A MEDIUM-SIZED PASSENGER CHASSIS.
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Details of the Latest Halley Product, which is especially Designed for Passenger Work and to Carry Bodies Holding 18 to 20 Persons.
TWO EXAMPLES of the new Halley passenger chassis will be exhibited at the Scottish Show this week, one carrying an 18-seater coach body, and the other a 20-seater saloon bus. One of the most interesting points about this chassis is that it can be provided with either a four-cylindered engine of 30 h.p. or the well-known six-cylindered type of 40 h.p., and the vehicles shown will embody these two power units, the smaller of which has a monobloc engine with cylinders having a bore of 4 ins. and a stroke of 5 ins., whilst the sixcylinder model is constructed with the cylinders in blocks of three, each cylinder being 4 ins. in .diameter and. with a 6-in. stroke.
These chassis are known as the QX type and have a wheelbase of 14 ft. The engine lubricant is circulated by a• gear-type oil pump, lubrication being assisted by the provision of troughs for the big-ends. Ignition is by high-tension magneto, and carburation is effected by a Halley-Zenith instrument.
In the ease of the four-cylinder unit the cooling water is circulated thermosiphonically, but with the larger engine a centrifugal pump is employed. In both cases a fan assists the circulation of the air.
The radiator differs considerably from s that employed in former models and conforms well with the streamlining of the bonnet. It. is of the straight gilled-tube type with header and bottom tank. Use " E28
is made of a large single-plate clutch 1
worki 5 between two fabric discs, and an effi lent clutch brake is provided.
Bet een clutch and gearbox are two universal joints and three-point suspension is employed for the gearbox, this being carried by two channel-steel crossmembers, well gusseted to the side memb6s. It provides four speeds forward and a reverse, direct drive being
on top gear. The controls are to the right of the driver, and the gearbox shafts run on Timken roller bearings. The drive is conveyed through a car. clan shaft with large fabric joints to the overhead worm of the rear axle.
All the road wheels are of the pressedsteel disc-type, running on Timken roller bearings, and Dunlop cord tyres, 34 ins. by 7 ins., are fitted all round These tyres, combined with the use of long flexible springs and a suitably arranged final-drive gear ratio, enable a road speed of 35 m.p.h. to be maintained with ease.
An important point in the steering is that the rake of the column is adjustable.
Our plan view of a typical 18-seater coach shows how this chassis can accommodate and lend itself to the construction of a torpedo-type body affording a high degree of comfort. We have not yet touched upon the matter of brakes. Both are of the internal-expanding type, and operate in the rear-wheel drums. They are compensated and easily adjustable. A fuel supply of 25 gallons can be carried in the tank at the rear of the chassis, feed being by Autovac. In spite of the use of large pneumatic tyres, the frame height has been kept _ low, the measurement from the ground to the top of the side members being only 2 ft. 5 ins.
The question of suitable engine power for various classes of work is one which constantly exercises the minds of designers. One power unit may give perfectly satisfactory results in easy country, but the vehicle may be much underpowered where many severe hills are encountered, consequently the decision of the builders of the Halley to give a choice of engines in this new vehicle is a step in the right direction.