One of the most unusual tractors ever built at Meltham Mills was the David Brown VAD12/V or 2D (as it was better known), which entered production in 1956 and lasted until 1961. This was a very small, lightweight tractor which featured a 2-cylinder 14 BHP air-cooled diesel engine which had been specially designed by David Brown’s, and had a mid-mounted tool carrier which carried a range of implements.
To tell the story of how the 2D was developed I enlisted the assistance of Derek Marshall (the current chairman of the David Brown Tractor Club) and, once again, Herbert Ashfield who writes about its development. ‘The sales director, Fred Marsh, cherished the idea of a low cost, 14 to 16 horse-power tractor which he believed would sell to the small farmer still using animals. As a basis for our design I looked at the Massey Harris “Pony” tractor of orthodox design which met the specification but it did not perform well under test, and so this particular project was stillborn.
The Sales Director, however, did not give up easily and he bought an Allis Chalmers model “G” for us to inspect. This was a twelve horse power tool frame tractor with the engine at the rear, tools in the middle and a hand lift. The driver sat in front of the engine and behind the tools. “It must have a power lift, it must be able to plough, and turn on its own length” said Mr. Marsh as he rapidly outlined requirements which, while making it superior to the “G”, would also make it more expensive. His eloquence, however, carried management with him and I was directed to produce a specification and design for such a tractor.
When we tested the “G”, we found it suitable for light cultivation only, its biggest problem was its petrol engine which stalled very easily. Another limitation was the excessive effort required to operate the hand lift, so we decided on a power lift. Being currently plagued by oil leaks on our standard hydraulic system, I opted for a pneumatic lift which, I decided, could leak all it wanted. Doubts were also expressed on a mid-mounted plough. “You can’t push a plough!” seemed to be a fairly general opinion but we did not intend to push it, rather we pulled it from the front axle. We then produced a functional prototype to try out our basic suppositions using a 10hp Ford car engine which, apart from stalling easily, performed satisfactorily.
The engine became our next problem. Because of being rear mounted, it overhung the back axle and any out of balance force resulted in excessive vibration. Small multi-cylinder engines such as the Ford car engine were acceptable as regards vibration but unacceptable because they stalled easily under varied loading. Small diesels which were available in the required power range were too much out of balance and indeed almost threw the driver out of his seat. I therefore decided we must build our own perfectly balanced 2-cylinder diesel with a heavy flywheel to avoid stalling. However, we adopted an unorthodox approach, because the reciprocating ‘out of balance’ force created by a piston can only be perfectly balanced by a similar reciprocating force 180° out of phase. To achieve this we put the pistons in line and balanced them by a dummy piston in between and opposite, thus 180° out of phase. The engine ran smoothly, beyond our expectations and we had no further trouble with vibration, but to simplify the installation, we designed the engine to be air cooled.
It met our requirements in the field. It would not stall and could be run at low speed in high gear for light work – above all, from a sales point of view it was very practical because the fuel consumption was extremely low. Sales of production tractors started slowly. The machine was viewed with caution by the farming community. On the other hand, the academic institutions both home and abroad, were loud in their praise for the revolutionary layout.’ However despite this great accolade, the tractor went through some difficult teething problems before it could be marketed, as Derek Marshall reveals ‘When the field tests began in earnest, we started with what was still a very basic unit as the engine and transmission units were not ready at this early stage.
Consequently, as the first mock-up used for trial was devoid of the two main power units, the prototype was pulled along by another tractor. At first sight this might appear to be rather pointless but, to the contrary, this provided valuable information and data which enabled us to make changes and improvements to the linkage geometry and steering even at this early stage. In view of the unique design and specification, it was intended to keep the project as secret and as far away from prying eyes as possible although it was inevitable that locals and casual observers could see what was going on. However, we were obviously quite pleased at the secrecy of the exercise, even though we were sure that questions were asked about the sanity of two or three grown-up people dragging this weird object up and down the fields for no apparent purpose or results. When the Ford engine was fitted the machine ran under its own power, and more meaningful tests could begin. During these tests two major problems arose and it became clear that these would need addressing before production could begin. Firstly, controlling the hand-lift mechanism with the implement attached, (despite the adjustable balance springs) required a Herculean effort on the part of the operator. Whilst lowering the implement was not too bad, once it touched the ground, it was then necessary to overcome the full resistance of the springs in order to provide the required working depth. As this was almost an impossibility, we considered it was essential to provide some power assistance to the lift, and this was achieved very successfully by fitting a small compressed air pump.
