The BMC Mini Prototype Tractor

The BMC Mini Prototype Tractor

Your Editor Stuart Gibbard has asked me to write an article on the latest addition to the Coldridge Collection here in Devon.  As most readers will be aware, this collection is more or less dedicated to all things Ferguson and this embraces the pioneering work done by Harry Ferguson Research Limited and its subsidiary Tractor Research Limited.  HF set up these companies after he sold out his Ferguson design and marketing company to Massey Harris in August 1953, that is 7 years before his death at 75 years in October 1960.

Part of this sell-out agreement was on the understanding that HF would not get involved in tractor development for 5 years, so HF Research concentrated on

4 W D systems, limited slip differentials and prototype cars, hence a later date for the establishment of Tractor Research.

There are some examples of the output of Tractor Research around today.

One example was research to produce a design on behalf of Calor Gas and develop what was to become the Turner Ranger Four and was ultimately manufactured by Turner Engineering of Alcester.  About 250 of these unusual 4 x 4’s were produced in the mid 1970’s.  Yet another development project taken on by Tractor Research was commissioned by B.M.C. who at the time were responsible for Nuffield tractor production and felt the need for a small compact tractor of about 15 HP to add to their rather limited range.  This was in 1960 around about the same time as HF died.

It is perhaps a strange coincidence that as HF reached the latter part of his life he suffered bouts of depression interspersed with periods of great energy and enthusiasm when his old spirit seemed to return.  On one of these occasions he was fired up with one of his pet dreams of creating a tractor design of about 15 HP incorporating many of the Ferguson patents.  Was it that this dream became a reality, if posthumously, in the form of the BMC Mini?

The design team at Tractor Research was headed up by Alex Senkowski (of LTX fame), Charles Black was Agricultural Advisor whilst the six engineers on the project were Gordon Edwards, Dennis Langton, Frank Inns, Bruce Cosh, Ray Tyrer, Geoff Burton plus a similar number of draughtsman.

The basic concept was to produce a tractor with an under body clearance similar to that of the TE 20 but available in 2 versions i.e. basic with no PTO or hydraulics, and a deluxe version with all the goodies of the day.  It so happened that the BMB President had certain features which met these basic criteria so 2 were purchased by Tractor Research and used with modification to test out the basic parameters prior to building prototypes.  The earliest dated drawing is 19-5-1961 as far as is known.

At an early stage 10 x 24 and 550 x 15 rear and front tyres were decided upon, as was the spur gear reduction final drives set at the outer ends of the rear axle.  Dry disk brakes were incorporated on the high speed axle shafts.  Similar to the BMB?  For the hydraulic linkage system, the normal Ferguson draught control system was dropped in favour of an earlier Ferguson patent of 1922 that consisted of height adjustable mounting points for the attachment of the forward ends of the lower links.  This proved to work fairly well in reasonably consistent soil conditions pulling a 2 furrow Ferguson plough, to which a depth wheel had been fitted (HF would have turned in his grave!) just in case maintaining an even depth became a problem; in practice this was not needed.  At this early stage one of the BMP Presidents was fitted with the Count Teramala torque converter to which HF had bought the patents to and which had been used in one of the prototype 4 WD Ferguson cars.  The converter performed reasonably well, but as one would expect, fuel consumption was increased by as much as 30% – not a feature that would appeal to farmers!  Also a sudden reduction in torque requirement e.g.  when the plough was lifted at the headland, caused the tractor to speed up dramatically and could catch a driver unawares with possible dire consequences!  The general conclusion was that this sophisticated type of transmission should be dropped in favour of a 3-speed reverse gearbox coupled to a 2-speed high/low range box.

At around this time BMC had been developing an automotive diesel engine of 948 cc under the control of Alex Issigonis, with the intention of it being offered as an option in the Morris 1000 cars and commercials, quite a pioneering concept!   This indirect injection engine was of a design by Riccardo with comet heads and was claimed to develop 15 BHP, which by all accounts was 2 HP over optimistic.

These early experimental engines,  prefixed SPL, had glow plugs in each combustion chamber and one in the induction manifold.

