Gate 1: Project Planning

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Group 22 - Tecumseh Engine Disassembly Process 2011

Figure 9: Tecumseh Gasoline Engine (Side View)‎


Project Management: Work Proposal

    Our product the Tecumseh TVS120 small 5hp internal combustion engine. It is a spark ignited, one cylinder, four stroke engine that runs on gasoline. Since the components of an engine do break and fall apart, the manufacturer has made it somewhat easy to take apart the engine in order to fix or replace a part. Despite our group’s limited amount of experience with engines some intricate research is necessary for our group to understand the components of the engine as well as their function. After the research is complete our group was able to propose a twelve step process for the reverse engineering of the engine. The reverse engineering process will consist of two main stages the disassembly of the external components and the disassembly of the internal components as shown below. During the disassembly of the external components, the group will begin to dissect the parts that are visible to the user. This includes the gas tank, recoil starter, engine case, air filter, pulley, carburetor, throttle and muffler. After each one of these parts is removed, our group will then be able to access additional external parts such as the oil pipe, magneto, spark plug, flywheel and piston head cover. Once stage one of the disassembly process is complete the group can then move on to the disassembly of the internal components of the engine. This process begins with the opening of the crankcase in order to access the inside of the engine. Once the crankcase is opened, the group can then dissect each of the internal components such as the governor, camshaft, oil pump, valves, springs, piston and crankshaft.

Table 1: Stages of Dissection and Components Involved
External Components Internal Components
1. Gas Tank 1. Governor
2. Recoil Starter 2. Camshaft
3. Engine Case 3. Oil Pump
4. Air Filter 4. Valves
5. Pulley 5. Springs
6. Carburetor 6. Piston
7. Throttle 7. Camshaft
8. Muffler
9. Intake Manifold
10. Oil Pipe
11. Magneto
12. Spark Plug
13. Flywheel
14. Piston Head Cover

    These steps of course may change as we encounter challenges throughout the disassembly process. Some challenges could range from striped screws to warped pieces of metal and plastic. Each one of the components on the engine are fastened together mostly by different sized hex bolts and screws. This means that the only tools that will be necessary are screw drivers and socket wrenches with a variety of sizes. However, as we get deeper in to the engine we may need some other tools.
    Dispite the litte knowledge our group has about engines, both the disassembly of external components stage and the disassembly of internal components stage will be very easy. This is due to the simplicity of fasteners used to hold the engine together and the small amount of tools needed. Therefore, the time taken to complete both stages of the disassembly process would be influenced by how many components each stage has and how many fasteners are used on each component. For instance, there are more external components to dissect than internal components making stage one of the disassembly processes more complex than stage two. However, since the detachment of hex bolts and screws should take less than a minute each stage should only take around 25-30 minutes with careful labeling and storage of each component.
    Our group plans to work on each section of the project by splitting up the work evenly and individually. To make sure everyone is up to date with the material and help the professional quality of each assignment our group will be meeting weekly at Capen Library to talk about each section and the work that was done for that week. Our point of contact will be Kevin Perez and will be reachable at

    Author: Ryan Sans

Groups Roles and Strengths/Weaknesses

Table 2: Groups Roles and Strengths/Weaknesses
Group Member Title Duties Strengths Weaknesses
Ryan Sans Project Manager
  • Makes sure work is done on time, correctly and looks professional
  • Organizes final assignments
  • Experience in AutoCad
  • Interested in engine design and production
  • Work experience as Maintenance at Autumn Creek Apartments
  • No previous knowledge of the engine’s components and their function
  • No wiki formatting experience

Matthew Whitman, Darroch Moorhead

Co-Technical Experts
  • Studies the product and applies outside knowledge to the reverse engineering process

Matthew Whitman:

  • Suitable documenting experience
  • Basic knowledge of engine functionality

Darroch Moorhead:

  • Respectable mathematics capabilities
  • Technical Communication strength

Matthew Whitman:

  • No wiki formatting experience

Darroch Moorhead:

  • No previous knowledge of the engine’s components and their function
  • No previous wiki formatting knowledge
  • Difficulty with availability for group meetings and will be hard to contact due to work and school hours

