One unusual American prototype of the tank was the
gas-electric hybrid built by Holt. It had a crew of six and used a
Holt four-cylinder motor to turn a generator in order to power two
electric track motors. This design was later used for giant mining
trucks and highway construction vehicles.
General Swinton visited Benjamin Holt in Stockton,
California, to salute him for his contribution to the war effort
and to inspect the Holt one-man tank prototype. Because the war
ended, the tank was never manufactured.
Most tanks used in World War I were of European manufacture, but
the Caterpillar and Bullock tractors had much influence on some
designs. In France there were differences and conflicts in the
approach to tank design. As an example, the French Schneider
Company bought two 45 hp Baby Holts (Holt 75) in April of 1915 and
used these as a basis for their versions, which had one 75 mm gun
and two Hotchkiss machine guns. The whole tank weighed 13.5 tons.
It was first tested at the Aberdeen Proving Ground in Maryland.
General Ernest Swinton traveled to Stockton in 1918 to meet with
Benjamin Holt to express his gratitude for the company’s
contribution to the war effort. Holt had also built a gun-mount
Caterpillar tractor capable of carrying a 75 mm gun at the then
unheard-of speed of 28 mph. Advances in metallurgy made this a
possibility so that transmission components would not disintegrate
from heat and friction, but it would be a number of years before
this would be proven in the field. A one-man tank prototype was
also developed by Holt/Caterpillar in Stockton, but it never went
into production. Existing photos show General Swinton thanking and
shaking hands with Benjamin Holt surrounded by Stockton factory
workers in front of a wooden mock-up of the tiny one-man tank.
Another single prototype was built by Holt in conjunction with
General Electric Company (GEC). It was completed in January of
1918. It used lengthened and upgraded iterations of the Holt
tractor with pivoting track frames on vertical coil springs and ten
road wheels on each side. The Holt Gas-Electric used a 90 hp Holt
four-cylinder motor to drive a GEC generator that powered two
electric motors, one for each track. By varying the current in
addition to the brakes on each shaft, the tank could be steered
more easily. This vehicle had a 75 mm gun in the nose and a
.30-caliber Browning machine gun on each sponson. The engine and
transmission at the rear nearly blocked the only door in and out of
the tank with a crew of six: commander, driver, gunner, loader and
two machine gunners. Only a prototype was built, but with its
weight of 25 tons it had considerable shortcomings in climbing and
speed, which was about 6 mph at best. Armor was between 1.4-inch
and 3.4-inch thick depending on section area.
This design was later used by a few companies, such as
Caterpillar, to build huge roadbuilding trucks and graders, even up
to this day. There was also a 20-ton tractor mounted with a truck
body, and this crawler was used to build yet another prototype also
called the ‘American Tank.’
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