Incidental Equipment that Means So Much
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Some Details of the Extensive Variety of Clayton Dewandre Specialized Products and Notes on the Improvements Which Have Recently Been E ected in Them to Increase Their Value ATOUR of the Titanic Works at Lincoln of the Clayton Dewandre Co., Ltd., is one of the most interesting that can be made, for the products of this live and well-managed concern are, in the main, unusual and diverse in their application, but they hold two characteristics in common, they are meticulously, made and are always up to date. Experiments are also constantly being conducted to develop new or improved equipment for commercial vehicles.
Foremost in the range is, of course, the vacuum servo, although the company has not neglected the pressurebraking side. Then, we have the wellknown and highly efficient Clayton-Still tubing, which is utilized for radiators and heaters (both factory and vehicle).
Considerable attention is devoted to hand and power-operated tipping gears, whilst for buses and express coaches there is the Unitype destination indicator.
An Automatic Shoe Adjuster. •
A notable device for which the company is the sole licensee is the R.P. adjuster for brake shoes and, last but not least, is the Clayton Verometel, a ticket-issuing and recording machine possessing considerable potentialities.
There are incidental items, such as exhausters and trailer pipe couplings, some of which will he referred to later.
Now we will deal more particularly with the individual articles, At the Commercial Motor Show of 1935 95 per cent, of the heavy passenger vehicles were equipped with Dewandre vacuum servos. The company is now in a position to supply complete vacuum braking sets (as against only the original master power booster)comprising reservoir cylinder and the company's
B38 own exhauster, whether for an oil-engined vehicle or trolleybus. A development is a combination of the Clayton vacuum servo and the Lockheed hydraulic unit, the latter being neatly bolted to the servo casing. The vacuum servo can also be employed most effectively in conjunction with Girling brakes.
A System for Trailers.
Especially designed for trailer work is the double-acting vacuum " suspended " system. In this the vacuum occurs at each side of the piston, and to apply the brakes it is destroyed at one side. This has been found to reduce the time lag, as the vacuum is already on the piston. It is recommended for trailers, because, in the unlikely event of a pipe line breaking, the brakes are applied automatically. Incidentally, a considerable number of trailers for the L.M.S. Railway is being equipped in this manner, and it is of interest to mention that every Bedford vehicle above and including the 2-tonner has Dewandre servo equipment.
At present the ratio of pressure-braking equipment to the vacuum is quite small. The pressure servo closely resembles that for the vacuum, but is reversed and the cylinder is naturally much smaller. Certain Scarnmell vehicles have employed this method for several years. The same Dewandre balanced-beam principle is utilized, but whatever type of engine be used, a pressure pump giving up to 80 lb. per sq. in. is necessary. With either type of braking supplementary cylinders can
be supplied, and the air or the racuum system tapped.
The vacuum braking can be rranged in three distinct ways. Thor is the single unit or monobloc type, md the double unit, which consists of master cylinder and piston controlling second cylinder usually placed on t le near . side and taking effect on the o her end of the main brake. cross-shaft, bus not only supplementing the vacuu effort, but relieving the cross-shaft of torsional stressing. The triple s stem is
becoming widely used. The master cylinder controls the rear brake., whilst a supplementary cylinder is mounted on each front stub axle, so that it can move with the steering and thus obviate the need for universal joints.
What almost constitutes a fourth arrangement is that in which the servo is added to existing manually applied brakes. In this type there is a separate valve connected with the induction pipe, and the servo is slu , wherever there is suitable accommodation on the chassis.
Standard Detachable Coupling.
Incidental to the system used on articulated six-wheelers or in conjunction with vehicles and trailers, is a quickly detachable pipe coupling, the design of which is about to be standardized for the whole trade by the Society of Motor Manufacturers and Traders, and any maker will be at liberty to use it.
It has been found best to employ aluminium cylinders, as it is an easy matter in manufacture to cast-on bosses or other fittings which, if the cylinders were of steel, would have to be welded on separately. All the servo pistouS are light-steel pressings.
Where much traffic work has to be undertaken, a small reserVoir and a larger tank are employed in conjunction with a diVerter valve, -whieli first exhausts the small container and thenthe large. The small tank is naturally, exhausted :rapidly and provides immediate vacuum . for rapid
braking. .
An improvement on all commercialvehicle-ser-Vo distributor valves is .special rubber seats, which are thoroughly time-tested for leakage and
not passed until perfect. Small leakages would not actually apply the brakes, but would cause loss of vacuum in the reservoir.
The Clayton exhauster is of unusually high efficiency, giving as much as .7 atmosphere down to 80 r.p.m. At this speed, with a l cubic-ft. tank, it takes 110 seconds to reach the figure mentioned. The actual time is not of great importance, depending upon the size of the pump; the vital matter is to give high efficiency at low r.p.rn., and few pumps can achieve these results.
