Our testers' heavy twelvemonths
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TRADITIONALLY at this time of the year we review the performance of trucks and buses which have been tested by Commercial Motor during the past 12 months. As usual we had a pretty mixed bunch. They ranged from the Mercedes-Benz 1608 at 6.5 tonnes gross up to the 32 and 38-tonne artics at home and abroad. (The lighter end — below 31/2 tons — was dealt with in our issue of November 12.) During the past two years the accent has been on the top weight long haul machines. This was not an intentional policy at CM. We just test what we can get our hands on — and, with some manufacturers, getting our hands on some of their models has proved remarkably difficult.
1976 was the year of the four-wheel rigid in terms of numbers tested with four 16tonners and three 7.5 tonne machines being put through the full CM road test and operational trial routine. Further up the weight scale the performance of an eight wheeler in haulage form at 30 tons gvw makes interesting reading when compared with several of the 32-ton artic units.
The comparatively recent change in drivers licensing requirements meant that we had a great deal of interest from readers in the 7.5 tonne gross sector. Accordingly, we tested Ford, Leyland and Chrysler trucks around the CM Midlands route.
Leyland's Terrier came first in the year with a 3.4m (lift) wheelbase model fitted with a timber dropside body. The TR738 was, in fact, a downplated version of the 750 and
we .tested it with the optional six-cylinder engine and fivespeed overdrive gearbox.
As far as fuel consumption was concerned, the Terrier recorded 17 lit/100km (16.6mpg) at an overall average speed of 60km / h (37.3mph). The full results of the 7.5 tonne tests can be seen in the accompanying results panel.
We were impressed with the good matching of engine to transmission with "ourTerrier. The overdrive top gear was used to full effect and off the motorway the sensible ratio spread meant that the right ratio was nearly always available — not so easy with small engines and few ratios (compared with the multi-speed heavies).
In July we got our hands on the Ford contender for nonhgv honours — the 00710. For our test we used the six-cylinder model with the Ford 4-310 four-speed synchromesh gearbox. Of the three trucks we put through a full test at this weight, the Ford returned the best fuel consumption (16.2 lit/100km or 17.4mpg) but took the longest time in doing it.
The major advantage shown by the Ford was its payload potential. Fitted with a Brade Leigh dropside body, the test truck carried a load of nearly 41/2 tons — not bad at 7,5 tonnes gross.
Chrysler's renamed Commando was the exact opposite of the Ford. It proved the fastest around the Midlands route but used the most fuel. A relatively heavy Barham body also cut down on the payload which.
came to 3.92 tonnes (3 tons 17 cwt) at the full weight.
The G08 was fitted with the optional six-cylinder Perkins 6.354 engine rated at 76kw (102bhp). A four-cylinder unit — the Perkins 4.236 — is listed as standard equipment. An axle ratio of 5.14 to 1 limited the top speed to around 55mph but alternatively allowed a restart, fully laden, on a 1 in 3 gradient!
Although we did not put it through a full test, we tried the Fiat T5 tonne integral van as part of a group test. The 0M75 is unique in the UK in that it is the only vehicle available in integral van form at this weight. Over the same route as the Ford, Leyland and Dodge, the Fiat recorded an impressive 15.7 lit/100km (18mpg).
Another model to take part m the group test was the Bedford TK. This was fitted with a Hawson box body. Even so the fuel consumption of 18.6 lit/100km (15.2mpg) was by no means excessive.
Four 16-ton rigids all represented differing approaches to the same basic job. First was the 1617 from Mercedes Benz, the first attempt by the German company at this sector of the market.
In comparison with the tra ditional opposition in 16-tonners, namely Leyland, Bedford, Chrysler and Ford, this newcomer was very high powered with its 124kW (168bhp) engine. In fact, this particular unit was a departure from normal Mercedes practice in that it was turbocharged. An interesting point of comparison is raised here as Chrysler fits the naturally aspirated version of this unit as standard equipment in the 16-ton Dodge Commando.
Our feelings towards the Mercedes were rather mixed.
As usual with trucks of this make, the fuel consumption was excellent at 25.1 lit/100km (11.3mpg) when taken around the Midlands route, and the general handling was beyond reproach.
As far as its performance was concerned, the 1 617 was an excellent truck — our reserva tions were centred around the specification, which we felt was overdoing it. Certainly around 170 horsepower and an eightspeed range change gearbox (with a reversed shift pattern) is decidedly upmarket as far as the four-wheel rigid market is concerned.
The new Fiat contender for 16-ton honours also has a power output on a par with the Merc — perhaps an indication that the 16-ton category will see a mini-version of the power race we saw in the long haul artic section a couple of years ago.
