connects the pressure difference valve (20) in communication with the percussion pressure line (13).

Abstract: A control system for a percussion drill with a hydraulically actuated drill rotation mechanism and drill feed mechanism which includes a control means which operates, in response to the hydraulic pressure in the drill feed mechanism, to start percussion movement of the drill.

Abstract: Pliers (1) have a pliers housing (2), a handle (6) which is articulated on the pliers housing (2), a pliers mouth (3) which accommodates processing elements, and a drive device, which can be operated by pivoting the handle (6), in order to drive the processing elements. An electric motor (18) is arranged in the pliers housing (2) in order to exert a further drive force on the processing elements during pivoting of the handle (6).

Abstract: Pliers (1) have a pliers housing (2), a handle (6) which is articulated on the pliers housing (2), a pliers mouth (3) which accommodates processing elements, and a drive device, which can be operated by pivoting the handle (6), in order to drive the processing elements. An electric motor (18) is arranged in the pliers housing (2) in order to exert a further drive force on the processing elements during pivoting of the handle (6).

Abstract: A handheld electromotive tool capable of efficient execution of a floor board and a ceiling board is provided. The tool is used in combination with a beam emitting device for emitting a radiation beam in a reference plane, and is provided with a housing held by an operator. The housing has a work member driven by an electric motor and a photo detector for receiving the radiation beam projected in the reference plane. Output signals indicating positional deviation of the photo detector from the reference plane are generated on the basis of output of the photo detector. Rotation of the motor is controlled as follows. Rotation of the electric motor is stopped when the radiation beam is received at a reference position of the photo detector. The electric motor rotates at high speed until the radiation beam is received in the vicinity of the reference position.

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 well rig lifting system and a hydraulic energy-storing well rig lifting system, wherein a high pressure energy-storing cylinder and a composite cylinder or cylinder group are used to carry out the lifting and lowering operations. During the lifting operation, a power machine under a substantially constant load continuously pumps oil to the energy-storing cylinder, and communication relationships of the energy-storing cylinder with various chambers of the composite cylinder or cylinder group is selected to provide an appropriate lifting force to lift the pipe string. Therefore, the installed capacity of the power machine can be reduced to 1/3-1/4 of that in a conventional lifting system.

Abstract: A pile driver includes an attachment frame fixed to a work arm of appropriate construction equipment that serves as a base machine, a vibration cylinder actuated and controlled by an electro-hydraulic hydraulic servo-valve and mounted on the attachment frame through a rubber buffer, and a counter weight and a chucking means for gripping a pile to be driven K provided on the axial ends, that is, on the cylinder base and on the forward end of the piston, the pile being held in such a manner that the drive direction coincides with the axis of the vibration cylinder.

Abstract: A telescoping drill has a base, a guideway displaceable longitudinally forwardly and rearwardly on the base, a guideway actuator braced between the guideway and the base and energizable for longitudinal forward displacement of the guideway on the base, a guideway source of energy connected to the guideway actuator for longitudinally forwardly displacing the guideway on the base, a drill carriage displaceable longitudinally on the guideway between a front position and a rear position, a drill actuator braced between the drill carriage and the guideway for longitudinal forward displacement of the carriage on the guideway, and a drill source of energy independent of the guideway energy source and connected to the drill actuator for longitudinally forwardly displacing the drill carriage on the guideway. A sensor detects when the drill carriage is in the rear position.

Abstract: A rock drill has a normally stationary base, a support movable longitudinally on the base forward toward and backward away from a rock face adjacent the base and having a part engageable forwardly with the face, a base actuator braced longitudinally between the base and the support for longitudinally moving the support on the base and for pressing the part of the support forward against the face with a predetermined anchoring force, a drill movable longitudinally on the support and having a drilling tool engageable in the face for drilling a longitudinal hole therein, and a drill actuator braced longitudinally between the drill and the support for longitudinally moving the drill on the support and for pressing the drilling tool longitudinally forward against the face adjacent the part with a predetermined drilling force. A pressure detector or sensor is provided on the part for producing an actual-value output corresponding to the reaction force or pressure exerted axially backward on the support by the face.

