Automatic Take-up of Valve Slack
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Fro provide automatic valve adjust' ment is the object of a device shown in patent No. 587,433 by Societe des Moteurs Gnome et Rhone, Paris. The drawing shows the scheme incorporated in a push-rod valve system, but it is not limited to this type, and could be built into a tappet if desired.
The push-rod is connected to the pressure-lubricating system of the engine so that oil is forced up through the central bore. The ball-end (1) of the rod seats in a spherical recess in the bottom of a piston (2) housed in a closefitting casing. A loose hall (3) acts as a one-way valve to the entry of oil In operation, oil travels up the rod on its way to lubricate the rocker system via the ports (4). Some, however, enters the hollow piston where it takes up all slack in the system. A spring urges the two pieces apart, and the oil forms an incompressible connecting medium. The piston cannot be inflated to an excessive pressure because the rapid reciprocation of the rods opens a ball-valve for an instant on every stnike.
CONSTANT CLEARANCE FOR BRAKES I N patent No. 587,306, from L. Chou ings and Automotive Products Co., Ltd., both of Tachbrook Road, Leamington Spa, is shown a simple addition to an hydraulic brake cylinder for the purpose of providing an automatic self-adjusting action. The drawing shows a crosssection of hydraulic cylinder employed; the cylinder is slidable in the back plate and thrusts on one shoe (1) while the piston operates the other shoe (2). The piston is extended to form a cylindrical portion (3) which has upon it a split ring (4).
The split ring is freely'slidable, and does not impede the spreading action, but on the return stroke it settles into a conical seating and grips the piston, thus limiting the return stroke to the amount permitted by the width of the gap (5). The shoes are thus compelled to maintain a constant clearance from the drums, irrespective of the amount worn from the facings.
HEADLESS HYDRAULIC VALVE A N hydraulically operated poppetP-Ivalve is the novel subject of patent No. 587,247 which comes from W. Smith, 180 Stratford Road, Birmingham, 11. The advantages claimed are quietness, self-lubricating action and cool working.
The valve consists of a plunger (1) having a conical end (2) which forms the sealing portion. The plunger is a close fit in its surrounding bore, and is fitted with piston rings to help in sealing. An enlarged end (3) forms the hydraulic area; this is acted upon by oil pumped by a plunger (4) operated by a camshaft of conventional design. When the plunger descends, the valve is moved into the open position, the return stroke being performed by an internal spring. An alternative type of spring is shown in dotted lines at 5.
A ring of ports (6) collects oil from the walls of the bore and conveys it to the interior for use as a coolant. Overflow arrangements are mentioned.
A possible criticism is that there is no pressure responsive area to give a selfclosing action, as with a normal poppet valve; in fact gas lealcage along the plunger could conceivably reach the enlargement and tend to open the valve.
This is assuming that a leakage would ca use the oil-return holes to become fouled.
AN instance of synthetic resin being used for a component normally made of metal is shown in patent No. 587,299 which comes from Borg and Beck Co., Ltd., and L. Godfrey, both of Tachbrook Road, Leamington Spa. The part described is a clutch-withdrawal fork, usually made of metal with a graphite ring attached to its working face.
The drawing shows the general section, which has been modified in detail to conform with moulding technique. The material used is a phenolic resin impregnated with graphite to perform the dual duty of conducting away heat and reducing friction. The trunnions are part of the moulding, and are heavily webbed to withstand the shear load of action.
A TIP-BY-BACKING TRAILER
Atwo-wheeler trailer which can be made to tip by the action of backing the tractor is shown in patent No. 587,223 by A. Oswald, 14 Damacre Road, Brechin, Angus, Scotland.
The drawing shows the trailer in the tipped position. The drawbar is a telescopic member having an inner sliding bar (1). Attached to this member is a carriage (2), running on rollers, which, when forced backwards, exerts a thrust on a roller (3) running in a channel (4) attached to. the body. A locking-pin (5) will fix the position, whilst an adjustable leg (6) enables the vehicle to stand when not attached to the tractor.
An alternative locking device is mentioned, providing other tipping angles.