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Cheap Transport for Light Loads

24th April 1959, Page 58
24th April 1959
Page 58
Page 59
Page 60
Page 58, 24th April 1959 — Cheap Transport for Light Loads
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000 Van Gives Commendable Economy and Satisfactory Performance for Short-distance Delivery: Simplicity and Manoeuvrability Are Other Assets

By Anthony Ellis

TAKE a motor scooter, remove the rear wheel and rear suspension arms, substitute a tubular backbone frame with outrigged members to carry semi-elliptic springs and a conventional rear axle, and there, in essence, is the chassis for the Larnbretta 150 FDC van.

On this chassis is mounted a cab with a two-man bench seat in place of the longitudinal saddle used for the scooter. As central handlebars are retained, it is necessary, if a passenger is carried, forthe driver to sit to the right of the seat, assuming an odd but surprisingly quickly adopted steering position.

The main body is an all-steel box with a lockable roller shutter at the rear. A truck body is also available from the manufacturers.

Mechanically, the FDC follows conventional scooter practice, with a 148 c.c. single-cylindered air-cooled two-stroke petrol engine mounted under the driver's seat in unit with a B74 three-speed constant-mesh gearbox. To allow maximum power to be used low down in the speed range, additional gearing between the engine and the main gearbox provides a stepdown ratio of 1.47 to 1, which has the effect of lowering each gear ratio.

The drive is taken from the output shaft of the gearbox through right

angle gearing and a one-piece propeller shaft to the spiral-bevel rear axle, which incorporates differential gearing.

The. driving controls are similar to those used on a Motor scooter. There is a twist-grip accelerator on the right handlebar and a similar twist grip on the left for gear-changing, with which is 'combined the clutch lever. The front brake is operated through a cable by a lever on the right, whilst the rear brakes are hydraulically operated by pedal. A pedal on the floor is depressed to engage reverse gear.

The test van had been used for demonstrations. The mileage recorder registered 200 miles and the vehicle was partially run-in, although the manufacturers recommend 900 miles of • operation at restricted speeds before opening the throttle fully.

Hinged doors, which are a production option, were not fitted to the cab. In this condition it weighed 51 cwt. unladen. It is this low weight—less than a third of that of conventional four-wheeled 5-cwt. vans—which makes it possible to provide sufficient

power for the vehicle with an engine having a maximum output of only 6 .b.h.p.

With myself and 5 cwt. of sandbags aboard, the complete vehicle was found to weigh 12+ cwt. The front wheel was carrying 3 cwt. and the rear axle 9-t cwt. It would be difficult to achieve equal distribution over the three tyres with an evenly spread load in the body. When a passenger is carried, however, weight distribution should be near the ideal.

Although I should have been warned by the retention of the scooter-type front end, I was somewhat taken aback, on first driving the Lambretta, by the extremely light and direct steering. One cannot, of course, lean it around corners as one does a motorcycle, but it retains this type of feel.

The other immediate impression gained was that, when cornering, the wheel opposite to the direction of turn would lift in a manner similar to a sidecar wheel. In fact, it did not happen even when the vehicle was driven at full throttle on full lock in forward or reverse gears.

To see how this low-powered vehicle could perform on gradients I took it to Spa Hill, near Crystal Palace. This hill, which is about +-mile long, with a nearly constant gradient of probably 1 in 8, was entered from a side road without stopping.

A quick change into bottom gear was made immediately and the van continued to the summit without trouble. Although the air-cooled engine had been operated at full throttle for the whole of the ascent, it did not seem unduly hot at the end of the climb. It Was, of course, impossible to take precise temperature readings with this type of unit, Knowing that small two-strokes are inclined to suffer from sparking-plug " whiskering after prolonged highspeed operation, I stopped the engine at the top of the hill. An immediate re-start was then made on the first pull of the starting lever, situated on the right of the seat, showing that the engine should not give starting trouble at its normal maximum running temperature.

Returned to the steepest section of the hill, the van was stopped and held on the hand brake without difficulty. Unfortunately, the ratchet on the awkwardly situated hand brake lever, which is between the driver's legs, had ceased to function.

This made it necessary to hold the vehicle on the front brake while attempting to start. Gripping the front-brake lever makes precise throttle control hard to achieve, which may have been a reason for the van failing to restart on this gradient. With an effective hand brake I think that the van would have just got away on the 1-in-7 incline, although this would be near the limit of its capabilities.

Attempts to restart took up all the movement on the clutch lever, but this was quickly restored by the thumbscrew adjuster provided-an indication of the ease of servicing and adjustment possible with a vehicle of this type.

Acceleration tests were carried out on the fiat road which runs along the south bank of the Thames between Mortlake and Hammersmith. Runs were made in each direction to achieve a mean for each final figure.

Compared with a conventional 5-cwt. van, the Lambretta is extremely slow to accelerate, 48 seconds being required to reach 30 m.p.h. with first gear in use to 9 m.p.h. and second gear to 18 m.p.h. However, it is essentially a vehicle for urban use and can make up for poor acceleration by its small size and manceuwability, which allow it to be driven through traffic with little more difficulty •than a motorcycle.