Abstract: The invention relates to a method and an arrangement for adjusting the percussion and the feed of a rock drilling apparatus with respect to each other. In the method, the volume flow of pressure fluid to be supplied to a percussion device (7) and a feed motor (8) is adjusted on the basis of the feed pressure of the feed motor (11), a volume flow adjusted pump (1) being controlled so that the ratio of the pressure applied to the persussion device (7) to the pressure of the feed motor (11) is set by control valves (10, 14). In the arrangement, pressure fluid is supplied to the percussion device (7) and the feed motor (11) by means of a volume flow adjusted pump (1). The arrangement further comprises control valves (10, 14) by means of which the volume flow of the pressure fluid fed by the pump (1) is kept such that the ratio of the pressure of the percussion device and that of the feed motor (11) remains substantially constant.

Abstract: An amplitude control unit for an ultrasonic machine comprises a load detector for detecting the load applied to the tip of a tool during ultrasonic machining on the work, a load/amplitude conversion circuit for converting the load output detected by the load detector into an amplitude conversion value appropriate for the load at the tip of the tool, an amplitude addition circuit for receiving the amplitude conversion value generated by the load/amplitude conversion circuit and for adding it to a predetermined amplitude value at no load. The vibration of the piezoelectric transducer is changed to correspond to the load applied to the work by sending the new amplitude value generated by the amplitude addition circuit to the high frequency oscillator.

Abstract: An apparatus for screwing a concrete pile (10) into ground comprises a rotary drive (26, 40, 42) and a linear drive (46, 48) both acting on the pile. An angle indicator (58) is associated to the rotary drive (26, 40, 42) and a linear position indicator cooperates with the linear drive (46, 48). A control unit (60) receives the output signals of the angle indicator (58) and the linear position indicator (56) and provides control signals to the rotary drive (26, 40, 42) and the linear drive (42, 48) corresponding to the pitch of the helical rib (16) formed on the concrete pile (10).

Abstract: The apparatus comprises a mine shaft roof bolting machine for drilling holes in a mine shaft roof in combination with an apparatus for controlling the thrust applied to the drill rod, commonly known as a pinning rod, to ensure that a buckling failure of the pinning rod will not occur. The thrust is controlled by a computer in conjunction with a solenoid controlled relief valve which is actuated by commands from the computer. The computer determines the length of the pinning rod exposed below the mine shaft roof from data received from one or more of the following sensors: an electronic device for measuring hydraulic cylinder rod extension, contact switches, rotary encoders, proximity switches, and ultrasonic transceivers and associated circuitry.

Abstract: The invention relates to a drilling system. It includes, in combination, a drilling derrick by means of which a string of drill rods can be suspended from a hoist, a motorized drilling head at the end of the hoist, means for bringing a drill rod into position to be added to the drill string from a stack, a motor to drive the hoist, a reversible control for the said hoist motor, sensors for determining the state of the system, and a programmable robot to supply the set points to the hoist motor control according to signals furnished by the said system state sensors.

Abstract: A power-wrench bolting spindle (1) is used to insert and tighten screws or nuts. The bolting spindle is driven at one end by a motor through a reduction gear (5) and at its other end a bolting tool is seated. A torque sensor (7) is mounted between the motor and the spindle. During bolting, other essential data besides the bolting torque are ascertained. The bolting spindle is equipped with a depth sensor (24) connected to the regulating circuit to measure the depth of bolting. An angular-speed sensor is connected to the regulating circuit and measures the motor or spindle angular speed. The bolting procedure is carried out in two operational stages separated by a pause, namely an application stage (L) and a tightening stage (Z). Each of these operational stages terminates when a specific shutdown bolting torque is reached.

Abstract: A control apparatus for a pavement breaker which includes a carriage, a lifting means for raising and lowering an impact arm which impact arm includes a tool for impacting a surface, mounted on one end and an oscillating member mounted on the other end. The control apparatus basically includes electrical apparatus for measuring the total weight being applied through the lifting means to the tool when it is in contact with the surface to be impacted and apparatus for limiting the amount of horizontal force that can be applied to the impact arm during the process of impacting the surface of the earth. A processor receives an electrical signal from the electrical apparatus which is applied to the lift control apparatus in a manner to stabilize the lifting force. A signal output is generated by the horizontal force limiting apparatus when a predetermined amount of horizontal force is received by the electrical device.

