David Roberts: Tractor Pioneer Extraordinary

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This Hornsby tractor was built in 1896. It featured a 20 HP oil engine of Akroyd design.
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Hornsby built a 40 HP tractor in 1903 on wheels and converted it to a tracked machine in 1906.
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Hurley, Berkshire England SL6 5LL

The following article, which is reprinted from Guard magazine,
was sent to us after a friend sent Russell Jones a copy of the
September/October 1984 issue of IMA. That issue contained a letter
and picture from George E. Hoffman, 9312-173A Street, Surrey, B.C.,
Canada V3S 5X7, asking for identification of the crawler he had to
restore. This article provides background information on that

The Englishman David Roberts is perhaps one of the least known
pioneers of the crawler tractor.

As the Chief Engineer, and later as the Managing Director of the
company Richard Hornsby & Sons Ltd., of Grantham, Line, his
design concepts promised world leadership at the turn of the

The machines he designed and built were at least a decade ahead
of any other development being worked on in the world at that

The strength was his engineering capability and the weakness
which frustrated the commercial development of his ideas was the
weakness in sales and marketing.

This weakness resulted in the decline of Richard Hornsby as a
company and the abandonment of their brilliant pioneering work on
the crawler tractor. Perhaps the whole situation is best summed up
by the press comment made sometime after the closure of the

‘Unfortunately the firm’s marketing was not always able
to match up to the situation either. Advertising seems to have been
a particularly weak point with Hornsbys. They neither advertised as
frequently nor as effectively as their competitors. Unlike their
engineering products, the Hornsby’s advertisements tended to be
unimaginative, and many good opportunities for promotion were

When one researches the progress and development of many British
companies, one sees the same trend repeated again and again. The
Roberts saga is especially disappointing as his designs and his
prototype machines showed great promise, which if the need for
marketing had been identified, they could have taken advantage of
enormous markets which within five or six years were identified by
American pioneers led by Benjamin Holt.

Whilst David Roberts gave up his work because he was incapable
of developing markets, the Holt organisation moved ahead strongly
and opened up sales opportunities in many parts of the world and
was soon manufacturing crawler tractors on a volume basis.

The Roberts story starts in 1903 when the war office offered a
prize of 1000 for a tractor which could haul a 25 ton load for a
distance of 40 miles without stopping to take on extra fuel or
water. This was a serious attempt to progress beyond the age of the
steam traction engines whose range depended on plentiful supplies
of fuel and water.

Messrs. Richard Hornsby & Sons Ltd of Grantham,
Lincolnshire, welcomed this competition. They had had long
experience with steam traction engines, and had built their first
oil engined tractor in 1896. This was a 20 HP machine, powered by a
horizontal single cylinder Hornsby Akroyd oil engine. Their entry
for the competition was an 80 HP twin cylinder machine. One
cylinder was horizontal, the other was inclined 30 degrees upwards.
The tractors had 4 speeds and weighed 12 tons.

From several entrants, the Hornsby tractor was the only one to
complete the course of 40 miles. A bonus of 10 per mile had been
promised for every mile in excess of 40. The Hornsby travelled a
total distance of 58 miles before running out of fuel thus earning
a bonus of 180 in addition to the 1000 First Prize.

Hornsbys were seeking much bigger prizes. Their Chief Engineer,
David Roberts, had an ambition to mechanise the Army’s military
units. He was secretly working on his chain track invention which
would enable tractors to travel with certainty and safety over
loose sand, soft ground, river courses, bogs and uneven ground.
Such surfaces were often impassable for traction engines fitted
with wheels. In 1904 Roberts took out his British Patent No. 16,345
which claimed: ‘My invention relates to Improvements in
Traction Engines, Road Locomotives and Motor Vehicles, or Vehicles
to be drawn thereby.

‘It is well known that traction engines or other heavy road
vehicles as now constructed are limited in their use by reason of
their wheels sinking to too great an extent when travelling over
soft or sandy ground and over surfaces of considerable

‘Now this invention has for its object to obviate this
defect and to this end the locomotive or other vehicle is mounted
upon a pair of front and a pair of rear wheels provided or formed
with peripheral sprocket teeth; these wheels are mounted upon front
and rear shafts respectively and either or both pairs may be driven
through the ordinary spur gearing when the vehicle is a
self-propelled vehicle.

