Austin Seven Powered Tractors - An Agricultural Austin - reply by Gerald Walker
Source: The Association Grey Magazine 1981A (Page 28)
I was very interested in Philip Merrill's article in 1980C about his Austin Seven Tractor. However, I feel his arithmetic is rather suspect when he says that two 3-speed gearboxes give nine forward and three reverse speeds. In fact, there are ten forward speeds as reverse/reverse is a forward gear and the lowest one of the lot.
Even that is not the end of the story because if, as I suspect, the internal ratios of the two gearboxes are the same, some of the gear-lever permutations give the same overall ratios and you are left with only seven actual different forward ratios and three reverse. They are R:R, 1:1, 1:2, 1:3, 2:2, 2:3 and 3:3 forward (not necessarily in that order) and R:1, R:2 and R:3 reverse.
We are quite familiar with Austin Seven Tractors in this part of the country. Mechanically they are the same as Mr. Merrill's, but they are definitely conversions of cars and retain the original bonnet and scuttle. Most of them seem to have been made just after the war and they are always based on magneto engined cars, presumably to save the bother of a battery and wiring. They differ only in details, e.g. the design of the towbars and whether or not the bellhousing of the second gearbox is retained.
My father's tractor has been seen at a few rallies and is a typical example. Registered in 1946 as a motor plough it is built on a 1928 chassis and the door catches on the scuttle identify it as having been an early type saloon. It is probably unique in that, despite having had quite a long life as a car and then having started a new life as a tractor, it still has its original engine which is still running (albeit smokily) on its original pistons. It is fitted with ordinary Seven wheels which means it can be used on the road. Acceleration is terrific and 60 m.p.h. is easily attained given a reasonably smooth road (no rear springs, remember). It used to do very well at the driving tests and hillclimbs organised by Cambridge Austin Seven Club. At the other end of the scale it has enormous torque in the lower gears and is limited only by lack of weight to make the wheels grip (perhaps just as well for the sake of the back axle).
I must say that I am not entirely convinced that Mr. Merrill's tractor was built by Austin's, unless he is sure that when it was originally registered it was as a tractor rather than as a car. He makes much of the wheels but I think he is underestimating the capabilities of the rural engineers and blacksmiths and it is quite likely that they are taken from obsolete machinery and adapted to fit. This would be quite an easy operation compared with the making of the steel wheels we have which are completely fabricated from plate and bar. We also have some rubber tyred disc wheels which have been adapted to fit the Austin Seven hub.
Still, there is no doubt that whoever made them, these tractors are fascinating and very versatile vehicles and I hope some more will be unearthed.
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