Kevin Perez Communication Liaison
  • Organizes each meeting to make sure each member is in attendance
  • Communicates with the professor to make sure the group is on track
  • Experience with Wiki formatting
  • Practical communication skills
  • No previous knowledge of the engine’s components and their function
Sangjoon Bark Research Expert
  • Provides necessary research for each operation
  • Experience with technical mainframe
  • No previous knowledge of the engine’s components and their function
  • No wiki formatting experience
  • Demanding school schedule leading to a decreased availability
  • Problematic communication skills being an international student

Author(s): Ryan Sans, Kevin Perez and Matt Whitman

Development of Skills:

As shown in the diagram above the skills that need to be developed are influenced by each member’s weaknesses. The most significant factor being the reduced knowledge of the engine’s components and each of their functions as no group member has any previous knowledge. Another huge disadvantage in our group is the lack of members that understand the application of wiki formatting. This means that in order to present each assignment, each member will either have to learn the formatting process or all assignments will have to be sent to the one member that has experience. Other skills that are going to play a huge role in the success of our group will be the communication and availability of each group member. For instance, if one of the members cannot make it to a significant meeting in the lab it will be extremely difficult to bring them up to speed. Also without the proper communication, each assignment given to the group might not get done in time.


Group Conflict Plan of Action:

If any group members are in a disagreement with one another, the group will assess the argument with a team vote to solve it. This means that the conflict between group members will be brought up to the group manager if not involved already, to assess the situation, in order to call a group meeting to physically explain each group member’s argument. After each case is explained the argument is discussed amongst the remaining group members and a solution is determined.


Project Timeline

A display of the work progress and date completed is related to table 2 in the management proposal and is illustrated in Figure 1, a Gantt Chart of our project's timeline which is shown below:

Figure 1: Gantt Chart of the Project Timeline

Author: Ryan Sans

Project Management: Management Proposal

Meeting Plan:

    • Who: Who is expected to attend; how many people have to be there to make a decision
      • Every member is expected to attend every meeting unless they have a reasonable excuse. The excuse is determined reasonable by the group manager and the information presented at the meeting is then passed on to the absent group member through email.
      • In order to make decisions for each assignment the majority of the group must be present. In other words three out of the five group members must be in attendance.
    • Where: Where will the group meet
      • The group meetings will mostly be held on the third floor of Capen Hall as it will provide the necessary research resources for each group member. Also a few days will be set aside to meet in the lab for the disassembly and reassembly process as shown in Table 2 below.
    • When: When are the meetings held, and for how long
      • Each meetings length is determined by the amount of information needed to be covered for each assignment. This can range anywhere from a few minutes to a couple hours depending on if the group must work together or if the material can be assigned to each individual.
    • What: What is expected to be done at meetings
      • The meetings are designed so that each member can share their input on the assignment given. The group is then able to discuss which member will be best to complete each assignment so that the workload can be distributed evenly. Once distributed the group then meets again the following week to examine one another’s work to be improved on.
    • Why: Why is the group meeting, what is the purpose
      • Each group meeting will provide the proper communication for the group to be successful in each assignment as each member will be able to work togeather as a team to accomplish each goal.

    Note: The roles of each group member and conflict resolution plan are identified in the work proposal section as they are related to the information in Table 1 for convenience.
    Author: Ryan Sans

Table 2: Project Schedule
Date Project Assignment Meeting Place
September 29, 2011 Gate 1: Management Proposal
Capen Library 1:00 PM
October 5, 2011 Gate 1: Work Proposal and Product Archeology
621 Furnas (Lab) 5:00 PM
October 12, 2011 Gate 2: Preliminary Project Review
621 Furnas (Lab) 5:00 PM
October 19, 2011 Gate 2: Excavation and Corrective Action
621 Furnas (Lab) 5:00 PM
October 27, 2011 Gate 3: Coordination Review
Capen Library 11:00 AM
November 3, 2011 Gate 3: Evaluation
Capen Library 11:00 AM
November 10, 2011 Gate 4: Explanation
Capen Library 11:00 AM
November 17, 2011 Gate 4: Critical Project Review
Capen Library 11:00 AM
November 24, 2011 Gate 5: Documentation
Capen Library 11:00 AM
December 1, 2011 Gate 5: Documentation
Capen Library 11:00 AM
December 8, 2011 Gate 5: Documentation
Capen Library 11:00 AM
December 16, 2011 Gate 5: Final Presentation
Knox 104
  • All meetings are not final and subject to change
    Author: Kevin Perez

