Abstract: A demolition cutter which can smoothly cut an object while eliminating the possibility of any gap being formed between mating surfaces having cutting edges. The cutter includes an arm pin 8 extending between a pair of side plates 6 of a movable bracket 3. Two arms 9a and 9b are mounted on the arm pin 8 so as to be pivotable about the pin 8 between open and closed positions. Cylinders 14a and 14b are connected to the arms 9a and 9b, respectively. The arms 9a and 9b have mating surfaces 11 formed with cutting edges adapted to cut an object when they cross each other. The cylinders 14a and 14b have their axes offset outwardly from the mating surfaces 11 so that when the cylinders are extended, the arms 9a and 9b are closed with their mating surfaces 11 in close contact with each other. This prevents the formation of a gap between the mating surfaces during cutting.

Abstract: The object of the classifier of the present invention is to reduce the classification point for classifying powder. The classifier includes a classifying cover having a conical bottom surface, a classifying plate provided under the classifying cover and having a conical top surface opposite the conical bottom surface of the classifying cover, and a plurality of louvers provided annularly around a classifying chamber defined between the conical bottom surface and the conical top surface to define passages for secondary air therebween. The conical bottom surface is inclined at a larger angle than the conical top surface.

Abstract: A crusher which is simple in structure and capable of dismantling a building structure and recovering iron material from among dismantled remains of a building. A movable jaw is provided so as to be opened and closed relative to a fixed jaw fixed to the crusher main frame. A magnetic case made of a nonmagnetizable material is provided on the bottom of the main frame. A permanent magnet assembly is slidably mounted in the case. The permanent magnet assembly is connected to a hydraulic cylinder for sliding the permanent magnet. By actuating the hydraulic cylinder, the permanent magnet will move down so that iron material is attracted through a bottom plate of the magnet case. By raising the permanent magnet assembly, the magnet weakens, so that the attracted iron material drops by gravity.

Abstract: A crusher having a bracket pivotally mounted on a free end of an arm of a civil engineering machine, a frame having a pair of support plates and rotatably mounted on the bracket, a lock arm having a pair of arm plates and pivotally mounted between the pair of support plates, the lock arm carrying at one end thereof a crushing jaw, a movable arm mounted between the arm plates of the lock arm so as to be pivotable about a first axis that is nearer to the tip of the arm than a second axis about which the lock arm pivots, a trunnion type drive cylinder mounted between the arm plates for pivoting the movable arm toward and away from the crushing jaw, the drive cylinder having pivots arranged on the second axis and pivotally supporting the lock arm, and a fixing means for fixing the lock arm to the frame at both ends of the pivoting motion of the pivot shaft about the second axis. The ends are separated a predetermined angle from each other.

Abstract: A chisel and a method of manufacturing a durable chisel. An axial hole is formed in a chisel so that the hole is open at the chisel tip. Non-metallic powder is then supplied into the axial hole. A core member made of cemented carbide or other material harder than the chisel body is then press-fitted into the axial hole. By inserting the core member into the hole, the non-metallic powder flows so as to fill up any space between the rear end face of the core member and the closed end of the axial hole.

Abstract: A shock-absorbing member is fixed to top brackets at the end of a boom opposite to the top of an impact tool. A stopper member is secured to one of the bottom of the shock-absorbing member and the top of the impact tool and the other of the same is formed with a guide recess in which the stopper member is vertically slidable. When the tip of the chisel of the impact tool is pressed hard against an object to be crushed, no turning force will be applied to vibration-damping support members which support the impact tool, thereby preventing the support members from breaking.

Abstract: A vibrating cutting tool capable of making uniform micro-vibrations at the cutter edge generated during machining. The vibrations at the cutter edge are transmitted to balls biassed by springs, compressing the springs. The vibrations are transmitted from the balls through the output shaft back to the cutter edge. While the cutting force is small, the amplitude of vibration of balls is relatively large. When it increases, the holder acts on the balls more than the spring does so that vibration is suppressed. As a result, the amplitude of vibration becomes uniform.

