Marshall Power The reasons why Marshall tractors were so popular for belt pulley work

Heritage THE PULLEY MARSHALL POWER UNITS Power on Marshall single-cylinder tractors were a popular and successful source of stationary power on the farm and in forestry too. Peter Longfoot discusses their design and looks at some of their most common belt pulley applications

Today, when we have an almost reliable supply of electricity that can be counted on 24 hours a day, every day, and electric motors of all shapes and capacities to turn that power into useful work, it is easy to forget that this wasn’t always the case.

The provision of electricity to farms and country businesses was a long time coming and some outlying farms remained unconnected to the mains until the early 1960s. Of course, such farms were not without electricity as practically all had provided themselves with a generating set for lighting.

The earliest form of mechanical power to reach the farm was the portable steam engine, whose main application was for power to drive a threshing machine. Portable steam engines even supplied the power for the very earliest cable ploughing systems. It was not unusual to see a windmill with a pulley on a sha on an outside wall, this arrangement enabling a portable steam engine to be used to provide power to the windmill when the conditions were very still.

When the same conditions prevailed there were instances when a portable steam engine was belted to a drainage windmill in the Fens to drive the scope wheel to prevent local ooding.

All this demonstrates the importance of portable stationary power before the general distribution of electricity. As steam power gave way to the tractor, this importance did not diminish to any great extent. The design of practically every early tractor incorporated the provision of a belt pulley, this attachment even being available as a standard item on most crawler tractors.

There are stories of Ransomes’ own Caterpillar Diesel 50 driving a dynamo by belt to supply power to crucial parts of the Ipswich factory during power shortages. International Harvester sales literature of the 1930s focused heavily on the ‘Triple Power’ features of its tractors, namely the drawbar, power take-o and belt pulley. Many manufacturers quoted belt horsepower as well as drawbar and brake horsepower in their literature. The Nebraska Tractor Tests included belt horsepower test gures from their instigation in 1920 until the late 1950s, when PTO horsepower began ABOVE: The Marshall T20 stationary power unit was to replace the belt test.

based on the engine used in the 15-30 and 18-30

tractors. Marshall had high hopes for its two-stroke A lthough farms usually had a full diesel engines, but the numbers sold could be generating set for lighting, counted on one hand. mainly for the house and also if there was a poultry enterprise, the available power was not su cient to drive such barn machinery as grinding and rolling mills, cha cutters, root slicers and occasionally a water pump. Although these tasks on many farms were carried out by small petrol stationary engines, it was here that the tractor with its belt pulley came into its own. The tractor could easily be moved around the farm to “ When a Marshall traction engine was retired it was provide power for the barn machinery and the rewood saw bench. And of course the almost always replaced with a Marshall tractor” tractor wasn’t slow in replacing the traction engine to drive and move the threshing out t,

A Kent-registered Marshall Model M driving a Marshall drum. The drum is on factory-fitted pneumatic Dunlop wheels. Thrashing from a barn was a little unusual. The straw is being bunched and the bunches put back in the barn. The man with the feed bowl in his hand is adjusting the weight of corn in the bag standing on the weighing machine. As the bags come off the drum they will be catch weight and he has to add or take out grain (that’s what the 40-gallon barrel is for) until the scales just tip. Photo: MERL

A rare and early photograph of a 30bhp Marshall Type A two-cylinder ‘Oil’ tractor driving a similarly early drum. Note the bottle jack against the tractor back wheel; this would be hooked under a cleat on the wheel and wound-up when the belt needed tightening.

whether the farm’s own set or that of a contractor. It must have caused consternation among the old ‘steam’ men to see one of these early tractors weighing less than three tons happily doing the same job as their 10-ton traction engine.

The tractors’ lack of weight, however, was a serious problem when it came to moving the threshing set around the farmyard or on the road. In fact a steel-shod tractor moving a ‘set’ on the road on anything other than almost level going was dangerous.

So where does the Marshall diesel tractor t into this? Marshall had dabbled in the internal combustion engine tractor market from the very early 1900s with its ‘Colonial’ range of tractors. These machines were primarily aimed, as the name partly implies, at areas of the world where water and coal happened to be in short supply, but by a quirk of nature oil was relatively plentiful.

They made little impact on the market as similar products from the American manufacturers had already penetrated these areas. Marshall therefore gave up until interest was revived in the early 1930s when, a er studying a Lanz tractor, the company designed and built its rst diesel tractor, the 15-30.

The history of the development of the Marshall range of tractors is not a feature of this article as it has been covered in other books and articles. Here we will concentrate on the reasons for the success of its later machines. The design of the Marshall low-speed, single-cylinder diesel engine with its close governing properties made it a very successful source of power for the threshing set and other stationary applications.

LEFT: The heavy construction of the Marshall T20 stationary engine is very evident. Starting one of these was all a man on his own could manage.

