Abstract: The present invention is directed to a hydraulic percussive machine with a shuttle valve to control the flow of fluid to and from a drive chamber without timing lands on the piston and a seal between the drive and return chambers. This is made possible by the use of a restrictive orifice connected to the shuttle valve and the port in the return chamber which is covered and uncovered by the piston. When the port is uncovered, the shuttle valve moves over under pressure. When the port is covered, pressure leaks away to the orifice so that the shuttle valve moves back again.

Abstract: A single supply line feeds hydraulic fluid under pressure to a hydraulic percussive machine with a percussion motor and a rotation motor. A constant flow device is positioned between the supply line and the rotation motor.

Abstract: A single hydraulic supply line feeds fluid under pressure to a hydraulic percussive machine with a percussion motor and a rotation motor. The feed passes through two valves of the constant volume priority flow dividing type. The first valve gives priority to the percussion motor to the extent of establishing idling speed. The second valve in the bypass of the first valve gives priority to the rotation motor while its bypass reaches the percussion motor. Working speed of the percussion motor can only be obtained after the rotation motor is up to speed and control of the feed above the priorities controls the percussion motor speed only.

Abstract: A hydraulic percussive machine comprising a piston and cylinder with a dashpot at the front end to cushion overtravel of the piston. Heat is removed from the dashpot by admitting pressure fluid to the return stroke chamber through a front chamber and the dashpot. On the pressure stroke fluid from the return stroke chamber is admitted to the working stroke chamber in one case by causing all flow to take place along that route and in the other place by having two feeds to the working stroke chamber with a flow restrictor in the direct feed line.

Abstract: A hydraulic percussive machine in which a piston is caused to reciprocate in a cylinder including a cushioning flange on the piston, a first space in which the flange normally moves, a second space into which the flange can move on overtravel of the piston during the power stroke to trap fluid into the second space so that a dashpot action takes place, and co-operating timing grooves and ports on the piston and the cylinder to connect the first space to a low pressure zone in the system.

Abstract: There is disclosed a rolling mill comprising a pair of generally discus shaped rolling heads affording opposed rolling surfaces, the rolling surface of each head being provided by its surfaces inclined at a substantial angle to the axis of rotation of the rolling head, the rolling heads being mounted so that their axes of rotation are in parallel planes spaced apart from one another, the axes of rotation of the rolling heads being inclined to one another, and drive means arranged to be capable of rotating the rolling surfaces of the heads in opposite senses relative to each other and at different speeds.

Abstract: A hydraulic percussive machine comprising a cylinder, a piston reciprocable up and down in the cylinder, an inlet for hydraulic fluid to the machine, an outlet for hydraulic fluid from the machine, valve and timing means for controlling the operation of the piston, a chuck for holding a tool, a mechanism for rotating the chuck, a cushioning flange on the piston, a dashpot space in the cylinder adapted to be entered by the flange on overtravel of the piston on its downstroke, and a first connection for feeding fluid trapped under pressure in the dashpot space to the chuck driving mechanism as a motive for that means.

Abstract: A shearing device for cutting rod of the type comprising a pair of coplanar discs with projecting blades has the blades mounted in grooves in the discs so that the tips of the blades can be moved into and out of the path of the rod, thereby enabling the discs to rotate continuously and thus avoiding the problem with the known shearing device of accelerating and stopping the discs and ensuring that the blades are moving at precisely the same speed as the rod during the cutting action.

Abstract: A known extendable and retractable mounting for rock drills is described comprising a drill feed leg, a vertical support, which may be mounted on a truck and a counter-balancing device for counterbalancing the drill during movement vertically from one drilling position to another. The new feature described consists in applying a turning moment to the vertical support by means of a spring, two springs or a fluid cylinder and piston arrangement. The turning moment counteracts a resultant force tending to move the feed leg sideways.