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148 
VOLVO F86 24 TON RIGID
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by Gibb Grace
SEVERAL IMPROVEMENTS in Volvo F86 models were introduced at the Brussels Show in January this year, and from this week the updated models will be available here. We have just completed a two-day operational trial on a 6 X 2 version of this latest F86 model.
The cab primer colour is now a biscuit colour instead of light grey. This may seem a small point but as very few, if any, operators paint the inside of the cab, choice of colour is important. In fact the biscuit paintwork blends well with the white headlining, blue seats, blue door trims and light grey floor mats and engine cover; and helps make the cab interior look "warm" and colourful.
Driver safety is the main theme behind the improved dash layout; the knee area for example has been cleared of all knobs and switches. These are now mbunted vertically so as to be out of the way of the knees in the event of a crash. The steering column and its potentially hazardous fixings are now shrouded by a tough plastics moulding.
The two-speed windscreen wipers are now combined with a powerful electric windscreen washer and an electronic delayed-action wiper control is a standard fitment. In drizzle and road spray conditions, the delayed wiper control proved to be really useful and not just another gadget. By turning the knob clockwise the delay between complete wipes can be • increased progressively from four to 21 seconds; on the test this variation was sufficient to suit all the road conditions we encountered.
• A Bostrom Viking 300 E suspension seat is now fitted as standard for the driver, and it has a good range of adjustment which will suit most drivers. I found it to be comfortable even after having driven 318 miles in seven and a quarter hours. Both seats were covered in a bright blue woven cloth material which completely stopped sweating of legs and small of the back. The material is washable and with care should stay clean and bright for the life of the vehicle.
Unfortunately, for some reason, the new seat seems to have been positioned to the right as compared with previous seats, for it is now some three or four inches out of line with the steering column and this offset driving position caused an ache in my right shoulder by the end of the day. The seat seems unnecessarily close to the door as there is plenty of clearance on the other side.
The seat is also displaced to the right relative to the pedals but I found no difficulty in using them. The throttle was pleasantly light, and so were clutch and footbrake, with 45 and 601b loads respectively. For a six-wheeled vehicle, I thou t the F86 ride was below par. Between a ut 35 and 42 mph the cab bounced annoyi gly at a frequency of about 2 cycles per s cond. Above and below this speed range, e ride was acceptable but still harder th one would expect from a six-wheeler. t all speeds, discrete bumps such as the Jo nts in a motorway caused jolts in the cab ncl in the dash area in particular. I ha not experienced similar characteristics in other F86s I have driven and it may be t t the tubeless tyres fitted did not ideally atch the road springs.
It was noticeable that the Bostro seat damped out some of the bounce but it did not isolate it completely.
The power steering was precise a d felt just right, although it was unnecessari y low geared at 64 turns from lock to lc:. The turning circle of 71ft is good or a long-wheelbase six-wheeler and made handling on narrow roads very easy.
Performance The TD70C engine gives 192 in tailed horsepower to BS AU 141a197 and allows the F86 6 X 2 to be plated at 32 tons gross combination weight. Wi h the solo 24-ton-gvw truck as tested, ho ever, the power to weight ratio jumps to 8 bhp per ton and naturally the perfo ance benefits considerably.
The F86 covered the 738-mile test route at a record average speed of 42.3 mph despite being fitted with a 5.4 to 1 rear axle ratio which gave a top speed of 55 mph at 2500 rpm. As some 400 miles of the route is motorway, the optional 4.9 to 1 differential would have allowed a faster cruising speed and possibly a better fuel consumption. As it was, fuel consumption worked out at 8.8 mpg, average which is good for a 24-tonner and excellent considering the average speed achieved.
