Maximum-gross models dominated thelest year'
Page 56
Page 57
Page 58
Page 61
Page 62
If you've noticed an error in this article please click here to report it so we can fix it.
MUCH of the emphasis in Commercial Motor road tests during the past year has been with vehicles—both rigids and artics—designed for operation at the maximum gross weight for their particular axle configuration. We have tested 27 vehicles since last June, and no fewer than 14 of the 22 goods chassis tested come into this maximum-gross category. Four passenger models and one dual-purpose type have been reported upon; among the goods vehicles there were five light models but in the medium weight range there have been only two road tests.
It is logical that the stress should be laid on maximum-gross machines for it is in this field that manufacturers are concentrating most of their efforts, so this is where the new models lie. Several especially interesting vehicles have been supplied for test, including chassis from Bedford and Ford which represent these companies' entries into the maximum-gross field, while one of the most recent reports referred to the first test of one of the latest Dodge models.
In the maximum-weight class two chassis which gave a peep into the future for British operators were the Leyland Beaver 30-ton-gross tractive unit with semiautomatic transmission and a Fiat three-axle model operating with a two-axle semitrailer at 38 tons gross. The Fiat is not the only heavy commercial from Europe that we have tested, as the two Swedish manufacturers who now market in Britain —Scania-Vabis and Volvo—are both represented in the list covering the past 12 months.
The lightweights In the lightest category the most interesting vehicles for us were two vans with automatic transmission, which is receiving increasing attention currently from operators of local delivery vehicles. The two vans in question were the Morris J4 10/12 cwt. and the Commer 1500 15 cwt. and both were fitted with the Borg Warner Model 35 transmission unit.
A criticism often made of fully-automatic transmission applied to commercial vehicles is that the loaded-to-empty weight ratio is such that the ratio-change pattern cannot be ideal for all conditions. But with both the Commer and the Morris there was never the feeling on the tests that an overriding manual control would have been an advantage. And compared with figures obtained on vans built to a similar specification but with a manual gearbox, the fuel consumption figures were not seriously inferior.
The Commer van was found to be a very comfortable vehicle to drive, with light controls, very good suspension, a lively performance and excellent brakes. Similar remarks were made in the Morris road test report, except that the steering was felt to be on the heavy side.
The second Commer model to appear in this section is the Imp 5 cwt, van which is based on the car of the same name and is unusual in that it has a rear-mounted engine. The relatively high floor height of 2 ft. 3 in. which results with this engine location has advantages in that it reduces stooping when loading and unloading. Excellent braking was a feature of the test and fuel consumption figures were remarkably good. But, on the debit side, the steering was found to be very delicate and demanded a lot of attention at high speed.
Excellent braking was also one of the main features of the 30 cwt. version of the Ford Transit tested last year. It is not difficult to see why the brakes proved to be so good because the model has 92.4 sq. in. of brake-shoe area for each ton of gross weight. And with 88 b.h.p. from the 2-litre V4 petrol engine, acceleration performance was of a high order. At speeds up to 70 m.p.h. the 30 cwt. Transit handled very well, although it was found preferable to restrict the speed to 60 m.p.h. to obtain reasonable fuel economy.
The final vehicle tested in group 1 was the Volkswagen 1-ton van and although little changed outwardly over the years this model was different in many respects from the version previously tested by COMMERCIAL MOTOR. General performance on the test was to an average standard and acceptable braking figures were obtained.
Two tippers
Both the vehicles tested in the next category were tippers. The first to be put through its paces was the Bedford KG Site Tipper. In many ways the KG bridges the gap between the normal type of 7-8ton model popular in Britain and the 4 x 4 tippers which are often preferred for arduous site work abroad. It is based on the KG haulage model but with flitch plates to the side members, heavier springs and axles and protection shield under the engine and gearbox. The test chassis had the new Bedford Series 60 diesel and a 10-ton rear axle and results obtained on test showed the model to have acceptable fuel consumption, good acceleration and excellent brakes.
Braking was the only aspect of the Dodge 1(800 which was not to a high standard and this was felt to be due to some maladjustment as well as too much effort at the driving wheels. Maximum-pressure brake stops were accompanied by a considerable amount of wheel locking which, as is known, extends stopping distances. Even so, braking results were acceptable and fuel consumption and general performance were good. The model was easy to handle and comfortable to drive.
A varied trio
Of the three vehicles in the section covering chassis designed for loads between 10 and 14 tons the International artic test results are largely of academic interest, International Harvester having shortly announced that it was giving up producing commercial vehicles in Britain. The International Loadstar was only produced in Britain from early 1966 and it was surprising to many people that the company had selected a normal-control chassis for their re-entry into the UK vehicle-manufacturing industry. Those who held the view that it was not the best selection from the wide range of models made by International Harvester in America will have been proved right if it is low volume of sales that has brought about the closure of the Doncaster truck plant.
