Scammell Pioneer R100 (1927)
 6x6 Tractor: 3,414 produced til 1945
 

The Scammell Pioneer was one of the primary tractors of the British Royal Army before and during WW2. It was used in three roles: Artillery tractor (primary), recovery vehicle (secondary) and tank transporter (tertiary). In the latter role this was practically the only one before its replacement by the Thornycroft Antar in 1952, and before the arrival of lend-lease M19, Mack, Diamond and others heavy duty semi-trailer tractors of flatbed trucks. Despite only 3400+ were built, they proved dependable, had solid output and off-road capablities, and soldiered from the BEF in France in 1940 to the last days of the war in the far east in the summer of 1945. Some even lingered in other roles until the late 1950s. This is the first part of the three parts article studying the different variants of the Scammell Pioneer.
Development
About Scammell
Scammell Scarab
Scammell started as a late-Victorian wheelwright/coach-builder as "G Scammell & Nephew Ltd" located in Spitalfields, London. George Scammell worked with his nephew Richard and his own sons Alfred and James. By the early 1900s, the company started to provided maintenance to Foden steam wagons and customer Edward Rudd, which imported a US Knox Automobile tractor asked Scammell to create a replica. World War I stopped this project, bu the coppany was convinced to double down on Mechanical transport, seeing its vast potential. A great nephew of the founder, Lt. Col. Alfred Scammell, injured, applied his practical experience to develop a articulated six wheeler usable as gun tractor foir the army. Percy G Hugh was its chief designer, but the war ended before it could be completed. It was presented however at the 1920 Commercial Motor Show, with 50 ordered, having a very low axle weight for a payload of 7.5 tonnes carried at 12 mph (19 km/h) instead of the usual 5 mph. This was a revolution.
Scammell Explorer
Scammell made this 7.5-ton articulated vehicle and for this, Scammell & Nephew founded Scammell Lorries Ltd in July 1922, with the managing director being Lt. Col. Scammell located at Tolpits Lane in Watford close to the West railway station with a branch direct to the factory. The HQ stayed in Fashion Street, Spitalfields until 1965. In 1929, Scammell created the "100 Tonner" low loader with two made, one to Marston Road Services in Liverpool, but the company looked at 4/6 six-wheel rigid designs as well, using balloon tyres to compensate for the absence of dedicated suspensions. In 1934 was the launch of its vaunted "Mechanical Horse" designed by Oliver North with an automatic carriage coupling, single front wheel steerable at 360 degrees in 3/6-ton either with a 1,125-cc side-valve or 2,043-cc engine. Karrier competed with the Cob. This model was replaced by the Scammell Scarab with a 2,090-cc, side-valve petrol engine or diesel Perkins in 1941.
Work went on in between on articulated and rigid 8-wheeler lorries and the result was the 6×4 Pioneer. This heavy haulage tractor emerged in 1927 and showed unbeatable cross-country performance due to its patented beam bogie rear axle having up to 2 ft (1 m) of vertical movement at the time, unrivalled, also by Oliver Danson North. It became a best seller in the oil field and forestry markets. In the British Army the R100 became at the same time its main heavy artillery tractor, recovery vehicle and 30-ton tank transporter. Production concentrated in 1939 on military Pioneers only. 
From colonial beast of burden to tank transporter

 The need to transport tanks was not an obvious one at first, at least given the network of railways cross-crossing the UK and proximity to tests fields. However, even before the war, there were "blind spots" in transportation between railways hubs and concentration points that needed that kind of transport. But the Scammell Pioneer did not started with that in mind. In 1924 the British authorities in India and other far-off territories expressed the need of a civilian 6×4 off-road vehicle that can be used as a multipurpose heavy duty vehicle in its colonies where metalled (sealed) roads were scarce. Scammell proposed its design in 1926, which was accepted, and a modest order was obtained at first.
Pioneer started to produce its Pioneer in 1927. It lacked an all-wheel drive, which was compensated by the use of a suspension with great travel, and an excellent traction provided by a low-revving engine with great capacity, ending with a generous output and even more impressive torque, impressive pulling power whatever the terrain, and still adequate low speed agility and flexibility. Soon, the results were impressive enough to have the army interested. The British War Office purchased one in 1932. The first use was to convert it as a tank transporter (which lacked in British inventory), when coupled with a tailored 18t semi-trailer. It was assigned to a training but did not succeeded to impres however and no order was passed. At least until 1937, as there was no urgent need, expecially in the concvept of cash-strapped Britain after the 1929 crisis. 
If not ordered as tank transporters, the british War Office purchased a new serie, equipped on demand with a beefier 102 bhp Gardner 6-cylinder diesel engine. It was driving only the two rear axles through a constant-mesh gearbox. it was also given a power take-off driving with a Scammell winch. Plus military grade tures, and properly military equipment. In 1935 these efforts culminated with the acceptance of the R100 Artillery tractor, which was ordered in numbers to pull the largest British ordnance. That's the first leg of our journey in this versatile type.
