Fluid Drive
Encyclopedia
Fluid Drive is the trademarked name that Chrysler Corporation assigned to a transmission driveline combination offered from 1939 through 1953 in Chryslers, 1940 through 1953 in Desotos
, and from 1941 through 1954 in Dodge
models. The fluid drive element was a hydraulic coupling
inserted in place of the flywheel
, and performed the same function as a modern torque converter
, only without torque multiplication. A conventional clutch
and three-speed manual transmission
was installed behind the fluid coupling, although a semi-automatic was optional from 1941 for Chrysler and DeSoto and from 1949 for Dodge.
AG). Following the development of the fluid coupling, Sinclair in turn licensed the fluid coupling, now also known as ‘Fluidrive Coupling’ to many companies including the Chrysler Corporation. Many automobile historians confuse Chrysler’s Fluid Drive with the Corporation’s so-called semi-automatic M5/M6 transmissions, which were marketed under various names as “Simplimatic” (Chrysler), “Tip-Toe Shift” (DeSoto), and “Gyro-Matic” (Dodge). Unfortunately, Chrysler itself contributed to the confusion by referring to both the standard-shift fluid drive and M6 installations indiscriminately as "Fluid Drive" in much of their marketing and sales literature.
General Motors also used a fluid coupling for the full-automatic Hydramatic transmission, introduced for 1940.
and clutch
in tandem. If the Fluid Drive was mated to a manual transmission, the driver still needed to use the clutch to shift between any of the gears. The presence of Fluid Drive, however, prevented the driver stalling when taking off from a dead stop. The driver could also come to a stop in third gear without using the clutch and proceed without downshifting. It must be emphasized that Fluid Drive was not a transmission, only a fluid coupling between the engine and clutch.
Fluid Drive could also be mated to the semi-automatic transmission, which was not automatic in any way and should not be confused with Fluid Drive. With the semi-automatic transmissions, the driver shifted manually, selecting reverse or a low range and a high range. Each 'range' had two speeds. To shift between them, the driver accelerated then released pressure on the accelerator. In high range, this shift point was about 23 mph (37 kmh). The transmission shifted into high speed range, the driver then depressed the accelerator pedal, and continued accelerating. The solenoids on the transmission connected to the carburetor and ignition system and momentarily interrupted engine operation to allow trouble-free shifting.
The driver could down-shift for passing by fully depressing the accelerator. The clutch was needed to change between low and high range. The fluid drive system allowed the driver to stop at a light or in traffic and remain in gear without depressing the clutch. The driver could, if not concerned with fast acceleration, drive the car all day long in high range, stopping and starting, without ever having to touch the clutch pedal or gearshift lever unless faster acceleration or reversing was required. For this reason, DeSotos and Dodges were favored by city cab companies from the mid Forties to early Fifties.
The semi-automatic came under a variety of names - Vacamatic, Prestomatic, Fluidmatic (Chrysler), Simplimatic, Tip-toe Hydraulic Shift (DeSoto) and Gyromatic (Dodge).
A Fluid Drive Dodge with Gyromatic was far cheaper than a Hydramatic
-equipped Pontiac
, and had the effect of making city taxi-driving far easier. In 1950, a Dodge Coronet, which had Fluid Drive standard, offered Gyromatic for $94.60, while Hydramatic was a $158.50 option on Pontiacs.
The fluid drive fluid coupling was also used in conjunction with Chrysler’s M6 Presto-Matic semi-automatic transmissions. The M6 was in reality a two-speed manual transmission with a conventional clutch mounted behind the same fluid coupling unit that was installed in straight Fluid Drive cars.
The M4 Vacamatic had two forward speeds and reverse. There was a manual Pull-Cable to lock out the underdrive in the early models.
From 1949-1952, Dodge models with the conventional 3-speed Fluid Drive carried front fender emblems that said “Fluid Drive.” The M6 Models had emblems that proudly proclaimed “Gyromatic.”
