Transmissions are needed to change the tractive force delivered to the drive axles and keep the engine operating in its optimal power curve for increased fuel efficiency. The main types are front-wheel drive, rear-wheel drive, and all-wheel drive/4-wheel drive. Front-wheel drive transmissions are called transaxles and place weight over the drive wheels while rear-wheel drive is more robust. Transaxle designs include planetary gear sets, gear and clutch types, belt-driven continuously variable transmissions, and dual clutch transmissions. Safety precautions must be followed when working on hybrid vehicle transmissions.

2. Why do we need Transmissions?
 To change the tractive
force to the drive axle
 T.F. Engine=torque X Gear Ratio
 Keep engine in the Power
Curve
 Increase fuel economy
 Match the need/use of
the vehicle

3. Transmission Types
 Front wheel drive
(transverse)
 Reduces vehicle weight
 Allows more interior
room
 Places weight over drive
wheels
 Compact design
 Is called “Transaxle”
because it transmits
power 90deg to engine.

4. Transmission Types
 Rear wheel drive
(longitudinal)
 More robust
 Easily modified for
accessories
 Rare in passenger cars
today

5. Transmission Types
 All Wheel Drive / 4
Wheel Drive
 Applies torque to all 4
wheels
 Can be “Automatic” or
“manual”
 Uses Transfer Case to
deliver power to non
driven wheels

6. Final Drives
Solid/Live Axle Integrated/Dead Axle

7. Transaxle Types
 Simpson gear set type
 Uses clutches & Bands
to hold and drive
different planetary
components
 Most common type

8. Transaxle Types
 Gear and Clutch
 Manual trans type
gear train with
clutch packs to
engage gears
 Typical for
Honda/Acura and
Saturn transaxles

9. Transaxle Types
 Belt and Pulley
 A common CVT design
used by Honda, Ford,
GM and many other
Mfg.’s
 Most “pull” belt but
Honda “pushes” belt
 Nissan CVT

10. Transaxle Types
 Dual Planetary
 Used by Toyota in
hybrid vehicles
 Very simple to
build…hard to
understand at first
 Honda using similar
design in 2014

11. Transaxle Types
 DCT Dual Clutch
Transmission
 Has gears and forks like a
manual transmission but
each shaft has a separate
clutch
 Allows for very fast gear
changes

12. Transmission Types
 GM RWD hybrid
transmission
 Simpson planetary
design
 Uses 2 motor generators
for power/regen.
 Has 12 pump to keep
clutches applied during
engine off stops/takeoff

13. Safety Precautions!!!!
 Anytime you service
Hybrid Vehicle you
MUST GLOVE UP!

16. 3 Phase Cable
Indexing.

17. High Voltage DC Cable routing.

19. 6 Bolts to remove Valve
Body and TCM

20. Gear Selector Positions

21. Gear Position
 Park
 Engages park pawl to prevent vehicle movement
 Many times you have to step on brake pedal to shift out of
park
 Shift Interlock
 Reverse
 Applies clutches and bands to move vehicle backwards
 Park pawl released
 Neutral
 Park pawl released, bands/clutches not applied
 You can’t tow a automatic in N because of lack of lubrication

22. Gear Position
• Overdrive / Drive / Third
 Allows for automatic shift
form 1st to hi gear
 May have OD switch to Lock
Out high gear and allow
engine braking
 Second
 Allows upshift form 1st to 2nd
only or locks in 2nd
 Allows engine braking

23. Gear Position
 Manual Low / 1st
 Lock in low gear
 Allows engine braking
 Many times applies
additional band/clutch
for additional load
’64 Dodge Wagon