Group 25 - Transmission

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Revision as of 03:54, 5 December 2008

Executive Summary

The demands placed on today's vehicles are immense. They must be able to travel at a wide range of speeds, to back up under their own power, to accelerate quickly, and to tow heavy loads, and they have to do all of these things without destroying the engine inside. It seems simple enough, but try to do every item on that list without changing gears and suddenly things get much more difficult. This is where a transmission comes in. A transmission alters the speed and direction of an output shaft, while allowing it's input shaft to rotate at a fairly constant speed, this allows the engine to remain at it's optimal speed, while allowing the vehicle to travel in the desired direction and speed, greatly reducing engine wear while improving performance and fuel economy. An automatic transmission is a step up from the manual or "standard" transmission. It allows the driver to focus on the road, without being distracted by the continual gear shifting required by a manual transmission. Furthermore, the manual transmission requires much less maintainence and is much harder to damage than a manual transmission. This is important as it provides the consumer with decreased maintainence costs, and increased vehicle reliability.

Introduction

Group Members

Leo Christian-Tabak
- Group Leader (organizational duties)
- Oral Presentation (Presentation and Preparation)
- Wiki Page
- Disassembly
- Reassembly
Andrew Roberts
- Disassembly
- Wiki Page
- Oral Presentation Preparation
Tom Svialia
- Disassembly
- Reassembly
- Wiki Page
- Oral Presentation Preparation
Vinisha Patel
- Disassembly
- Reassembly
- Wiki Page
Mike Allen
- Reassembly
- CAD Drawings
- Wiki Page

Product

Type: Automatic Transmission
Manufactured by: General Motors
Type: Hydramatic
Non Working
- Severe damage to housing and cover plate.
- Drained of all fluids and lubricants.
- Bent drive shaft couple.

The automatic transmission's function is to change the speed and direction of an output shaft, while allowing the input shaft to remain within a small speed range. Most commonly used in vehicles, this device protects against engine wear, allows for greater acceleration, allows the engine to disconnect from the wheels, allows the vehicle to stop and reverse direction, and provides increased performance and fuel economy. This is done by activating or deactivating sets of discs called Clutch Packs which change which gears in the transmission receive power, thereby changing the speed or direction of the output shaft.

Before Disassembly

The transmission was given to us in a non-working state. The transmission had sustained severe damage to the main body, in the form of a large crack encircling the point where it connected to the engine. There was a somewhat deep dent running the length of cover plate A. A disc shaped part inside the transmission had shattered beyond the point where we could determine it's function. The transmission had been drained of all working fluids. The transmission requires electrical power to operate and the corresponding power supply was not provided. There were several bolts missing from one of the cover plates.

The purpose of the product is to variate the speed and direction of the output shaft, while allowing the engine to remain in its optimal range of speeds.

The transmission is made up of the following materials:

Steel
Aluminum
Cast Iron
Copper
Plastic
Filter Material

Disassembly Procedure

We broke the transmission down into four distinct sections, each having it's own purpose.

Before disassembly:

Section 1

Purpose: Park and fluid filtration.

Step #	Procedure	Tools Used	Picture
1	Remove cover plate and 16 Bolts	13mm socket wrench
2	Remove filter	None, held in by friction
3	Remove filter bracket	13mm socket wrench
4	Remove parking lock actuator bracket	13mm socket wrench
5	Remove parking lock actuator rod	No tools required
6	Remove valve cover	10mm socket wrench
7	Remove valve piston	No tools required
8	Remove short metal tube	13mm socket wrench
9	Remove long metal tube, plastic cover, metal clip	13mm socket wrench
10	Remove parking latch	Needle nose pliers

Section 2

Purpose: Fluid control and distribution.

Step #	Procedure	Tools Used	Difficulty (1-5)	Picture
1	Remove cover plate	13mm socket wrench	1
2	Remove Valve Actuator	10mm socket wrench	1
3	Remove small cover plate	13mm and 10mm socket wrenches	1
4	Remove hydraulic block	10mm Socket wrench	1
5	Remove shattered disk	No tools required	1
6	Remove valve body	10mm socket wrench	2
7	Remove hinged ring assembly	Pliers (something to hold the spring in compression)	2
8	Remove hydraulic valve assembly	Circular punch (to remove retaining pin)	1
9	Remove hydraulic valve assembly	Circular punch (to remove retaining pin)	1
10	Remove valve body backplate	13mm socket wrench	2

Section 3

Purpose: Speed and direction control.

