THE CHEVROLET
TURBOGLIDE TRANSMISSION

First appearing as an option for the 1957 Chevrolet, the Turboglide transmission was a marvel of engineering. The problem was that too many people did not understand what it was, what it was designed to do, and what it was not designed to do. And when they misused it, they broke it.

The wonderful design:

1957 Chevrolet

1957 Chevy
 

The Turboglide transmission had the following design features:

  1. The transmission has a torque converter with an impeller, three turbines, and a stator
  2. This is combined with two planetary gearsets, four fluid controlled clutches, and three one-way sprag clutches.
  3. Each of two of the turbines drives one of the planetary gearsets. The third drives the drive shaft directly
  4. It does not shift gears as most transmissions shift gears. It phases between gears.
  5. There is no active logic for gear selection in the valve body.
  6. The pull on the drive wheels and the sprag clutches select the gear ratio.

     Sprag clutches are one-way clutches. The couple the shafts in one direction, and freewheel in the other direction.

  7. The only time the valve body changes the clutches is when the gearshift is moved.
  8. It behaves very similarly to the new Continuously Variable Transmission (CVT), but it works in a totally different way.
  9. It's a shiftless transmission.
  10. GM essentially had a CVT in the 1950s.

How it works

Turboglide cross section

Turboglide cross-section
 

TURBOGLIDE CLUTCH OPERATION
GEARSHIFTKEY PRNDGR
Reverse Clutch  OFFONOFFOFFOFF
Neutral Clutch  OFFONOFFONON
Forward Clutch  OFFOFFOFFONON
Retard Clutch  OFFOFFOFFOFFON
Park Latchno vis ONOFFOFFOFFOFF

The parts

TORQUE CONVERTERSPRAG LOGIC
Impeller - Engine shaftFront sun - Sprag middle
1st Turbine - Back sunForward clutch - Sprag outer
2nd Turbine - Reverse clutch - Front ring Retard clutch - Back ring - Sprag inner
3rd Turbine - Neutral clutch Planet carriers - Neutral clutch - Drive shaft
Stator - Variable pitch blades - Sprag stator Sprag clutch

The connections

Neutral and Park

Drive

Grade Retard

Reverse

My experiences with the Turboglide.

Angle section

Turboglide angle section
 

Gearshift Quadrant

Gearshift quadrant
 

I spent 21 years knowing the Turboglide.

Characteristics I observed in the Turboglide.

If given an otherwise equal choice, I would buy a car with the equivalent of a Turboglide over a CVT or any other car.

Reported troubles with the Turboglide.

Many people said the Turboglide was a bad transmission. These were the cited reasons:

The Turboglide had an undeserved bad reputation due to the bad turbine design and the transmission abusers.

These were the ways to damage the Turboglide:

Because race drivers didn't like it, the rest of us have been denied Turboglide for decades.

The GM ads selling the Turboglide misportrayed how it works.

The cartoonists who made the ads did not understand how it worked.

1st Turbine 2nd Turbine 3rd Turbine

Turboglide ad
 

Turbines

Real Turboglide
 

I have seen two ads intended to sell the concept of the Turboglide.
  They were animated cartoons with drawings of three turbines (right).

Both cartoons showed each of the three turbines active at powering the car while the other two turbines were stopped.

That is NOT how Turboglide works.

My edited image at the bottom is a better rendition.
 - In the first part, the 1st Turbine spins faster than the others.
 - In the second part, the 1st and 2nd Turbine spin faster than the other one.
 - In the third part, all three turbines spin at the same speed.

As the car accelerates, Turboglide's turbines work as follows:

This table shows the relative speeds of the turbines for the various phases of operation.

TURBOGLIDE RELATIVE TURBINE SPEEDS
PHASELOADED
TURBINE
. PORTION OF IMPELLER SPEED . PORTION OF OUTPUT SPEED . IMPELLER TO
OUTPUT SPEED
INNER
SPRAG
OUTER
SPRAG
Turbine 1Turbine 2Turbine 3Turbine 1Turbine 2Turbine 3
Stopped10:10:10:1 ---1:0HoldHold
Part 110.5:10.3:10.18:1 2.67:11.60:11:15.34:1HoldHold
Full 111:10.60:10.375:1 2.67:11.60:11:12.67:1HoldHold
Part 220.80:10.80:10.50:1 1.60:11.60:11:12.00:1FreeHold
Full 221:11:10.625:1 1.60:11.60:11:11.60:1FreeHold
Part 330.80:10.80:10.80:1 1:11:11:11.25:1FreeFree
Full 331:11:11:1 1:11:11:11:1FreeFree

Other transmissions which behaved like Turboglide.

The original Buick Dynaflow (1948-1952)

The original Chevrolet Powerglide (1950-1952)

The Buick Twin-Turbine Dynaflow (1953-1954)

The Buick Variable Pitch Dynaflow (1956-1963)

The Buick Flight-Pitch Triple Turbine Dynaflow (1958-1959)

Other products which behave like transmissions:

Philco M22

Philco M22
Manual 7, 10, & 12-inch
Turn shelf to select size
≈ Manual transmission
 

Garrard AT-6

Garrard AT-6
Automatic 7, 10, & 12-inch
Dropped record moves sensor
≈ 3 speed Turbo Hydramatic
 

Collaro Conquest

Collaro Conquest
Any size 12-inch to 6-inch
Arm measures exact size
≈ Turboglide
 

The page author noticed the similarities in design philosophies between transmissions and other technologies. Here are some of those similarities: