Group 15 - GM Transmission
A transmission is a highly complicated piece of precision machinery. In the automobiles of today, a transmission is an essential element. Group 15 was given a General Motor's transmission, and was tasked with completing a product dissection of it. From the beginning the group functioned well and was able to meet all deadlines and goal which were set. The entire transmission was dissected and recorded in great detail. This was a great accomplishment considering the lack of technical skills with in the group. Perhaps more impressive is the fact that the transmission was reassembled. The wide variety of parts meant that all of the notes, photographs and minds were used extensively. The entire process has been chronicled here on this wiki page, and several highlights were selected for a presentation in class.
The reassembly of the transmission was essentially the opposite of the dissection. First the governor was reattached. After this the planetary gear was inserted, followed by a ring bearing and the ring gear. The spurred shaft was inserted next with a retaining ring being put in next. The retaining ‘C’ clips were much easier to get in than to take out. This is because the rings expand into slots in the side of the case. The only issue was that multiple rings are used in a transmission, which means that the rings would occasionally get caught in the wrong grove, but it was still easier to push down the clip than to remove them. Next the clutch rings were put back in, another planetary gear set then followed. A circular ring bearing was placed in next. A spring loaded metal plate was then inserted and another retaining ring was then used. The spring loaded plate was especially difficult because it fit very tightly. The end of a hammer was used to force it down.
The next section was perhaps the most difficult because of the closely messing pieces. This made reassembly difficult because the pieces refused to stay in a position which would allow the reassembly to happen. The solution which was devised was to preassemble the short shaft, bell shaped housing, planetary gear set, ring gear and inner clutch pack all into one piece which allowed for easier reassembly. After this sub-assembly was used, the locking belt was next followed by a retaining plate.
From this point on, the job became markedly easier. It was literally the exact opposite of the disassembly. The drive train assembly was then placed back onto transmission. The hydraulic system was preassembled while the rest of the transmission was being reassembled. This made for a quicker reassembly. The side of the transmission for hydraulic distribution was then put back together, using pictures taken during the disassembly.
The transmission did not run before disassembly and it continues not to work after reassembly. A gear on the inside of the transmission is broke into eight pieces. Tape is also on several parts because previous groups had used tape to label them. Further, there were several cracks in the case itself. The product has not worked in a while and more than likely will never work again.
The disassembly process was easier than the reassembly process because of the numerous components that had to fit back into place. Since there were a lot of components, it would have been even more difficult to keep track of where each piece fit without having the assistance of pictures or videos. The tools used for the dissection were also used for reassembly but for the components inside mostly hands were used. For the bolts and screws 10mm and 13mm socket wrenches were used. It was not possible to reassemble the entire product due to missing and broken components and it took a longer time to figure out which bolts fit with which components. Overall, the product is reassembled to the state it was in before the dissection.
With limited knowledge of how different transmissions work, recommendations are difficult to make. The reason the transmission did not work was essentially that one piece shattered. The design of the transmission provides no fail safes against this types of problem. The transmission could have a by pass system, such as a direct connection to the drive shaft which is engaged in an emergency. This would make it so that the vehicle could be safely driven to a mechanic to be repaired, rather than stranding the person in the middle of the road.
The fasteners used to keep the gear packs in place were also a hassle to remove and an easier alternative could be found. Rather than using a ring and groove system; a ring bolted into place would be more effective and easier to repair.
There have been many new improvements to transmissions, including a belt system and systems that have the next gears pre aligned, essentially using two separate gear packs on parallel shafts that the clutch switches back and forth. These methods provide smoother and more efficient alternatives to many standard designs. However, they are expensive and probably can not carry the required torque.