Because of the Hawson lightweight aluminium bodywork, which weighed only 13cwt, the payload was 16.8 tons. This is about one ton more than would be possible with a 24-ton-gcw artic and about 3 tons more than could be carried on a 22-ton-gvw rigid. As a result the characteristic payload factor worked out at 149 ton-miles per gallon, which is almost the same as the 152.5 ton-miles per gallon achieved by the Volvo F86 CM tested in drawbar form last year. (CM March 31 1972). Both these characteristic payload factors are well above average for their weights, particularly that for the 24-ton vehicle, which means that the F86 is competitive with lighter vehicles when running part laden.
An average 16-ton-gvw vehicle carries a 10-ton payload and returns about 10 mpg but does not have a large enough engine to haul a worthwhile drawbar trailer. The F86 on the other hand could almost certainly match 10 mpg with a 10-ton payload and, as our tests have shown, it returns 8.8 mpg with a 17-ton payload and 6.9 mpg with a 22-ton payload.
This tremendous flexibility of operation must make the F86 very attractive to the small operator who may have to carry a variety of loads throughout the year.
Good acceleration and hill climbing ability made driving very easy. Forty mph
-could be reached in half a mile from rest and 50 mph in one mile. On the level the F86 pulled away happily from rest in second gear and it was often possible to miss third and fifth as well. Once under way the engine was flexible enough to allow the vehicle to run using the top four gears only. The hills on A5 needed only seventh gear and the long climbs on the northern end of M6 were taken at 42 mph in top gear, apart from the first half of the section between junction 36 and 37 which brought us down to 32 mph in seventh. The "slow lorries"
climbs at Watford Gap and Keele were taken in top gear at 43 and 41 mph respectively. Only the notorious Leicester Forest "slow lorries" on the homeward leg really slowed the F86; this reduced our speed to 25 mph in sixth gear at two points.
On the northern leg of the route where the hills go up to 1 in 5.5, performance was also noticeably good. Very rarely were any of the four lowest gears called for; Carter Bar, for example, was climbed in fifth gear but the steepest hills on route, Riding Mill and Castleside, needed second gear. Braking Braking tests were carried out at MIRA in very wet conditions and the results were slightly below average for a 24-ton rigid. Average (as distinct from peak) deceleration from 30 mph and 40 mph worked out at 0.46 g whereas recently two 30-ton-gvw eight-wheelers have bettered 0.52 g. This lower performance was not entirely due to the weather, as no skidding occurred. The front axle linings are only 5in. wide compared with some British vehicles which have 7in.-wide linings at this gvw, and this could be a contributory factor.
In hilly country the front brakes certainly heated up much more quickly than the rear drums and it needed only one or two hard applications of the brakes to produce a smell from the linings. Like all Volvos the F86 was fitted with an exhaust brake, but its retarding effect was minimal and this discouraged its use.
Noise level No external noise readings were taken because of the wet weather conditions, but in-cab noise levels were checked.
At maximum power in the lower gears on hills and at maximum speed in top gear the motorway noise level was 93 dbA, but this level soon dropped as either road or engine speed fell. At 40 mph in top gear the noise level, for example, was 87 dbA.
These noise levels are good but higher than one would expect from the average F86. During a service, just before the teat, a mechanic had stood on the cab seal w`rich surrounds the gear lever and although it had been straightened out before the test, the seal was obviously not up to scratch and was allowing some noise into the cab. If nothing else, this incident serves to underline the importance of careful mechanics and well-maintained cab seals.
The basic price of the F86 is £7070 but this includes the differential lock, seven-day tachograph, the option of tubeless tyres and the excellent delayed-action wiper switch.
To sum up The latest cab changes bring a definite improvement in instrument layout and driver safety and the latest Bostrom seat will be welcomed by the driver. The seat alignment problem mentioned is annoying, but should be easy to put right. The ride could set a harder problem to solve, but might be just a simple matter of damper settings.
These relatively minor problems, however, are overshadowed by the F86's performance. The F86 6 X 2 has an excellent performance at 24 tons gcw and offers good results over a wide rangc of payloads. This, together with the unlirru edmileage 12-month warranty, make it a real operator's vehicle.