GB191514919A - Improvements in Percussive Engines, such as Rock Drills, Channelling Machines and Coal Cutters. - Google Patents

Abstract

14,919. Mauss, W. Oct. 21. Cushioning reciprocating parts; engines working on special systems or cycles.-The speed of a percussion tool is increased by causing the piston to compress a limited body of fluid, at a high initial pressure by which it is stopped on its rearward stroke and re-started on its forward stroke. A non-return valve is arranged in the supply passage to permit cushioning and the passage of fluid to compensate for loss by leakage. In the construction shown in Fig. 1, the tool is provided with differential heads 3, 4 upon the smaller of which fluid constantly acts. The space between the pistons communicates with the exhaust. The inlet and outlet passages 9, 10 are controlled by a valve 7 which has equal actuating-areas alternately put into communication with the cylinder pressure and exhaust through ducts 12, 13. The main supply passage enters the cylinder at some distance from the end, and has an auxiliary-supply passage 17 containing a non- return valve 18. During the forward stroke, the pressure of the compressed fluid is maintained by the main supply. In a modification, the non-return valve is arranged in the inlet 9. In a further modification, the port 16 leads to the end of the cylinder and is provided with a non-return valve. Modifications are described wherein the power piston has equal heads and the rear chamber is alternately put into communication with the supply and exhaust.