GB293228A - Improvements in or relating to striking or boring tools - Google Patents

Abstract

293,228. Pfl³ger, A., and Haage, K. Aug. 31, 1927. Rammers.-A striking tool, such as a paving ram, having an impact element connected to the cylinder of an internal-combustion engine, comprises a rod carried by the piston and adapted to bear against the surface to be operated on, and of such length that when the piston is at the top of the cylinder the end of the rod is spaced away from the striking face of the impact element by an amount corresponding to the suction stroke of the piston. The ram 2 is rigidly connected to the cylinder 1, the head 3 of which carries handles 4 connected by springs 8 to cross arms 7 secured to the piston-rod 6. A spring-pressed lever 10, Fig. 5, pivoted at 9 on the cylinder head, normally maintains a sleeve 13 and suction valve 14 in the open position shown; air is admitted through the air jet 15 and fuel through a nozzle 16 whilst extra air may enter through the passages 18, 19. In the position of rest, Fig. 1, with the ram 2 and rod 6 resting on the ground, the space between the piston and the head .3 is filled with fuel mixture. The valve 14 is closed by depressing the lever 10 and the mixture is ignited by any suitable means, e.g. a sparking plug and contacts closed by depressing the lever. At first, the rod 6 remains stationary whilst the cylinder and ram are lifted by the ignition of the charge, but at the extreme position shown in Fig. 3, after the cylinder has exhausted through .exhaust ports, the tensioned springs 8 lift the piston, which is thereby driven against the head 3 to complete the expulsion of exhaust gases through the passages 18, 19, the lever 10 having meanwhile being released. The ram then falls and the piston and rod 6 return to the position of Fig. 1, drawing another charge into the cylinder. The hand-lever 10 may be connected to the suction valve by a coupling which is released by the explosion, as in the modification shown in Figs. 6, 7, wherein a collar 29 at the upper end of the stem 27 of the valve 14 is engaged by a weak spring 42 so that the valve is normally held open but is adapted to be lifted to close the valve through the intermediary of a heavier spring 30 and bush 28 loose on the valve stem by means of a fork 26 on an arm 24 mounted on the pivot 9 of the hand-lever 10 and locked to move with the lever by a pivoted pawl 22 engaged by a spring 23. When the charge is fired, the pressure of the .explosion acts through an aperture 46 on an auxiliary piston 47 and piston-rod 49, the latter lifting the tail 50 of the pawl 22 and releasing the arm 24, thereby causing the valve 14 to be opened by the spring 42. The fuel mixture enters the cylinder through the ducts 32, chamber 33, ducts 34, chamber 35, ports 36, and plate valves 37, whilst the combustion gases escape through the outlet chamber 39, ports 40, and plate valves 41. The handles 4 and transverse rod 7 may be replaced by guide-arms sliding on rods secured to a framework.