On journeys of 5 to 10 miles in fairly heavy traffic it was possible to H25

maintain the same average speed as private cars, solely through the little van's ability to weave through the densest traffic,

Moreover, few operators are likely to run the Lambretta continuously at its maximum payload rating. Concerns using it in London include florists and others making special deliveries of individual lightweight items.

Although I did not take acceleration figures for the vehicle part-laden and unladen, I drove it without payload during the fuel-consumption tests, and the acceleration rate up to 30 m.p.h. then came much nearer that of a conventional vehicle.

Top Gear Lethargic

In top gear, which is indirect, the speed would drop to 10 m.p.h., but the van would not accelerate from this speed without help from a downward gradient. Consequently, for the topgear acceleration tests I timed each run from 14 m.p.h. As the engine thrives on high revolutions I did not expect acceleration in • this gear to be particularly satisfactory below 20 m.p.h. and was not surprised by the figures recorded. During these runs the transmission was smooth and free from vibration or snatch even at 10 m.p.h.

For the fuel-consumption runs I chose a residential area in Barnes which seemed to me to be typical of a locality in which this van might be employed most usefully. The course was 2.9 miles Icing and, although mainly flat, included 11 intersections for which it was necessary to use second gear. Wherever possible I kept the speedometer needle at 25 m.p.h., and during the stopping runs the van was halted with the engine idling for 15 seconds on each occasion.

Outstanding Economy

The results show that the Lambretta can carry a 5-cwt. payload more economically than any other van of similar capacity at present available in this country. The low rate of fuel consumption is, however, offset somewhat by the amount of oil used by the two-stroke engine.

As is normal, the oil is mixed with the petrol at the ratio of 16 parts ofpetrol to one of oil and this works out at under 1,000 miles to the. gallon of lubricant. Even-so, the Lambretta still scores on fuel economy. Admittedly, speed is sacrificed, but this, perhaps, is not of the greatest importance on local delivery work.

Braking performance is adequate, although the front brake could have been more effective. On all applica a26 dons from 20 m.p.h. and 30 m.p.h., both the rear wheels locked immediately, even on a dry, rough-surfaced road. The front brake was applied during each stop and whilst, on its own, it provided smooth, though gentle, retardation, when used in conjunction with the rear brakes, it produced violent bottoming of the front suspension.

This is possibly because of the trailing-link layout of the front forks, combined with weight transference. The movement was uncomfortable for the driver, but with the friction steering damper correctly adjusted, it did not cause any directional instability.

It was not possible to carry out our normal hand-brake tests, as the situation of the lever makes it extremely difficult to reach. It is apparently not intended for use while on the move.

At the conclusion of the tests, having driven the Lambretta for some 150 miles, my feelings about it were mixed. 1 enjoyed its part-laden liveliness, but its acceleration fully laden was tedious. Parking was a pleasure with small overall dimensions and a 15-ft. turning circle. • 1 regretted that its maximiim speed of 35 m.p.h. could not be used in comfort, as vibration and noise above about 28 m.p.h. became intense. Below this speed, however, the volume of noise was acceptable and vibration was largely absent.

This is one of the ever-Present problems with an enclosed two-stroke engine and in the Lambretta little appears to have been done to overcome it. Indeed, the half-shield beneath the engine seems to be a highly resonant structure, which certainly throws back engine noise into the interior of the cab and probably amplifies it. A few minutes' work by the driver on the inside of the engine cowling with a tube of adhesive and some felt would, r think, pay handsome dividends in increased comfort.

The ride is good laden or unladen and cornering, once one has mastered the knack, can be fast.

Visibility through the one-piece curved windscreen, with its manually operated wiper, could hardly be bettered. Rearward vision is aided by two mirrors. Although of good size, the mirrors are mounted on long stalks and vibrate at speed, thus losing most of their effectiveness.

Starting was good at all times. Only after the vehicle had stood out overnight was it necessary to use the dashboard-mounted choke control, and then only for a short time. The tick-over was slow and regular for a two-stroke engine, whilst four-stroking was never unpleasantly obvious..

Above all, 1 liked the Lambretta's meagre fuel requirements. The 21-gal. fuel tank fitted below the dashboard gives a range of about 150 mites and has a reserve compartment controlled by a two-way tap.

Easy Maintenance

Maintenance presents few difficulties. The seat and the cowling to which it is attached can be hinged forward to expose the engine-gearbox unit or be removed completely after pulling out two split pins. I was able to change the sparking plug, which is slightly shrouded by the air ducting, in 46 seconds, and remove the prefilter and clean the gauze of the Dell orto carburetter in I minute 6 seconds.

The fluid reservoir for the hydraulic rear-brake system is fitted beneath the floor of the cab under a panel secured by eight screws. A thumb screw on the operating lever permits adjustment to the front brake, whilst • the rear brakes are 'taken up by nuts on their backplates.

So light is the van that even when laden any wheel may be lifted clear of the ground by one man, making a jack superfluous. A spare wheel is supplied and this is fitted in a cradle below the rear of the vehicle.

A tool box is mounted behind the cab below the frame in an exposed position. The one fitted to the test vehicle had suffered damage, Showing that this item could be better placed.

In chassis and cab form the Lambretta 150 FDC costs £243 6s. The van body adds £57 10s. 6d. to this making the total cost £300 16s. 6d.

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People: Anthony Ellis
Locations: London

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