GB260354A - Improvements in or relating to portable power-operated tools - Google Patents

Abstract

260,354. Bird, P. C'. July 30, 1925. Drilling-machines. - The drillspindle is actuated by an internalcombustion engine of the opposedcylinder type and forms therewith a unitary structure. The crankshaft a of the two-stroke engine with opposed cylinders b, b has its axis parallel to the axis 35-35 of the spindle which is provided with a socket j and is driver through spur gearing c, d, g, h the wheel d forming one member of an expanding ring clutch, the other or ring member l of which is fast on a shaft f. The member e is cut through at a point in its circumference and is expandec to grip the wheel d by forcing radially into the cut a pin t which bears against a waist-shaped spindle r against which, through a ball q, presses a spindle p secured to a screwed cap o adapted to be rotated by a Bowden cable. A spring may assist the return of the spindle r. Combustible mixture is produced by spraying fuel through a nozzle z, Fig. 3, into a choke tube x the outlet from which to the induction pipe y is controlled by a spring-loaded piston throttle valve v. The nozzle is situated at the end of a tube 11 parallel to the axis of the cylinders b, b the float chamber 12 being rotatably mounted at the other end of the tube so that it may remain vertical irrespective of the inclination of the shaft a, the cylinders remaining substantially horizontal. The float cham. ber is fed from an overhead tank through a flexible pipe 15 and the outlet of the nozzle z, when the tube 11 is horizontal, is above the fuel level in the chamber 12. The upper end of the crankshaft carries a contact breaking device 18, as well as a pinion 20 which can be normally rotated through a wheel 21 to start the engine. A single lever actuates, through Bowden cables, the throttle valve, and the clutch and may, at the same time, actuate the ignition timing gear. An axial thrust is exerted on the tool by a screwed member 23 which presses, through balls 25, against a shoulder 24 and over which is threaded a sleeve 26 adapted to be rotated by a handle 27 with coned end 28 which bears against a fixed abutment. The tool may be ejected by a drift pin 29 by screwing the sleeve 26 over the part 23 to the extreme position shown in Fig. 2, when the small end of the pin will pass through the hole 30. The engine is provided with a combined fly-wheel and fan 31 and, in order to direct the flow of air and to prevent accidents, the flywheel and part of the cylinders are enclosed 'by a casing 33.