Now, having fully evaluated the modified BMB Presidents, the time came to build four prototypes registered as 495, 496, 497 and 498 EUE.  As can be seen from the photographs, 495 EUE is the one that has recently come to the Coldridge Collection, having been first registered on 30 November 1962 with Warwickshire County Council – colour – blue in the name of Tractor Research Limited.  The writer first heard of the existence of this tractor back in April 1997 in the afternoon following the Ferguson Club AGM held at the White Hart, Moreton-in-the Marsh.  Earlier that day, Ray Fardon, for many years HF Head Gardener at Abbottswood, Stow-in-the-Wold, gave us a very interesting talk on his experiences of working for HF.  In the afternoon, the guests had the opportunity of visiting the gardens at Abbottswood in heavy and non stop rain – not the ideal way to view a garden of that calibre.  However, I remember talking to Ray with a few other club members sheltering in a building, and saying to Ray, “You know what these chaps are hoping to find here – an oddball Ferguson tractor”.

Ray’s reply was – “the only oddball tractor is in my care” – a BMC prototype that he used regularly to cut the cricket pitch at Bourton-on the-Water.  So I arranged to make another visit to the area to take photographs and had the privilege to test drive this unique tractor (unless there are any other survivors out there somewhere).  Eventually the Cricket Club decided to sell me the tractor, but I had to undertake to provide them with a tidy replacement.  This I duly did in the form of a BMC4-25.  Just recently I asked Ray how he found HF as an employer – “He was my friend and I was his friend” – what a lovely comment.

Taking a look at this tractor, we find that a good number of Ferguson patents are incorporated i.e. the adjustable front axle, double drop arm steering box, stepped adjustable rear wheels, cat I3-point linkage, but without draft control.

Now to list the differences that have come to light on this model when compared to the production version.  The most noticeable differences must be the hand-fabricated bonnet and rear mudguards followed by the more crudely fabricated radius arms particularly at the yoke ends.  Next, the observant viewer would notice the fact that the wheels have an 8 stud fixing to the wheel centre as opposed to the production version with 6.  Likewise the wheel centre to wheel rim attachment points are 6 on the prototype and 4 were considered sufficient on production versions.  The front wheels of 550 x 16 have a 5 stud fixing whilst the production models only have  4 : cost cutting measures no doubt !   The gearbox arrangement is totally different in that the prototype has only 6 forward and 2 reverse,  This was achieved by having a 3 speed and reverse box coupled to a high and low range box with no facility for isolating the starter circuit when in gear.  The production version on the other hand had 9 forward and 3 reverse speeds, and the starter motor was controlled by the gear lever closing the circuit in the solenoid wiring thus eliminating the risk of the engine being started whilst in gear.  So on the production models we have a gear lever controlling a 3 speed box with a start position and one secondary gear lever controlling 1-2-3 and reverse of the auxiliary box.  This in fact provides a shuttle facility when operating in medium and reverse – ideal for loader work.  Other smaller details that are apparent: the hydraulic oil tank differs in pipework arrangement to that of production models; wider foot boards are fitted made of wood with aluminium trim.  No doubt other minor differences will come to light as time passes.

From these early days in 1960, the BMC Mini tractor was eventually launched in 1965.  BMC claimed that 4 years of development work had gone into its evolution, however by 1968 the Mini label had been dropped when it was decided to install a 1.5 litre BMC B series diesel engine that developed 25 BHP – this was designated Nuffield 4-25 and still produce in the orange livery.  Near to the close of 1969 the Leyland Blue was applied and hence it became the Leyland 154.  Late production of these compact tractors had been transferred to Izmir in Turkey, a company in which Leyland had a 10% share.  These were fitted with the upgraded series B diesel engine of 1.8 litres producing 30 BHP at 2500 RPM.  They were sold in the UK, painted red and branded Leyland 184.  The final evolution of this range must be the Marshall 302 also built in Turkey starting in 1982 and ending in the late 1980s.

So from sketchy beginnings and a bumpy passage through development, time and use, the concept stayed established for approaching 25 years.  No doubt if 4 WD had been an option like the Japanese compact tractor manufacturers offered, the story may have been a different one.

It would be interesting to hear from any readers who can add to this story – their observations and comments would be very much appreciated.  Likewise, if you would like to visit the Coldridge Collection to view, just call Mike Thorne on 07966 328600.

© Michael Thorne