Step #	Procedure	Tools Used	Difficulty (1-5)	Picture
1	Remove chain, gears, and spurred shaft	No tools required	1
2	Remove pin from parking lock actuator gear	Cylindrical punch and hammer	3
3	Remove parking lock actuator shaft, gear, and push rod.	No tools required	2
4	Remove plastic cap	No tools required	1
5	Remove retaining plate	No tools required	1
6	Remove clutch pack	No tools required	1
7	Remove clutch pack retaining ring	Pliers, screwdriver	2
8	Remove clutch pack clutch rings	No tools required	1
9	Remove inner clutch pack	No tools required	1
10	Remove clutch pack retaining ring	Pliers, Screwdriver	2
11	Remove clutch pack clutch rings	No tools required	1
12	Remove locking belt	No tools required	1
13	Remove ring gear	No tools required	1
14	Remove planetary gear set	No tools required	1
15	Remove sun gear from planetary gear set	No tools required	1
16	Remove bell shaped housing	No tools required	1
17	Remove short shaft	No tools required	1
18	Remove gear train retaining ring	Pliers, Screwdriver	2
19	Remove spring loaded metal plate	No tools required	4
20	Remove circular bearing	No tools required	1
21	Remove planetary gear set	No tools required	1
22	Remove clutch pack retaining ring	Pliers, Screwdriver	3
23	Remove clutch pack clutch rings	No tools required	1
24	Remove ring bearing	No tools required	1
25	Remove spacer ring	No tools required	1
26	Remove ring gear	No tools required	1
27	Remove spurred shaft	No tools required	1
28	Remove inner retaining ring	Pliers, Scredriver	4
29	Remove indented ring	Pliers, Screwdriver	2
30	Remove ring bearing	No tools required	1
31	Remove ring gear	No tools required	1
32	Remove sun gear	No tools required	1
33	Remove planetary/reversal gear housing	No tools required	1

Section 4

Purpose: Speed/Direction sensor providing feedback to vehicle.

Step #	Procedure	Tools Used	Difficulty (1-5)	Picture
1	Remove cover plate and attached electronics	4.5mm wrench	2
2	Remove speed sensor housing	10mm socket wrench	1
3	Remove speed sensor shaft	No tools required	1

After Disassembly

Most of the components inside the transmission were made out of steel. There were also a few plastic parts (such as the gaskets) and one rubber hose on the external frame of the transmission. Steel is an alloy consisting mostly of iron, with a carbon content between 0.2% and 2.14% by weight. Carbon is the most cost-effective alloying material for iron. Carbon acts as a hardening agent, preventing dislocations in the iron atom. The reason why steel was used for the majority of the parts is because steel can take the tremendous stresses present during operation. The fact that steel is competitively priced means it is easy to obtain and also cheaper if bought in bulk; reducing production costs.

Plastic was used for many of the non load-bearing parts because it is light, inexpensive, corrosion resistant, and easy to manufacture.

Aluminum was also used for a lot of the parts of the transmission. It is common in the automotive industry to make parts using the Aluminum die casting method, because making parts in this way is inexpensive. Also the properties of Aluminum make it lightweight and strong. The fact that it is one third the weight of steel makes it an ideal component for many cars today. Aluminum is corrosion resistant and also extremely durable. They are necessary in the production of cars today because it tremendously reduces the weight of the car, increasing performance and fuel economy.

Design Changes or Improvements

The pin from Section 3 step 2 should be replaced with a set screw to make disassembly and service easier.
The cover plates over sections 1 and 2 should be made out of aluminum to reduce weight, as they carry no load.
The bolts holding the cover plate of section 4 should be larger to reduce the possibility of stripping.

