History of the Nuffield Tractor - Part 2
1951-1969
By Anthony West

In February 1953 production of the ETC T.V.O engine started, ready for the March 1953 press announcements. The new TVO engine had a number of improvements which resulted in a 10 per cent more power (43bhp as against 38 bhp on the earlier engine) and 10 per cent more fuel economy. Some of the improvements are listed below:

Redesigned combustion chamber, improved spark plugs and positioning, plug size 14mm(earlier size 18mm).
Cooling of the engine considerably improved
Coil ignition on all models
Starting model dog on crankshaft
Camshaft cam profile was modified
Piston ring groove, positions changed
No liners and no valve seat inserts

In 1953, the original draw bar was replaced by a mid mounted draw bar for better weight distribution, this also allowed room for an overload release and hand clutch.

The three-wheeled version of the Nuffield-Universal tractor was changed from single front wheel to a "V" twin wheel arrangement.

In March 1954, Morris-Motors introduced the new "Nuffield-Universal" 4DN tractor, using a B.M.C 4 cylinder Diesel engine type OEA 2 which developed 45 bhp.at 2,000 rpm. The 4DM went on sale at £597.00, for the basic model only (no price increase over the Perkins P4 tractor)

First shown at the Royal Highland show in June 1954, the OEA 2 engine, has a 5 main bearing crank shaft and was of a direct injection type it was fitted with wet cylinder liners and aluminum pistons. The crankshaft is driven by a triplex roller chain, it was a 3.7" bore and 4.724" compression, ratio is 16.5:1 and normal operating speed range of 1,000rpm to 2,000 rpm. The injection pump was a "SiMMS" inline SPE4A/755 and had a built in pneumatic governor, serial numbers for a 4DM started at DE 1001 to DE 106387.

In 1954 the hydraulic live pump pressure was increased from 1,000 lbs/psi. to a 2,000 lbs/psi, in March 1955, the engine oil filter was modified to protrude the bonnet top to allow easier filling. In 1956-1957, "Roadless Traction Ltd" of Houndslow Middlesex. Produced a half track conversion for the Nuffield, the "Roadless D.G. general purpose" half track as it was known, which consisted of two tracks to replace the rear wheels each track had 34 track plates which were 12" wide with 17 grousers 4.25" deep. Idler wheel centers were adjustable from 27&3/4 to 31&5/8ths diameter track pins, Tooth driving sprockets of pitched diameter 40" the face width 2.5", idler wheel rolling diameter 25&1/4". The normal speeds at 1,600 rpm. Rated engine speed as follows.

1st gear--- 1.46mph
2nd gear--- 2.33mph
3rd gear---- 3.26mph
4th gear---- 4.82mph
5th gear---- 11.12mph
reverse ----- 2.56mph

The Nuffield tractor fitted with roadless half tracks could not be used with a hydraulic linkage, it came with a draw bar and P.T.O. (due to the idler wheel extending out further than an ordinary pneumatic wheel) the overall length of the roadless conversion was 12'.7.5" and 6'.11" wide. A new " independent" P.T.O. (I.P.T.O.) for the Nuffield tractor (as an optional extra) was introduced in Feb 1956.

It was only available on new tractors and not as conversion kit for older machines, the I.P.T.O, was driven from the engine via a second clutch (mounted behind the main clutch) the clutch is operated by a hand lever located on the left hand side of the gear box, prices as follows:

IPTO (no hydraulic lift) £57.00 ($92.00 US)
IPTO and hydraulic lift £ 110.00 ($178 US)
The original PTO was still available at £ 12.00,10s. and PTO hydraulic lift at £ 65.00 ($105 US)

In August 1957 ' The Nuffield Organization' announced a new 37 bhp. tractor "the Nuffield-Universal three" it was similar in appearance to the DM4 (which was renamed the Nuffield-Universal 4). The three was only available with a BMC 2.55 3 cylinder diesel engine, but many of the parts were interchangeable with the four. (the Nuffield universal 4 was still available with a petrol os TVO engine which later became export only). The wheels and tires were smaller on the three 5.50X15 front and 10.28 (4 ply) rear. where as the four had 600x16 front and 11.36 rear. The "three" was not available with sliding rear hubs (an optional extra on the four). Adjustment of the rear track was by moving the center disc round in relation to the rims, the three was not available in "V" format rowcrop either and the whole machine was 5" smaller, a ratchet type handbrake was standard and the handbrake lever optional. The hydraulic power lift (Max pressure 2,000 lbs/psi.) would take both cat1 &2 implements maximum life capacity at draft link ends was 2,500 lbs tp 2,900 lbs.

Weight transfer was also available as an optional extra. A number of improvements were made in June 1959, main ones being: the inclusion of differential lock and independent wheel brakes. Vacuum brakes made by Clayton and Dewandre became available for trailer attachments and cost £55. Weight transfer. The Hydraulic lift value was changed to facilitate weight transfer to rear mounted implements.

In 1959/60 production was listed as being 25 per cent universal 3 and 75 per cent universal 4. Out of all machines produced total of 78-80 per cent were exported to 78 countries. Whilst those produced for the UK only had diesel engines fitted. In December 1961 Two new models were introduced they were the 4/60 and the 3/42. They replaced the older Universal 3 and 4 models used since 1946.

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