The actual model tested was the 1700 coupled to a York single-axle semi-trailer and although better fuel consumption was obtained than with similar models previously tested there was a general feeling of low power with the Perkins 6.354 having to pull just over 18 tons. Very good braking results were returned.
The remaining two models in this section are the Bedford KM and Ford D1000. It is not surprising that Ford and Bedford have "gone heavy", as General Motors and Ford of America have been producers in this field for many years. The natural trend is for medium-weight manufacturers to move up the weight scale and, with plating coming into effect from January 1, 1968, operators who, for example, buy 8-tonners will not be able to run them at the maximum legal gross. To maintain sales to these operators manufacturers have to extend into the category at which some fighter models will already have been used in many fleets.
Both the 16-ton-gross chassis were found to be excellent machines. The Bedford KM gave good fuel consumption, acceleration and braking figures and an excellent powerassisted-steering layout made handling very easy. Braking was also very good but on the debit side the gearchange action was not sufficiently precise for my liking.
The Ford D1000 was also open to criticism for its gear-change action-like the KM, the model has a Turner synchromesh gearbox—and the mirrors did not give such a good view to the rear due, in my opinion, to bad selection of units and vibration at the front end of the vehicle. These criticisms were, however, of a minor nature when compared with the excellent results obtained for fuel consumption, acceleration and braking on the test. A Cummins VALE lightweight V8 is used by Ford in the D1000 and once again this unit was seen to be economic on fuel, giving 12 m.p.g. on trunk-road running and almost 10 m.p.g. when at high speed. With 162 b.h.p. available the model was impressive on motorway running and the speedometer needle rarely dropped below the 70 m.p.h. mark when on Ml.
A dozen heavies
We now come to the category which includes the largest number of models tested in the past year. No fewer than 12 vehicles carrying loads of more than 14 tons have been put through their paces.
Starting at the bottom end of the weight scale in this section, the first test report in the section was of the Atkinson 22-ton-gross six-wheeler. The results given by the model were generally very good but it was noticeable that loading a chassis of this type could raise problems in ensuring correct distribution. With almost 6 tons over the front axle, power steering would have been beneficial on the test vehicle but apart from heavy steering the Atkinson was pleasant to drive and provided a good "ride". General performance was good and brake tests produced reasonable figures.
The second six-wheeler tested was the Guy Big J and this chassis, which has the heavier Cummins VIM V6 diesel, produced very good fuel consumption, acceleration figures and brake results. The Big _I strikingly illustrated the change that has been made in heavy-vehicle design in the past 10 years: it made very light work of the load being carried and maintained 40 m.p.h. more or less continuously on one particular trunk road trip. Here again the front axle weight was just over 6 tons but power steering meant that controlling the chassis required little effort.
All the remaining chassis in this section were artics, this illustrating the current degree of interest in this form of transport. The lightest model tested was a tractive unit ■fersion of the Bedford KM running at just over its designed gross figure of 22 tons. Fuel consumption was reasonably good and braking performance was excellent but with a power-to-weight ratio of 6.1 b.h.p. per ton coupled to a maximum speed of around 65 m.p.h. this was not a lively chassis. The slightest adverse gradient made a big difference to progress along the road, but except for this aspect the test vehicle had the same general character as the KM rigid already referred to. Shortage of power was the only real criticism of the AEC Mercury tractive unit which was tested at the new maximum weight of 24 tons for three-axle artics. The test proved that it is not difficult to load an artic with three axles to the maximum without overloading any one axle, but it also showed that more than the 145 b.h.p. provided is desirable to meet present-day conditions. Fuel consumption, although acceptable, did not benefit by having a small engine. A wet day marred brake tests but the impression was that reasonable figures would have been obtained on dry roads.
AEC tractive units ..grossing 30 and 32 tons were also tested during the year, giving this company complete coverage in the weight categories currently of most interest to heavy-artic operators. As all three had the Leyland Group Ergomatic cab similar remarks were made in each test report about the high standard of comfort provided for the driver. The model at 30 tons was the Mandator which can also be used at up to 32 tons and this gave reasonably good results. An axle ratio of 7.08 to l was considered to be on the low side and to have affected fuel consumption adversely. This factor also gave the machine a maximum speed of 47 m.p.h. which raised difficulties on motorway running, even though performance in general was quite lively.
The Guy Big J 30-ton model has the higher-power version of the Cummins V6 used in the Guy six-wheeler. Again this diesel was shown to give good fuel consumption, with over 9 m.p.g. returned on a trunk road test and almost 8 m.p.g. on a motorway run. Braking performance was to a high standard although acceleration times were a little below par. A 7 ft. 9 in. wheelbase, as on the test vehicle, was felt to be inadequate for a model of this type, causing difficulties in smooth take-up of drive from rest.
