3 GREAT MAGS INSIDE

Four-wheel drive is virtually standard on most farm tractors these days but, as Pete Small explains, it took a very long time for it to be a musthave specification

Gaining extra traction has always been a key aim of tractor designers as they tried to improve the grip of wheeled machines.

In the very early days all sorts of designs were tried, including a single wide drum-type driven rear wheel and even three-wheel drive.

However, one of the pioneers of a true fourwheel-drive wheeled tractor was farm machinery giant Massey Harris.

The Canadian firm was famous for its hay and harvest machinery and had dabbled in tractors since the First World War, but tended to badge engineer

“A brave decision to design its own revolutionary tractor”

existing models from other makers.

In 1928 it put down a marker of intent by purchasing the JI Case Plow Works, which gave it the successful Wallis line of tractors.

Not content with just developing the Wallis designs, the firm took the brave decision to design its own revolutionary tractor.

Despite buying the wellregarded line of Wallis tractors, Massey was keen to bring out a design which it was thought to have been working on before the acquisition.

Launched in 1930, the ground-breaking new tractor was called the Massey Harris General Purpose, or GP, and was the first mass-produced four-wheel drive.

It was powered by a Hercules four-cylinder side-valve distillate engine. This was positioned well forward over the front axle to put weight on the driven front wheels, with implements on the back end giving weight to the rear axle.

It was rated at 15 horsepower (hp) on the drawbar and 22hp at the belt pulley. With good ground clearance, it was ideal for travelling through growing crops.

There was a choice of five track widths depending on what crops it was likely to be working in, and an orchard version was also available.

There was also a choice of wheel types from spade lugs to skeletal wheels for delicate row-crop work, and subsequently rubber tyre options.

“Appealed to many arable operations in Angus and Fife”

It had three forward gears, with a top speed of 4mph.

An oscillating back axle to make it more able to cope with uneven ground.

Optional extras included electric starting and lighting, power take off, power lift, and extension controls for riding on a following implement such as a binder.

Massey Harris also launched several implements to match the tractor. These included the No 23 plough, a powerdriven mower, and tool-bar attachments to use with the power lift system in a rowcrop environment.

The GP was brought to the UK in 1931 and seems to have found more favour on this side of the Atlantic compared to North America.

Many of the cropgrowing areas of North America tended to be flatter than those over here and in less need of extra traction.

Many of these farmers still preferred a threewheeled row-crop tractor with mounted tool bars as they were much more manoeuvrable compared to the GP, which needed more than six feet to turn.

However, the GP was seen as a beneficial tool by some progressive UK farmers working steeper ground and often wetter soil.

Its high clearance, dedicated row width, power lift and of course extra traction appealed to many of the arable operations in Angus and Fife, especially with their potatoes, sugar beet and fodder root crops.

In 1936 Massey Harris introduced an improved version with its own overhead valve fourcylinder engine.

These later models are easily recognised by their sloping bonnets.

Although popular with some owners the extra cost involved in the purchase was a stumbling block, while other operational problems were highlighted when in the field.

It was noticed when working on steeper land that the shallow oil sump led to starvation of lubricating oil to crankshaft bearings while working up and down slopes.

These slopes often proved problematical due to the light rear end, and reversing up slopes was not recommended as the tractor could tip forward.

Weak castings on the top of the drop boxes on the front wheels often cracked and needed welding up.

Like so many innovative designs the slow sales were also due to this iconic tractor being too far ahead of its time.

Another 50 years passed before four-wheel drive really took off.

GROUNDBREAKING: A Massey Harris GP working in Glenogil in Angus during the 1930s – the model seems to have found more favour on this side of the Atlantic

One of the innovative Massey Harris GPs – which could once be seen at work in Newburgh in Fife – but is now in preservation in England

The Massey Harris GP was well suited to pulling a trailing combine