Fuente: WIPO "rice" 19,379. Rice, J. V. Aug. 23. Percussive drills.-A two-stroke-cycle internalcombustion engine having two opposed cylinders with trunk pistons working therein, has an eccentric pump cylinder arranged between the working cylinders. Fig. 1 shows an engine of this type in which the pistons 4, 5, 6 are formed in one piece. The cylinders and pumps are cross-connected. The piston-rods 7 are attached to the pump piston 6 and carry crossheads 9 working in guides 10, and the cranks 13 are turned by suitable connecting-rods 11. The pump piston 6 may carry, instead of the piston-rod, a block which actuates a percussive rock drill. Fig. 5 shows a modification in which the pump piston 31 is connected to the working pistons 29, 30 by rods 33 and ball-and-socket joints 34, 35. The rods are attached to the pistons by screwed, slotted disks 37.