Product Archaeology: Preparation and Initial Assessment

Development Profile:

    The Tecumseh TVS120-63000 was developed in the 1990s. Although Tecumseh specialized in a variety of products, the engines primarily used aluminum die cast engines with a power output range of two and twelve horsepower. The TVS120-63000 series is a gasoline engine with a power output of five horsepower. Economic and global factors became a significant influence to the engine’s design. Among the most important was the type of units used on the fasteners (metric vs. english), the engines size and amount of material used. This means that our product has many design considerations to research before manufacturing the product. Due to the engines intended use of lawn care discussed in the usage profile below, the engine is designed to be pushed around by the user for longer periods of time. This is an example of how design limitations such as weight and size affect the manufacturing of our product as the user would have more difficulty pushing around a larger engine. As these factors are resolved to make the engine lighter and more maneuverable for the user our product becomes more economical. Tecumseh engines are sold to over 120 countries throughout the world to locations in North and South America, Europe and Asia. As these engines are sold in locations that use english units such as the countries in North America and locations that use metric units such as the countries in Europe it poses the problem of which units to use when manufacturing the product. The inventory of European engines must be taken separately from North American engines to be manufactured separately based on proper units. The intended impact on the consumer and society was to create the most efficient engine to satisfy individual or professional lawn maintenance while sustaining factors like: the safety of the consumer(s), emission regulations and ease of use.
    Author(s): Ryan Sans and Matthew Whitman

Usage Profile:

    The intended use of the Tecumseh TVS120 is to be placed inside a lawn mower for the purpose of landscaping maintenance. This is achieved by the crankshaft as it is attached to cutting blades under the casing of the lawn mower. Our products main job it to provide the necessary net power output from the piston to the crankshaft to rotate these blades for controllable use inside a lawn mower. Note that our product is not the lawn mower but the engine inside it. The manufacturing of the engine is designed for a lawn mower and therefore the specs and dimensions are influenced by the intended use of our product as discussed in the development profile. For the reason that lawn mowers can be used by individual home owners as well as professional landscaping businesses, the Tecumseh TVS120 5hp small engine can be used for home and professional use as well.
    Author: Ryan Sans

Energy Profile:

    The engine uses a combination of human, magnetic, electrical, chemical, pneumatic and mechanical energy in order to function. The human energy is initiated through the pull cord that is connected to the recoil starter inside the engine case. As the cord is pulled by the user, it increases the angular velocity of the flywheel which results in the production of rotational mechanical energy. As the flywheel rotates the attached magnet acts with the engines magneto to create magnetic energy that is turned into electrical energy by the spark plug. The chemical energy is imported through the air/fuel mixture that is delivered by the carburetor into the combustion chamber through the intake valve. The spark generated by the spark plug (electrical energy) works with the air/fuel mixture (chemical energy) to create an internal explosion inside the combustion chamber. This explosion creates pressure (pneumatic energy) from the expanding gases to push the piston down the cylinder creating translational mechanical energy. Due to the component connection of the piston onto the crankshaft the crankshaft is able to transfer the translational energy from the piston to rotational energy. This rotational energy is then used to produce the necessary desired output of the engine based on the application of the engine. Energy Flow illustrated in Figure 2 below:
      Figure 2: Energy Flow of Engine

        Author: Ryan Sans

      Complexity Profile:

        The components that are used are listed above in the explanation of the disassembly process. Each component is classified by the location of either inside or outside of the crankcase. There are fourteen external components and seven internal components, their complexity and component interactions are illustrated in the table below: (For further knowledge of each part and its orientation on the engine pictorial representations are supplied for convenience, check out exploded diagram #1 and exploded diagram #2).
      Table 3: Component Matrix
      External Components Component Complexity Component Interactions
      Gas Tank The gas tank is one of the least complex components, it consists of a large plastic container for fuel storage The gas tank interacts with the carburetor to control fuel dispersion
      Engine Casing The engine casing also is very simplistic as it consists of a metal casing used as protection for the engine and the user from moving parts The engine casing interacts with no other component
      Air Filter The air filter is more complex than the gas tank and engine casing as it consists of a plastic container and a sponge filter to filter the air being extracted from the engines surroundings The air filter interacts with the intake manifold once air is brought in through the air filter it is sent to the intake manifold
      Recoil Starter The recoil starter consists of a pull cord and rotational device to retract the cord The reoil starter is attached to the flywheel to provide the human interaction to start the engine
      Throttle The throttle consists of a complex setting of small metal parts and a spring The throttle interacts with a internal component called the govenor to regulate the amount of fuel/air mixture being burned
      Muffler The muffler consists of a metal casing with tubes and holes to reduce engine noise The muffler interacts with the engines exhaust valve as the differences in pressure from the gas and the exaust system are reflected back to partically cancel the sound waves
      Intake Manifold The intake manifold consists of metallic piping for transportation of air from the air filter to the intake valve The intake manifold interacts with the air filter and the intake valves
      Flywheel The flywheel consists of a steel rotating wheel and magnet to produce the magnetic energy The flywheel interacts with the magneto as the recoil starter is pulled to rotate the wheel and generate the magnetic energy necessary
      Magneto The magneto is a complex small electric generator containing a permanent magnet used to provide high-voltage pulses The magneto interacts with both the flywheel and the spark plug to transfer magnetic energy into elecrtical energy
      Spark Plug The spark plug is a very complex component that delivers electrical current The spark plug interacts with the magneto and the combustion chamber to deliver the electrical energy to chemical energy inside the cylinder
      Oil Pipe The oil pipe is a simple component made of a long plastic tube The oil pipe interacts with other components inside the engine for lubrication
      Carburetor The carburetor is a more complex component consisting of a metal container The carburetor interacts with the gas tank and the intake manifold to mix the proper amount of gas and air used during combustion
      Pulley The pulley is a simple component made of a small metal cylinder with two groves The pulley interacts with the crankshaft to rotate and component attached to it
      Piston Head Casing The piston head casing only consists of an aluminum cover with many groves for engine cooling The piston head interacts is the top of the combustion chamber and is used to contain each combustion
      Internal Components Component Complexity Component Interactions
      Governor The governor is extremely complex as it consists of a plastic gear, spool and two clips to hold the system together The governor interacts with the throttle as it uses centripetal force from the engine to act on the throttle and regulate the amount of fuel burned in each combustion
      Camshaft The camshaft is a simplistic component with a huge responcibility. It consists of a metal rod with metal bumps called cams attached to a gear The camshaft interacts with the crankshaft, intake and exhaust valves. It provides the proper timing to open and close each valve on the engine.
      Oil Pump The oil pump is a simple component made of a short plastic tube The oil pump interacts with other components inside the engine for lubrication
      Valves The valves are two simple steel components that are placed inside the combustion chamber The valves interact with the camshaft and allow for the intake of fuel/air and the exhaust of combustion products
      Springs The springs are as simple as possible at these two components are made of metal The springs interact with the valves to provide to necessary recoil to close each valve promptly
      Piston The piston is very complex, it consists of an aluminum piston head, connecting arm, an oil ring and two compression rings The piston interacts with the crankshaft and the combustion chamber to produce the translational energy from the pneumatic energy from the expanding gas
      Crankshaft The crankshaft is a simple shaft made from steel located in the center of the crankcase The crankshaft interacts with the piston to transfer the translational energy to the rotational energy creating the engines power output
        Author: Ryan Sans

      Material Profile:

        The material clearly visible without going beyond the functional use of the consumer is mostly plastic, rubber and metal. However, the components that the group believes to be metal could be made from either steel for increased temperature tolerances or a lighter material such as aluminum for a lighter operational value of the consumer. Based on the complexity profile of the engine, the internal and external components are mainly the same material used throughout the external components. On the other hand, as the temperatures experienced inside the engine are extremely higher than the temperatures experienced outside the material used for the internal components must be stronger. This means that materials such as steel and aluminum would most likely be used for the piston and the combustion chamber as both materials can withstand more extreme temperatures. On the contrary, the material used for simple tasks such as the gas tank, can be made from a lighter material such as plastic as it does not need a higher tolerance for temperature.
        Author: Ryan Sans

      Interaction Profile:

        It is necessary for the user to interact with the product for functionality and maintenance purposes. To begin the operation of the product the user first must provide the engine with the proper fresh, clean, unleaded gasoline as it burns cleaner, extends engine life and reduces build up inside the engine. If the user imports gasoline that contains methanol, gasohol containing more than 10% ethanol, unleaded regular gasoline containing more than 15% methyl tertiary butyl ether or white gas it could significantly damage the engine and fuel system. This is an easy process as long as the user understands the type of fuel and the amount needed to fill the gas tank they will be able to refuel the engine whenever necessary. Once fuel is added to the tank, the user then must make sure there is enough oil in the engine by checking the dipstick located on the top of the engine. This process is simple as the user just has to read the end of the dipstick and add more based on the reading. Next the engine must be primed, this is achieved by pushing down on the rubber bubble located on the side of the carburetor. During this process gas is imported into the fuel system for the initial start-up. Lastly the user must hold the choke down while pulling the pull cord to begin the rotating process of the flywheel to turn the engine. This is the most difficult and strenuous process as it may take multiple tries to finally get the engine started. However, the engine will continue to run once started until either the engine runs out of gas or is cut off by the choke. The overall process is simple to use, this is assuming that the user is an adult or an experienced and capable child above the age of thirteen. Regular maintenance is required for the engine to run properly as it requires the constant refueling of gas and oil based on the usage rate of the user as described above. Both processes are extremely simple given that the user is knowledgeable and has experience with the product. Maintenance also includes the repairing of the engine throughout its lifetime. This could include simple repairs such as cleaning parts for better usage or more difficult repairs like replacing a spark plug, replacing a restricted air filter or fixing the timing on the camshaft. The more difficult the repairs are the more knowledge and experience the user must have to effectively fix the functionality of the product. For more information on engines functionality and user interaction Click Here to view the owner's manual
        Author: Ryan Sans and Kevin Perez

      Alternative Profile:

        The product alternatives are compared in Figure 3. Our product, the Tecumseh TVS120 is compared to three other vertical engines in it's class. The main differences include the position of the valves and camshaft as well as the amount of strokes during the combustion process. Although the 2-Stroke Tecumseh TV085XA is relatively simple, inexpensive and has high power-to-weight and power-to-volume ratios it's major drawback is the that the 2-Stroke engine does achieve a complete burn of the gas making the engine less efficient and more harmful for the environment. The overhead camshaft on the Honda GCV160LA-S3A allows for a higher power output and reduces amount of parts leading to a higher engine life without failure. However, the major draw backs of this engine is that it is heavier than other engines in it's class this could make this product less economical for a home owner that desires a simple engine to get the job done. The position of the valves on the Briggs and Stratton 126L021625F1 is oriented over the head of the piston and allows for a more direct injection of fuel/air for a more complete burn inside the combustion chamber. This engine is also on the heavier side due to its massive power output of 6.5 horsepower and correlating larger components when compared to other engines in it's class. The Tecumseh TVS120 model's main disadvantages are the older style oil pump and side valve orientation placing it at the lower end of the engines in it's class. However, due to the low amount of cost our product might be more economical for the simple homeowner with a smaller amount of land. These are just three examples of the many alternative engines in its class. To learn more about these alternatives and compare the Tecumseh brand to other company products visit Jacks Small Engines

      Figure 3: Alternative Comparison of Verticle Shaft Engines

        Author: Ryan Sans