Abstract: A hydraulic percussion device comprising a piston mounted for reciprocal motion within a cylinder to impact a percussion bit and a control valve to control reciprocation of the piston. A valve pilot line is arranged to switch the control valve based on the position of the piston within the cylinder, wherein the valve pilot line is alternately connected, by the reciprocal movement of the piston, to high and low pressure lines (P, T) via an undercut in the piston. The undercut is located at a portion of the piston having a diameter less than the maximum sealing diameter of the piston.

Abstract: A wind-propelled vessel is described herein. The vessel includes at least one hull and at least one set of paired masts. Each paired mast of the at least one set of paired masts has a first mast located to one side of the vessel and a second mast located on the opposite side of the vessel. Also, each mast of the at least one set of paired masts has a spar located at or near the top of the mast. Moreover, each one of the spar located at or near the top of the mast extends inwards towards a center plane of the vessel, and an inward end of the spar is connected by a connector to another inward end of another one of the each one of the spar located at or near the top of the mast.

Abstract: A valveless, pneumatic motor including a cylinder within which a hammer piston reciprocates and a buffer ring fixedly secured within the cylinder. A source of motive fluid under pressure cooperates with the buffer ring which through supply porting provides pressurized motive fluid alternately to opposed faces of the piston head. Intake ports are formed within the piston stem and adapted to cooperate intermittently with the buffer ring supply porting to provide motive fluid to the piston interior wherein an axial bore transmits the fluid along the stem toward the piston head and discharge porting delivers the motive fluid to the forward face of the piston head thereby urging the piston rearwardly. A reduced diameter portion of the piston stem then comes into communication with the buffer ring supply porting and permits the motive fluid to impinge directly on the rearward face of the piston head without passage through the piston to urge the piston forwardly.

Abstract: A liquid pressure striking device defines a double-acting cylinder in a main body thereof having a tool at its lowest portion, and the double-acting cylinder houses therewithin a piston having an upper rod and a lower rod. The lower rod suspends a hammer for striking the tool, and the upper rod is provided on its outer circumference with a change-over valve mechanism which comprises a valve body of special structure for automatically switching the liquid flow under pressure by vertical movement of the piston, and a valve chamber having a plurality of concaves for controlling said valve body. Above the upper part of the valve chamber, there is provided an accumulator serving as a cap or cover of the main body. The main body is formed with an inlet passage of the liquid and an outlet passage, communicating with the accumulator and the valve chamber.

Abstract: A hydraulic impact tool providing improved force absorption for facilitated manipulation by an operator. In the illustrated embodiment, the tool comprises a tamper which provides substantial tamping force with minimum vibration and uncontrolled bounce. The tool utilizes a hydraulic power system for improved noise reduction and minimizaton of fatigue. The tool provides a forward stroke wherein the force is applied for a preselected time, and a retraction stroke wherein the moving elements are retracted to a preselected position. The tool is adapted for use with a wide range of load resistances.

Abstract: A machine having a housing wherein are arranged a stepped hammer piston adjoining the front portion of the machine and a stepped plunger adjoining the rear portion of said machine, said hammer piston and plunger being adapted for an axial movement in said housing. The hammer piston and the plunger are separated by resilient means. The pressure fluid fed into the housing provides for reciprocation of the hammer piston and the plunger. The hammer piston reciprocations consist of forward and return strokes. During the forward stroke the hammer piston transmits impacts to the tool. The presence of the hammer piston and the plunger with the resilient member in between increases the power of the hammer piston impacts transmitted to the tool, hence the machine efficiency. The machine may be advantageously used as a hydraulic hammer (quartering hammer) and a hydraulic percussive device for making holes and deep wells in soil.

Abstract: A shaking machine for shaking core sand out of hollow castings includes a pair of coaxial cylinders containing pistons with piston rods arranged to grip a casting, and a rotating vane air valve for supplying compressed air alternately to each of the two cylinders.