Scammell's 100-Tonner

In typical heavy haulage tradition, the Scammell 100-Tonners were conceived through the needs of a particular job.

Steam locomotive makers, Kitsons, needed a means of transporting out of gauge locos from Leeds to Liverpool for their overseas markets. The contract for transporting these heavyweights across the arduous trans-Pennine routes was entrusted to M.R.S. Ltd., (Marston Road Services) of Lightbody Street, Liverpool.

Long established as heavy hauliers, Ernest Charles Marston had developed a strong working relationship with Scammell Lorries Ltd., Watford. It was in 1929 that Marston approached Scammell with the idea that a lorry with a 100 ton carrying capacity would be ideal for the Kitson's contract.

The challenge of building what would be the world's biggest lorry was taken up by Scammell's Director of Engineering, Percy G. Hugh and his brilliant, though sometimes eccentric, young designer, Oliver D. North. In a remarkable feat of motor lorry development, it was a mere 8 months from the initial enquiry to the first 100-tonner (KD 9168) being delivered to M.R.S. Both 100-Tonners were supplied in early 1930, with the second (BLH 21) delivered to H.E. Coley Ltd., Dartford, Kent.

The measure of this achievement is not only in comparison with modern day development times, but also that Scammell's biggest lorry at the time was the 25-ton Machinery Carrier introduced in 1927. It was a further 20 years before lorry development allowed the two pioneers of internal combustion-engined heavy haulage to gracefully retire and allow the more modern and powerful machines to take up the ever bigger gauntlets thrown down by modern industry.

The motive unit was based on a massive frame of riveted steel plates. These were built into a box-frame with apertures for the engine, transmission and the turntable.

The engine was the Scammell 4-cylinder, 7094cc petrol engine used in the rest of the Scammell range of motive units. To cope with increased load capacity from 25 to 100 tons, the engine was tuned, increasing the standard 80bhp to 86bhp.

To accommodate the 0.75 mpg fuel consumption, three fuel tanks were fitted, giving a capacity of 103 gallons. In 1932, Pelican Engineering Co. (Sales) Ltd., of Leeds, replaced the original engine with a Gardner 6LW oil engine. This increased the power to 105bhp and the fuel consumption to 4 mpg.

The gross train weight of 130 tons with only the modest power available inevitably meant that the transmission would need careful consideration. The gearbox used was the standard Scammell 4-speed box from the articulated 8-wheeler range.

Power was taken from the back of the gearbox to a central primary differential via a Spicer jointed telescopic shaft. This differential incorporated spur gears that doubled the available gears to eight. Power was then transmitted to each of the two in-line drive axles by way of chains. The two adjustable chains for each axle were 2.5 inch pitch roller chains. Adjustment was by screwed radius rods.

The gear ratios were changed by two levers mounted one each side of the chassis behind the cabin. Each drive axle had to be changed separately of each other from outside the cabin.

Each axle had two driving wheels with 8" x 771 solid tyres. The load carried by the four driving wheels being 40 tons. The axles were located by way of forward mountings on a heavy cross tube and trailing arms that were ball-jointed to the rear corners of the chassis frame. Rubber buffers were incorporated into the rear of the frame to absorb vibration, particularly when running empty. The locating ball-joints allowed the axles to pivot and keep each of the four wheels squarely in contact with the ground.

The primary differential compensated the left and right drive axles to allow corners to be turned. The track of the drive axles meant that it was also necessary to include a differential in each axle to compensate the left and right road wheel on each axle.

The gearing of 196:1 in low ratio first gear enabled the 100-Tonners to negotiate gradients as steep as 1 in 10 and it was possible to achieve a road speed of 5-6 mph in the high ratio top gear.

Despite the modest road speeds, a gross weight of 130 tons still needed an impressive braking system. Sixteen inch internal expanding transmission brakes were fitted to each of the cross-shafts from the primary differential. They were operated by a choice of foot pedal or hand lever by the driver. The hand lever enabled the driver to hold the vehicle still on a hill while leaving both feet free to operate throttle and clutch pedals for clean re-starts without the need for wheel-chocks. Additionally, a hand-wheel to the driver's right operated screw brakes to each of the drive wheels.

The front axle was a massive double cranked unit with a design loading of 8 tons. Steering was by screw and nut steering gear and required seven turns of the cast steering wheel from lock to lock. Despite this low gearing, considerable effort was required at manoeuvring speeds.

The motive unit was completed with a large, square wooden cabin that had all the styling features of a garden shed. Originally, both 100-Tonners had vertical windscreens, although sloping windscreens were later built into KD 9168.

The motive unit was only part of the 100-Tonner. The other half was the huge load carrying semi-trailer. Scammell at this time always referred to their trailers as 'carriers' to differentiate between their articulated semi-trailers and the traditional drawbar trailers, common to the period. This tradition continued into the 1950's and had its origins in the road tax laws of the 1920's.