The Artillery Tractor R100
The artillery tractor Pioneer R100 was the primary heavy artillery tractor used from 1935 to World War II. it was tasked of tow heavy, but also if needed, medium artillery pieces. Its roomy cabin could accommodate not only the whole gun's crew, but also all the tools, equipment, and ammunition needed to operate the gun, so no more vehicle was required, simplifying logistics considerably. From 1935 to WW2 it was tested and used for towing the 60-pounder, 6-inch howitzer, 4.5-inch gun and 5.5-inch howitzer. However it was criticized as being slow and for this, the 
AEC Matador impowed itself and a solid alternative as the standard British WW2 medium gun tractor, when provided in sufficient numbers. 
But the Pioneer was still the one and only towing the 6-inch gun, 7.2-inch howitzer, 8-inch howitzer, and in WW2 via lend-lease, the 155 mm Long Tom. In the end until 1945, "Only" 980 Pioneer R100 heavy artillery tractors were manufactured, which was still insufficient to meet requirements, and it was supplemented by the more modern 
Albion CX22S from late 1943. Its postwar replacement was the Thornycroft "Mighty" Antar in 1951, capable of lifting heavy tanks such as the 64 tonnes Conqueror.
Chassis and general design
The Scammell Pioneer R100 (the artillery tractor) shared about the same caracteristics with its siblings, the recovery variant SV1S/T and the tank transport tractor TRCU20. The forward part and chassis were identical, only the flatbed (or lack thererof) was different. Unladen, the R100 was 8.38 long tons (8.51 t) with a useful payload on its flatbed cabin on 2.95 long tons (3.00 t) between the gun crew, gear, tools and ammunitions. Its towing capacity went to 19.64 long tons (19.96 t) max.
From bumper to hook the chassis measured 20 feet 7 inches (6.27 m) and 8 feet 6 inches (2.59 m) in width, as well as 9 feet 9 inches (2.97 m) in height at the top of the roof forward. The engine was placed under a relatively narrow bonnet, topped with a distinctive vertical flanges radiator calander. The bonnet's top opened in two parts hinged along a central spine and there were two more accesses on either side for quick daily service and maintenance. The forward axle was covered by a pair of mudguards and the road lights were installed on poles seated on the base of the chassis but there was no bumper per se, and instead a winch and hook for self-unditching.
The cabin started right past the bonnet, and was quite large, tall and roomy. Underneath was the main fuel tank on the right while the left was occupied by an open netted storage area. Access via the two main doors was done via a simple step at the base of the fuel tank. The doors were hinged foward. There was a single seat in front pf the steering wheel, two gears, pedals, and a bunk large enough fr 2-3 more passengers in the forward cabin alone, and two smaller windows. Main windows were generally closed before the war, but wartime production simplification had them eliminated and instead simple rolled canvas was dropped in heavy weather. The forward windshield was composed of four windows, with a flat frame. There were rear mirrors fixed to the forward frame. 
The flatbed was occupied by a cab large enough for the whole gun crew, 6 to 8 ùen seated on folding bunks, with a lot of room for ammunition crates and gear in the middle. Access was via two small doors accessible by steps or ladders. The two rear axles had no protection but were toppd by the overhangin cabin. A fixed heavy durty hook at the end of the chassis allowed the towing of the largest artillery poiece in british inventory, the most often seen being the 7.5 inches howitzer. One intereting aspect was the presence of a crane under the top of the roof with a telescopic gantry and pulleys for lifting and unloading heavy ammunition crates. The very large "balloon type" off-road wheels had no spare. The Pioneer was a tall vehicle due to its massive suspension system, high ground clearance, and an easy target, as it was unarmed and completely unprotected.
 
Mobility

Under the hood took place a valiant 510 cu in (8.4 L) Gardner 6-cylinder Diesel as requested by the army in 1933. it provided 102 brake horsepower (76 kW) at 1,700 rpm and a masive torque through a 6-speed constant-mesh gearbox. There was a 6x4 drive with Walking beam Suspension	which combined with large wheels authorized near acrobatic obstacle crossing, clearing, climbing abilities on all terrains. Operational range was limited to 430 miles (690 km) in normal conditions, half perhaps when towing a 10tons ordnance. Top speed was limited to 24 miles per hour (39 km/h) unladen on road, far less with the same payload off-road. By 1943 standareds it appeared underpowered compared to new vehicles but was a true progress compared to horse-drawn carriages which were still around in 1936.
