Light Vans and Parcelcars : No. 14. E T_h c e w r t % . 1 eg o u d rz
Page 8
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An Interesting Model which is the Outcome of Considerable Experience in Chassis Design.
The light-van model. which we shall introduce to our readers this week is that built by the Medina Engineering Co., Ltd., Gould Road, Twickenham, S.W., and after an inspection which we made of the chassis one day last week we have no hesitation in stating that the makers can well lay claim to having put on the market a compact, and sturdily-built industrial unit.
The machine is British-made throughout, and it is quite evident that the material and finish are the best of their respective classes. For some time past the company has produced a successful light touring runabout, and this industrial unit is the outcome of experience gained in that direction. There are several new and special features which have been introduced into the machine under present consideration, and these should go far towards maintaining high efficiency in service.
Self-aligning Ball Bearings are fitted.
Component parts are accurately machined to jigs, and consequently interchangeability of parts is a feature of the Mercury van. One of the outstanding features of the construction is the embodying of self-aligning ball bearings of large dimensions in the engine, gearbox, back axle, and all four road-wheels.
It Has a 10 h.p. Four-cylinder Monobloc Power Unit.
Coming to the general constructional features of the chassis, the power unit comprises a four-cylinder casting of the monobloc type,
the inlet and exhaust manifolds being separate adjuncts. The 64 mm. bore and the 102 mm. stroke (R.A.C. rating 10 h.p.) are ample. The cylinders are cooled by thermosyphon action, and the large-sized radiator which is fitted has proved to be most efficient even for machines which are being run. in the tropics. All the valves are disposed on one side of the engine, and, as in modern practice, are interchangeable and provided with adjustable tappets, which are enclosed in an oil-tight aluminium cover. As before mentioned, the crankshaft runs on self-aligning ball bearings, whilst the big-ends themselves are of the conventional white-metal type. An automatic carburetter is fitted, and this embodies all the latest improvements.
The ignition is effected by a hightension Mea magneto of the latest pattern, which is driven through a flexible coupling. The engine is lubricated by the aid of a rotary pump driven off the end of the camshaft ; this pump has to deliver oil into troughs under the big-ends. There is a tell-tale on the dash which at once indicates whether the oil circulation is quite in order.
Unit Construction is Embodied.
The front portion of the transmission is constructed on the unit principle, and the engine, clutch and gearbox can be mounted in the chassis en masse, but so designed that it is possible to remove and replace any one portion without dismantling the whole of the construction; it is supported on the frame by the three-point system. The Expanding Clutch.
From the engine the power is transmitted through a metal-to-metal clutch of the internal-expanding type. This runs in oil, so that upon engaging the expanding member a film of lubricant is utilized to act as a damper. The gearbox affords three speeds and a reverse, and on " top " the drive is direct from the engine to the back axle. A cardan shaft transmits the drive to the back axle, and at its forward end is fitted the only universal joint in the chassis. The final drive is through bevel gears, and the propeller shaft with its universal joint is enclosed in a torque tube, so that not only are the rear springs relieved from taking the whole of the drive, but the tube provides a dust and oilproof cover to this portion of the transmission. A 15-in, diameter steering-wheel manipulates the worm-and-nut type of steering gear, which is irreversible. A notable feature here is that the column can be re-adjusted to suit any particular type of body.
Back-axle Accessibility.
A close inspection of the back axle revealed the fact that the differential gear and the driving shafts can be readily removed for inspection or for the purpose of making small adjustments without detaching the whole of the axle component from the chassis. There is no propeller-shaft brake fitted, the two independent sets of braking gear taking effect on the rear road wheels. All four brake shoes are lined with Ferodo, and they face up to pressed-steel drums of ample surface, and to which are fitted dust-proof covers. With regard to suspension, without undue flexibility the system of springing is quite good. The front semi-elliptic springs are 36 ins, long, and the full cantilever type at the rear are 48 ins, between their respective eyes.
The Standard Model is Fitted with Sankey Steel Wheels.
The road wheels which, as we have already stated, run on ball hearings, are of the Sankey alt. steel detachable type. The rims take 700 mm. by 85 mm pneumatic tires ; for machines which are for export the diameter is increased to 800 ram. The main chassis dimensions are : track, 4 ft. ; wheelbase., Oft. ; distance behind the dash, 7 ft. 8 ins. ; overall length, lift. 8 ins. The model we inspected was fitted with a roomy box-van body, and its cubic capacity we ascertained to be 68 ft. The selling price of the complete van is 2190.