In the 1941 brochure for Chrysler automobiles, a silhouette of the car's drivetrain was depicted against an outline of the car body, with the astonishing caption of an arrow pointing to the transmission: "Miracle Happens Here"! The transmission shown was an early variant (M4 "Vacamatic") of the later M6 transmission and was marketed to compete with the new Oldsmobile
fully automatic, clutchless Hydramatic
transmission, introduced in the fall of 1939 on 1940 Model year Oldsmobiles. The Hydramatic was embraced enthusiastically by consumers, and was installed in 45% of 1941 Model Oldsmobiles.
DeSoto (automobile)
The DeSoto was a brand of automobile based in the United States, manufactured and marketed by the Chrysler Corporation from 1928 to 1961. The DeSoto logo featured a stylized image of Hernando de Soto...
, and from 1941 through 1954 in Dodge
Dodge
Dodge is a United States-based brand of automobiles, minivans, and sport utility vehicles, manufactured and marketed by Chrysler Group LLC in more than 60 different countries and territories worldwide....
models. The fluid drive element was a hydraulic coupling
Fluid coupling
A fluid coupling is a hydrodynamic device used to transmit rotating mechanical power. It has been used in automobile transmissions as an alternative to a mechanical clutch...
inserted in place of the flywheel
Flywheel
A flywheel is a rotating mechanical device that is used to store rotational energy. Flywheels have a significant moment of inertia, and thus resist changes in rotational speed. The amount of energy stored in a flywheel is proportional to the square of its rotational speed...
, and performed the same function as a modern torque converter
Torque converter
In modern usage, a torque converter is generally a type of hydrodynamic fluid coupling that is used to transfer rotating power from a prime mover, such as an internal combustion engine or electric motor, to a rotating driven load...
, only without torque multiplication. A conventional clutch
Clutch
A clutch is a mechanical device which provides for the transmission of power from one component to another...
and three-speed manual transmission
Manual transmission
A manual transmission, also known as a manual gearbox or standard transmission is a type of transmission used in motor vehicle applications...
was installed behind the fluid coupling, although a semi-automatic was optional from 1941 for Chrysler and DeSoto and from 1949 for Dodge.
History
The fluid coupling and torque converter was invented by the German engineer Foettinger in the early 1900’s. For non-marine applications he licensed the development of the fluid coupling to the British engineer Harold Sinclair and his Fluidrive Engineering Co Ltd (now part of VoithVoith
The Voith GmbH, which is headquartered in Germany, is a family-run corporation in the mechanical engineering sector with worldwide operations....
AG). Following the development of the fluid coupling, Sinclair in turn licensed the fluid coupling, now also known as ‘Fluidrive Coupling’ to many companies including the Chrysler Corporation. Many automobile historians confuse Chrysler’s Fluid Drive with the Corporation’s so-called semi-automatic M5/M6 transmissions, which were marketed under various names as “Simplimatic” (Chrysler), “Tip-Toe Shift” (DeSoto), and “Gyro-Matic” (Dodge). Unfortunately, Chrysler itself contributed to the confusion by referring to both the standard-shift fluid drive and M6 installations indiscriminately as "Fluid Drive" in much of their marketing and sales literature.
General Motors also used a fluid coupling for the full-automatic Hydramatic transmission, introduced for 1940.
Configuration
The standard Fluid Drive configuration consisted of the fluid coupling and a manual transmissionManual transmission
A manual transmission, also known as a manual gearbox or standard transmission is a type of transmission used in motor vehicle applications...
and clutch
Clutch
A clutch is a mechanical device which provides for the transmission of power from one component to another...
in tandem. If the Fluid Drive was mated to a manual transmission, the driver still needed to use the clutch to shift between any of the gears. The presence of Fluid Drive, however, prevented the driver stalling when taking off from a dead stop. The driver could also come to a stop in third gear without using the clutch and proceed without downshifting. It must be emphasized that Fluid Drive was not a transmission, only a fluid coupling between the engine and clutch.
