Development of the Mechanical Horse
In the late 1920’s the railway companies
were looking for a suitable vehicle to use on their town parcels delivery
traffic, which was predominately horse drawn. The London Midland & Scottish
Railway experimented with various ideas and in late 1930 announced, jointly with
Karrier Motors, a tractor unit for this purpose. The vehicle, the Karrier Cob,
was powered by a twin cylinder Jowett engine and utilized a mechanism to couple
existing horse trailers to the tractor unit. Meanwhile the London and North
Eastern Railway had approached Napier's, the quality car and aero-engine makers
for an answer to the same problem. They came up with some ideas, but didn’t wish
to develop the concept and sold the project to Scammell Lorries of Watford.
Their designer, O. D. North refined and further developed the concept of the
three wheel tractor unit which automatically coupled and un-coupled trailers and
in 1934 announced the introduction of the Mechanical Horse.
The Mechanical
Horse
This
was a very simple and sturdy vehicle constructed on a steel channel frame with a
cab made of wood, the early versions having canvas doors. The Mechanical Horse
came in two sizes, capable of carrying loads of 3-ton and six ton, These were powered by Scammell's own
side valve petrol engine of 1125cc (3-ton) and 2043cc (6-ton), The engine was
situated offset to the left. The vehicles are very manoeuvrable, (with a 16 foot
trailer they can turn through 360O in 19 feet) have a road speed of
about 20 mph and do between 10 and 20 mpg. They were used by quite a number of
companies including the armed forces where they were used in stores and on
aircraft carriers as well as with railway companies. The 6-ton coupling was also
fitted to popular makes of light trucks such as Bedford’s.
Scammell Scarab
After the end of the Second World War, Scammell
Lorries looked at the Mechanical Horse, which was basically unchanged from its
1934 design, realised that something more modern was called for and set about
re-designing the vehicle. The successful Automatic Coupling was retained, but
the rest of the tractor was completely new. The frame was cranked downwards, the
engine, gear box and rear axle were built as one unit and fitted low down in the
frame behind the cab, the radiator was fitted in the back wall of the cab,
drawing cooling air from a duct behind the driver’s door. The side valve petrol
engine of 2090cc was used for both the 3 and 6-ton models. Later Scammell
offered diesel engines. These were the Perkins 4-199 for 3-ton and P4 and P4203
for six ton. The low mounting of the engine and other design changes made the
Scarab more stable and its rounded all steel cab was more comfortable for
drivers. The Scarab lasted in production until 1967.
The
Scammell Townsman
The
“New” Scammell Townsman three wheeler replaced the 3-ton Scarab in the Railway
industry. It closely followed the Scarab in its basic design at the front. The
futuristic lines of the fibreglass cab hid a great many new developments, such
as vacuum-assisted hydraulic brakes. Fitted equipment included a
heater-demister, two rear view mirrors,
interior sun-visors, totally enclosed oil-immersed coil spring front
suspension and duel rate mounting of semi-elliptic leaf springs at the rear. An
unusual feature of the day was provision on the steering column for a Waso lock.
The frame was of a welded construction and had integral coupling ramps fitted
with Scammell Mechanical Horse automatic coupling. A vacuum operated release
mechanism replaced the hand lever in the Scarab. The engine, gearbox and driving
axle formed a ridged assembly pivoted at the front end in a large rubber bush.
The
Townsman is seen here in its familiar “later” British Railway Yellow livery.
Later a larger engine was supplied and fitted - the Leyland OE160, but even with
its better driver controls and faster road speed, (50mph) it was mainly supplied
to British Rail. A few however
found employment with other operators including The Royal Mail. Production ended
in 1968.
The Reliant Ant
The last flowering of the Mechanical Horse (three wheeled) concept is by Reliant who
with Dunn BTB produced an articulated version of their TW (Three wheeler) 9.
This is a 3/4 ton pick up. Several members of the club have these vehicles and
the club have welcomed them for their contribution to the preservation &
restoration of these classic vehicles. Most are of the pick up truck variety,
but one artic unit survives, pictured below.
The TW9 was produced by
Reliant in the late 1960s onward and is still being made overseas. The design
was taken on by Dunn BTB and called the ANT. A lot of the production went abroad, especially to
Greece & Turkey
The engine is Reliant
own 750cc aluminium unit with a 4 speed gearbox. The chassis is a pressed steel
frame with tubular cross members. The truck has a payload of 16 Cwts and does
60mph and around 35 miles per gallon. The cab is a Fiberglas moulding. A variety
of bodies were offered by various different coachbuilders and included dustcart,
tower wagons, tippers and street washers/gully cleaners and suckers as well as
the pick up truck. Quite a lot of the vehicles were Milk floats or were used by
council Parks & Gardens Departments.
With their
Fiberglas
cab and sturdy chassis construction, these vehicles are fairly easy to restore.
parts are still available from Reliant parts or from your local motor factor. A
lot of proprietary parts were used by Reliant - for example the front brakes are
from the Ford Escort and the rear ones from a Ford Capri. The engine is the same as that
used in the contemporary Regal and later the 850cc Robin engine can be easily be fitted.
The trucks are quite
nippy and economical and make excellent runabouts.
The Mechanical Horse
Club has links with Reliant Club, especially in the Essex area who's Chairman
and Club historian Bob Neale is a member of both clubs.
Reliant is now
importing the three wheeled APE a 5 Cwts truck made by Piaggio
Home
Page