1) Most of the transmission’s components are made up of a metal material, mainly steel and aluminum. Steel is chosen because it is durable and less pliable, making it harder for it to bend unnecessarily in certain components due to the combination of iron and carbon elements. An alternative to steel is aluminum which is used in other components because it is less expensive than steel, very durable and resists corrosion over time. Aluminum also has a lighter weight than steel and can contribute to a better fuel efficiency in a vehicle overall. Plastic is used for components that are the easiest to replace due to the inexpensive cost to produce, its resistance to corrosion and its light weight.
2) The forces applied to each of the components are normal force and gravitational force. The forces applied to the components are dependent on the components mass and is linked to the amount of stress the source of the force application may put on the other component. Most of the components use a force exerted by steel bolts to hold the component in place to avoid unnecessary friction between other components in the transmission. The stress is then measured by a ratio of the force applied over the surface area to which the force is being applied to resulting in the metric units, Newton/ m^2 and English units, pounds/ in^2. The amount of force applied to an object will vary throughout the components due to the varying masses of the components. For example, a plastic component held in place by a bolt with a mass of about .003kg may need a force greater than 0.0294N to hold it in place, whereas a steel rod component of about 2000kg may need a force greater than 19600N to hold it in place.
3) Each component’s material affects the manufacturing process because the cost to manufacture the component, availability of material, the component’s main function, and the component’s expected durability must be considered. During the manufacturing process, particular care must be taken to make the component fully functional, thus making sure that the component’s measurements are accurate and precise to prevent faulty components that may contribute to a malfunctioning transmission in the long run. Most of the components in the transmission are made of steel because it is a strong material and can withstand more pressure than a plastic component can for example. The outer cover that houses the components must be made of a strong material to prevent damage to the interior components which is why steel and aluminum are used the most in the manufacturing of a transmission.
4) Does the shape affect the manufacturing processes? Yes, the shape of the component does affect the type of manufacturing processes used to make the component. The different types of manufacturing processes are Casting, Injection Molding, Sheet Metal Forming, Machining, Extrusion and Bending. An example that shows that shape does affect the manufacturing processes is as follows; a bolt is made by Machining, due to its rod shape, and the threads that are implemented on the rod. A bolt would not use say Sheet Metal Forming, the processes would be too complicated and expensive, when an easier alternative is present, Machining.
5) Why was each manufacturing processes chosen for that component? Each component was made from a specific manufacturing processes based on the component’s size, shape, and material it is made of. The processes used to produce the component was the least complex, and most efficient way to produce the part, while maintaining the integrity of the part as to make sure the component does not fail when in use. The plastic components used Injection Molding, the easiest and most efficient way to create the component due to the properties of heated plastic.
6) Do any components have a particular shape? Why? Every different component has a particular shape, or else the different components would be performing the same job. A bolt has threads to hold pieces together securely, while a gear has threads to rotate another threaded part, creating rotation and movement of mechanical energy. Also the components have to fit together, thus differences in the components’ shape.
7) Our product is designed to be completely functional and not for cosmetics. The reason that our product is not cosmetic is because it is designed to be placed under a car where no one can see it. The transmission is functional because it designed to run for long periods of time with little to no maintenance at all. The designs of this product works really well since most transmissions are reliable and kept out of mind.
8) I believe the manufacturing process was chosen for this product due to the large quantity of products and the amount of parts for it that need to be produced. The manufacturing process would be an ideal solution to both of these problems. During manufacturing, identical parts could be made cheaply and quickly. This is extremely beneficial for making transmissions because large quantities of identical parts is all they are composed of.
9)Our product is fairly complex for its size. The inside of the transmission is composed up of many different smaller parts that all work in unison with each other. The amount of parts inside is what makes our product complex
Uniform Bolt Head Size One design revision would be changing the different types of bolts used in the assembly of the transmission. Throughout the transmission there was 10 mm and 13 mm head bolts, and in a room where a large amount of students were sharing the same tools, finding two different unused sockets and wrenches was a challenge. If all the bolts could be converted to a uniform head size, that would decrease the complexity of maintenance. Using a uniform bolt head size requires only one size socket or wrench, decreasing the amount of tools needed for maintenance, thus increasing the efficiency of maintenance, saving the owner of the product money.
