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A Unit-construction Mixing Valve

18th June 1943, Page 29
18th June 1943
Page 29
Page 29, 18th June 1943 — A Unit-construction Mixing Valve
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A Well. designed Instrument with Simplified Control, Automatic Lubrication and Ready

Adaptability

T• HE need-for-providing something more than a compromise in the way of a mixing valve on engines destined to operate on producer gas has been appreciated by Thomas Tilling, Ltd., New Kent Road, London, S.E.1. The result is to be found in the Swain mixing valve, which has been developed by the company and used by the bus companies associated in the Tilling group.

Two of the main features which the designer set out to secure were, first, to remove, so far as practicable, the • human element in its control, and, • secondly, to make the valve readily adaptable to different types of engine with a minimum of trouble. . In order to achieve the first essential, the designer has built the valve as a unit, even to the extent of incorporating automatic lubrication of the barrel-type throttle valve, and a diaphragm-type petrol cock, which is controlled with the mixing lever. The adaptability feature has been met by making available both straight and elbow flanges. In addition, a throttle flange has been embodied in the design, and this can be fitted to any of the three flanges on the main body of the instrument, in conjunction with the straight flange or elbow coupler.

The diameter of the butterfly of:the throttle flange has been standardized at 55 mm., but one of 45 mm. diaMeter can be fitted if required. By the use of this valve, full advantage can

he taken of the slow-running jets and starting carburetter in an instrument of the Solex type.

It is claimed that the employment of a barrel-type throttle in the mixing valve eliminates the formation of glin on the valve edges, such as May be experienced with the usual type of butterfly valve..

Referring to the Iubrica,tor, this is so arranged that, when running en gas, a film of oil is always present around the whole surface of the paTrei valve, . as the nil enters the gas port in the form of Spray. As the valve is moved • to the petrol position, the oil supply' is automatically Gut off.

As an example of the manner in which the designer has cut out the human element, ,.all the readjustments necessary, when changing over from petrol to. gas, are accomplishedin one movement of the mixing lever, 'The readjustments affect the ignition, the petrol. supply and the idling position of the throttle.

A. point in connection with the special type of petrol cock employed is that a certain degree of lag in the cutoff is provided fpr, so that there is an overlap until the engine is running only on gas.

Servicing and cleaning were major considerations to be studied, and in these respects the necessary work can

be performeeitin 15 minutes. A figure of 4,000 miles Is given as a reasonable period of running before cleaning becomes necessary, but this mileage would, naturally, vary wit)) conditions of service, quality of gas and other features.

The only tool required to service the unit is a I..in. Whitworth—box spanner, and the work consists of undoing four nuts, disconnecting the petrol cock unions, and withdrawing the barrel valve. Thy last-named is cleaned with a cloth, as is the throttle butterfly.

This latter is made accessible after the barrel valve has been withdrawn. Replacing of the batsel valve and the re-connecting of the ball joints completes the service operation.

Although the instrument is net available in a general way outside the Tilling's group of companies, We understand that Thomas Tilling, Ltd., will • attend to any inquiries whith inay he made to it by operators interested in the instrument.

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Locations: London

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