7 manual transmission updated

8/13/2019 7 Manual Transmission UPDATED

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LEARNING OUTCOMES:

Understand functions, construction and

operation of manual transmission and its

components

Understand the power flow in transaxleand transmission



● The purpose of the manual

transmission is to provide the operator

with a selection of gear ratios between

engine and wheel so that the vehiclecan operate at the best efficiency under

a variety of operating conditions and

loads.



Manual transmission



Gear Knob of Manual Transmission



Transmission Case

Provides support for the

bearings and shafts, aswell as an enclosure for

lubricating oil.

Case is cast from either

iron or aluminum.

The drain plug is located

on the bottom of the case,

whereas the fill plug islocated on the side.



Extension Housing

The extension housingbolts to the rear of the

transmission case.

It encloses and holds

the transmission outputshaft and rear oil seal.



Transmission Shafts

A manual transmission has four steel

shafts mounted inside the transmission

case. These shafts are the input shaft,

the countershaft, the reverse idlershaft, and the main shaft.



INPUT SHAFT

The input shaft, alsoknown as the clutch

shaft, transfers rotation

from the clutch disc to

the countershaft gears. The outer end of the

shaft is splined except

the hub of the clutch

disc.



countershaft assembly

The countershaft,

also known as the

cluster gear shaft,

holds thecountershaft gear

into mesh with the

input shaft gear and

other gears in the

transmission.



REVERSE IDLER SHAFT

The reverse idler shaftis a short shaft thatsupports the reverseidle gear.

It mounts stationary inthe transmission caseabout halfway between the countershaft and output shaft,

allowing the reverseidle gear to mesh withboth shafts.



Main shaft assembly

The main shaft, also called theoutput shaft, holds the output

gears and synchronizers.

The rear of the shaft extends to

the rear of the extension housing

where it connects to the driveshaft to turn the wheel of the

vehicle.

Gears on the shaft are free to

rotate, but the synchronizers are

locked on the shaft by splines.

The synchronizers will only turn

when the shaft itself turns.



Synchronizers Synchronizer is a drum

or sleeve that slides back

and forth on the splined

main shaft by means

of the shifting fork.

1. Lock the main shaftgear to the main shaft.

2. Prevent the gear

from clashing or grinding

during shifting.



Shift Forks

Shift forks fit around the

synchronizer sleeves to

transfer movement to the

sleeves from the shift

linkage.

The shift fork sets in a

groove cut into the

synchronizer sleeve.



Shift Forks



Working Principle



Shift Rail



Shifting Mechanism



1st Gear



2nd Gear



3rd Gear



4th Gear



5th Gear



Reverse Gear



Formula how to calculate gear ratio

Number of teeth on driven gear

-----------------------------------------Number of teeth on driver gear

= Gear ratio



Rear wheel drive

transmission The manual transmission transfers power

from the engine to the propeller shaft.

It converts and multiplies rotational speed,

allowing engine RPM to remain in it’slimited optimal power range while providinga wide range of RPM to the propeller shaft;which, in turn, controls vehicle speed.

The rear wheel drive transmission isconstructed with three shafts, five forwardgears, and a reverse gear.



Rear wheel drive

transmission



Power Flow



Transaxle

A front wheel drive vehicle utilizes a

transaxle to transfer power from the

engine to the drive wheels.

The transmission portion of thetransaxle shares many common

features with the transmission.

Differences in design include: number ofshafts, power flow, and the addition of

final drive gears.



Transaxle



Power Flow



First Gear

To get the vehicle movingfrom a standstill, theoperator moves the gearshiftlever into first. The mainshaft first-reverse speed

gear is slid into position,meshing the gear with thecountershaft first-speedgear. The countershaft first-speed gear and main shaft

first-reverse speed geartransmits power to themain shaft. Gear ratio isapproximately 7.55 to 1.



Second Gear To shift into second, the operat

or depresses the clutch andmoves the shift lever into secondgear. The second-third-speedsynchronizer has been moved to the right so its internal teethengage the external teeth of the

main shaft second-speed gear.Power is transmitted by thecountershaft second-speed gearto the main shaft second-speedgear, which is coupled to the mainshaft by the second-third-gear

synchronizer, and to the mainshaft. Gear ratio is approximately4.18 to 1.



Third Gear To shift into third, the operator

depresses the clutch andmoves the shift leverdisengaging the second-thirdsynchronizer from the mainshaft second- speed gear. Thesecond-third-speedsynchronizer has been moved

to the left so its internal teethengage the external teeth ofthe main shaft third-speedgear. Power is transmitted bythe countershaft third-speedgear to the main shaft third-

speed gear, which is coupledto the main shaft by thesecond-third synchronizer andthrough the main shaft. Gearratio is approximately 2.45 to1.



Fourth Gear The operator depresses the

clutch and moves theshift lever disengaging thesecond-third synchronizer fromthe main shaft third-speed gear.The fourth-fifth- speedsynchronizer has been movedto the right so its internalteeth engage the external teeth of the main shaft fourth-speed gear. Power is transmitted by the countershaft fourth-speed gear through the mainshaft fourth-speed gear, which

is coupled to the main shaftby the fourth-fifth-speedsynchronizer, and throughthe main shaft. Gear ratio isapproximately 1.45 to 1.



Fifth Gear The operator depresses the

clutch and moves the shift

lever disengaging the fourth-fifth-speed synchronizer fromthe main shaft fourth-speedgear. The fourth-fifth-speedsynchronizeris moved to the left so itsinternal teeth engage the

external teeth of theinput gear. Power istransmitted by the input gear,which is coupled to the mainshaft by the fourth-fifth- speedsynchronizer. Since theinterlocking action of thesynchronizer, in effect, makes

one continuous shaft of theinput shaft and the main shaft,the drive is direct. Gear ratiois 1.00 to 1.



Reverse Gear

The addition ofsynchronizers allows the

gears to be constant mesh

when the cluster gears and

in passing from neutral to

reverse, the first-reversemain shaft gear is shifted

rearward to mesh with the

reverse idler gear. The sole

function of this gear is tomake the main shaft rotate

in the opposite direction to

the input shaft; it does not

affect gear ratio.



FRONT WHEEL DRIVE GEARBOX

( 5 speed)

7 manual transmission updated

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