Another make of vee engine was fitted in the Dennis Maxim 30-ton-gross tractive unit, this being the Perkins V8.510. With an output of 160 b.h.p. net this power unit provided 5.31 b.h.p. per ton in the test vehicle and quite naturally the model was not endowed with a surplus of performance. Nevertheless, well-spaced gear ratios in conjunction with a two-speed axle helped produce acceptable times for acceleration. Both fuel consumption and braking were reasonable and all-important features of the Maxim were commendably easy handling characteristics and a low unladen weight which permitted a load of over 21 tons to be carried.
A taste of the probable future for heavy transport vehicles was given on the road test of the Leyland Freightfine Beaver with semiautomatic transmission. This chassis put up an extremely good performance on the test and the standard of comfort in the Leyland Ergomatic cab was well matched by the minimal effort needed to drive the outfit. Little difficulty was experienced in becoming accustomed to the semi-automatic gearbox, while fuel consumPtion turned out to be better than that obtained with a similar outfit with a manual gearbox. Instant ratio changes could be made and it was noticeable that this feature gave the effect of about an extra 15 b.h.p. when going up gradients.
Braking was also very good and the main impression was that the Beaver automatic was a most enjoyable vehicle to drive.
The two Swedish makes of commercial vehicle which are now available in Britain were both obtained for road test in the past 12 months. Each gave a good account of itself and this was particularly true of the Volvo F 86 30-ton-gross model which gave over 9 m.p.g. for a normal-road consumption and over 8 m.p.g. on motorway runs. Acceleration times and braking figures were also very good. Quietness inside the cab was one of the most striking things about driving the F 86 and the standard of construction of the cab and the interior fittings was very high.
The specification of the F 86 included a turbocharged diesel (giving 195 b.h.p. gross, 170 net) and a two-range gearbox giving eight fully-synchronized forward ratios. These two items represent a departure from the practice common on British vehicles, and similar types of engine and gearbox were employed in the Scania Vabis LB76 tested. This tractive unit was tested with a York three-axle semi-trailer to make up a five-axle outfit. Extremely complimentary remarks were made about the model from a driving aspect---quietness, comfort and easy handling-but with a gross weight just over the 32 tons limit, fuel consumption was relatively poor and below-standard braking figures were achieved. Part of the reason for the extended stopping distances was put down to excessive effort at the semi-trailer wheels, which locked on every stop.
Three-axle semi-trailers are being used in Britain to enable a four-wheel tractive unit to be used up to 32 tons gross. The outeraxle spread requirement makes this maximum virtually impossible on a four-axle outfit although if proposed legislation to raise the length limit is ratified, there will be a different story. Another way of getting 32 tons in the lightest possible way is to use a twin-steer tractive unit with a conventional tandem axle semi-trailer and such an outfit tested during the year was an AEC Mammoth Minor with Taskers trailer. Fuel consumption was little different from that of the Mandator grossing 30 tons, which had basically the same mechanical corn ponents except for a higher driving-axle ratio of 6.25 to 1. Braking results were better than with most four-axle outfits and road performance was considered to be well up to standard.
Completing the models in the highestpayload section was the Fiat 693 T. This 6 x 4 tractive unit was tested in Italy with a Viberti two-axle semi-trailer at a gross train weight of 38 tons. An interesting aspect of this test was that the configuration and gross weight of the outfit are likely to be included in British legislation before very long. Considering the weight being
hauled and the fact that the Fiat had axleratios more suitable for mountainous country, fuel consumption figures were very good. General performance and brake figures were also adequate and the main impression from the handling point of view was that of driving a medium-weight artic rather than one running at 38 tons.
The passenger vehicles
Of the four passenger vehicles covered in this review, two are Daimler Roadliners. The first to be tested was the 49-seat coach version whilst the second had a 50-seat bus body. Although having the same basic mechanical components the two chassis differed in that the coach model had the Cummins V6 engine rated for 192 b.h.p. whilst the Roadliner bus chassis had the power unit derated to 125 b.h.p. Another difference between the two test vehicles was that the coach had air suspension and the bus the Metalastik toggle-link rubber suspension which is now available on the model. Both Roadliners gave results which explain the demand from operators for this type, and both were found to be very easy to drive.
After re-entering the open market, Bristol Commercial Vehicles revised its vehicle building programme and made changes to certain models to bring the standard specification into line with general practice. It was one of the RE bus chassis to the latest specification that was subjected to a full road test and the results obtained were very good indeed. The changes in specification make the model competitive in price with other makes and the test chassis showed that it was competitive in performance also, with very good fuel consumption figures and excellent braking results.
The final p.s.v. tested in the past 12 months was the AEC Ranger with Marshall bodywork which was one of an order of 25 similar vehicles for Mosul. Based on a goods chassis, the Ranger showed itself to be a sturdy design for difficult terrain, yet satisfactory for passenger use and giving acceptable performance.
Only one vehicle which can be classed as a "special type" has been tested in the period under review, this being the Land Rover. As usual, part of the test included rough-country work at the FVRDE tracks at Chobham and Bagshot Heath. In spite of some very hard treatment on the off-theroad run, the suspension and chassis showed no distress and the general results obtained for fuel consumption and so on were very good.