With its Crane Fruehauf Imperial dropside body, the Mercedes had a potential pay load capacity of 10.3 tonnes (10 tons 2 cwt) in its 5.2m (17ft lin) wheelbase form.
In the 16-ton market, Bedford is lucky in that it has two distinct model types available to suit individual operator requirements — the long-serving TK and the relatively new TM. The latter is intended fo long-distance delivery sidi the urban delivery side which i: more for the TK.
We tested the TM 1700 ir 5.23m (17ft 2in) wheelbasi form, fitted with a dropsidi Anthony Carrimore body. It test trim the TM was a fractior under the 16-ton limit with a payload of 10.1 tonnes (9 tons 19 cwt).
The Bedford 500 engine was fitted, developing 112kW (151bhp) and this was coupled to the optional six-speed Eaton gearbox (a Turner five-speed box is standard equipment). The ratios of this six-speed 'box came in for criticism. It was felt that the spread between certain ratios could have been better.
On the motorway, the TM returned a fuel consumption of 25.2 lit/100km (11.2mP9) well up with the competition. On the latter portion of the test consisting of normal duty A roads between Minster Lovell and Hemel Hempstead, i.t worsened considerably to 30.1 lit/100km (9.4mpg). This had the effect of increasing the overall fuel consumption to 26.7 lit/100km (10.6mp9).
No reason could be found for this: such a characteristic is uncommon on the Midlands test route.
When the Seddon Atkinson 200 was announced late last year, the main point of interest concerned the engine which was a German-built unit of International Harvester design (IH, of course, has a controlling interest in Seddon Atkinson).
The D-358 develops 100kw (134bhp) which made it one of the more powerful 16-tonners when it was announced before the arrival of the Mercedes and the Fiat.
On the CM test the overall fuel consumption was an excellent 24.2 lit/100km (11.7mpg) while the real eye-opener was the performance under motor
way conditions when the 200 recorded 22.6 lit/ 100km (1 2.5mpg) at an average speed of 87.2km/h (54.2mph).
No truck is perfect, however, and cumbersome steering (over eight turns lock to lock), plus a peculiar vibration at 40mph took the edge off the very good impression we formed of this newcomer. We say "newcomer" somewhat loosely, as the chas sis of the 200 is all Seddon 13:Four, but we feel the unique engine and the new cab justify the title.
It is interesting to note that when the 200 was first announced Seddon Atkinson did not offer a two-speed axle even on option. Operator reac
tion caused a change of heart at Oldham and the 200 is now available with an Eaton twospeed unit — fitted for the CM test.
Chrysler's renamed Dodge Commando 16-tonner came next, fitted with a flat platform body from Barham. Despite bad weather and very heavy traffic conditions, the Commando did well on the test despite — or perhaps because of — its rather peculiar transmission matching.
The optional six-speed Chrysler synchromesh gearbox was fitted in conjunction with an Eaton two-speed axle which, in theory, gave 12 forward speeds. In fact, the overall ratios tended to overlap in certain areas with fifth high, for example, being very nearly the same as sixth low.
When fitted with the optional turbo-charged Perkins T6 354 engine, as with our test model, we think that many operators could manage quite happily with a single-speed axle.
The overall fuel consumption of the Commando was 25.9 lit/100km (10.9mpg), which would almost certainly have been improved in better weather. One of our favourite features of this particular truck is the tilt cab. Yes, we know that having a tilt cab does not necessarily make the Dodge unique, but for simplicity and ease of operation it takes some beating.
Although we did test a Ford 16-tonner, it was as an urban artic, the DA 1611. This was designed around the require ments of Bass Charrington and achieved an overall fuel consumption of 26.4 lit/100km
(10.7mpg) with a payload of just over 101/2 tons on the 7.6m (25ft) platform Crane Fruehauf trailer.
Ideally, Bass Charrington would have preferred a six speed overdrive top gearbox to provide the widest performance range. Although the company has had to settle for a five-speed box with a direct drive top, this did not seem to impair the performance to any great extent. One shortcoming of the transmission which did show up, however, was the wide gap between third and fourth.
One of Bass Charrington's main reasons for specifying the Ford artic was the fact that the axle configuration allowed the vehicle to be progressively unloaded without overloading the individual axles.
Summing up the Fiat 130 in a few words is not easy.
Although it is plated for 23
tonnes (22.6 tons) gcw, we felt that this was asking too much
from the 104kW (140bhp) engine. The payload at this weight was an impressive 15.5 tonnes (15.3 tons), partly due to the low kerb weight of the Fiat at 4.45 tonnes (4 tons 7 cwt).
