An Oil-cooled Piston
Page 60
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ANOVEL design of piston for which many advantages are claimed is shown in patent No. 591,348, by Shell Development ,Co., San Francisco, California, U.S.A. An oil-cooling circuit is provided through the head.
The most striking feature of the design is the ball joint at the upper end, which takes the place of the usual gudgeon pin. The connecting rod terminates in a half-halt onto whichis screwed the top half (1); this portion also forms the crown and is subject to the flame of combustion. The piston is spherically bored to receive the ball, the lower part of the seating consisting of a screwed-in ring (2). An oil-retaining ring (3) is fitted to form a seal.
The cooling arrangements comprise an internal nozzle (4) fed from the crankshaft; oil is sprayed onto the inside surface •just where the maximum heat is generated. The oil then runs down the ball and escapes from. ports (5).
Tests show that whereas a conventional piston may reach a temperature of 500 degrees F., this one attains only 200 degrees F. under similar conditions. Carbon and " lacquer " are reduced to negligible quantities, and that which does appear is soft enough to be wiped away with a cloth. As the piston is free to rotate, the wear on rings and cylinder would be more uniform.
A RAPID-CHANGE IGNITION . ADVANCER
AN ignition timer in which the change from retard to advance occurs suddenly over a small speed range, instead of the usual progressive Motion, comes in patent No 590,922, from Rolex, Ltd., and D. Miller, both of Rotax Works, Victoria Road, London, N.W.I0.
The drawings .show the centrifugal mechanism forming the essence of the patent. A pair of bob-weightS (I) can move along slims froM the inward position (drawing laty to the outermost
limit, as shown in the drawing right. In the inward position, however, centrifugal:force has no effect on the bob weights because the sleeve pivots (2) are dead in line with the weight centres, and the coupling is locked.
As the speed rises, nothing happens ,
A Resurne of Recently Published Patent Specifications
until another centrifugal action occurs; this time arising from arms (3). These move outwards slightly, and unlock the bob-weights, which then take charge and move rapidly to their limit. The operation is assisted by the toggle-like action of the springs (4), which pass over their dead centre each time the .action takes place.
THE LUBRICATION OF DIFFERENTIAL GEARS
PATENT No. 590,867 comes from the 1. Ford Moto]. -Co., Ltd., -88, Regent Street, London, "WA, and deals with lubricating arrangements for differential gears. The scheme is principally intended for use with the heavier types of vehicle, the differentials of which are often heavily loaded at low speeds.
The main feature of the scheme is a stationary scoop (1), which just clears the back of the, crown wheel (2), with the minimum practicable clearance. Oil carried by the crown wheel is thus wiped off, arid gravitates through the scoop into a channel (3). From here, drilled passages in the differential case lead to all the important lubricated surfaces, including the pins carrying the planet pinions.
The action of gravity is intensified by the forward velocity of the oil as it leaves the crown wheel, and thus the flow would increase with the speed of the vehicle.
PROMOTING SWIRL IN ENGINES WITH HEMISPHERICAL HEAD5 DATENT.No. 591,157 comes from H.
Wesiake, 41, Fuller's Way, Kingston By-pass, SUrbiton, and deals with modifications to hemispherical cylinder heads, the aim of which is to promote an orderly swirl around the combustion space. Two features form the basis of tfie patent, one being that the inlet passage (1) is curved so that the incoming charge is directed to one side of the cylinder. The other point is a device intended to smooth out eddies that may originate in the carburetter or the induction pipe. It consists of the formation of a venturi (2) in the inlet passage. The sparking plug is arranged to
lie in the path of the incoming mixture, and the exhaust valve is dished to conform to the general outline of the chamber.
TOOL FOR EXTRACTING BALL-RACES
DATENT No. 590,298, refers to ball1 races of the journal-cum-thrust type, as often used in magnetos, for example. Such races are notoriously difficult to remove from their housings, there being nothing on which to get a grip. A tool for assisting in this respect is described in the patent by Jack and Heintz Incorporated, Bedford, Ohio, U.S.A.
The drawing shows sufficient of the device to illustrate the action. The chief part is a sleeve (1) drilled w,ith a ring of holes and fitted with a set of balls. Sliding inside, the sleeve is a conical plug (2) which is permitted to have a limited movement by a pin-and-slot (3).
The end is placed in the race it is desired to remove, and the centre plug is then pulled upwards by a lever. The balls are thus thrust outwards into the groove of the race and so obtain suffiicent grip to enable extraction to be performed. The assembly is housed in an outer sleeve (4) which abuts the face of the housing and provides a clearance for the reception of the extracted race. The device would, of course, have to be specially dimensioned to suit the particular size of race.
It is claimed that this tool is quick in operation and no damage is done to the race which may be retained for further use.