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The Critchley-Norris Motor Company.

26th March 1908, Page 16
26th March 1908
Page 16
Page 16, 26th March 1908 — The Critchley-Norris Motor Company.
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Exhibit : —A New Steam System for Lorry and Omnibus Work.

A very interesting and a certainly novel steam bus or lorry chassis is shown on the stand of the CritchleyNorris Motor Company (a branch of Peter Pilkington, Limited), of Bamber Bridge, near Preston. This machine embodies many of the best ideas of other makes of steam vehicles, together with many features which are original. In appearance, the machine resembles a petrol-propelled chassis. The threecylinder, vertical steam engine is situated under the bonnet, and immediately behind this is a hood which covers the generator. From the engine, the power is transmitted through two short cardan shafts, to a differential countershaft, and thence, by side chains, to the rear wheels, The three cylinders of the engine, which, by the way, is a single-acting one, are cast in one piece with the valve boxes. The pistons are first ground parallel to ensure cylindrical form, and the upper portions are then ground slightly tapered, so that there is less chance for the pistons to score the cylinders owing to the unequal expansion of the metal when under the influence of highly-superheated steam. Each piston is fitted with seven piston rings ; between the fourth and fifth rings there is an annular groove, which communicates with the atmosphere, in order to allow any steam that may pass the top four rings to escape, instead of its being allowed to find its way into the crank case, and there to condense and interfere with the proper lubrication of the working parts : similarly, the three lower rings and the annular groove, prevent an excessive amount of lubricating oil from passing into the cylinder and being carried from thence to the condenser. The inlet and the exhaust valves are arranged at opposite sides of the cylinders, and they are operated by cams, in the same manner as those of a petrol engine ; by moving the camshafts along in the direction of their lengths, the point of cut off may be varied from a full stroke to about 25 per cent, of cut off, and, by the same means, the engine may be reversed. The normal speed of the engine is soor.p.m., and at that speed it develops about 35h.p., but it may be accelerated to Roor.p.m.

The condenser occupies the front end of the bonnet, and is of the gilled-tube type, with top and bottom vessels connected by vertical tubes. The top vessel contains a feed-water heater coil, and, in the bottom vessel, two oil filters are fitted ; these filters may easily be removed for cleaning. Behind the condenser, a large fan is mounted, and this is driven by a light Hans Renold chain. The fan serves a treble purpose : it draws a current of air through the condenser ; it keeps the burner supplied with sufficient air to support combustion ; and it creates a drautt-ht for the purpose of carrying away the products of combustion.

The design of the steam generator is a compromise between the water-tube and the flash types--a combination which, we might add, has proved, in actual working, to be a very practical and efficient one. It consists of a central cylindrical vessel, round which a series of external coils of mild-steel tubes are arranged. Each coil has three complete turns, and their ends are expanded into the central vessel. A feedwater heater is coiled round the central

vessel, above the water-tubes, whilst, below the latter, and surrounding the burner, a superheater coil, proportioned to raise the temperature of the steam to soo degrees Fahrenheit, is fitted, and is connected up between the throttle valve and the engine. The body of the generator partly projects through the dashboard, under the bonnet, and the remaining portion is covered by means of a neat sheet-steel casing, as shown in the illustration which we reproduced on page 41 of our last issue. The casing is easily removed, and, by undoing eight bolts, the generator can be lifted away from the chassis.

The burner consists of a single jet, from which the fuel issues in the form of gas, having previously passed through a vapnriser. The flarnfrom the jet strikes an inverted cone-shaped deflector, and the latter fitting causes the flame to spread out into a thin film, in which form the fuel takes up suffi

cient air for its complete combustion. The regulating needle, which rises or falls inside the jet piece, is the only movable part contained in the burner.

The fuel tank is situated under the driver's seat and is constructed to with stand a pressure of 30 lb. per square inch, at which pressure the paraffin is fed to the burners. The water tank is carried below the frame, and behind the back axle.

A short cardan shaft transmits the power from the engine to a claw coup ling which is contained within an oil.

tight ease, situated under the driver's seat : this casing also contains a pair of skew gears which drive, at a reduced speed, a double-throw crankshaft, and from this the water and air pumps are driven. Ball-thrust bearings are fitted to both the shafts within this gear case, and the whole of these parts work in a lubricating medium. Another short cardan shaft is employed to transmit the power to the differential shaft. All the transmission shafts are mounted on Hoffmann ball bearings.

From the above description, it will be seen that there are no parts under the body-work which are likely to re quire any attention or adjustment. All the power plant is arranged forward of

the body, and the only parts which are

placed behind the generator are the two pumps, and their driving mechanism. The water pump supplies the necessary amount of water to the generator, and the amount can be regulated by means of a small lever which is situated below the steering wheel. The air pump supplies the pres sure under which the fuel is fed to the burner, and the lubricating oil to all the bearings. Both these pumps are readily accessible when the footboards, between the driver's seat and the back of the generator, are removed. The remainder of the chassis is built on well-tried motorbus lines, and the materials include some of the best brands of steel and bronze that it is possible to procure. Although this is an entirely new steamer, its maker has had no difficulty in finding a purchaser. The Rossendak Division Car riage Company, Limited, of Bacup, will shortly take delivery of this chassis. We hope to be able to reproduce a selection of detail photographs and drawings of this interesting vehicle, as soon as the pending patents have been finally settled.

The marked absence of any machinery beneath the bus body, and the placing of the complete power plant' forward of the dashboard, will at once commend themselves to those who have experienced, in other steam vehicles, the objectionable transmission of heat from the engine or generator, to the body of the vehicle. If the engine, generator, and burner prove to be reliable and economical, we shall expect to hear that much useful work has been done by this chassis.

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Organisations: US Federal Reserve
Locations: Preston

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