RINGLESS PISTONS

Press, Volume LXX, Issue 21179, 1 June 1934, Page 6

RINGLESS PISTONS

CLAIMS OF A NEW TYPE Unusual claims are made about the advantages of a new make o£ piston, which can be used in internal combustion engines without the need for fitting piston rings. The invention is at present the subject of experiment in England, and is being tested in a fleet of heavy commercial vehicles. It is said that a great benefit procured is that a deeper oil film can be maintained on the cylinder walls and that as the new piston also accommodates itself to all distortion oC the cylinder, wear is greatly reduced. But it is thought that for various technical reasons it will most probably be suitable only for large engines of wide cylinder bore and having a fairly slow working speed. This ringless piston takes the form of a thin cast iron shell, which is bolted to light alloy blocks, which provide a mounting for the gudgeon pin. It has a microscopically fine taper, the wider clearance at the head when installed in an engine being .01 inch, but reducing to the normal clearance employed with a ringed piston. The gudgeon pin being separately mounted and inside the piston walls cannot possibly cause scoring, and it is maintained that the tapered shape ensures an excellent oil film and so retards wear and tends to prevent crankcase dilution. A large engine in a havy truck was equipped with these pistons, and run for 9000 miles, after which the engine was stripped and a close examination made. It was then observed that the thin carbon deposit on the cylinder walls ended abruptly at the point where the tapering of the piston skirt ceased, and the overall wear of the piston unci the bore was negligible.

Guy Moll, winner of the Monaco Grand Prix, is a comparatively littleknown French racing driver, but his victory in a race contested by leading English and Continental drivers brings to the forefront. Moll, who is only 25 years of age, snatched victory from the famous ace, Louis Chiron, who was leading two laps from the finish, but hit a barrier and was delayed until the younger man had passed.