Thornycroft Hathi
Encyclopedia
The Hathi was an early four wheel drive
lorry built by Thornycroft
in the 1920s. It was used by the British Army
as an artillery tractor
.
Training College, Aldershot
, using parts of a German Erhardt
tractor. Production models were built by Thornycroft
, 25 being built in 1924.
Although capable for its day, the Hathi was a complex and expensive vehicle which required regular maintenance if the front axle was to remain reliable. For most purposes it was soon replaced by 6×4 lorries with just as many driven wheels, but without the need for the complex combined driving and steering axle. Even half-track
s, particularly the Kégresse system, were more popular in this period.
As for other Thornycrofts the radiator surround was a massive casting (in aluminium, to save weight) topped by a brass header tank with the "Thornycroft" name prominently cast into it. A distinctive feature of the Hathi, appropriately giving its elephantine appearance, was the extreme width of the bonnet. The top panels of the bonnet cover were also noticeably concave and are recognisable in photos.
Prominent spare wheels were mounted high up, on each side of the rear bodywork.
for heavy vehicles in this period was difficult and the Hathi used a complex arrangement of bevel gear
s to transmit drive through the steering joints of the front axle. Rather than the common system of articulated drive shafts to the front hubs (the shaft either inside an axle casing or external), fixed shafts were used. Shafts inside the axle casing carried power to the ends of the axle, then a bevel gear drove a short shaft running through the steering kingpin. A further bevel on the outer part of the hub carrier (the part moving with the steering) drove the hub itself.
The constant velocity joint used to make modern articulated drive shafts was unheard of as yet and even the simpler Hooke-type universal joint
wasn't yet in common use. Thornycroft's usual practice for prop shafts at the time was to use a flexible leather disk joint
. To save weight, the axle casings were cast in aluminium.
" or "Inlet over Exhaust" arrangement, with overhead valves (in the head) for the inlets and side-valves (in the cylinder block) for the exhaust. Dry sump lubrication was used, to avoid problems when tilted off-road.
, as at this time the RASC supplied transport to the Royal Field Artillery
. Very few Hathi were built, possibly just the original batch of 25.
Hathi were still in reserve service in Australia in 1945.
collection, although it is not on regular display.
Four Wheel Drive
The Four Wheel Drive Auto Company, more often known as Four Wheel Drive or just FWD, was founded in 1909 in Clintonville, Wisconsin, as the Badger Four-Wheel Drive Auto Company by Otto Zachow and William Besserdich.-History:...
lorry built by Thornycroft
Thornycroft
Thornycroft was a United Kingdom-based vehicle manufacturer which built coaches, buses, and trucks from 1896 until 1977.-History:Thornycroft started out with steam vans and lorries. John Isaac Thornycroft, the naval engineer, built his first steam lorry in 1896...
in the 1920s. It was used by the British Army
British Army
The British Army is the land warfare branch of Her Majesty's Armed Forces in the United Kingdom. It came into being with the unification of the Kingdom of England and Scotland into the Kingdom of Great Britain in 1707. The new British Army incorporated Regiments that had already existed in England...
as an artillery tractor
Artillery tractor
Artillery tractor is a kind of tractor, also referred to as a gun tractor, a vehicle used to tow artillery pieces of varying weights.-Traction:...
.
Development
The Hathi prototype was developed by a team of P Company under Professor (honorary Colonel) Herbert Niblett of the Royal Army Service CorpsRoyal Army Service Corps
The Royal Army Service Corps was a corps of the British Army. It was responsible for land, coastal and lake transport; air despatch; supply of food, water, fuel, and general domestic stores such as clothing, furniture and stationery ; administration of...
Training College, Aldershot
Aldershot
Aldershot is a town in the English county of Hampshire, located on heathland about southwest of London. The town is administered by Rushmoor Borough Council...
, using parts of a German Erhardt
Erhardt
Erhardt is a surname, and may refer to:*Bruna Erhardt , Brazilian fashion model*Carl Erhardt , English Olympic ice hockey player*Christopher Erhardt , American video gamer producer...
tractor. Production models were built by Thornycroft
Thornycroft
Thornycroft was a United Kingdom-based vehicle manufacturer which built coaches, buses, and trucks from 1896 until 1977.-History:Thornycroft started out with steam vans and lorries. John Isaac Thornycroft, the naval engineer, built his first steam lorry in 1896...
, 25 being built in 1924.