Abstract: A programmed automatic drill control for optimizing the drilling of subterranean holes by large drilling machinery such as blast hole drills. Sensing means are provided to sense a first set of drilling parameter limits to effect maximum r.p.m. of the motor to rotate the pipe drilling bit and to sense a second set of drilling parameter limits to effect a maximum rate for the motor to drive the hoist pull-down mechanism. These conditions will prevail until a sensed limit is reached or the drilling conditions require operation along a torque or force limit set value. When a limit is reached, the control will regulate at a value of r.p.m. or rate which is consistent with maintaining operation at the limit value.

Abstract: According to the applicant's invention a load detector is used, in which a load sensor and a vibration sensor are combined using an AND gate. A load signal from the load detector is used for the feedback control of the cutter drum height and double ranging drum cutter running speed, so that a person who is not skilled can operate the double ranging drum cutter while preventing overload acting on the cutter drum.

Abstract: A cold pressure-welding apparatus has a pressure-welding load detector and a displacement detector for detecting the displacement of pressure-welding parts which are mounted on a cold pressure-welding apparatus main body; and an arithmetic operation control circuit which receives output signals from the detectors to detect yield points on a load-displacement curve, calculates an optimum load for optimally performing cold pressure-welding on the basis of a yield load at a second yield point, and outputs to the cold pressure-welding apparatus main body a signal for stopping cold pressure-welding when an actual pressure-welding load reaches the optimum load.

Abstract: An electrohydraulic control system for an arm assembly of the type described in U.S. Pat. No. 4,364,540 utilizes an electric computer (microprocessor) which receives a nonlinear or harmonic signal from the rotary hydraulic motor of the arm of this assembly and converts the harmonic signal into a linear signal which is applied to a comparator as the value signal for comparison with a command signal from the computer. Similar comparators are provided for each of the hydraulic operators and the sensors thereof can provide direct actual value inputs to these comparators.

Abstract: The feed support of a rock drilling unit is adjusted to be a given distance from a rock surface wherein holes are to be drilled. A drill bit is moved into abutment with the rock surface. The feed support is moved relative to the bit toward the rock surface. Such movement is stopped when a depth measuring instrument determines that the feed support is at a position spaced the given distance from the rock surface.

Abstract: An explosive charging apparatus for charging controlled amount of explosives sequentially to bores drilled in a rock surface. The charging apparatus includes an explosive charging pipe, a boom mechanism carrying the explosive charging pipe, boom actuators for actuating the boom mechanism so that the explosive charging pipe is moved to a desired position, a control circuit for controlling the boom actuators and the explosive charging pipe.

Abstract: This invention relates to an automatically controlled rock drilling apparatus which performs rock drilling operations as well as post-drilling operations such as explosive charging. Memory means are used during the drilling operation and reused during subsequent operations for follow-up work, specifically the charging of explosive to the drilled bores.

Abstract: The invention comprises generally apparatus for use with an underground mine-shaft roof-bolting machine having a torque motor, a pinning rod held for rotation by the torque motor, a controllable arrangement for exerting upward thrust on the torque motor to force the pinning rod upwardly into the roof of a mine shaft, and a manual control for the upward thrust arrangement. An infrared source is held stationary with respect to the rod, and a detector moves upwardly with the rod. The detector receives radiation from the source and emits a signal which varies in accordance with the source to detector distance. This signal is used to control the upward thrust applied to the torque motor in accordance with the length of a pinning rod exposed below the roof being bolted. In one embodiment, the detector produces a signal based on the intensity of the received light.

Abstract: The method and apparatus for preventing runaway lowering of a hook block in an oil drilling rig characterized by monitoring the instantaneous values of hook load and speed and using these values together with parameters associated with the rig drawworks to calculate an energy value which must be dissipated during a braking stop by the drawworks brake. The brake or an emergency brake associated with the drawworks is automatically actuated when the calculated energy value reaches a predetermined value representative of the maximum energy absorbing capability of the brake. The brake may also be automatically activated when the position of the hook block reaches predetermined upper and lower limits.

Abstract: The present relates to machine tools, such as hond drills and more particularly to control devices utilized for controlling the speed of the machine tool.

Abstract: The invention comprises generally apparatus for use with an underground mine-shaft roof-bolting machine having a torque motor, a pinning rod held for rotation by the torque motor, a controllable arrangement for exerting upward thrust on the torque motor to force the pinning rod upwardly into the roof of a mine shaft, and a manual control for the upward thrust arrangement. The invention utilizes a light beam to detect buckling of the pinning rod and to disable the upward thrust arrangement.