The carriers for the 100-Tonner were built in two sizes. The smaller intended for 65 ton loads and the larger for loads up to 100 tons. The main components of the two carriers were the same with the extra capacity of the 100-Tonner gained through the addition of extra axles.

The carrier comprised two box-girder side members. These were attached by pin bolts to the side webs of the riveted swan neck. The tremendous strength required of the swan neck came from a three feet diameter cross tube between the side webs. The connection between motive unit and carrier was through a six-inch ball joint.

The 65-Ton carrier had a wheelbase of 50 feet and two in-line axles with four solid tyred wheels. These axles were mounted by means of massive rearward projecting trunnions to the rear of the carrier bed. They were free to oscillate on a vertical axis and could be steered by a huge vertical wheel similar to a ship's wheel.

Initially only a platform was provided for the steersman, though a wooden cabin was soon added as protection from the elements. At first, a tiny open-sided cabin was built on the left rear corner of the carrier. The open-side allowed the steersman to lean out to operate the centrally mounted steering wheel. This was later replaced by a full width, fully enclosed cabin with windows all round. The steersman's cabin was removable to accommodate over length loads.

Clear communication between driver and steersman was obviously of vital importance on a vehicle of this size and weight. To overcome the 78 feet distance between the driver and steersman an Alfred Bell Admiralty type telephonic communication system was installed. When the cabin needed to be removed, the steersman and driver communicated by whistles.

A wheelbase of 50 feet, gross weight in excess of 100 tons and the uneven road surfaces of the period inevitably resulted in ground clearance problems. These were largely solved with the fitting of hydraulic rams at the joint between carrier bed and swan neck. By using a hand operated, double cylinder flywheel pump the rams could be used to raise and lower the carrier bed.

Fully extending the rams raised the front of the carrier by 15 inches, which resulted in an additional 8 inches of ground clearance. The carrier could also be lowered by 12 inches when overhead clearance was a problem.

This jacking system could also be used when the drive wheels sank through the road surface, which was a common problem of the day. By raising the carrier and placing it on bolsters, steel plates could be positioned under the drive wheels and, when lowered facilitate the continuation of the journey.

The 100-Ton carrier was identical to the 65-Ton carrier. The additional payload was gained by the addition of a second pair of axles. These were mounted between the carrier frame and the original steering axles of the 65-Tonner. This gave a bogie carrying weight of 80 tons. Although the leading axle was fixed the bogie was still steerable by the rearmost axle.

Both axles comprised fully interchangeable parts, which made it easy to transform the carrier from 65 tons to 100 tons and vice versa, depending on each individual job requirement.

KD 9168

Sales Order
Chassis Number
23 / 5 / 1929
100-Ton M.U.
23 / 5 / 1929
100-Ton Carrier
23 / 5 / 1929
65-Ton Carrier

Vehicle delivered on 20/1/1930.

Cost: 475.00.00.

A note on the Scammell sales ledger stated that mechanical parts for the 65-Ton carrier were to be fully compatible with the 100-Ton carrier and that enough additional parts be supplied to convert it to 100 tons.

KD 9168 was originally supplied to M.R.S. in M.R.S. livery and then re-painted in Edward Box livery when M.R.S. bought the Liverpool haulier for his name. It was then absorbed into the Pickford's fleet before passing to Jack Hardwick of Ewell, who restored and rallied it. KD 9168 now resides in the British Commercial vehicle Museum in Leyland, Lancs.


BLH 21

Sales Order
Chassis Number
23 / 5 / 1929
100-Ton M.U.
H.E. Coley Ltd
23 / 5/ 1929
65-Ton Carrier

Vehicle delivered on 27/2/1930.

Cost: Motive Unit 3100.05.00 Carrier 1800.00.00 Total 4900.05.00

A note on the sales ledger describes BLH 21 as a standard 65/100-Ton Motive Unit with still radiator, 80bhp engine, complete with cab and short platform for tools.

BLH 21 was originally supplied to H.E. Coley, Dartford, Kent, though it was liveried as 'Metallic Ore Production Company', before passing on to Norman E Box, who were by then, part of the Hay's Wharf and Cartage Company. It was then absorbed into the Pickford's fleet and it's believed now resides with Rush Green Motors.

Comparing the Scammell sales ledgers, it is interesting to note that the second 100-Tonner was ordered before work had even started on the M.R.S. original concept. This shows remarkable confidence by Scammell that Percy Hugh and Oliver North could build a vehicle capable of carrying more than four times the load of their biggest current lorry.

There is also the huge disparity in cost of the two machines, for which no irrefutable and recorded reason has, as yet, come to light.

It would seem that the 4900 cost of BLH 21 would be the true cost as the biggest Scammells at the time, the Pioneer cost 2000 and the Pioneer Gun Tractor, 2800. The 475 paid by M.R.S. would only have bought a Dennis or Albion 40cwt truck in 1930.

Word of mouth theories are that M.R.S. helped with the development and initial build costs and that this is reflected in the price. Or, that it was part of a deal struck to allow Scammell to sell, what was in effect Ernest Marston's idea to competitors of M.R.S.

