Automatic transmissions

For this week, we are working on automatic transmissions with Brian.
Day 1: On tuesday, we stripped down the entire rear wheel drive automatic transmission into all of its separate components.

The automatic, rear wheel drive transmission

Removing the oil pan

Here we can see the valve body,
servos, and oil pipes with the oil
pan removed.

The valve body controls the transmission. It directs
oil to the right places to allow for different ratios to be selected.

The transmission with the valve body removed.

This piece is what houses the output shaft
and the governer.

The transmission with the valve body and the servos removed.

The servos are hydraulically controlled by the valve
body and are what apply pressure to the bands which
hold the drums. 

This is the governer that senses the speed
of the output shaft. It feeds this information
to the valve body.

This is the oil pump which is driven by the impeller
part of the torque converter. It supplies oil for
lubrication and also pressurised oil to the valve body.

The front of the transmission showing the
input shaft after the oil pump has been
removed.

The input shaft removed with the front clutch
pack. The clutch packs are locked up by oil
pressure which flows through the shafts.

Looking inside the trans at the rear clutch
pack with the intermediate shaft inside it. 

The intermediate shaft inside the rear clutch clutch pack,
and has the 2 sun gears inside it, which mesh in with the
pinions inside the planetary gears.

This is one of the bands which are used to  hold the clutch
packs/ gear sets.

This is the planetary gear set.  The pinions that can
 be seen are what mesh with the output shaft ( on the outside)
and the intermediate shaft (inside).

Looking into the transmission with the output shaft
still in there. The output shaft is connected to the planetary
gear set by an internal ring gear on the output shaft.

The rear band, which is operated by the servo which
makes the band clamp down on the planetary gears.

The housing of the transmission as we removed
 the output shaft.

The output shaft which sends power out to the diff.

Day 2.

We had torque converters explained to us. It is there to couple the engine to the transmission. The torque converter works by the engine driving the impeller, and by the centrifugal force, and using the vanes, forces oil out and into the turbine side of the torque converter which intern makes that spin. This torque is then transferred down the input shaft to the transmission. There is also a stator between the impeller and the turbine. The stator is there to redirect the oil flow as it enters the impeller and is also there to increase torque. This is so that the oil enters the impeller in the same direction as the impeller is turning, which also assists in turning the impeller.

Day 3.
Today we were asked to do some work out of the workbook. What we had to do was to list the major parts of an automatic transmission and give a brief explanation of each part
1. Torque converter: This takes the place of a clutch and transfers torque to the transmission. It also increases              the torque.
2. Oil Pump: Provides oil pressure for transmission control systems and supplies oil for lubrication.
3. Planetary Gears: Supplies power flow through the transmission and to change ratios.
4. Input and Output shafts: Input supplies power to transmission, output supplies power from transmission.
5. Governor: Senses vehicle speed and and provides information to the valve body.
6. Front and rear clutch assemblies: Lock components to change gear ratios.
7. Bands: Hold components to change gear ratios.
8. Valve body: Brains of transmission, decides what gear to select.

What does the servo do in the transmission?
The servos operate the bands. The bands hold the drums etc. to provide different gear ratio's.

Give two advantages of using a 'lock up' torque converter:
1. Increase power (by about 2% ish)
2. Increase fuel economy.

Day 4:
On friday, Jiejun, Cody and myself, after assembling the rear drive auto trans, we took apart and reassembled    an automatic transaxle.

The assembled auto transaxle.

The valve body. This has a vacuum system to determine
throttle position. It uses vacuum from the intake manifold to
operate the valves.

The trans after the valve body has been removed

The bellhousing. We can just see the various shafts.
The small one in the centre drives the oil pump, the
middle one is the input shaft and the big one is the
stator shaft.

Here we can see the oil pump which is on the back of
the trans. It is driven via a shaft which goes through the
entire trans from the torque converter.

The housing of the trans after the  clutch  packs
and planetary gears have been removed.

The governor which sticks out the side of the trans.

The clutch packs and planetary gears  and bands etc.