Abstract: A vibrating cutting tool having an input shaft driven by a live spindle of a machine tool and an output shaft having a cutter mounting portion. The input shaft and the output shaft are coupled together through a coupling mechanism so as to be at least circumferentially movable relative to each other. Recesses are formed in one of the input shaft and the output shaft and holes are formed in the other at locations opposite to the recesses. Moving elements are mounted between the recesses and the holes with a predetermined gap defined between the moving elements and the recesses or the peripheral surfaces of the holes. The gaps serve to restrict a circumferential movement of the moving elements. Springs are provided to urge the moving elements against the recesses. The movement of the moving elements is restricted by stoppers. An adjusting ring may be provided to adjust the biasing force of the springs.

Abstract: An impact tool including a cylinder, a piston slidably mounted in the cylinder and a valve for selectively opening and closing oil feed channels to move the piston up and down. A cylindrical member is slidably mounted on the piston around its large-diameter portion or thereunder. Its bottom end defines the top end of a lower chamber formed in the cylinder. The cylindrical member is adapted to descend together with the piston. But when the piston strikes the object and rebounds upwardly, the cylindrical member keeps descending away from the piston owing to the inertia force. Thus the volume of the lower chamber is kept from increasing excessively after the piston has struck the object. This will prevent cavitation in the lower chamber. When thereafter the lower chamber communicates with the oil feed port and pressure oil is fed thereinto, the cylindrical member will be pushed up toward the large-diameter portion under oil pressure in the lower chamber.

Abstract: An impact tool for striking a tool such as a chisel includes a piston mounted in a cylinder. Upper, middle and lower chambers are formed therebetween. Pressure oil is fed into and discharged from the middle and lower chambers to reciprocate the piston in the cylinder under oil pressure. During a downward stroke of the piston, the oil pressure in the lower chamber is kept low. But just before it strikes a tool, the oil pressure in the lower chamber is adapted to increase so as to prevent what is called cavitation or prevent air bubbles mixed in the pressure oil in the lower chamber from growing suddenly owing to a sharp drop in the oil pressure which is caused by the rebound of the piston after striking the tool.

Abstract: An improved hydraulic pulse wrench provided with a hydraulic pulse generator has a liner, an anvil rotatably mounted in the liner and having a longitudinal slit, and two blades loosely mounted in the longitudinal slit. The liner has an elliptic hole. The two blades have their outer edges beveled in different directions. The anvil has a pair of axial ridges and the liner has on its inner periphery a total of five axial ridges. The blades, anvil and liner cooperate with one another to form pressure chambers while the liner is rotated.

Abstract: An improved mechanism for mounting an impact tool on the boom of a power shovel or the like. A mounting member is bonded to each side of the vibration insulating rubber member. The bonded surface between the rubber and the mounting member at at least one side of the rubber is oblique with respect to the axis of the impact tool. This reduces the shearing load to the vibration insulating rubbers, prolongs their life, and lessens the fear of the rubbers peeling off the mounting members.

Abstract: A tool abnormality detector for use with a machine tool for detecting any abnormality of a tool mounted on the tool mounting shaft. When the tool mounting shaft is in a correct position with respect to the tubular body secured to the spindle, the air pressure is kept constant. When an abnormal resistance is applied to the tool mounting shaft, the latter will lag in rotation with respect to the tubular body, so that the exhaust air passage will be blocked. A pressure sensor detects an abnormal increase in the air supply line, giving a signal for stopping the spindle of the machine tool. This prevents the tool from damage.

Abstract: A control device for an air hoist drives an air motor rotated by an air supply. The air hoist lifts or lowers a load by rotating a chain wheel. When the chain wheel rotates to lower the load, a small amount of air is supplied to the air motor in order to drive it in the normal lifting direction so that the braking force generated by the motor may reduce the load lowering speed and may gradually lower the load utilizing its own weight. Also, a mechanism for restraining the rotation in the normal lifting direction, when the chain wheel is under slow speed control, is actuated to restrain the rotation of the air motor, thereby stopping the chain wheel in a safe and sure manner without using a mechanical brake.

Abstract: The invention relates to a control apparatus for a pneumatic impact wrench driven by an air motor.

Abstract: An air classifier having a ring-shaped high-pressure air chamber disposed around a classifying chamber and communicating therewith by means of a plurality of small openings, such as air injection nozzles or a louver, these openings face in the direction of movement of material entering the classifying chamber and traveling in a vortex so that the material is accelerated by the air which is injected into the classifying chamber through the small openings.