Fluid Drive could also be mated to the semi-automatic transmission, which was not automatic in any way and should not be confused with Fluid Drive. With the semi-automatic transmissions, the driver shifted manually, selecting reverse or a low range and a high range. Each 'range' had two speeds. To shift between them, the driver accelerated then released pressure on the accelerator. In high range, this shift point was about 23 mph (37 kmh). The transmission shifted into high speed range, the driver then depressed the accelerator pedal, and continued accelerating. The solenoids on the transmission connected to the carburetor and ignition system and momentarily interrupted engine operation to allow trouble-free shifting.
The driver could down-shift for passing by fully depressing the accelerator. The clutch was needed to change between low and high range. The fluid drive system allowed the driver to stop at a light or in traffic and remain in gear without depressing the clutch. The driver could, if not concerned with fast acceleration, drive the car all day long in high range, stopping and starting, without ever having to touch the clutch pedal or gearshift lever unless faster acceleration or reversing was required. For this reason, DeSotos and Dodges were favored by city cab companies from the mid Forties to early Fifties.
The semi-automatic came under a variety of names - Vacamatic, Prestomatic, Fluidmatic (Chrysler), Simplimatic, Tip-toe Hydraulic Shift (DeSoto) and Gyromatic (Dodge).
A Fluid Drive Dodge with Gyromatic was far cheaper than a Hydramatic
Hydramatic
Hydramatic was an automatic transmission developed by both General Motors' Cadillac and Oldsmobile divisions. Introduced in 1939 for the 1940 model year vehicles, the Hydramatic was the first fully automatic mass-produced transmission developed for passenger automobile use.-History:During the...
-equipped Pontiac
Pontiac
Pontiac was an automobile brand that was established in 1926 as a companion make for General Motors' Oakland. Quickly overtaking its parent in popularity, it supplanted the Oakland brand entirely by 1933 and, for most of its life, became a companion make for Chevrolet. Pontiac was sold in the...
, and had the effect of making city taxi-driving far easier. In 1950, a Dodge Coronet, which had Fluid Drive standard, offered Gyromatic for $94.60, while Hydramatic was a $158.50 option on Pontiacs.
M4 and M6 transmissions
- Main articles: VacamaticVacamaticThe 1941 M4 Vacamatic transmission by Chrysler was, historically, the first semi-automatic transmission which was marketed by a major manufacturer. It was an attempt to compete against rival's automatic transmissions, though it still had a clutch, primarily to change range. In normal driving, the...
and Presto-MaticPresto-MaticThe M6 Presto-Matic was a Chrysler Corporation transmission produced from 1946-1953. It was a hybrid manual transmission with a torque converter or fluid coupling like an automatic...
The fluid drive fluid coupling was also used in conjunction with Chrysler’s M6 Presto-Matic semi-automatic transmissions. The M6 was in reality a two-speed manual transmission with a conventional clutch mounted behind the same fluid coupling unit that was installed in straight Fluid Drive cars.
The M4 Vacamatic had two forward speeds and reverse. There was a manual Pull-Cable to lock out the underdrive in the early models.
From 1949-1952, Dodge models with the conventional 3-speed Fluid Drive carried front fender emblems that said “Fluid Drive.” The M6 Models had emblems that proudly proclaimed “Gyromatic.”
In the 1941 brochure for Chrysler automobiles, a silhouette of the car's drivetrain was depicted against an outline of the car body, with the astonishing caption of an arrow pointing to the transmission: "Miracle Happens Here"! The transmission shown was an early variant (M4 "Vacamatic") of the later M6 transmission and was marketed to compete with the new Oldsmobile
Oldsmobile
Oldsmobile was a brand of American automobile produced for most of its existence by General Motors. It was founded by Ransom E. Olds in 1897. In its 107-year history, it produced 35.2 million cars, including at least 14 million built at its Lansing, Michigan factory...
fully automatic, clutchless Hydramatic
Hydramatic
Hydramatic was an automatic transmission developed by both General Motors' Cadillac and Oldsmobile divisions. Introduced in 1939 for the 1940 model year vehicles, the Hydramatic was the first fully automatic mass-produced transmission developed for passenger automobile use.-History:During the...
transmission, introduced in the fall of 1939 on 1940 Model year Oldsmobiles. The Hydramatic was embraced enthusiastically by consumers, and was installed in 45% of 1941 Model Oldsmobiles.