Although the 130 put up a reasonable performance at its plated weight, we think that it would be a tremendous rival to the Dodge Commando artic if the gross weight were dropped to around 18 tons. That would give it a power to weight ratio of 5.7kW/tonne (7.8bhp/ton).
We remain surprised at the Fiat logic with the 130. The 16-ton 159 goes in exactly the opposite direction regarding power output, being well over the required minimum.
The overall fuel consumption of the 130 worked out at 27.2
lit/100km (10.4mpg) for the 312km. (194 mile) Midlands route.
Two eight-wheelers were tested but, because of their dissimilar application, they were taken over different routes — the Octopus haulage model over the Scottish route and the ERF tipper over the Midlands circuit. Sharing many of the same components, 'comparison between the Leyland Buffalo and the Octopus is inevitable. In fact, the eight wheeler beat the Buffalo on fuel consumption and journey time and only took second place on payload capacity by a mere 300kg (6cwt).
Our test Octopus was fitted with the latest turbocharged 511 engine which now produces 172kW (230bhp) — a very useful output for a 30 tonner. In keeping with its haulage application, the 6.25 to 1 axle ratio made it very much a motorway vehicle, where it consistently recorded over eight mpg. .
We will deal with the productivity figures for the Octopus in greater detail later in this article, but a payload of over 21 tons and a fuel consumption of 37.7 lit/100km (7.5mpg) could persuade several artic operators to change their allegiance.
The ERF eight wheeler was fitted with an Edbro alloy tipper body. As we mentioned earlier, taking a tipper round the Scottish route isn't really on, so we tested the ERF on site and then used the Midlands route to check the fuel consumption.
In recent years not many trucks with Rolls-Royce engines have come our way at CM, so we were pleased to try the ERF with its Eagle 220 engine producing 159kW (214bhp).
For the Midlands route the fuel consumption was 38.7Iit/ 100km (7.3mpg), coupled with a short round-trip journey time for this category of truck.
Top weight
Usually tne CM testers year
is full of 32-ton artics but this time we tested "only" four — mainly due to the fact that we have tested most of the other models already during the _ previous two years.
Known by the Foden computer as the 04A 032 C25 08 but better known to the operator as a Cummins engined tractive unit with an 583 cab, this particular truck still relies on more "in-house" components than, for example, its Sandbach neighbour.
The gearbox is the "eightspeed" constant mesh while the axle is the overhead worm and wheel type which has served Foden so well over the years. We have put "eight speed" in quotes because all ratios from the old 12-speed unit are still in there if the driver cares to look for them.
Bad weather, including thick fog, on the second day of the road section influenced the Foden test figures, with the result that the overall average speed was on the low side. Overall, the fuel consumption was 44.3 lit/100km (6.4mpg), which would have been excellent two or three years ago but, with the continual improvements to trucks over recent years, is now below average.
In the Testers Twelvemonth articles in the oast we have often had to make excuses for the con-completion of road tests involving Scania trucks. The reasons have ranged from insecure loads to failure of trailer brakes. Happily, this situation did not arise this year and we carried out a test of the LB81 tractive unit with excellent results.
With its comparatively low kerb weight and with the assistance of a York Yolloy trailer, the 81 pulled a payload of a fraction under 32 tons with a fuel consumption of 38.4 lit/100km (7.4mpg).
The 81 was fitted with the turbocharged DS8 engine which gave 153kw (205bhp) and this was coupled to Scania's own five-speed synchromesh gearbox with splitter. In combining a good fuel consumption and short journey times with a useful payload, the 81 was one of the best trucks we tested during the past year.
Pushing it very hard was the OAF 2800, fitted with the optional charge cooled DKS engine of 229kW (307bhp) output. This returned an excellent fuel consumption overall of 38.7 lit/100km (7.3mpg), which was stretched to a remarkable 25.7 lit/100km (11.0mpg) on the 40mph stage betweeen Nevilles Cross and Darrington.
In contrast to the less powerful DKTD model, with its ZF gearbox.. the DKS uses a 13-speed Fuller unit and this proved a well-matched combination. With its 5.03 to 1 axle ratio, the DAF was an ideal motorway vehicle which had no difficulty in maintaining average speeds in the high fifties.
Something out of the ordinary was provided by our test of the Volvo N10 on /off site tipper. Again relating the test procedure to the work the truck is designed to do, we tested the on-road performance and the performance on-site.
The N10 is primarily designed for arduous site and quarry work at up to 28.9 tonnes (26.5 tons) gvw, but it also conforms to C and U regs for highway use. The only problems on the road, of course, is that it is still limited to 24 tons gvw for a three-axle vehicle.
