A Simplified Method of Crankshaft Grinding
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Iv/HEN crankpins have to VV be reground, each has to be set up to run true before grinding can cornmence. This takes some
time on a multi-throw crank, and to obviate the need for it is the object of a design of grinding machine shown iii patent No. 556,274 by V. Prince, 14, Park Road, -Kingston-on-Thames-: This inventor proposes to mount the grinding wheel on a rocking frame, so that it can follow the reciprocation of the crankpin as the shaft revolves about the main-bearing axis. The drasving shows an end-section of the machine-bed with the rocking frame in position.
Along the bed slides a carriage carrying a rocker (2) which is' pivoted about a pin (3). The upper end carries the grinding wheel (6)„ which is shown engaging one of the phis of a. crankshaft (7). ' The oscillatory motion is produced by the crankshaft itself, the position of the grinding wheel being determined by an adjustable steady (8), the frame (1)' of Which is journallecl about the grinding-wheel axis. The wheel is belt-driven from an electric motor (4) carried on the lower end of the rocking frame.
A hand-wheel (5) and its associated mechanism are for the purpose of controlling the size of non-oscillating work such as the main journals, and can be latched in or out of action as required'.
FILTERING SYSTEM WHICH FUNCTIONS WITH COLD OIL
PATENT No. 556,304 shows an engine-oil filtering system designed to maintain the supply to the bearings in spite of the high viscosity of cold oil. The patentees are C. he Clair and Tecalemit. Ltd., both of Great West Road. 'Brentford. The difficulty of filtering a,large quantity of cold oil is overcome by attempting to deal with Only the small flow required to feed the bearings, the remainder being by-passed in an unfiltered condition.
The drawing shows the filter and the rest of the systena diagrammatically. In operation, oil is drawn from a sump inlet (4) by a pump (&) and delivered to the inlet (6) of the filter. After passing the cleaning unit, the oil. leaves via spa Ce 8 and pipe 9 which leads to the engine bearings. , • At all times, the quantity that the bearings can accept is much less than the delivery, and so, when the working pressure has been built up in pipe 9 a spring-loaded piston (10) is forced to the right; this brings a groove (11) into line with a discharge port (12) and permits the excess oil to escape via pipes 7 and 3. A spring-loaded valve (2) is normally closed.
• When the oil is thick and cold the bearings' will, take even less, which means that the bulk of the oil is returned via pipe 1. Valve 2 is opened by the excess quantity, and the oil . completes a circuit by returning to the pump. The quantity of oil in thecircuit being small, it is rapidly heated ' by the amount of work performed by the pump, so that a small supply of warm MI is soon provided. • .
LIGHT•ALLOY PISTON FOR OIL ENGINES
THE successive oil dilution and formation of acid products that occur in oil,engines are responsible for much corrosion of light alloy pistons, and this is often apparent around the working surface of the gudgeonpin bosses. Such are t h e views expressed in patent No. 556,224 by Spe
cialloid, L td., and E. Graham, both of Friern Park, London, N.12, in which is disclosed an improved piston in which the gudgeon-pin bosses are protected by 'bushes.
The drawing shows a section of the piston according to the invention, in which the thin bushes are indicated. They are made from austenitic iron or steel, preferably of the stainless variety. Although the coefficients of the two metals differ slightly, the patentees . state that it i4snot sufficient to cause looseness, The Piston is also fitted with a steel insert to carry the piston rings.
NOVEL TYPE OF PORTLESS SLEEVE VALVE PORTS in sleeve valves usually create problems in connection with the piston rings, which tend to spring
open while passing over the ports,. A new design of sleeve, which avoitis this difficulty, • is. shown in patent No. 555,521, by P. Fraser, Hamble House, Warren Road, Chelsfield, Kent.
The drawing shows sufficient of an engine to illustrate the scheme; men' tion is made of its suitability for application to engines of the Opposed-piston two-stroke type. The cylinder liner (1) is enlarged at the bottom end to house the sleeve valve (5), .which is of the same bore as the cylinder so that the piston can enter. The sleeve in its upper position (as shown) abuts on a shoulder (7) and makes a gastight joint at this point. The sleeve is upwardly biased by a spring (3) of large diameter. The lower end of the sleeves is channelled at 4 to receive the skirt of the piston.
As, the piston approaches bottom dead centre, its skirt engages groove 4 and the sleeve is carried downwards, opening the inlet port (2) and the port 6, which, presumably, is the exhaust. To cushion the effect of the piston striking the sleeve, the ' groove (4) is a close fit and acts as a pneumatic dashpot.
A novel feature of the scheme is the', use of balls and, grooves (not shown) to guide the sleeve, instead of the more usual lubricated surfaces. The grooves
may bestraight or helical; in the hatter case the sleeve would be given a semirotary motion.