Clutch

Clutch provides for the transmission power from the drive shaft to the driven shaft.
It controls whether car's transmit engine power to the wheels). To make it simple, in clutch, the drive gear attached to a motor while the driven gear provides output sharft power for work to be done. The clutch connects the two shafts so that they may be locked together and spin at the same speed (engaged), locked together but spinning at different speeds (slipping), or unlocked and spinning at different speeds (disengaged).

Universal joint

Universal joint is to transfer power from the gearbox to the output drive shaft upto 12 degrees of angle.

before disassembling the universal joints, put the marks to make sure the shaft will be assembled to manufacturers specs. start by removing snap rings , circlips. once those were out of the way, the cups came off surprisingly easily.

  when the dissassembly was completed, clean up all the old grease so we could inspect the joints properly. we noticed that more than half the rollers were broken and another quarter were missing. the reason why we were not getting a smooth joint operation . after regreasing the internals and assembling the entire thing back.

Drive shaft

A driveshaft is a bar to extend rotational torque.  Driveshaft is connected on one end to the transmission and on the other end to a differential (which is connected to an axle).  A it simply rotates at the exact same rpm as the output of the transmission/transfer case.
(http://www.car-videos.net/whatis/driveshaft.asp)

 Basically, drive shaft is to torque and rotation. They are different in a front wheel drive car and a rear wheel drive car.


what to do (inspect, test and mesure to assess the condition of the driveshaft)

Before any inspection, the first thing we need to do is to look at the phasing of the friveshafr. Read the manufactures specs and see if the phasing is correct or not. If not, dismantle the phasing from the shaft and put it  in the ringt way to fix.
when you check, check for cracks and corrosion by visual checking then  dissassemble them all, clean off the grime with WD-40 and wipe off the lubricated layer.

Constant velocity joint

volocity joints are to connect from the gearbox to the wheels. The inner part joins to the gearbox and the outer part is to the wheels.

The purpose of velocity joint is to transmit power through an angle at a constant speed without increase in friction or play.

by checking if its moving (smoothly or not) and any cracks or rips on rubber boots before dismantling, we can start to disassemble the joint and inspect.

Velocity joints are protected by a rubber boot from the cracks and it is usually positioned in front wheel drive.
It allows a drive shaft to transmit power through a variable angle, at constant rotational speed, without an appreciable increase in friction or play.

we disassembled joint to inspect and cean it up by reading instruction. It is essential that we should follow the instruction because we might not know what should we take the part off first. first of all you need to remove the boot retaining clips to remove the boots and make sure that you put the mark on the joint and the driveshaft to put that back when you are done checking.

remove the joints from the shaft and check the outer and inner race, ball cage, rollers, circlips and grooves to know what are wrong. we have got ball cage, splines and threads were in bad condition.

MAUNAL and AUTOMATIC transmissions

The purpose of manual and automatic transmissions is basically same. they accomodate require torque at the specific speed needed.

top picture shows manual transmissions and bottom one is automatic transmission.
The differences between manual and automatic transmissions are -
*Manual transmissions

1. They let the drive to select a suitable gear ratio to increase the speed to match the load requirement.
2. They allows driver to select neutral and disconnect drive. And also to select reverse gear.

which means they let the driver to go faster, slower and reverse by changing the gear.

*Automatic transmissions
 : These gear box can automatically change gear ratios as the behicle moves, and let the driver feel from having to shift gears manually.

Manual gear box has three types.

• spur toothed gears :  usually used for reverse gear however it's not used frequently and for long period.
• helical toothed gears :  used in most gear boxes because of increased wtrenth, durability, quietness and moedrate cost.
• herringbone toothed gears : seldom used in automotive applications due to high cost.

Purpose of detent mechanism

1. accurately locate the selector rails in their correct position
2. provide a positive "feel" to the gearshift, so the driver is awaer of which gear is selected.
3. it prevents the gears moving out of mesh when there is little of no load on them

And i think this is the most important mechanism of the gear box. that is interlock mechanism.
the purpose of it is that interlock prevents the engagement of more than one gear at a time. which mean once the gear is selected by driver, it hold the gear not to moving or going to nuetral.

Above all, i really enjoy every classes because everything is new to me. tried to get in to it and do it to know more.

Differential

differential or "diffs"is a device which transmitts torque and rotation through three shafts, one input and two output, also allowing one of the output to rotate at a different speed than the other.

The purpose of differential is that

1. to aim the engine power at the wheel
2. To act as the final gear reduction in the vehicle, slowing the rotational speed of the transmission one final time before it hits the wheels
3. To transmit the power to the wheels while allowing them to rotate at different speeds

I haven't done any of the idfferential classes because of sickness. so what i had to do was just research till i understood. Still got little bit confused but as far as i got the general purpose of differential, i would know the process of it.