New Heating and Ventilating Unit.
In a very interesting paper read by Mr. H. Blomeley at the T.L.R.T.A. Conference held at Llandudno last Year, reference was made to a new Clayton heating and ventilating system in which the air is not recirculated. This has been supplied to London Transport for a large number of A.E.C. 6Q6 vehicles, whilst further orders for 4Q4-type coaches have been received.
In this type there is a circular heater with -Still tubes, and a " runner " (blower) driven by a 24-volt motor which forces the air under slight pressure to a delivery system, from which it is supplied to various points in the eehicle. All the air is drawn from outside, from inlets which can be around a headlamp, an indicator, or behind a separate grille. Tappings can be taken to discharge warm air over the inside of the windscreen, thus lowering the dew point and preventing condensation. The water circulation does not interfere in the slightest degree with that for cooling the engine, as. the flow is arranged in parallel. The temperature control is effected by varying the flow of water. This is achieved automatically by an R.V. regulator in which evaporation of a volatile liquid produces pressure on a bellows. ,If ,neeessary the Supply of water to the heater can be entirely shut Off.
The ducts through which the air enters the vehicle are arranged around the bottom framing of. the body, the air. passing behind a curved panel mounted between the sides and floor
and being directed in a downward direction from orifices immediately above this.
This system is, of course, additional to the original Clayton heater. Messrs. S. E. Willett and H. Blorneley are associated in the patents covering the new unit.
Another development is a more powerful heater for front bulkheads. This provides greater heat to deal with more rigorous weather conditions, and may eventually become the standard model.
More Powerful Clayton Heater.
The fan takes about 20 watts at 12 volts, or 1.8 amp. Normally, this current is derived direct from the dynamo, so that the battery is not drained. The thermostatic control cuts out the fan by means of a mercury switch, which is operated by three-degree variations, or can be regulated to one-degree differential.
In some cases the standard heater is incorporated in a panel. This avoids giving any impression that the device has been fitted as an afterthought. The air is then taken from the sides and upper part of the vehicle. In a large number of cases the heaters are duplicated, an additional unit being mounted at the back.
On the R.P. self-adjusting brake mechanism a new feature is the enclosfrig of the ratchet wheel. The adjniting mechanism is built into the nose of the brake-shoe, and comprises a sliding wearing plate which is extended by a worm-reduction gear automatically operated by a rack and wheel. The sliding plate is screwed on to an extending piece which, at its other end, has a worm wheel. As the brake is operated, the ratchet wheel slides up and down a spring-loaded rack; when this movement is increased by wear oC the facing material the rack engages with the next tooth on the wheel, and when the brakes are released the shaft upon which the ratchet wheel is mounted is turned slightly, a worm on this shaft unscrewing the extending piece and so pushing forward the wearing plate.
Ingenious Duplicating Gear.
The action has -to be duplicated on the other shoe, and to effect this the drive is taken from the main extending piece to that on the other shoe via a flexible shaft passing through a hole in the cam.
The company has an end-tipping gear, Of which a considerable number is sold, but for certain models, where it is essential to cut down the unladen weight, it has been necessary to
develop specially light gear, which is capable of dealing with loads up to 5 tons.
There is also a two-way tipping arrangement, adaptable in principle to make a three-way tipper, giving an angle of 55 degrees.
A regular feature of the gears is unit construction, thus preventing errors in fitting up by the bodybuilder or agent. 3339
The twin telescopic underbody type avoids the use of any flexible piping, and there is a scheme for operating the hinge pins from the cab, but this is not used on the lightest gears. This hydraulic gear is intended for 2-3-ton, short-wheelbase chassis. End tippers only are supplied for long-wheelbase models.
The linitype destination indicator is a particularly interesting product. Not only is it easily readable both by day and night, but it permits the operator to deal with an alteration of destination on any route within a few moments, and without the need for carrying blinds other than the four contained in the device, so that there is no likelihood of these becoming damaged or soiled. Lighting is efficiently carried out by two 24-watt lamps with parabolic reflectors giving excellent visibility up to 100 yds.
Our reference to the matter of changing blinds refers to the latest improved pattern, which is known as the magazine type. This gives a sight opening 10 ins. deep. Each of the four blinds permits 44 changes of route.
and so easily that the operation can be effected by one hand.
The cage containing the rollers is held by a spring plunger, and a release action at one side of the indicator slides a curved wedge under the knob of this plunger, thus releasing the roller cage so that it can be rotated to a fresh position.
An important development has been introduced in the Verometer. A new model, the BM, has been designed, which provides for all fares f to us, 114d., representing values. The ticket gives all information as with the smalle the type B, and the shillings a values are printed in bold let A particularly neat cancellin used in conjunction with this This device not only gives a cancellation mark and mutilat also records the number of ti treated.
era id. 87 fare elevant model, d pence IS.
unit is achine. definite on, but kets so