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The British truck building firm Thornycroft was founded in 1896 but is with us no longer.
After WWI, Thornycroft built a number of 4x4 Hathi (Hindustani for elephant) trucks and it is believed that perhaps seven of them came to Australia.
During this period, the British War Department
patented a flexible rear suspension for six wheeled lorries
which was used by various manufacturers including Thornycroft.
(An installation in a 6x4 Thornycroft is shown right.)
It involved upper and lower inverted semi-elliptical leaf
springs. The connection from the end of each spring
to an axle was fully articulated so that there was no
twisting force on the spring leaves.
Bushes at this point had a certain amount of side-play
so that there were no side forces either, even with an axle
at an extreme angle.
Many British lorries were built under a subsidy scheme where the government paid part of the running costs on the understanding that the truck could be resumed for war service; in order to qualify trucks had to be sufficiently agile offroad. 4x4's and 6x4's with the department's rear suspension qualified and the 6x4's were understandably more attractive to road haulage firms.
Thornycroft persevered with the 6x4 suspension system after WWII, using it on the Nubian 6x6, which was the basis of many an airport Fire Tender.
The Mighty Antar 6x4 prime mover
is perhaps the most famous Thornycroft truck.
It was used as a tank transporter by the British Army
from 1952 until the 1980's.
Thanks to Bill Dawe and Gregor Rusden of the Historic Commercial Vehicle Club for information.