Lighter Metal Casing
Another design revision would be the reduction of the weight of the transmission casing itself. The casing is made of steel, to withstand the extreme temperatures and forces within the working transmission. The casing is made of thick steel, which vastly increases the weight of the system. By either reducing the thickness of the steel casing, or using a lighter alloy, the transmission system would become lighter, thus increasing the performance and fuel economy of the vehicle. This same idea could be used on other steel parts throughout the transmission. By substituting these parts with more lightweight components, the transmission’s weight will be reduced also, increasing performance.
One change that could be made to our product is the use of stronger gears. With the addition of newer stronger gears the transmission would be less likely to break down and become more efficient. Another change would be to put in a better oil pan to keep the gears more lubricated and thus cutting down on the heat that is being produced. Keeping the heat low in transmissions is key to making them last longer and not fail.
Solid Modeled Assembly
The job of the solid modeler is to create digitally rendered assembly showing how some of the parts of the transmission fit together. The parts that we decided to be reconstructed digitally belong to the valve piston. Essentially the piston valve used to control the flow of a fluid by using linear motion. Having some background for the job Mason Roalsvig was a good choice to solid model the piece.
The CAD that was eventually decided on was Autodesk Inventor Professional 2010. While Mason has experience with AutoCAD, most of his experience was with Inventor 2003 during high school. Once a base of knowledge is established with Autodesk Inventor, using it becomes easy. Which is much easier than trying to imagine a designated view, to build the part and projecting the designated views. Inventor is also much more powerful with many tools for anything from stress testing to deriving volumes. It also comes with a studio portion in which you can provide a path for parts to enter their constraints.
The piece which was solid modeled was selected because the majority of interlocking pieces in this project were too large to easily transport out of the dissection lab. Therefore this small piece was selected because it was easily taken from the lab to be measured and worked with.
Base Assembly with no additional pieces
First rubber ring applied
Second small rubber ring applied
Washer placed over spring
Pin inserted through assembly
Key inserted through key hole
Plastic ring applied around pin
- Note: To open the previous link, you must click on one, then click on the name again the the window which opens*
Problem Statement: The clutch disc in a GM transmission makes it difficult for a vehicle operator to shift gears. The operator notices a grinding and chopping noise and it is most noticeable while driving up or down a hill, during passing of another vehicle and when an extra load is being tugged by the vehicle. Inside of the transmission, the clutch disc is producing more heat that it should be experiencing while shifting gears and braking. What amount of friction must be causing this detrimental wear on the clutch disc?
|| ==>Friction Heat
Assumptions: •The vehicle containing the transmission was manufactured within the last three years, eliminating assumptions that the vehicle is relatively aged.
• There are no engine malfunctions.
• There are no brake malfunctions.
• There is no amount of clutch/ brake fluid leaking onto the clutch disc.
• There is no hydraulic linkage malfunction.
• The coefficient of static friction for steel against steel is μs=0.74.
• The coefficient of kinetic friction for steel against steel is μk=0.57.
• The vehicle is not driven under extreme winter conditions.
fs(max)= μs Fn
∆K=-K=-1/2 mv2 <br<
Discussion: The clutch disc is the barrier between the transmission and the engine. Its primary purpose is to absorb friction from the contact which produces heat. As the clutch disc begins to wear down, more heat is given off when the clutch disc comes in contact between the flywheel and the pressure plate. The more friction the clutch disc experiences the more slipping it begins to do when the transmission is shifting. This friction must be more than the normal friction that the clutch disc experiences under non-hazardous conditions, and conditions that do not put an extra strain on the clutch disc. In order to get a more precise friction measurement, the wear on the clutch disc and the steel it comes in contact with must be examined to analyze the effects of placing an extra payload on the vehicle. Once the calculated amount of friction that the clutch experiences is determined, a value of which it must surpass must also be determined. The value should be greater or equal to the threshold value of the friction. The energy can be calculated using the formula to find the kinetic energy and then converted into heat energy dissipated during contact of the clutch disc.