The 1896 machine from Hornsby was redesigned in 1905 and
equipped with full tracks. The engine was the same single cylinder
used in the wheeled unit.

‘Two pitched chains of links and pins with cross bars or
blocks of metal or wood to make contact with the ground are passed
around the front and rear sprocket wheels, one on each side of the
vehicle and form a track. The weight of the vehicle body (and
engine) is taken by side brackets provided with curved pathways or
bearing surfaces resting on rollers which, in turn, are supported
on the chains, or on rollers of large diameter revolving on fixed
pins. With this arrangement when the vehicle is running the body
is, so to say, rolled forward on the chains. Steering may be
accomplished by varying the speed of the driving sprocket wheels on
either side of the vehicle. Dated this 23rd day of July,

Four further patents were taken out by Roberts in the following

No. 23,736 of 17th November 1905 claimed: ‘Improvements in
or connected with Road Locomotives and Vehicles.’

No. 7,289 of 26th March 1906 claimed: ‘Improvements in
Variable Speed Driving Gear.’

No. 19,574 of 31st August 1907 claimed: ‘Improvements in or
connected with the steering of Road Locomotives and

No. 16,436 of 14th July 1909 claimed: ‘Improvements in and
connected with the Driving Axles of Chain Track Tractors and

In 1905 one of the 1896 type single cylinder oil tractors was
fitted with the Roberts chain track. This machine was rated at 20
HP and weighed 17 tons. Trials at Grantham in July 1905 and
February 1906 were observed by War Office staff.

Encouraged by the success of the first chain track tractor, the
1903 prize-winner was fitted with chain tracks in August 1906.
Private trials of this machine were carried out in July 1907. It
was on this occasion that the British ‘Tommies’ coined the
name Caterpillar to describe the fantastic machine. These trials,
again, were very successful and it was decided that royalty would
have the pleasure of inspecting the new invention. In May 1908
trials at Aldershot were attended by King Edward VII and the Prince
of Wales (later King George V). David Roberts had the honour of
being presented to the royal observers at the trials. This must
have been his proudest moment. It seemed his ambition was about to
be realised. At his suggestion dummy wooden guns were fixed to
trailers which were also fitted with chain tracks. The Army were
indeed interested. Glowing reports were produced by the Army
Mechanical Transport Committee. With the basic idea proved, Roberts
decided to experiment with faster machines, to see what speeds
could be attained.

A further development was the steam powered crawler built for
the Yukon. This machine has recently been located near Vancouver,

The Hornsby machine met with little commercial success whilst
Holt of America moved ahead with expanding worldwide sales. The
track design of Hornsby was sold to Holt and the English company
gave up their development work,

In August 1906 Hornsbys had purchased a 40 HP petrol-engined
Rochet-Schneider car. This was fitted with chain tracks in 1907 and
was thoroughly tested at Grantham before being taken to Aldershot
for Army Trials in November 1907. This lightweight machine,
weighing only 4 tons, achieved speeds of 15 mph, over rough ground.
Hornsbys commissioned a movie film of this model, to be shown in
London and provincial cinemas as part of an advertising campaign to
sell the chain-track idea for a variety of uses. The film was
included on the bill of the Empire Theatre in Leicester Square,
London, in the summer of 1908. Other attractions on the same bill
were: ‘The Belle of the Ball’ featuring Adeline Genee, a
world famous Danish dancer, and ‘Dialect Recitations’ by a
gentleman. Even so, the star item was, without doubt, the Hornsby
film, which incidentally is reputed to be the first film ever made
for commercial purposes.

So far each of the tractors built was designed for operation
over rough, hilly or boggy land. David Roberts’ fertile mind
turned next to a vehicle suitable for desert warfare. This had to
be a light tractor capable of operating at high speeds on sand. In
1908 a 75 HP Mercedes car was purchased. It was powered by a
6-cylinder petrol engine. In contrast with the Rochet-Schneider,
the Mercedes was fitted with wooden wheels to carry the chain
tracks. Trials were held on the beach at Skegness during 1908 and
1909 when speeds of 25 mph were attained! Such speeds were not
achieved by any other tracked vehicle until the Second World