To have been the only operator of such a vehicle would have been of immense advantage to M.R.S. and there is also the question of how H.E. Coley knew enough about the vehicle to have the confidence to invest nearly 5000 before the first one had even started to be built.

Although the initial inspiration for the 100-Tonner was the Kitson's locos, one of the first loads carried by KD 9168 was very different. It was a 25 ton, 56 foot launch, built for the Royal Air Force by Harland and Wolff at their Bootle works. Large crowds lined the 1.5 mile route to the Hornby area of Liverpool docks for what, in 1930, was regarded as a mammoth operation.

From 1943, regular work for KD 9168 was Transporting 2-8-0 type locos from Newton-le-Willows to Gladstone Dock, Liverpool. Weighing 75.5 tons, 37'11", long, 10'4" wide and 14'1" high, these locos were built for the Ministry of Supply by Vulcan Foundry Ltd. Destined for Czechoslovakia, Poland, Yugoslavia and Luxembourg, over 80 of these out of gauge giants were transported by 1946. Special tracks were laid in the dock to unload the locos and Scammell Pioneers from the Edward Box fleet were used to control each loco during unloading and position it for the ship's loading cranes.

The first load for BLH 21 was a stone crushing machine for the Metallic Ore Production Company Ltd., of St Austell, Cornwall. It is likely H.E. Coley bought BLH 21 purely for this job. The cab was liveried with the Metallic Ore Production Company name, but in a handwritten style and not the pristine standard that would have been expected on such a moving advertisement. BLH 21 appears to have passed into Norman E Box ownership almost immediately afterwards. With no local means of lifting the crusher, the carrier was left on site as the base for machine. There is no record of Scammell Lorries ever building a replacement carrier. Crane of Dereham built a 110-Ton trailer in 1930 for Pickfords and this was supplied in the winter of 1930. By this time BLH 21 was liveried in Pickford's colours following their take over of Norman E Box in early 1930.

Although built as a semi-trailer, it was quickly converted to drawbar configuration in keeping with the majority of the predominantly steam powered Box fleet. This configuration naturally meant that less load was placed on the motive unit. The conversion allowed the carrier to be used as a conventional semi-trailer or drawbar trailer depending on the individual jobs requirements.

When used as a drawbar, BLH 21 had a propensity to lift the front high into the air when moving away from a standstill. This earned it the nickname of 'Leaping Lena', a name that remained with her for the rest of her life.

The main girders for the Cumberland Hotel at Marble Arch in London were delivered by BLH 21 and one of the more unusual loads carried by either of the 100-Tonners was a stranded 85 ton whale.

One of Leaping Lena's more arduous tasks was to transport 3, 100 ton, 242KV transformers from BTH at Rugby to Manchester docks for export to Russia in December 1943. With the winter conditions, even double headed by an ex-Norman E Box steamer, the journey took ten days.

In 1951, BLH 21 transported a Vulcan diesel loco from Newton-le-Willows to London for the Festival of Britain.

The heaviest load carried by either 100-Tonner was a 165 ton ingot mould in December 1935. This was carried from the Brightside Foundry and Engineering Co., Sheffield, to the Vickers Works of the British Steel Corporation, also in Sheffield by KD 9168. After taking 3 hours to load, the journey was completed at an average of 2 mph.

It is testimony to the design skills of Percy Hugh and Oliver North, and the strength of these two goliaths of road haulage that it was over two decades before they were allowed to retire in 1953. Even so, the trailer for BLH 21 survived in the Pickford's fleet into the 1960's. Until Foden and Pacific produced their 100-Tonners in the early 1950's, KD 9168 and BLH 21 remained the only two lorries with a genuine 100 ton carrying capacity, without the need for doubling or trebling up prime movers.

Whilst KD 9168 and BLH 21 justifiably hog all the limelight, there was a third Scammell 100-Tonner.

Built to a scale of 1.25" to 1', it was built entirely of Meccano and powered by electric motors. It was an exact replica of the full sized 100-Tonner and included a 16-wheel drawbar trailer.

It was built to plan a particular load, presumably to be carried by BLH 21 as it involved a drawbar configuration. The load was a pre-formed, 99 ton steel girder of huge proportions.

The model was used to determine the correct lines to take around corners and to determine if the route was indeed possible, by using a scale plan. Once the correct lines had been determined, the route was marked with chalk to assist the driver and steersman.

However, even this level of forward planning was found to have a major flaw. It failed to take into account the huge crowds that assembled to watch the movement of such massive loads. By the time the load arrived, the crowd had obliterated all the chalk marks and it is testimony to the crew that the journey was completed without incident. It was, however, necessary to use a steamer to winch the carrier sideways to negotiate some of the corners en-route.

Even allowing for the size and power of today's heavy haulage lorries, there can be few, if any, vehicles built that have had the impact on heavy haulage that these two grand old ladies must have had in 1930.

From my article in Heritage Commercials, March 2003.