Front axle
Diesel engine
specs. R-100 artillery tractor | 
| Lenght | 20 feet 7 inches (6.27 m) | 
| Width | 8 feet 6 inches (2.59 m) | 
| Height | 9 feet 9 inches (2.97 m) | 
| Total weight | Light 8.38 l.tons, max 19.64 l.tons | 
| Payload | 2.95 long tons (3.00 t) | 
| Crew | 1+8, see notes | 
| Propulsion | 8.4 L Gardner 6-cyl. Diesel 102 bhp (76 kW)/1700 rpm | 
| Suspension | 6x4 Walking beam | 
| Transmission | 6-speed constant-mesh gearbox | 
| Speed (road) | 24 miles per hour (39 km/h) | 
| Range | 430 miles (690 km) | 
| Armament | None | 
| Production | 980 1935-1945 | 
Recovery vehicle SV1S/T
From 1936, the British Army started to receive 43 Pioneers SV1S heavy recovery vehicles. Many of these SV1S and R100 vehicles were lost in France in June 1940, destroyed by withdrawing troops or captured by the Germans. The SV2S version had a redesigned crane with greater lifting height, introduced in 1938. A total of 1,975 SV2S were built. Delivery of a tank transporter began in 1937. This variant was fitted with a longer chassis for an extended cabin to accommodate the tank's crew and 459 of this sub-variant were produced.
The first 43 were indeed designated Pioneer SV1S3 and Pioneer SV1T and both had in common their 3-ton foldout crane and lockers for equipment and tow bars. By these were nearly all lost in 1940 following their abandonment by the retreating BEF, whereas the SV2S4 had a new, simpler crane providing greater pulling power when introduced by 1938, which remained in production until the end of the war (1,975 total).
This V2S had a pair of tracks that could be fitted on the two rear axles in order to convert it into a half-track, improving grip on soft ground.
The SV1S's body consisted of parallel lockers with a full length one, right and two shorter ones, left, plus the access space to the well and jib winch controls. There was a drop down side door fitted with steps. The hand operated jib winch was behind the cab, forward end of the body, above the chassis and below the flatbed with its steel cable attached to the crane.
The lockers carried the recovery gear and the towing bars were stowed on the top of the right hand locker. The early ones had a towing ambulance with a long pole with towing eye  and cross piece to attach small wheels and the support the front end weight of small towed vehicles. When towing vehicles at one end, when suspended from the crane jib, the latter were free to bounce into the back, causing damage, and the issue was solved by addin an ‘A' frame which base was secured to the casualty and apex to the towing hook. As counter weight for the suspended casualty, there was a ballast weight on a frontal frame forward of the radiator.
The early development of the breakdown tractor started with a simpler crane needed for the Scammell, a fixed angled single jib crane designed by John Morris Ltd. It had on the S2V a sliding section which could be extended for a greater lifting height. The remaining 1600 or so Pioneer breakdown tractors were converted to this new system, with a manual winch raising the load on the jib allowing a man to raise the 3 ton maximum weight at its shortest extension.
Method to lift heigher liftes included to park the Scammell on a tank transporter trailer and pile up railway sleepers or gun planks and reverse the vehicle up this slope if no proper workshop crane was available. There was also the pair of flexible racks to convert the vehicles as half track, stowed on an an open crate-like locker under the drivers cab.
specs. SV1T/S* recovery/supply tractor | 
| Lenght | 6.09 m (20 ft 3 in) up to c21 feet (6.90 m) | 
| Width | 2.66 m (8 ft 9 in) | 
| Wheelbase | 3.70 m (12 ft 2 in) | 
| Height | 2.87 m (9 ft 5 in) | 
| Total weight | max 18 l.tons | 
| Payload | Winch, 8 tons capacity, Crane lift 2½ tons max | 
| Crew | 1+2 | 
| Production | c2000 1937-1945 | 
Tank Transporter Pioneer TRCU20/30
The Scammell Pioneer as we saw was at the same time an artillery tractor, recovery vehicle and tank transporter. They arrived with standard 102 bhp Gardner 6 cylinder diesel engines. The production of the tank transporter called TRCU-20, started in 1937 with the prototype ready and tested from 1932. Production was greenlighted for 300 vehicles and production setup in 1934. 
The TRCU-20 was a bit different than the others, equipped with a longer chassis plus an extended cab to accommodate the tank crew ((generally five men), passengers in the front and rear cabins. The tank commander likely sat alongside the driver forward. It seems also they had larger rear wheels than the Artillery tractor and Recovery vehicle. The "20 ton Pioneer" gave the acronym TRCU 20 and it came with a 20t trailer, whereas the 30 ton capacity trailer have the Pioneer TRMU30/TRCU30 couple trailer/tractor. The tractor had the same 510 cu in (8.4 L) Gardner 6-cylinder Diesel which developed 102 brake horsepower (76 kW) @ 1700 rpm
coupled with a 6-speed constant-mesh gearbox transmission, Walking beam 6×4 suspension, 38 kph for the tractor alone, and 290 km range unladen from a fuel capacity of 245 liters.