Causes for Corrective Action
The work and management proposals from Gate 1 worked out fairly well. The issues which needed to be addressed were things such as having meeting times that worked for everyone, while falling during the lab times. This meant that our group was only able to meet as a complete group once. However, on several different occasions small “task groups” met to work on a specific part. These times were decided by Bryan, and were coordinated these in order to fit into the schedule of the involved people. Group conflicts were avoided all together because each part was delegated evenly and played into each team member’s interests and skills.
The challenges which faced the group were primarily due to inexperience of the team in the dissection of automotive parts. A transmission is an extremely complex piece of equipment, and this meant that the wide array of pieces lead to challenges. However, all team members used perseverance and intelligence to overcome any dissection issue which arose. The primary difficulty which was encountered with the way the internal workings of the transmission are all kept in place. GM used a design that implemented a ring with a small section missing that sits between the part that is to be kept in place and a brace. The brace and cylinder have grooves that are designed to allow the cylinder to slide past the brace and in to place. Inserting the ring without grooves prevents the cylinder from sliding back out. In the cramped area of the transmission, and in at least 4 other instances, the rings are very difficult to pry out. The process held up the dissection but eventually was over come.
After dissecting almost the entire project the group came across the last piece inside the outer case. Even with the automotive experience Patrick brought, there was no obvious way to remove the piece from deep in the transmission. Assuming that another point of entry was available the project was flipped over. This allowed the part inside to loosen up and fall out. After taking care of another issue that was easy to do with the case positioned on its side, we lifted the case and managed to get the last few pieces out.
Product Dissection Plan
The product is not intended to be taken apart easily. It requires quite a bit of time to disassemble our transmission. Overall the product is not hard to take apart; it just takes time due to the large quantity of pieces that have to be removed. One part that takes a little time to remove is the many "C" clips that are inside. These "C" clips are designed to hold the different areas of the transmission in place while the transmission is in operation. If these clips were not there then internal parts would be slipping and could possibly ruin the transmission. The only tools needed to disassemble the transmission are basic tools such as screwdrivers, wrenches, and sockets. There is no need for any special tools to be used.
The difficulty scale ranges from 1 to 5 based on level of effort required, time required, tools required and ease of disassembly. 1 being the easiest level requiring minimal time, no tools other than hands required. 5 being the most difficult requiring more time and effort to accomplish using at least one tool or a combined set of tools.
Reverse engineering our transmission is not going to be an easy task. A lot of time is going to be required due to all the parts that are inside. Taking out the pump is going to be the first step. Then you put the transmission on its pan to remove the tail shaft housing, governer assembly, and speedometer gear. The right tools are going to be a necessity for the successful outcome of this project. Some tools that will be required to take apart our project will include screwdrivers, both standard and Phillips head; socket wrenches, either english or metric; and pliers to remove the small parts.
As a group we need to work together to optimize our advantages with our individual skills, and use these skills to mitigate our short-comings. Our team possesses very unique skills and disadvantages which are outlined below, pertaining to each individual teammate.
Miata Wright has had much experience with analytical skills, but mainly her knowledge of disassembling and reassembling machinery and electronics will be of most benefit to the group, since these skills apply completely to the mechanical dissection of our GM transmission. However, Miata’s disadvantage is she is not extremely experienced with specific car components and parts, which could slightly slow down the efficiency of the dissection of the transmission. Nonetheless, her skill in mechanical dissection should outweigh that of little knowledge of car parts.
