Abstract: An automatic grinding apparatus includes a constant rotating grinder (24) having a motor (25) in which a load current increases or decreases due to the metal removal rate per unit hour, a travelling device for moving the grinder three-dimensionally along the grinding surface, a sliding device (20) for adjusting the distance between the grinder and an object (50, 51) to be found and a controller for controlling the sliding device to allow the load current of the grinding motor to be constant. An articulated robot or a cartesian coordinate robot is used for the travelling device. The automatic grinding apparatus starts the grinding motor at first, halting the travelling device at the initiation of grinding, permitting the grinder to approach the object to be ground after a time interval and starting the travelling device simultaneously or a little later after detecting that the grinding disk (26) contacts the object to be ground, due to the variation of the load current of the grinding motor.

Abstract: An ultra-high-pressure rotary water-jet gun capable of removing rust, scale, burrs, paint film and other unwanted deposits from the surface of metal, concrete and other materials. An air turbine serves to rotate an eccentric rotor within the gun housing. A high pressure water line passing through the rotor is connected to a nozzle head on which are mounted several nozzle tips. The nozzle head is rotated in a circular path by the eccentric rotor while directing the high pressure water jets against the work piece. A pneumatic circuit and a hydraulic circuit with certain controls are provided.

Abstract: An extra-high pressure water pump includes a cylinder barrel, a piston and a pair of double check valves. The piston is composed of a main piston and a lubricating oil piston. The lubricating oil piston has a double piston ring and is slidably mounted on an additional piston rod connected to the main piston head. Lubricating oil is filled in a lubricating oil room made between the main piston and the lubricating oil piston in the cylinder barrel. The pressure between the lubricating oil and water in the pump is naturally kept at the same level by sliding a position of the lubricating oil piston on the additional piston rod, so that a sudden imbalanced pressure between the lubricating oil and the water in the cylinder barrel does not break the lubricating oil piston.The extra-high pressure water pump supplies extra-high pressured water to its small carriable water jet gun.