Part Table

Name	Number	Material	Manufacturing Process	Image
Cover Plate	1	Aluminum	Casting
Filter	1	Aluminum, Plastic, Filter material	Injection Molding (Plastic), Sheet metal forming (Aluminum), Unknown (filter)
Filter Bracket	1	Steel	Casting
Parking lock actuator bracket	1	Steel	Casting
Parking lock actuator rod	1	Steel	Machining
Valve Cover	1	Steel	Casting
Gasket	1	Plastic	Injection Molding
10mm Bolt (3/4" long)	4	Steel	Machining
Tube clip	1	Aluminum	Sheet metal forming
Valve	1	Steel	Machining
Short tube	1	Steel	Extrusion and bending
Plastic Cap	1	Plastic	Injection Molding
Metal Clip	1	Aluminum	Sheet metal forming
Tube Clip	1	Aluminum	Sheet metal forming
13mm Bolt (1/2" long)	1	Steel	Machining
Long Tube	1	Steel	Extrusion
Parking lock	1	Steel	Casting
Return Spring	1	Steel	Extrusion
Hinge Pin	1	Steel	Machining
Retaining clip	1	Steel	Extrusion
13mm Bolt 1”	16	Steel	Machining
Washers	16	Steel	Machining
Throttle Cable	1	Plastic, Rubber, Steel	Extrusion, Injection Molding	200px
13mm Bolt (1" Long)	11	Steel	Machining
Back Cover Plate	1	Steel	Casting
10mm Bolt 1 ¾”	1	Steel	Machining	200px
10mm Bolt 2 ½”	1	Steel	Machining	200px
Valve Lever Actuator	1	Steel	Sheet Metal Forming
10mm Bolt 1”	3	Steel	Machining	200px
10mm Bolt 3 ½”	4	Steel	Machining	200px
13mm Bolt 5 1/12”	1	Steel	Machining	200px
Backplate	1	Steel	Casting
Hydraulic Block With Solenoid	1	Steel	Casting, Machining
Valve Housing	1	Steel	Casting
Shattered Disk (not shown)	1	Steel	Casting, Machining
Ring Gasket	1	Rubber	Injection Molding
Ring with tab	1	Steel	Casting, Machining
Spring	1	Steel	Extrusion
Hinge Pin	1	Steel	Extrusion, Machining
13mm Bolt 1 ½”	1	Steel	Machined	200px
13mm Bolt 2 1/4”	1	Steel	Machined	200px
13mm Bolt 2 ½”	1	Steel	Machined	200px
10mm Bolt 2 ½”	1	Steel	Machined	200px
Valve Retaining Pin	6	Steel	Sheet metal forming
Valve assembly	6	Steel	Extrusion, Machining, Bending
10mm Bolt 1”	2	Steel	Machined
Screws ½”	4	Steel	Machined
Speed Sensor	1	Electronic	Machined
Circular Bearing	1	Steel	Metal Casting
Plastic Gasket	1	Plastic	Injection Molding
Metal Gasket	1	Steel	Machined
13mm Bolt 1”	7	Steel	Machined	200px
13mm Bolt 1 ¾”	5	Steel	Machined	200px
Chain Drive Housing	1	Aluminum	Metal Casting
Center Valve	1	Steel	Machined
Parking Brake Push Rod	1	Steel	Metal Casting
Parking Brake Lever Control	1	Steel	Machined
Parking Brake Control Pin	1	Steel	Machined
Parking Brake Control Rod	1	Steel	Machined
Valves	6	Steel	Machined
Springs	3	Steel	Machined	200px
Broken Section	10	Cast Iron, Aluminum	Machined
Pin	1	Steel	Machined
Hinge	1	Steel	Machined
Valve Housing	1	Steel	Machined
Cap	1	Plastic	Injection Molding
Drive Chain	1	Steel	Machined
Bearing	2	Steel	Metal Casting
Plate	1	Steel	Machined
Drive gear w/shaft	1	Steel	Machined
Drive gear w/out shaft	1	Steel	Machined
End Cap	1	Aluminum	Machined
Crank Washer	3	Steel	Machined
Sun Gear	2	Steel	Metal Casting
Ring Gear	12	Steel	Metal Casting
Orbital gear Holder	2	Steel	Machined
Orbital Spring	2	Steel	Machined
Orbital Washer	2	Steel	Machined
Orbital Gear Set	2	Steel	Machined
Casing	1	Steel	Metal Casting
Inner Key Shaft	1	Steel	Machined
Key Shaft	1	Steel	Machined
Clutch Pack	1	Steel	Machined
Clutch Pack Housing	1	Steel	Machined	200px
Gears	12	Steel	Metal Casting	200px
Parking Brake	1	Steel	Machined	200px
Gear Box	1	Steel	Machined	200px
Planetary Gear	4	Steel	Machined	200px
Reversal Gear	4	Steel	Machined	200px
Solar Gear	1	Steel	Machined	200px

CAD Drawings

Assembled Bearing:

Bearing Base:

Bottom:

Top:

Drive Shaft:

Assembly

The assembly of the product was the exact reverse order of dis assembly. There were some parts that could have been removed and put back in any order because it did not connect to other parts in the transmission.

We came across many difficulties whilst trying to assemble the transmission. The difficulty areas were with placing the pistons back in and also with the compression rings. We struggled getting the compression rings out safely during dis assembly and once again during assembly. The problem was that we did not have the specific tools to push back the compression rings into the correct slots and so we had to be innovative and use pliers and screw drivers to push the rings in. This proved to be quite a challenge but it gave us a better understanding as to why they need to be fitted in so tightly. It explained the complexity of this transmission and put the job at hand into context.

As mentioned before, the tools that were needed were not available to us so instead what we ended up using was a sharp nose pliers and a set of different sized screw drivers. What we did was cranked the compression rings into place whilst one or two of us compressed the rings using these sharp nosed pliers. It was a great group achievement once the rings fitted into place.

After Assembly

Constructive analysis can be used to design and test the transmission system. We need to come up with a transmission that is extremely durable. This should mean that in a car crash, the internal parts of the transmission should remain intact. The external body should be as strong as possible so that the delicate internal parts are safe from day to day wear due to severe weather and car crashes. The only problem with making a very strong and sturdy external body is that it will most likely be cast iron which is extremely heavy. Aluminum would seem the obvious choice here but Aluminum's durability is not so good. All the internal parts were made very well. They look like they would be able to survive a car crash. They are placed in such a way that keeps it rigid and steady. In this case we would need to use extremely precise models because we are dealing with a car; something which needs extreme precision for everything else in the car to work sufficiently.