All the work at Grantham was not restricted to chain tractors.
Wheeled Tractors were constantly being improved. The War Office
purchased three 50 HP four-cylinder oil engined tractors in 1909
and conducted extensive road trials. This purchase was quickly
followed by an order for similar machines fitted with chain tracks.
Four tractors were purchased. The first Hornsby No. 35082, was a 60
HP six-cylinder oil engined machine, delivered to the War Office on
5th May 1910. The other three machines were all fourcylinder 50 HP
oil engined tractors. They were delivered on 16th July (two
machines) and 26th July 1910. No. 35082 was driven by road all the
way from Grantham to Aldershot. This machine was converted to
petrol fuel in 1911, raising the HP to 105. It is the only one of
the War Office machines to survive, and is preserved in the Royal
Armoured Corps Tank Museum at Bovington, Dorset.

Hornsby’s main effort was aimed at mechanisation of the Army
Artillery units although they expected to find a large market
amongst civilians wherever a machine was required to operate in
difficult terrain.

Although Hornsby’s designs were, in the writer’s
opinion, brilliantly ahead of the world, the facts are they only
sold one machine in their history for civilian use.

This contrasts with the brilliant success of Holt and Best and a
number of other manufacturers, who within a year or so of the
Hornsby developments, had thousands of machines at work.

The only crawler tractor that Hornsby sold commercially, was to
work on hauling coal in the Yukon. This was an 80 HP, 25 ton
machine. Due to operational conditions, the machine was not a great
success. What is interesting, is that this tractor still exists in
Vancouver, Canada, and currently work is afoot to restore it to
working condition.

So apart from this isolated machine, Hornsby’s campaign to
replace wheels with chain tracks (by now commonly called
‘Caterpillar’ tracks) was having little success. Despite
the various tractors that had been sold to the War Office, a
similar fate was in store for military applications of the
revolutionary idea. The following extracts from Army reports are
indicative of their attitude:

‘It is impossible in a column with other troops, its noise
and smell are abominable and very few horses will pass it. The
wooden blocks forming its feet are nearly worn away, and it is
unable to carry sufficient fuel for itself for any time, and its
machinery appears to be unreliable. The team of eight horses in my
opinion is far superior under every condition.’ Thus spoke a
Horse-Artillery senior officer!

The War Office Mechanical Transport Committee replied as

‘If mechanical transport is sandwiched in between
horse-drawn vehicles in a column or route it will always show to a
disadvantage, because it is slower up the hills and retards the
column, but on the level or downhill it will be impeded by

‘Increased horse-power of the engine will also tend to
remedy slowness on bad roads, but it should be borne in mind that
the Committee never contemplated that the tractor should work in
columns of horse-drawn vehicles, as in principle mechanical
transport does not fit in with horse transport,.. .the present
machine is more noisy than desirable or necessary, but it should be
remembered that the design is experimental. So far as fuel capacity
is concerned, the tractor can carry sufficient fuel to take it 100

The tractor in question was returned to Hornsby’s factory
where the engine was converted from paraffin to petrol. Many other
improvements were made to the machine and it was driven by road
back to Aldershot where it completed further successful trials with
the Heavy Brigade. Even so, it remained an experimental vehicle as
far as the artillery officers were concerned.

By the end of 1913 Hornsby’s had become thoroughly
disillusioned. Thus, early in 1914 they sold the patent rights of
the chain-track invention to the Holt Manufacturing Co. of New York
for the sum of 4000. Holts had been working on chain track designs
for a number of years. They had preferred to concentrate on a
combination of tracks and a wheel for steering.

Within a year the War Office were placing orders for hundreds of
chain track tractors to the Holt design! Rustons built 442 of these
machines at Lincoln under license from Holts. They were
four-cylinder 60 HP petrol engined machines, powered by
Baker-Perkins engines produced at Peterborough. They were fitted
with a two-speed gearbox. Steering was controlled by the
front-mounted wheel, assisted by separate brakes and clutches
acting on the chain tracks. A number of these Ruston built tractors
were shipped to Russia.

No evidence can be found of any further Hornsby interest in
chain (Caterpillar) tracks.

The David Roberts story commenced in 1895 when he joined the
firm of Hornsby as their Chief Engineer. Clearly the records show
that his engineering ideas were years ahead of the world. One
ponders on the questions, where would the company be today if their
marketing skills and awareness had been as strong as their
engineering vision.

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