In both cases with  the trailer was fixed to the tractor and on the trailer, Hinged ramps were used to get the tank onto the trailer, then pulled on with the tractor unit's winch vertical. The trailer had a rear twin axle double wheels rep:icating the rear tractor chassis arrangement, but with different details. There was also a n electric connection to turn off the tail lights of the trailer from the tractor's cabin. The engine and transmission were the same as the others however, but performances were far less impressive due to the massive towing weight, with a top speed on road of about 30 kph at best, less than 15-20 kph in more adverse condition and foor pace off-road. 
This Pioneer tractor/trailer combination remained in production throughout the war with a grand total of 459 in WW2, 527 overall produced in total from 1937 to 1945, but without details about the number of trailers of both sides provided. It was clear however the TRCU-30 became standard, due to the new tanks adopted from 1940 such as the Covernanter, Valentine and Matilda II, and later in north Africa, the M3 Grant and Sherman. The TRCU-30 was not able to carry the mighty Churchill tank however. The TRCU family took part in a vita role to carry tanks from ports to the frontline, or to and from railway lines, notably in Europe. They took part in the North African Campaign until the victory at El Alamein and Tunis, the Italian campaign and the landings in Normandy.
The Pioneer tractor/trailer combinations proved however too tall to carry higher profile US tanks under some British bridges. The trailer was criticized as too high, notably forward. From 1941 they started to be replaced by the lend-lease US built Diamond T tank transporter and after 1945, unable to carry the new generation of British tanks, the trailer were scrapped and the tractor were sold on the civilian market. None survived to this day however.
specs. TRCU-30 tractor/trailer combo | 
| Lenght | 15.14 m trailer alone | 
| Width | 2,89 m | 
| Wheelbase | 3.70 m (12 ft 2 in) | 
| Height | 3,33 m fwd trailer | 
| Total weight | 20.22 tons less 30t payload: 50 tonnes FL | 
| Payload | Winch, 8 tons capacity, Crane lift 2½ tons max | 
| Crew | 1+2 | 
| Production | c2000 1937-1945 | 
The Scammell Pioneer in action

Despite its archaic appearance and ponderous gait, Scammell’s Pioneer remains a legend among fans of antique trucks. Originally introduced in 1929, its military career did not begin until three years later when the War Office bought a single example equipped with a tank-transporter semi-trailer. In 1937 this was followed by a modified production version, first rated at 20 tons, then upgraded to 30 tons. 
There were also artillery tractor and heavy recovery versions, dating from 1935 and 1936, respectively. Where the prototype tank transporter had been fitted with a petrol engine, all subsequent production was powered by Gardner’s inimitable 6LW six-cylinder diesel engine, producing 102hp from 8,396cc, and driving through a six-speed gearbox to walking beam gear-cases at the rear. At the front was a transversely pivoted axle. Military production continued until 1945, by which time 2,783 Pioneers had been delivered. Surplus Pioneers formed the basis of many heavy haulage and recovery fleets during the 1950s.
Many Pioneer gun tractors were lost in France in June 1940 with the evacuation of the British Expeditionary Force (BEF), either destroyed by the withdrawing troops or captured by the Germans. Next stop however was its use North Africa, where the tank transporter took all its sense as the ARV variants. They were used in Italy but less present in France after D-Day, already susperseded by the Albion CX-22S or lend-lease vehicles. They saw service also in the far east and even ended still in service with some Royal Engineer Regiments in Germany (BAOR), before being phased out in 1955. Many had survived to this day.
Many of the Scammells of 1939-1940 shipped to France served with the RAOC(E) with the BEF. Many were left behind during the evacuation in June and a few were captured by the Germans, others remained in the UK. One ended in the Far East after he war and saw action in Korea, damaged by a mine but repaired. One SV1S from 13 Command Workshop REME at Aldershot and was subsequently presented to the Museum.
This vehicle was also modified in service, with the main frame of the crane locked into position, horizontal jib/stays removed altogether. A larger pulley was fitted in the fork of the main frame alo to take the cable of the hand winch, providing a higher lifting force a take on the main chassis winch cable. The casualty was placed a great strain on the cable, bend in a sharp curve under the rear winch rope upper guide roller. The last Pioneer support vehicle (S) was withdrawn from service in the British Army as late as 1980s in Belize. It was shpped back home in parts and reconstructed at the 43 District Workshop REME at Aldershot, named ‘Swampy'.
Read More/src
archive.commercialmotor.com
rememuseum.org.uk query
rememuseum.org.uk on the Model SV1S
rememuseum.org.uk on the R100
Footage of recoveries (video)
en.wikipedia.org scammell lorries
Photos
o5m6.de tank transporters
rememuseum.org.uk
panzerserra.blogspot.com
Model TRCU details
Videos