On entering the market place, the Marshall tractor had several advantages over other available makes and the early 15-30 and 18-30 models should have had more success than they did. But being very expensive and beset by mechanical problems, they basically failed and production remained at very low levels. The take-over of Marshall by Thomas W. Ward from She eld gave the tractor programme a The Marshall could extract the new impetus and the smaller, less costly 12-20 biggest trees from the most diffi cult areas of woodland set the pattern for the future. It was followed by the model M and then the Series 1, 2 and 3 machines,

Marshall 18-30 tractors on the line at Gainsborough. Just 74 of these models and the early 15-30s were sold. They were too expensive, too heavy and prone to fuel problems and broken crank-shafts.

Marshall Model M and Field Marshall Mark 2 Contractors models at Trent Works, Gainsborough, in 1945. It is worth noting that the Series 1 was never known as such, it was either a Mark 1 (Agricultural) or Mark 2 (Contractors). Photo: Stuart Gibbard Archives

all of which became rm favourites with the farming fraternity.

As a power source for stationary work they were ideal, with the added advantage that they were heavy enough to handle a full threshing set on the road in most terrain. In addition to that, when tted with a winch, either Marshall’s own or by manufacturers such as Lainchbury, the Marshall tractor could manoeuvre threshing machines in the most di cult farmyard conditions with ease. With the belt pulley arranged on the end of the cranksha it was comparatively easy to line the belt up.

The Marshall Series 3 tractor engine ran in the opposite direction to the previous models and allowance had to be made between the models with an un-crossed or crossed belt. One minor disadvantage was that when the tractor

RIGHT: The Marshall 12-20 was welcomed by customers and set the Marshall diesel tractor on the way to becoming a house-hold force in the tractor market.

reversed to tension the belt the pulley had to turn with the transmission. To the old steam-era men this was of little concern as the same happened with the ywheel on a traction engine.

It should be said at this point the Marshalls enjoyed a high degree of customer loyalty and when a Marshall traction engine was retired it was almost always replaced with a Marshall diesel tractor. The only modi cation required to the threshing machine to change from steam to tractor power was that the pulley on the main drum sha had to be changed to allow for the higher speed of the tractor’s pulley. Of course, the Marshall wasn’t perfect, no machine ever is, and we mention a few of its minor shortcomings elsewhere – see ‘Marshall foibles’ panel. On

Marshall foibles

Marshall and Field Marshall tractors, as the later models were called, did have a few foibles. The exhaust, which was designed to minimise the effect of oil being blown out with the exhaust gases, would collect oil and soot. This was especially likely to happen during long spells of constant speed half-load running. The Marshall engine was not under anything like full load when threshing or other stationary jobs and if these deposits were not removed now and again they could catch fire – a dangerous and embarrassing situation when near stacks of corn.

There are tales of Marshall men who would remove the exhaust stack from the tractor and set fire to it to clear these deposits out. The engine oil reservoir had to be checked regularly as the engine lubrication system was of the total loss type; failure to do this could result in serious engine problems.

Marshalls and Field Marshalls were just about the only tractors that were capable of wearing their steering gear without moving. The continuous vibration from the engine was a source of considerable wear to the steering components.

the upside it had no magneto to give trouble, and the whole machine was simple and strong, even if some users referred to the transmission as being made from ‘Mangle Cogs’. The tractor would thresh all day on less than ve gallons of cheap diesel fuel and water consumption was negligible.

BELOW: A view of the Marshall stand at the 1951 Royal Show. A Field Marshall Series 3 with a Fisher-Humphries plough can be seen in the foreground, along with a Fowler Challenger III, Fowler VF and a Challenger III with a blade.

ABOVE: As this advertisement states the Field Marshall was very economical, simple in design, reliable and long-lived.

There is one more application of the Marshall diesel tractor that we should mention here and that is its role in the timber extraction industry. Again, tted with a winch, the Marshall could extract the biggest trees from the most di cult areas of woodland. Also the winch could be used to load the timber on to the timber ‘drugs’, which then pulled it up on to a hard road for transport to the sawmills by road-going timber tractors such as the Foden.

The Marshall would also drive the saw benches, which were sometimes used on site to reduce the timber to useable dimensions and then saw up the o -cuts for rewood. It was also in the timber industry that these tractors were subjected to the most abuse. Winching tree stumps out was the greatest cause of trouble. Severe winch loads could cause cracks to appear in the transmission casings and there is one record of a tractor being pulled clean in half when the front was anchored to a tree while trying to get a ‘hold’ to winch out a particularly stubborn stump.

All in all the Marshall tractor was very successful as a stationary power source, helped to a large extent by

“The tractor would loyal customers who stayed with it until the end. Marshall did thresh all day on less than fi ve gallons of cheap diesel fuel” produce purpose-built stationary versions of its tractor engines but they sold in tiny numbers and remain extremely rare as collectors’ items.

AMarshall handled a threshing set no better and no worse than other tractors of its day. An old Fordson could drive a drum with no problem, but wasn’t so suitable when it came to moving the set. Even with the arrival of tractors such as the IH W-9, the MinneapolisMoline GT and GTA, the Oliver 90 and the John Deere model D, the latter being a dream to listen to when threshing, the Marshall stood its ground and stood it well.

A Field Marshall Series 3 working with a Foster drum and Lanz press in February 1956. Photo: Stuart Gibbard Archives