This we mounted directly to the front of the gear-box and pressure was fed to the tubular main frame which, when suitably adapted, provided an excellent air tank for the system. Secondly, depth control of the implement was still somewhat erratic, particularly with the long tool-bar or cultivator; a condition which appeared to be due to the fact that the two lift ropes controlling the depth (and being attached centrally to the tool-bar) allowed it to ‘yaw’ or see-saw. Fitting a small depth wheel at the outer ends of the tool-bar, overcame this problem, and also provided a more accurate control of the working depth.
It soon became evident that the engine was well able to provide ample power, even under the most severe conditions but, once again, two fundamental problems had to be solved. The inertia start system as a unit worked reasonably well, but difficulties arose however under cold start conditions when the engine invariably failed to pick up before the inertia unit wound down; in turn this required the operator to continue frantically cranking to effect a start. As the starting problems continued, a major (and much welcomed) change was made at this point with the development and introduction of a full electric system. including starter, alternator and full lighting. We considered this to be a necessary requirement, and we were delighted with the satisfactory and meaningful tests which resulted in only a few alterations or changes being required.’
The old hank winding shed at Meltham Mills, had meanwhile been converted to a special assembly line for the 2D, and production began shortly after the tests were completed. The tractor made its first public appearance at the Smithfield Show in December 1955 where it was promoted as ‘A multi-purpose machine to work on any farm or horticultural holding.’
In total some 2,008 were produced, with a large variety of special models appearing in short and long wheel-bases, wide or narrow widths, low or high clearance models, and even one which had the look of a small conventional tractor. It was widely praised by various universities and agricultural colleges, and the farming press called it ‘the tractor of the future’. However, as the 1960s dawned, it became clear that the sales targets were not being achieved. I asked Herbert Ashfield why this was, and he recalls; ‘The 2D never sold in the quantities originally forecast, but we were receiving orders for all sorts of modified machines which only sold in small quantities to specialist markets and incidentally with a profit margin which took no account of the extra overheads incurred in producing them. Admittedly, it was very popular in places and we sold a lot in Holland, France and around the market gardens near London. For example, it sold well because you could plough right up to the hedge bottom but its enemy was always the second-hand tractor.
It was when it was sold to a big farm that the troubles began, because the farmer wanted all sorts of elaborate equipment, hoes etc. Sadly the 2D never really took off as David Brown and Fred Marsh imagined it would, even though all the institutions and universities said this was the tractor of the future. Then in 1961 the Managing Director, Jack Thomson, instituted an enquiry in to the question of why they weren’t selling. So I looked at it very coolly and the first thing I did was to ask how many salesmen they had trying to sell standard tractors and how many were selling 2Ds. I found out it was taking about three times the salesman hours to sell a 2D as opposed to that taken to clinch a deal on a standard tractor because operators had to be convinced to use the tractor. So, talking to both my field test personnel and farmers, I found that many users were wanting a rear mounted linkage and they were buying small second-hand tractors. This meant that the enemy of the 2D was the second-hand Fordson, Ferguson and David Brown, so if the farmer could buy a good used tractor for about the same as they were paying for a new 2D, he would probably go for a machine with rear-mounted linkage. This set us thinking, could we produce a small standard tractor at a reasonable price?
So we got all the figures out and looked at the profit margin on the 2Ds, and these showed us that if you took the standard overheads you were making a profit on the 2D, but when you added all the extras such as extra salesman hours and whatnot you were actually making a loss. So out went the 2D and in came the 880s and later we developed the 770 which we did in narrow and low-clearance versions and this took over a lot of the 2D’s functions. This was a really superb lightweight tractor of conventional design and relatively low enough in price for the small farmer and it could therefore compete with the second-hand 30 horse-power tractors from Ford and Ferguson.’