Although capable for its day, the Hathi was a complex and expensive vehicle which required regular maintenance if the front axle was to remain reliable. For most purposes it was soon replaced by 6×4 lorries with just as many driven wheels, but without the need for the complex combined driving and steering axle. Even half-track
Half-track
A half-track is a civilian or military vehicle with regular wheels on the front for steering, and caterpillar tracks on the back to propel the vehicle and carry most of the load. The purpose of this combination is to produce a vehicle with the cross-country capabilities of a tank and the handling...
s, particularly the Kégresse system, were more popular in this period.
Construction
Bodywork of the Hathi was typical for the time with a wide bench-seated open cab and not even a windscreen. The only weather protection was a folding canvas roof.As for other Thornycrofts the radiator surround was a massive casting (in aluminium, to save weight) topped by a brass header tank with the "Thornycroft" name prominently cast into it. A distinctive feature of the Hathi, appropriately giving its elephantine appearance, was the extreme width of the bonnet. The top panels of the bonnet cover were also noticeably concave and are recognisable in photos.
Prominent spare wheels were mounted high up, on each side of the rear bodywork.
Transmission
Four wheel driveFour Wheel Drive
The Four Wheel Drive Auto Company, more often known as Four Wheel Drive or just FWD, was founded in 1909 in Clintonville, Wisconsin, as the Badger Four-Wheel Drive Auto Company by Otto Zachow and William Besserdich.-History:...
for heavy vehicles in this period was difficult and the Hathi used a complex arrangement of bevel gear
Bevel gear
Bevel gears are gears where the axes of the two shafts intersect and the tooth-bearing faces of the gears themselves are conically shaped.Bevel gears are most often mounted on shafts that are 90 degrees apart, but can be designed to work at other angles as well...
s to transmit drive through the steering joints of the front axle. Rather than the common system of articulated drive shafts to the front hubs (the shaft either inside an axle casing or external), fixed shafts were used. Shafts inside the axle casing carried power to the ends of the axle, then a bevel gear drove a short shaft running through the steering kingpin. A further bevel on the outer part of the hub carrier (the part moving with the steering) drove the hub itself.
The constant velocity joint used to make modern articulated drive shafts was unheard of as yet and even the simpler Hooke-type universal joint
Universal joint
A universal joint, universal coupling, U joint, Cardan joint, Hardy-Spicer joint, or Hooke's joint is a joint or coupling in a rigid rod that allows the rod to 'bend' in any direction, and is commonly used in shafts that transmit rotary motion...
wasn't yet in common use. Thornycroft's usual practice for prop shafts at the time was to use a flexible leather disk joint
Rag joint
A rag joint refers to certain flexible joints found on automobiles. They are typically found on steering shafts that connect the steering wheel to the steering gear input shaft, usually at the steering gear end. They provide a small amount of flex for a steering shaft within a few degrees of the...
. To save weight, the axle casings were cast in aluminium.
Engine
The engine was a Thornycroft GB6 11.3 litre straight-six petrol engine. As was common for the period, the cylinders were cast in two blocks of three. Valves used the "IOEIOE engine
The intake/inlet over exhaust engine, also known as F-head and pocket valve, is a valvetrain configuration used in early four-stroke internal combustion engines...
" or "Inlet over Exhaust" arrangement, with overhead valves (in the head) for the inlets and side-valves (in the cylinder block) for the exhaust. Dry sump lubrication was used, to avoid problems when tilted off-road.
Service career
Initial production was as an artillery tractorArtillery tractor
Artillery tractor is a kind of tractor, also referred to as a gun tractor, a vehicle used to tow artillery pieces of varying weights.-Traction:...
, as at this time the RASC supplied transport to the Royal Field Artillery
Royal Field Artillery
The Royal Field Artillery of the British Army provided artillery support for the British Army. It came into being when the Royal Artillery was divided on 1 July 1899, it was reamalgamated back into the Royal Artillery in 1924....
. Very few Hathi were built, possibly just the original batch of 25.
Use as a breakdown recovery vehicle
In 1926, at least one Hathi was converted as a breakdown recovery vehicle. A fixed jib with a small hand-operated winch was mounted on the rear deck, with the frame for a canvas tilt over it. Other examples were converted for the RAF and the Royal Navy, a naval example from Portsmouth Dockyard being the survivor today.Australia
Some time in the early 1930s a number of Hathi, possibly seven, were transferred to Australia.Hathi were still in reserve service in Australia in 1945.
Survival today
A single example survives today, in The REME Museum of TechnologyREME Museum of Technology
The REME Museum of Technology is located south east of Reading. The museum holds collections of various technological artifacts associated with the work of the REME, the corps of the British Army responsible for the maintenance, servicing and inspection of electrical and mechanical equipment hence...
collection, although it is not on regular display.