VAD6 50D (1953-1959)

At the beginning of 1953 another new product came out from the company, in the shape of the Cropmaster 50. It had been the long-held dream of David Brown to make a 6-cylinder diesel capable of producing 50 horse power, and with this model it was hoped to provide a tractor which could break into, and then capture the top end of the agricultural and industrial market. It was an ambitious concept, and it owed its origins to the 50 hp crawler tractor of 1952 rather than the 30 hp Cropmaster.

David Brown 50D

Initially designated the VAD6, the name Cropmaster 50 was employed more as a marketing concept, rather than specifically conveying the actual pedigree of the tractor. After it began rolling off the production line in January, its initial market was aimed specifically at the company’s export trade.

It was envisaged that it would satisfy a demand for countries where tractors were needed to pull large trailers, specifically in South America and the developing countries of the Commonwealth. The first major public appearance of this large towing tractor in Britain was at the Harrogate Convention in April 1953, but by this time it had already undergone a sea-change and been renamed as the 50D.

I asked Herbert Ashfield to explain why the tractor had come about, as it seemed to be so much at odds with the company’s stated policy of the day. He told me; ‘The idea for the 50D came about because a lot of people in the organisation were saying we wanted a big wheeled tractor that was like a powerful crawler and fitted with a big 6-cylinder engine. So we made a big engine and a transmission that was rugged enough to stand up to it, and on this power unit we developed the TAD6 crawler and then the VAD6 wheeled tractor. It was designed basically from scratch, and it wasn’t related to any of the others; in fact it was more closely related to the early DB4 tracklayers than it was to the Cropmaster. However, neither of these machines ever sold in quantity because a) we couldn’t produce enough and b) the export market was a bit dodgy! In fact, we were selling more overseas than we were in this country, and its always a bad policy to have a machine who’s primary market is an export one.

DB 50D

The trouble with an export market is you can’t easily cure problems which develop with the equipment; but if you have a good home market, you can sort out the teething troubles on your own doorstep. The 50D sold quite well in South Africa, Australia and South America, in fact anywhere where there was a requirement for hauling big four wheel trailers. The main thing that was wrong with the original 6-cyIinder engine was its cylinder head, in that it was a single head. Because of this it used to warp quite badly and you’d blow the gasket between the cylinders if you overloaded the engine. It was a common fault, and it wasn’t really overcome until the 1970s when I devised an arrangement which employed two 3-cylinder cylinder heads on the 6-cylinder block.’

The 50D was quite unlike any other David Brown wheeled tractor, as it had no hydraulics, a side-mounted belt pulley and a 4-speed PTO. Its 6-cylinder engine was, like the Cropmaster, a 3 5/3” Bore and a 4” stroke, and it used many components that were employed in the Cropmaster engine, however it was not an uprated Cropmaster engine as some commentators have stated. It was a high, rugged tractor with a good bench seat, but it could hardly be called handsome. Its headlamps, particularly those mounted on stalks which gave an elevated position above the radiator grill gave it an ungainly appearance. It was the same with those models which had the air-cleaner mounted in a higher than normal position, and thus imparted a less than aesthetic look to the tractor.

Big, powerful and rugged it may have been, but it was not a popular model and in total only 1,260 were produced before construction was brought to an end in the summer of 1958. The market for a 6-cylinder in this country had not yet developed sufficiently for the company to maintain its confidence in the product and develop it for a wider UK application, but it would come again with the 1200 series.

Again, Herbert Ashfield provides another insight into the 6-cylinder engine’s demise, noting ‘I felt we should go on with a 6-cylinder and bring out a big tractor for the 1960s, but we would have had to make substantial improvements on our existing design. Unfortunately it was the cost of both tooling and the re-designing of the tractor which killed that one, so out went the 6-cylinder idea. These development costs were so high that the management wouldn’t pay for them, but even so they wanted a more powerful tractor.

Over the years I‘d been planning ways that we could achieve this by turbo charging, but we could never get a turbo charger that could give the life we required so we continued on with a four-cylinder engine and waited for someone to come up with what we needed.’ Accordingly the 50D went out of production and the 6-cylinder DB tractor came to an end for the meantime, yet the 50D itself has become a much sought after collector’s piece thanks to its rarity!













VAD6 50D


900 Series


VAD12 2D


950 Series


850 Series


880 Series


990 Series