Our test truck was fitted with an Edbro body and underfloor gear. Unladen it tipped the scales at 11.5 tonnes (11 tons 6cwt). The Volvo had an impressive performance which included restarting, laden, on a 1 in 3 gradient. At the other end of the scale, the maximum speed with the 6.14 axle ratio was around 45mph.
Still talking about Volvo, during the year we got our hands on two Club of Four trucks — an exclusive test to British publications — as part of our Euro Truck Press involvement. The Club of Four, you will remember, is a collaboration between DAF, Magirus-Deutz, Saviem and Volvo, sharing the design and tooling costs of a new range of light vehicles, Much of the specification of the vehicles is common, including gearboxes, cabs and axles. The choice of engines, however, is open and for our Euro Truck examples, the F613 and the F609 engines of Volvo's own manufacture, were used — a naturally aspirated six-cylinder for the lighter model and a turbocharged version of the same unit for the heavier 613.
Both the trucks returned excellent results in respect of fuel consumption and journey time, but, as far as I was concerned, they suffered from the same problem as the 1617 Mercedes in that they are over-specified for their particular sector of the market. We will be interested to see if the Club Volvos are ever marketed in the UK and, if so, what the price will be.
Our Euro Truck involvement gave us another exclusive test in 1976 — the Mack F786T-5505. This test coinciding with the appointment of a UK distributor for the marque, the Mack was taken around our 400km test route through Belgium. Germany and Sweden, with absolutely shattering results in terms of fuel economy.
The overall figure of 38,9 lit/100km (7.3mpg) beat everything else out of sight.
Mack has one great advantage with this model. The drive line was designed as a complete package and, as such, the matching was superb. The 11 litre (672cu in) Maxidyne engine with turbocharging and charge-cooling develops 228kW (306bhp) at a Gardner-like 1800rpm and no less than 1560Nm (1150 lb ft) torque at 1200rpm.
The Euro Truck criticisms of the American truck were all centred around the cab, which fell far short of the European opposition.
Even Ford's Transcontinental could not match up to the Mack's fuel consumption, but it certainly tried hard. The test truck was the top of the range HA4234 fitted with a turbocharged Cummins NTC355 engine developing 254kW (340bhp).
The overall fuel consumption for the test was 41.4 lit/100km (6.8mpg), which was still a very good result for this arduous test. The final Euro Truck Press verdict was that the Transcontinental was an extremely well thought-out piece of engineering — all the more praiseworthy as it was Ford's first attempt at the heavy end of the European market.
Now to the bus and coach side of things. On the midi front, British operators have had a choice of only a small number of chassis, so we looked forward to our test of the L608D Mercedes-Benz with a great deal of interest.
Fitted with a 29-seat Duple Dominant body, the coach returned a fuel consumption of 16.4lit/100km (17.2mpg) around the Midlands route.
The Mercedes produced a lively enough performance when empty, but the test load of 1800kg (36cwt) certainly took the sparkle out of the vehicle.
Tested in Plaxton Supreme bodied form, the Ford R1114 invited comparison with its main rival the Bedford YMT. We found that the Ford scored on fuel consumption but the Bedford was quicker and quieter, The actual fuel consumption figures were 26.3 lit/100km (10.7mpg) for the Bedford (also with a Supreme body) and 22.1 lit/100km (12.8mpg) for the Ford.
Our test report of the Seddon Pennine 7-Alexander 'T' type spoke of "excellent fuel consumption and ample power" — an excellent summing-up of a coach which performed very well during our operational trial. But, as the chassis price was on the high side, one could argue that it should have done well.
When assessing the overall performance of the commercial vehicles tested during the year, we compare the. productivity factors based on the test results of the individual vehicles.
In the tractive unit category we substitute an "estimated" trailer weight to arrive at the payload for the calculations. To do this because, with this particular weight of truck, the variation in trailer weight has a disproportionate effect on the productivity and it is, after all, the tractive unit we are testing.
Thus, for the productivity calculations, the potential payload is based on using a trailer weighing exactly 4 tons. This is derived from a cross-section of trailers, ranging from the ultra lightweight aluminum jobs such as the Welford, at around 21/2 tons, to the 6-ton TIP types.
Depending on the type of work involved, different operators have differing requirements. Because of this, we have made comparisons of the trucks on a payload-ton-miles-per-gallon basis and also a payload ton miles per gallon per hour basis.
The first figure is arrived at simply by multiplying the payload by the overall fuel consumption result. To illustrate the method for the productivity factor, including average speed, here is a sample calculation based on the results of the Cummins engined ERF tractor_ Payload 21 tons 4cwt (=21.2 tons) Fuel consumption 6.8mpg Average speed 41.9mph Thus the productivity factor for this particular truck is: 21.2 x 6.8 x 41.9 =6.05