Looking at what model best describes this transmission, it is safe to say that not alot of the mathematical models apply here.

-Fatigue models may be needed to test the endurance of the transmission. Cars are designed to last for many years so if it needs to work for years, then yes fatigue models would be required. The transmission can run under loads under varying conditions.

-Circuit models will not be required simply because a transmission runs entirely on mechanical power.

-The main function of a transmission is translation and alteration of mechanical energy. So analysis of power entering and leaving the transmission is required. This means a power transmission model is required for testing and design purposes.

-Thermodynamics and heat transfer models are not required because a transmission itself produces a negligible amount of heat.

-A transmission itself does not deal with fluid flow, but models are necessary to make sure all the parts are well lubricated.

-Static-loading models are not required because the transmission is not under strain when stationary.

-Endurance and strength of the materials in the transmission must be tested and so material stress and strain models would be required. The maximum power inputs and outputs must be determined to outline the capabilities of the transmission.

How an automatic transmission works

This product that we were given is one of two types of transmission systems. There is an automatic and manual transmission. The two main differences between an automatic and manual transmission is that the automatic has no clutch pedal and most importantly, no gear shift. With an automatic transmission, once it is placed into drive mode, nothing else has to be done for the car to move. It is the transmission that allows a car to have gears and thus have variate speeds. It is also the one piece in a car that makes more effective use of the engines torque; achieving better efficiency in the long run. Without a transmission in a car assembly, the car engine would not have different speeds. Focusing more on automatic transmissions, different gears are not locked and unlocked; simply the same set of gears are used. The device which makes an automatic transmission possible is the planetary gearset. This small piece creates the different gear ratios. We must understand to an extent the vital role this tiny planetary gearset plays in the transmission. To put it into context, everything in the transmission is there just to aid the planetary gearset. It is one of many of the main components of an automatic transmission system. The modern automatic transmission consists of many components and systems that are designed to work together in a symphony of clever mechanical, hydraulic and electrical technology that has evolved over the years.

THE MAIN COMPONENTS INCLUDE

-The planetary gearset: These parts are the mechanical systems that provide the various forward gear ratios as well as reverse.

-A hydrolic system: This uses a special transmission fluid sent under pressure by an oil Pump through the valve Body to control the clutches and the bands in order to control the planetary gear sets.

-Seals and gaskets: Are used to keep the oil where it is supposed to be and prevent it from leaking out.

-The Torque Converter: This acts like a clutch to allow the vehicle to come to a stop in gear while the engine is still running.

-Large gear pump: What this does is move the transmission fluid around (we did not have this inside our transmission,

-Set of bands: The role of these is to lock parts of a gearset

-Wet plate clutches: This means the clutch runs in a bath of oil and thus gives better performance in getting the car to a smooth stop. Dry plate clutches run dry with no oil and thus more maintenance required.

Since the transmission was given to us damaged and drained of fluids, it remained inoperable when re-assembled. We discovered that many crucial parts were missing once we disassembled; including the gear pump.

This video shows how an automatic transmission works:

Power flow of an automatic transmission system

The power flow is pretty straightforward. Mechanical power from the engine is delivered to the transmission through the torque converter. Then through the transmission and drive shaft, it reaches the final drive where it is split into two and delivered to the two back wheels (this is assuming it is a rear wheel drive and so no mechanical power is delivered to the front wheels)

== The significance of a transmission ==

It is the device that is connected to the back of the engine and it sends the power produced from the engine to the drive wheels and depending on what kind of wheel drive it is (four wheel or two wheel drive), it will make the wheels rotate. The transmissions job is to make sure the power supplied by the engine is delivered to the wheels. This is primarily done through gear combination's. When the transmission is in neutral position, it disconnects the engine from the drive wheels, thus the car can back up as the wheels are now free to rotate in the opposite direction. It is the drive shaft which connects the rear of the transmission to the final drive which is found at the back of the rear axle (used to send power to the rear wheels). Without the presence of a transmission the engine would have no effect on the wheels of the car, thus no movement.

References

APA Style You must use this format (It's easier than MLA, so don't worry). APA Style

@@ Line 691: / Line 691: @@
 |Steel
 |Sheet metal forming
-|[[Image:Trans131.jpg|200px]]
+!rowspan="2"|[[Image:Trans131.jpg|200px]]
 |-
 |Valve assembly
@@ Line 697: / Line 697: @@
 |Steel
 |Extrusion, Machining, Bending
-|[[Image:Trans132.jpg|200px]]
 |-
 |10mm Bolt 1”