A Presentation on Manual Trans

A PRESENTATION ON MANUAL TRANSMISSION 716.640

CONTENTS An overlook on TRANSMISSION

Definition Need of transmission Power flow Types of transmission Types of gears Transmission designation

TRASMISSION 716.640

Constructional details Features of 716.640 Working Synchronisation Lubrication

AN OVERLOOK ON TRANSMISSION

DEFINITION The word ‘Transmission’ means the whole of the mechanism that transmits the power

from the engine crankshaft to the rear wheels, providing the suitable variations of the engine torque at the road wheels, whenever required


NEED OF TRANSMISSION

• To provide a means to vary the torque ratios between the engine and road wheels as required

• To provide a neutral position with the clutch engaged• To drive the vehicle in reverse direction• Variation of resistance and tractive effort of the vehicle at different

speeds


POWER FLOW


TRANSMISSION

MANUAL AUTOMATIC

SLIDING MESH

CONSTANT MESH

SYNCHROMESH


SPUR GEARS Teeths are parallel to the axis of the gear Only one teeth of the meshing gear is in complete

contact Torque transmitting capacity is less Noise level is high

HELICAL GEARS Teeths are at an angle to the gear axis More than one teeth are in contact at a time Torque transmitting capacity is higher Low noise level

TYPES OF GEARS


• Oldest and the simplest type of transmission• Spur gears were used• Main shaft gears splined to the main shaft• Gear shift is achieved by sliding the gears on main shaft• Low mechanical efficiency• Noisy operation

SLIDING MESH TRANSMISSION


CONSTANT MESH

• The gears on the main shaft and layshaft are in constant mesh• Main shaft gears are free to rotate• Gear engagement is achieved by dog clutches splined to the main shaft• DOUBLE DECLUTCHING needs to be done for smooth gear shifting• Helical gears are used


SYNCHROMESH Gears are in constant mesh Instead of dog clutch synchroniser unit is used Each pair of gear has one synchroniser unit Gears are first brought into frictional contact which equalizes their

speed after which the actual engagement takes place Eliminates the requirement of double declutching


GEAR RATIO AND ITS CALCULATION Gear ratio gives the mathematical relation between two

gears It is the ratio of the no. of teeth on the driven wheel to

no. of teeth on the driver wheel or the speed of rotation of the driver to the driven

Gear ratio gives the value of torque multiplication

For example:

Gear ratio,

G=(20/10)=2:1

(smaller gear is the driver)

20 Teeth

10 Teeth

TRANSMISSION 716.640

Transmission DESIGNATION

SG-S 370/6.1

SG – MANUAL TRANSMISSION

S – STANDARD TYPE OF GEAR

370 – TORQUE TRANSMISSION in Nm

6.1 – SPREAD ( RATIO OF LOWEST TO HIGHEST GEAR )


CONSTRUCTIONAL DETAILS

Transmission 716.640 consists of

Gears Shafts

input / clutch shaft

lay / counter shaft

main shaft Shift unit Bearings Synchroniser units Breather Front and Rear Housing


• Fig. 1 shows the neutral position in which the synchroniser unit is in the center position

• When the gear is shifted, the spring loaded balls pushes the slider which in turn pushes the friction ring

• The inner cone of the synchroniser unit first comes in contact with the outer cone of the gear wheel

• The frictional contact results in the equalization of the speed of both the wheels

• Until this equalisation of speeds, the sleeve of the synchroniser unit cannot move forward due to the presence of detents (dog teeth) on the friction ring which blocks the path of the sleeve

• As the equlisation of the speed is achieved the detents are pushed away from the way of the inner teeth of the sleeve and the sleeve gets fully engaged with the teeth on the appropriate gear wheel

SYNCHRONISER UNIT

SPRING LOADED BALLS

SELECTOR SLEEVEFRICTION CONE

SYNCHRONISER ASSEMBLY

SHIFT SPLINESSPRING LOADED BALLS

SELECTOR SLEEVEFRICTION CONE

SYNCHRONISER ASSEMBLY

SHIFT SPLINES

GEAR WHEEL


sleeve

Synchroniser assembly

slider

spring

ball


detent

Friction cone

Internal splines

sleeve

Synchroniser ring

NORMAL POSITION DETENTS OBSTRUCTING SLEEVE SPLINES


Disengaged position Engaged position


SYNCHRONISATION:

TYPES: SINGLE CONE SYNCHRONISATION -

Has only one frictional surface

• MULTICONE SYNCHRONISATION Has an additional friction cone

TRIPLE CONE SYNCHRONISATION

Has an additional frictional lining on the friction cone DOUBLE CONE SYNCHRONISATION

Frictional lining is absent

1. GEAR WHEEL

2. GEAR WHEEL

3. CONICAL RING

4. FRICTION CONE

5. FRICTION LINING

6. SYNCHRONISER RING


NEUTRAL POSITION


POWERFLOW IN FIRST GEAR


POWERFLOW IN SECOND GEAR


POWERFLOW IN THIRD GEAR


POWERFLOW IN FOURTH GEAR


POWERFLOW IN FIFTH GEAR


POWERFLOW IN SIXTH GEAR


SHIFT ASSEMBLY

• Shift Lever (Gear lever )• Selector Rod (4)• Selector Cable (1)• Shift rod(2)• Transfer lever (3)• Swivel lever (12)• Coupling arm (13)

Selector cable

Shift Rod

Transfer lever

Central shift shaft

Shift arms


Shifting mechanism

The sideways movement of the gear lever is transferred due to the selector cable which is responsible for the rotational movement of the central shift shaft

The to & fro movement of the gear lever is transmitted through the shift rod which results in the to & fro movement of the central shift shaft


• Grade of transmission fluid— 70W-80W

• Capacity of transmission — 1.5 litres

Capacity has been revised from 1.8 litres to 1.5 litres to facilitate the shifting of First and Second gears when the engine is cold

LUBRICATION

FEATURES OF 716.640

This transmission is used in 220 CDI engines It has 6 forward and 1 reverse gear It is a fully synchronised transmission with synchroniser on reverse gear also Counter shaft is a hollow design to reduce weight Has synchroniser assembly on counter shaft to reduce size Has multi-cone synchronisation Needs no end shaft play adjustments due to very tight production tolerances and housing halves as well as the use

of roller sleeves Rear and front half housing are sealed with liquid sealing agent Precise and light shift due to-


• Transmission of shift lever movement to transmission by shift rod and shift cable

• Central shift shaft supported on needle bearings • Multicone synchronisation on I, II, III & IV Gears

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A Presentation on Manual Trans