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Critchley-Norris Motor Co.

14th March 1907, Page 17
14th March 1907
Page 17
Page 17, 14th March 1907 — Critchley-Norris Motor Co.
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Exhibits :—One 35-40h.p. Bus Chassis; one Bus Body.

This stand contains an omnibus chassis and a double-deck body, which is evidently intended to be fitted to the chassis. The body is painted for the London Central Motor Omnibus Company, Limited, for whom the Critchley_Norris Motor Company is contracting to supply several chassis. The omnibus shown is an improvement on the vehicle we described in our issue of the 22nd March last. The engine, which is made by Crossley Bros., Ltd., of Manchester, is rated as a 4oh.p., ano has four cylinders, of 4!,1inches in the bore and has a 6-inch stroke ; it gives 3ob.h.p. at 800r.p.m. It is, however, capable of considerable acceleration, and can be run at 1,tootep.m. The ignition is by low-tension magneto, the magneto being driven by enclosed gear. Supplementary high-tension ignition

can be fitted if required. Unusually long journals are employed on the crankshaft, which is of nickel steel. The inlet and exhaust valves are on opposite sides, and the camshafts work in a special oil-retaining chamber. Both the cams, and the rollers on the tappetrods, are c.ase-hardened.

A new form of radiator has been adopted, with very large surface, and of simple construction, special provision being made for the expansion of the tubes, so that there is no risk of leakage, whilst a large-diameter fan is employed.

A new form of automatic forced-feed lubrication has been introduced, in which the oil is fed through sight glasses, containing glycerine, so that the drops flow upwards, instead of

downwards. The oil is afterwards forced forward by air pressure to the various parts of the vehicle. The engine can be controlled either by the foot-pedal or hand-lever, and the clutchpedal is connected to the throttle so that the engine does not race when the clutch is taken out The carburetter is automatic, both the gas and the air being controlled independently. This is effected by a sleeve which covers or uncovers. the admission ports, and sudden changes are prevented by a mercury dash-pot. Half-compression is obtained for starting by means of wedges, which are inserted between the tappet-rods and the exhaust-valve stem in order to

hold them partially open. There is a neat eccentric arrangement for withdrawing the clutch, as illustrated in the sketch, and the clutch is controlled by a square-sention spiral spring instead of the usual circular-sectioneo. spring. The male portion of the clutch revolves on ball bearings.

There is a universal joint immediately behind the clutch, and another in front of the gear-box. A strong caststeel cross-member carries the pedals and change-speed box, and has a bridle surrounding the propeller shaft to comply with the Metropolitan Police regulations. The gear-box is particularly well designed for accessibility, as the whole of the front of the box can be removed in order to draw the gears. Special nickel-chrome gear wheels are employed, the sliding pinions being on

the primary shaft, and the fixed spur wheels on the secondary shaft, being bolted to flanges. The feathers on the primary shaft are solid with the shaft, which is machined from a special forging. Four forward speeds and a reverse are provided, with gate change. There are ball bearings to all the gear shafts, and to the differential, and special provision has been made to secure accurate adjustment of the ball thrusts at the front end of the secondary shaft in the gear-box; and on the differential casing, so that perfect line contact between the teeth of the bevel drive can be assured. This is a feature of great importance from the point of view of maintenance. The final drive is by two Hans Renold roller chains to the back axle. The chain sprockets are of unsually large diameter, having 13 and 26 teeth respectively.

The structural details have been well thought out, especially the steering gear, which will be found to be of ample proportions and with spring controlled joints. The frames are of channel steel with particularly strong crossbracing, and very long, flat, resilient springs are one of the most prominent details.

One of the neatest features in this chassis is the compensation of the brakes. The illustration above shows that a jockey pulley is attached to the

crank on the brake-lever shaft, and a parallel-motion arrangement ensures that this pulley shall always he in the same plane as the cables, whatever may be the angle of the crank that operates it. The steel cables lead from one brake, round the pulley, and to the other brake, so that the tension on each brake must be equal. The pedal applies two band brakes operating on drums at each end of the differential shaft, which drums are of unusual dimensions, being is inches in diameter

by 3:1 inches in width of face. The hand-lever operates on two internal-expanding brakes in the back-wheel hubs. A sheet-steel apron extends from the front of the engine to the gear-box, to protect the mechanism from road dirt, and to catch any oil that may drop. This make of omnibus appeared for the first time a year ago, and in the meantime has been thoroughly tested in the hilly districts of Lancashire and Yorkshire. It is a firm proof of the excellence of the workmanship, arid of the design, that so very few alterations should have been made since the chassis was first put upon the market. The ample dimensions of all wearing parts will convince engineers of the lasting qualities of this chassis, and of its suitability for hard and continuous work. The makers have been experiencing very great pressure upon their works at Bamber Bridge, partly owing to excessive demands upon the shops for pneumatic hammers, but arrangements for output are now such as to allow reasonably early delivery. Mr. J. S. Critchley will be in attendance at the stand until the conclusion of the show.


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