Canadian manufacture of the Rota-trailer
by Roger V Lucy
The Rota-trailer was a British design, intended to provide armoured units with additional supplies of ammunition and fuel by towing them in a two-wheeled trailer behind their tanks. Successful trials of the initial version, the Rota-tank, were undertaken at the British Directorate of Tank Design’s (DTD) Wheeled Vehicles Experimental Establishment (WVEE) at Farnborough, in January 1942. By May a contract had been placed with a British firm, Tecalemite, to produce Rota-trailers for the British War Office.
The Rota-trailer comprised two cylindrical drums, with tires, which formed the wheels; held together by a central framework comprising the axle, platform box and towing bar. Ammunition (or other supplies) was carried in the platform box and fuel in the hollow wheels, each of which held 60 imperial gallons (300 litres). The platform box could carry 900 rounds of small arms ammunition (.303 or Besa) and either 106 2-pounder or 37mm rounds; or 40 6-pounder or 75mm rounds. Additionally it carried lubricating oil (30 litres), water (50 litres) and seven ration boxes. Overall it was 3.1 metres long, 1.9 metres wide and 0.96 metres high. Its unladen weight was 1.6 metric tonnes, its gross weight 2.6 tonnes. Each unit cost about £200 (about $1,000 at the exchange rate of that time).
Based on the British War Office’s policy, First Canadian Army directed on 2 September 1942 that all its tanks should be fitted with a towing attachment with a quick-release hook that could pull a Rota-trailer. Trials using Canadian Ram tanks to tow the Rota-trailer were undertaken by 5th Canadian Armoured Division. In normal training the trailer itself stood-up well. Except in extreme conditions (such as steep muddy slopes) towing a Rota-trailer did not affect the Ram’s performance nor did it appreciably increase fuel consumption. Initially it was proposed that one trailer be issued to each troop (three tanks) or six per squadron, bringing the estimated Canadian requirements to 300-400 trailers. As the British could provide the Canadian Army Overseas (CAOS) with 20 Rota-trailers a week, from their own production, Canadian Military HQ’s (CMHQ) preference was to procure its Rota-trailers locally.
Canadian-made Rota-trailer. Note the DND number 42-1-8283
However, in the event that Canadian production might be required, CMHQ sent a set of plans and drawings to Ottawa, in July 1942, followed by a complete Rota-trailer shipped at the end of August. The Canadian Department of Munitions and Supplies (DM&S) used these to build a pilot version which was ready in November. By then, the proposed scale of issue for Rota-trailers had increased to one for each tank, bringing the requirement to 1,140. The War Office offered to provide the CAOS with 30 to 40 a week from British production. In Canada DM&S estimated that within three months of its receiving the go-ahead it could have the Rota-trailer in production in Canada.
By January 1943 CMHQ had decided to bid for 600 British-made Rota-trailers for use with the Ram, while DM&S would contract for 1,350 for use with its planned production run of the Grizzly (M4A1). An initial order for 500 Rota-trailers was placed under Contract Demand LV1704. According to DM&S Design Record, a single pilot was built, incorporating a number of modifications to make it sturdier. [i]
In actual operations the Rota-trailer proved less robust than advertised. Towing the trailer placed considerable stress on the tow-bar, which needed to be strengthened, and on the tank’s towing hook and its attachment to the hull. Cases were known of trailers being turned upside-down as they bounced along – completely bending the hook out of shape. A specially designed towing hook was required.[ii]
By April 1943, the Rota-trailer was about to enter production in Canada, based largely on the original British No.1 Contract design. By then, the British had made a number of design changes to rectify the various weaknesses revealed by actual service conditions. Various parts were reinforced, the trailer lid was raised by 10cm to accommodate 6-pounder and 75mm APCBC ammunition, and the standard British 2-gallon oil and water canisters were replaced by jerricans. These modifications were not incorporated in the first batch of British Rota-trailers received by the CAOS, which had racks only for 2-pounder or 37mm ammunition. Production in Canada was put on hold until the design changes could be passed back to DM&S. In April CMHQ asked the DTD for a copy of the plans and drawings of the changes, and for an example of one of the 50 pilot No.2 Contract Rota-trailers that, it understood, were being built by Tecalemite. The War Office, however, refused to finalize the design, pending the results of large-scale trials planned for September. It did not expect the redesigned trailers would be in service before 1944. These delays made DM&S uneasy, as its contractor’s production facilities were tied-up pending release of the final design. Some parts had already been fabricated for the Canadian trailers and major design changes could render them obsolescent. CMHQ tried to reassure DM&S that the design of the wheels, bearings, axles and main components would not be affected, but no revised pilot was likely to be available before mid-October 1943. By then the trials had shown the Rota-trailer’s problems could not be fixed and that it was tactically and mechanically unsatisfactory. On 29 October, CMHQ advised DND that Rota-trailers were no longer a CAOS requirement and on 3 November 1943, DND’s Director of Mechanization asked the Secretary of DM&S, to cancel the order.[iii]
Editor’s note – The following photograph was recently discovered and shows a similar item dating from the First World War. This dates from October-November, 1918. The photo was taken at Bovington, in the UK.
[i]. LAC RG24, volume 9364, file 38/ARM VEH/26, DM&S, Design Record, Volume III, History of Tanks in Canada page 2.
[ii].idem, LAC, RG24, reel C-5778, file 55/621 /T24; CWM, Box 21, DMS report E301.
[iii]. LAC RG24, volume 9364, file 38/ARM VEH/26
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You can read more about the Ram tank by ordering the author’s book “Canada’s Pride” available from Service Publications
MilArt 
Excellent article Roger, well done!
Greetings. This article raises a few questions, given the documents I have found in the US National Archives. A company in New Jersey named “Armored Tank Corp” submitted to the US Army a RotaTrailer in May of 1942. Ordnance Branch had no interest in the device, but ordered it to be tested anyway at the request primarily of the British Military Mission. See http://worldoftanks.com/en/news/21/The_Cheiftains_Hatch_Trailer_Ammo/
However, your text indicates that the device was of British design and was in fact tested by the British some five months previously. This thus asks…
1) Who was it that first came up with the design? Did ATC license/steal it from a British company? Did it go the other way around? I can’t imagine ATC submitting it to the UK five months before submitting it to its own Army.
2) Why did the British Mission in the US ask that the device be tested when the British Army had already done so at home?
3) What do the primary sources from the British/Commonwealth side say on the matter? I cannot answer 1 and 2 from what I’ve found in the US thus far.
I’d email you this, but can’t find a ‘contact the author’ button.
Interesting, I was unaware of this US Rota-trailer design, and the Canadian Military HQ files which are my main source make no reference to it either. The British Rota Trailer was designed by the Ministry of Supply’s Directorate of Tank Design. Armored Tank Corp’s design appears similar but clearly differs in a number of ways. They may have been aware of the Rota-trailer’s concept but not of its design details..The British Missions main interest was sourcing military equipment in the USA to supplement British production, which might explain their interest.