Trying Ailsa's decker in London by.....yes

13th September 1974, Page 143

13th September 1974

Page 143

Page 143, 13th September 1974 — Trying Ailsa's decker in London by.....yes

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FOR MANY bus operators these days driver reaction can be all-important when specifying new vehicles. Cases of crews and their unions refusing to accept new types of vehicles are not unknown. It was because of this that I was particularly anxious to try Ailsa's new double-decker for myself. Its "back-to-front" treatment would seem to indicate inherent compromises in putting the engine at the front and retaining sufficient space in the driving cab.

As part of our exclusive review of the Ailsa's secret development programme (see CM last week) I have several times been able to drive the bus during its simulated service route trials in and out of London. The 96km (60-mile) route runs from the Military Vehicle proving ground at Chobham via Chiswick, Knightsbridge, Piccadilly, Westminister Bridge, Clapham, Putney, Twickenham and back to Chobham.

Simulated bus stops, 138 of them, are used in the less heavily trafficked sections of the route — between Knightsbridge and Westminister Bridge. The route itself is normally covered twice a day at times when heavy traffic is prevailing but without the long delays which would be involved in running during the most intensive part of the rush hour. As it is, driving time is about 31/4 hours, giving an average speed of about 29 km/h '(18 mph) including stops.

Probably the single most noticeable thing about the Ailsa bus from the driver's viewpoint -and something which is crucial to the vehicle's success — is its performance. There have been many doubts cast about the potential of such a small (6.7-litre) engine for bus use. The principle of turbocharging is also relatively unknown in intensive stop-start operation. From my experience I can say that these doubts are mostly unjustified in respect of performance. Because of the gearing of the • bus, full throttle application from rest with test weights simulating a 89 passenger load produces apparently very gentle acceleration initially. It is in the 10-25 mph band that the vehicle is so impressive. Then it really steams away and can catch the driver out if he does not keep a close eye on the speedometer.

Light to drive

As with most power steering systems the amount of effort at the steering wheel is optional. However, most operators should find the 5 kg (111b) to 6.4 kg (14 lb) effort chosen by Ailsa just right. This giVes enough effort to make the driver wary of high-speed cornering yet makes light work of getting in and out of awkward bus stops. Controls are sensibly placed, with the gear selector on the left of the instrument panel and parking brake on a console to the driver's right. Although the parking brake control is well sited I felt that it was a little too heavy for comfort in repeated applications. This will be receiving attention on production models, I was told. Bedford's recently rationalized, column-mounted switchgear is used and is excellent.

Another point of controversy about the Ailsa is the driving compartment. I found that entering the cab from the offside can certainly not be classed as easy but it is tolerable with practice. My main objection was the small amount of space — little more than 102mm (4in) — between the driver's seat and the righthand side of the cab. This has already been modified on later models and the switchbox moved forward to allow more space.

It is really quite a squeeze to get through at present. Getting out is best tackled backwards, which can be somewhat hazardous in heavy traffic: Once in the seat, however, there can be few complaints although space to swivel round to the nearside in order to operate fare collection apparatus is restricted. The test vehicle I drove had no engine cover insulation so could not be judged in terms of noise and heat.

Both prototype vehicles have been returning very similar overall fuel consumptions, although one is operating in service and the other on test. The typical figure seems to be about 2.6km/ 1 (7.4mpg).

More detailed analysis of the Ailsa's on-road performance will have to await a full CM road test — which we hope to publish before long — but initial impressions are basically favourable.