and Evolution Time
General Motors introduced the first semi-automatic transmission, which
they called and promoted as the “Automatic Safety Transmission” or AST
for short. The AST had four forward speeds and used a
gear set and a friction clutch. Cadillac and Oldsmobile used
AST is some models from 1937 through 1939 and Buick offered it in the
1938 Buick Special for a limited time. In short, the
Safety Transmission was pretty much labeled a failure from the very
beginning. Besides being unreliable, the AST was a $80 option
cost Oldsmobile $140 per unit to manufacturer. Vehicle buyers
the time were also unreceptive to the AST, which made the decision to
discontinue the transmission after just 2 short years quite easy.
Automatic Safety Transmission was promoted as the New Driving
Sensation, but lasted on two years in production.
unsuccessful as the Automatic Safety Transmission, a newly designed
version of the AST by General Motors called the Hydra-Matic would
become legendary. This fully automatic transmission (the
transmission requiring no clutch pedal) debuted as a $57 option in the
1940 Oldsmobile. The Hydra-Matic was the world's first
mass-produced and commercially used fully automatic transmission.
as Oldsmobile’s advertising had overstated the capabilities and
reliability of the Automatic Safety Transmission, advertisements
promoting the new Hydra-Matic transmission were equally as
One advertisement claimed that the Hydra-Matic transmission represented
the most significant technological advancement since the
starter. Another advertisement claimed that the Hydra-Matic
transmission increased fuel economy by 10 – 15% over a standard
transmission. But, this time it was all true. The
Hydra-Matic fully automatic transmission was truly groundbreaking - it
established the foundation from which future automatic transmissions
would be designed and built.
the first true automatic transmission (no clutch pedal) consumers
ordered the $57 Hydra-Matic transmission option in impressive
numbers. By 1941, roughly 40% of all Oldsmobile passenger
and 30% of all Cadillac passenger cars sold in the U.S. were ordered
with Hydra-Matic transmissions.
1942, when automobile manufacturing plants stopped manufacturing
vehicles to build war machinery, more than 200,000 Hydra-Matic
automatic transmissions had been sold.
Hydra-Matic transmission did not have Park. Instead, a
pawl engaged when the transmission was shifted into Reverse and the
engine was shut off, which kept the vehicle from rolling when it was
automobile manufacturing plants building tanks instead of cars, use of
the Hydra-Matic transmission in military applications (primarily
tanks), without any major changes to the transmission solidified the
Hydra-Matic as being one of the most significant and important
developments in automotive history.
the post war boom, the demand for vehicles with automatic transmissions
continued to grow despite the increased cost. By late 1948,
of new Oldsmobile passenger vehicles sold were equipped with the
optional (and more expensive) Hydra-Matic transmission.
this same year, sales of Hydra-Matic equipped Cadillac passenger
vehicles had reached 95%. For Cadillac, the Hydra-Matic was a
$175 option. By this time, the Pontiac division of General
offered the Hydra-Matic tranny as a $150 option, which three out of
four buyers chose.
the loudest critics of the automatic transmission could not ignore the
facts; the commercial success of the Hydra-Matic automatic transmission
in passenger vehicles mandated that all car manufacturers offer an
automatic transmission as an option to the standard "manual"
transmission or risk going out of business.
the introduction of new automatic transmissions in the late 40s and
early 50s, the automatic transmission wars between the big automakers
1948, 1949 and 1950:
1948, the first fully automatic transmission using a torque converter
was introduced by Buick. Buick called their transmission the
"Dynaflow". Packard and Chevrolet promptly followed Buick
their own transmission designs, both of which incorporated the use of a
torque converter. Packard introduced the Ultramatic fully
automatic transmission in 1949 and Chevrolet introduced the Powerglide
fully automatic transmission in 1950. While these
had only two forward speeds, the use of a torque converter enabled
additional torque multipliers, effectively increasing the forward gear
ratios and forward speeds.
three-speed automatic transmissions using torque converters were
developed by Borg Warner in the early 1950s for a number of automakers
including Ford and Studebaker. In 1953, Chrysler introduced the
two-speed torque converter driven PowerFlite automatic transmission.
Other vehicle manufacturers, including Rolls Royce, Hudson, Bentley and
even Lincoln (a Ford Motor Company division) purchased Hydra-Matic
transmissions from General Motors to fill their needs.