Bryan Carter possesses great communication, math, and organization skills. Being the head of our group, the traits that stand out to be the most important are his communication and organization. Being the leader of the group will not be an easy task, however, through clear and concise communication and the ability to file and move data and information in a very organized manner will greatly increase the efficiency of our group. The main disadvantage that stands out for Bryan is his lack of patience. Being the leader of our group, Bryan will have to be ready to face the challenges of five individuals working on simultaneous tasks, and the possibility of the group failing to stay with the projected timeline. There are always unforeseeable problems that can occur in a team project of such magnitude that we have, but patience will be the key to keeping the group working smoothly with each other.
Patrick Wright has advantages of hands-on experience with rebuilding cars, and designing and building of robots. That in combination with his above average knowledge in car mechanics and part knowledge will greatly aid our group in the dissection of the transmission. The fact that he has automotive knowledge will help us plan the way we want to dissect the transmission, increasing the efficiency of our group in this project.
Mason Roalsvig has had a history of engineering processes that have shaped him to be strong in the intellectual field of this task. Throughout high school he has taken technical courses that have increased his knowledge with shop tools and components of many mechanical objects. The fact that he has high experience with shop tools will also help us to plan how to dissect the transmission. Since Mason’s strong point is conceptualizing ideas, he will be most useful interpreting the questions we are asked to the data we will have collected, allowing us to forego answering the questions. Mason’s disadvantage is that he is apt to make minor calculation errors in math, which will cause errors in the answer we get, leading to an incorrect answer. Therefore, Mason will be more prominent on the planning of the task, along with the main dissection itself.
Michael Babala also possesses great conceptualizing skills which will help with the overall plan of action for the dissection of the transmission. Michael is able to assess a situation and be able to look at it from multiple points of view, allowing the best option to be decided upon. The disadvantage that Michael has is that he has little to no knowledge of car parts and mechanics at all. This means that Michael will not be the best person to decide how to proceed with the dissection if a problem should arise, however if shown what to do by other members of the group he could carry out simple to moderate difficult tasks within the actual dissection itself.
In order for the dissection to be successful, there needs to be an establish plan. Each member needs to have a set role, so that everyone knows exactly what is expected of them. With these set roles, each person will be free to work on the project as they deem fit. The only restriction being that each member has deadlines to complete his or her part. Some duties intrinsically overlapped, while others may elect to work independently. Each member realizes that they probably will be called upon to assist others when necessary. A key concept of this group is the creation of a position which is flexible, giving that person the ability to work on whatever is needed at the time. Meetings will be set as needed and during times which are convenient for the majority of the group. Conflicts will be resolved by the people involved, if this can not be done, then Bryan will help and then either the professor or a Teacher's Assistant will be contacted. Each team member and their role are as follows:
Project Manager - Bryan Carter
The primary responsibility of this position will be to organize the each portion of the project, step by step. Bryan will be responsible for the delegation of work, organization of final materials, establishment of meeting times and locations and assistance to whoever needs help at a given time. Also, Bryan will serve as the primary connection point. He will be responsible for the keeping members updated on current information and deadlines
Lead Technical Advisor – Mason Roalsvig
This position will be responsible the technical side of the project. His primary task will be the work on the solid modeling portion of the project. Mason has extensive experience in the use of solid modeling programs which is why he is the perfect candidate for this position. Further, Mason will help with the construction of the wiki page.
Head Wiki and Media Developer – Michael Babala
Michael will be accountable for all media required for the project. He will take pictures of the project as it is undergoing its various stages. Also, Michael will further be liable for the construction of the Wiki page and making it functional as well as aesthetically pleasing. This is a key position because the Wiki page is the end product. Mike will also be the wiki contact person.
Materials and Components Consultant – Miata Wright
This position was created so that the dissection and piece analysis will had string leadership. Miata will take the reins when it comes to the analyzing each piece of the transmission. She will be responsible for cataloging each piece and making a materials list.
Functioning Analysis and Information Liaison – Patrick Wright
This is the position with the widest array of potential work. The main focus of this position is to work as a bridge between all of the members of the group. Patrick will be responsible for establishing continuity between the members of the group. This will ensure that there are no gaps between phases and insuring the accuracy of what is reported on the Wiki page. Patrick will be an integral part of the team because he will be present during all phases of the project to assist in any way possible.
