the is about manual

1. MANUAL
TRANSMISSION

2. PRESENTED BY.
• AHIRE SATISH B.

3. BASIC LAYOUT OF TRANSMISSION
SYSTEM

4. INTRODUCTION
1> Also known as Manual gearbox or Standard
Transmission.
2> It generally uses a driver-operated clutch, typically
operated by a foot pedal(car) or hand lever(motorcycle).
3> Clutch is used for regulating torque transfer from the
internal combustion engine to the transmission.
4> Gear stick, either operated by foot (as on a motorcycle)
or by hand (as in a car) is used for shifting to the lower
or higher gears.

5. BASIC LAYOUT OF A 5-SPEED
TRANSMISSION

6. CUT SECTION OF A MANUAL GEARBOX

7. Parts of a Gearbox
• Shifter Lever
• Input Shaft or Clutch Shaft
• Counter Shaft
• Main Shaft or Output Shaft
• Gears (Helical/Spur)
• Synchronizer unit or Dog Clutch Unit
• Shifter Forks
• Transmission Casing

8. Shifter Lever
• It is a lever that facilitates the driver to change
the gear arrangement according to his driving
conditions.
• The bottom end of the shift lever is connected
to the shifter shaft in the gearbox.

9. Input Shaft or Clutch Shaft
• It is also called as Clutch Shaft because it is
driven by the clutch plate.
• It Has external splines so as to mesh with the
internally splined clutch plate.
• It transmits power from the engine to the
counter shaft via the clutch.
• It helps in rotating the gears inside the
gearbox.

10. Input Shaft

11. Counter Shaft
• It holds the counter shaft gears which mesh
with the main shaft gears.
• It is a shaft that receives power from the
Clutch Shaft or the Input Shaft and transmits it
to the Main Shaft.
• It helps in achieving the desired torque ratios
by meshing with the corresponding gears
when required.

12. Counter Shaft or Lay Shaft

13. Main Shaft
• This shaft is also called the output shaft.
• It receives the power from the Countershaft
and transmits it to the final drive like the
differential.

14. TYPES OF GEARS USED IN GEARBOX
• Spur Gears :- Used in Sliding mesh and some types of
Constant mesh gearboxes.
In this type the teeth are straight cut.
Angle of cut is 90 degrees.
• Helical Gears :- Used in most types of constant mesh and all
synchromesh gearboxes.
In this type the teeth are cut at a certain angle.
Angle of cut is 17-20 degrees.

15. DIFFERENCE BETWEEN SPUR AND HELICAL
SPUR GEARS HELICAL GEARS
These are more efficient because less teeth
touching when two gears are connected.
These are less efficient because they have
more teeth touching when two gears are
connected, leading to increased friction.
Spur gears cost less to manufacture than helical
gears.
More costlier due to higher design costs.
Due to less teeth touching when two gears are
connected load capacity is less.
Because the load distributes across more
teeth the load capacity is high.
Are less durable due to teeth bearing excessive
load.
These are more durable due to the reason of
uniform load distribution.

16. Shifter Fork
• It is the unit for moving the gears into the
desired arrangement.
• The Shifter fork slides the corresponding
sliding sleeve or synchronizer sleeve according
to the driver input.

17. Shifter Fork

18. MATERIAL USED IN GEARBOX
• Numerous nonferrous alloys, cast irons, powder-metallurgy
and plastics are used in the manufacture of gears.
• However steels are most commonly used because of their
high strength to weight ratio and low cost.
• Gearbox housings are made up of Aluminum alloys, cast iron

19. FUNCTION OF GEARBOXES
• It is used to increase/decrease the engine torque.
• To enable a neutral position of the gearbox while in
rest position.
• To be able to move the vehicle in reverse direction
• It is used as a housing for gears and also the gearbox
oil and other components

20. FUNCTION OF GEARBOXES
Reversing in Gearboxes
The reversing in gearboxes is achieved by using an Idler Gear.

21. TYPES OF GEARBOXES
Unsynchronized Type of Gearboxes
1> Sliding mesh gearbox
Synchronized Type of Gearboxes
1> Constant mesh gearbox
2> Synchromesh gearbox

22. EVOLUTION OF GEARBOXES
SLIDING MESH GEARBOX
• Known as sliding mesh gearbox or Crash Box.
• “Gears are slid to mesh with each other to transmit
power”.
• No synchronizer unit hence crashing of gears occurs
due to variable speeds of the different gears.
• Double Declutching required to shift to lower or
higher gears without crashing of gears.

23. LAYOUT OF SLIDING MESH
GEARBOX

24. EVOLUTION OF GEARBOXES
CONSTANT MESH GEARBOX
1> In this type gears are always in mesh and rotating, but gears on
one shaft can freely rotate or be locked to the shaft. “The gears are
fixed to the shaft and cannot slide sideways”.
2> The locking mechanism for a gear consists of a collar (or dog
collar) on the shaft which is able to slide sideways so that teeth (or
dogs) on its inner surface bridge two circular rings with teeth on
their outer circumference: one attached to the gear, one to the
shaft
3> When the rings are bridged by the collar, that particular gear is
rotationally locked to the shaft and determines the output speed of
the transmission.

25. DOG CLUTCH/DOG GEAR

26. CONSTANT MESH GEARBOX

27. EVOLUTION OF GEARBOXES
SYNCHROMESH GEARBOX
• Synchromesh gearboxes are similar like constant mesh
gearboxes except that these type of gearboxes use a
Synchronizer unit to match the speed of the gear to that of
the shaft.
• Synchronizer unit avoids the necessity of double declutching
while shifting gears.

28. LAYOUT OF SYNCHROMESH GEARBOX

29. FUNCTION OF SYNCHRONISER UNIT
• An automobile has a synchronizer mechanism or
synchromesh, which consists of a cone clutch and blocking
ring.
• Before the teeth can engage, the cone clutch engages first
which brings the selector and gear to the same speed using
friction.
• until synchronization occurs, the teeth are prevented from
making contact, because further motion of the selector is
prevented by a blocker (or baulk) ring.
• When synchronization occurs, further passage of the selector
which brings the teeth together.
• The synchronizer has to overcome the momentum of the
entire input shaft and clutch disk when it is changing shaft
rpm to match the new gear ratio.

30. COMPONENTS OF A SYNCHRONIZER UNIT