The following Gantt chart presents when each deliverable task will be worked on and completed.
Initial Product Assessment
1) Automatic transmission is used in vehicles to initiate the clutch and switch between gears with out the aid of user input. Gear changes are now based on the RPM’s of the engine.. The gears switch at corresponding speeds that optimize power and fuel economy. It is optimization is achieved by using gears that change torque and rotation speed.
a. This product is used in both public and commercial use. Vehicles for business and public use both utilize transmission to optimize fuel economy and thus efficiency. This reduces transportation costs for both industry and personal expenses.
b. The product disengages a clutch, which transfers power to the drive shaft. When the clutch is disengaged the gearshift can occur by either shifting up or down in the gear ratios.
2) The transmission works using hydraulic systems consisting of a torque converter which connects the transmission to the engine. The torque converter prevents the engine from stalling while transitioning to higher speeds. A planetary gear set contains clutches and bands that control the timing of clutch release and application sequences. A transmission uses electrical, mechanical, chemical energy to fully operate. Chemical energy stored in a car’s batter provides electrical impulses needed by a transmission. Electronic controls use these signals to initiate mechanical operation among the gears to adjust to the appropriate gear ratio. Its hydraulic system responds by using transmission fluid to negotiate optimum gear selection that would allow an engine to shift smoothly, thus, resulting in higher speeds.
3) The product we received either requires a large amount of torque to use, as well as some electrical power (as there is an outlet of some kind) or does not work. To the best of my knowledge the product does not function.
a. It does not run by itself. It needs to be connected properly to a vehicle or other power source to even find out if it works.
b. The problems it has may be just the fact that upon testing it I could not make it function with the tools that I have but it seems as though it is stuck in its currently place. A miss-aligned shaft or a bolt too tight could cause this.
4) The transmission is a complex product due to the various components that work simultaneously in order for an engine to produce various speeds. A transmission contains over 200 components, most of which contributes to the transmission’s output of power and function of an engine. Each component has a separate function and may be placed into a system that accomplishes a certain task. The individual components by themselves are not as complex as the transmission as a whole. However; the electronic control system, gears and wires are mostly responsible for carrying out the transmission’s operation.
5) A transmission is comprised of mostly metal, most of which forms the visible frame that cover inside components. The gears and bolts within the transmission are also made up of metal. The wires that transmit electrical impulses are made of copper with rubber insulation, allowing for signals to be exchanged between the mechanical components and the transmission’s computer system.
6. The product seems to a larger truck or van transmission. Seeing as the part is not currently working I wouldn’t be so happy with it. I believe it is an automatic transmission, which I do prefer over manual, especially in something like a truck where on a work site there are many things to look for.
a. Automatic transmission is easy to use provided they work. Operation is as simple as driving your car.
b. Any transmission require some level of maintenance. Maintenance is fairly simple. Check for leaks periodically and insure the transmission fluid is changed as per the owners manual. Unfortunately if transmission breaks, especially automatic transmission, repairs are very expensive and sometimes warrant buying a different car.
7) Many automakers develop their own transmission systems. Transmission systems commonly range from 3 to 6 gears. Higher end performance cars and high power vehicles generally have more gears than lower cost economy vehicles. Manuel transmission is also available. This is engaged by a pedal the driver uses and gears are switched using a shifter.
a. Manuel transmission will generally cost $1000-$2000 less in most vehicles, as automatic is more complex and more convenient to operate.
b. A bonus of manuel transmission for experienced drivers is increased fuel economy as well as more control over the wheels. Keeping a car in low gear is important if you get stuck in snow or mud.
c. Automatic transmission is generally better for new drivers as you do not need to focus on the RPMs or speed of the vehicle and can focus more on the road itself. This can be safer due to the fact that new drivers have more trouble gauging speed and RPMs.