Gate 2: Product Dissection

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Group 22 - Tecumseh Engine Disassembly Process 2011

Disasembly of Pulley from Crankshaft.

Contents

Project Management: Preliminary Project Review

Assessment of Work Plan:

In the groups initial work proposal an educated plan of dissaembly created with basic knowledge and research was determined in order to create a safe, quick and successful disassembly. In the conclusion of the Gate the plan was very accurate when considering the main idea and overall set up of the engine’s disassembly process. However, as stated on the proposal: "These steps of course may change as we encounter challenges throughout the disassembly process." This expectations came to occur when the group encounter several obstacles that prevented the full trail of the dissaembly stages presented on Gate 1:

(Gate 1)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


Most of these stages were followed accurately but certain parts demostrated higher difficulty rate at the realization that either a different tool, not available in the Lab, was needed or that it required a different dissaembly approach than predicted. Some processes demmostrated a danger of causing damage to the engine and/or the person treating it, this force the group to practice new ways of performing the disassembly in a different manner and as safely as possible.

While the dissassembly of the external components went smoothly most of the conflicts came from the dissasembly of the internal components. The group’s first conflict came about when trying to disassemble the crankcase to open the engine. It seemed as if there were no more hex-bolts of screws to take off and the lawn mower’s pulley was stuck on the crankshaft. The stuck pulley made it impossible to open the crankcase. This led to many frustrating problems as the group did not know what to do from here. After a few short hours of research that night, the group met back in the lab the next day to discover that the only way to break open the crankcase was to dismember the piston from the crankshaft. This took an extensive amount of time as it was extremely hard to reach inside the engine with the proper wrench to detach the piston. The group successfully pulled the piston from the chamber and opened the crankcase. However, the pulley was still stuck onto the other side of the crankshaft making it difficult to separate the crankshaft from the other side of the case. The group then had to take the two remaining parts to Jarvis Hall to use a more advanced tool called the wheel puller to grasp on all ends of the shaft and pull it off with the torque generated by turning the puller. This pulley caused two minor setbacks in the overall process of disassembly which were both overcome by the use of proper tools and research.

Author: Kevin Perez, Ryan Sans

Assessment of Management Plan:

The original management plan introduced the weaknesses and strengths of each member, information necessary to assigned titles depending on their strengths and understand what each member is capable of doing depending on their weaknesses. Each member was inform what of their titles and what it was expected of them. Taking in consideration the groups weaknesses a Meeting Plan and work distribution coordination was design, two concepts that were conflicted during Gate 2 progress. The Meeting Plan states the following:

" 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. "

" • 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. "

Informed about and understanding Darroch Moorhead, one of the group's technical experts, schedule conflict with meetings a plan that attempted to work around his school and work schedule was made. Withing the start of Gate 2 lack of attendance and work contribution was presented, with the failure of showing to the first few meetings Darroch did not have enough information to contribute productive work. Attempts to share information through email were attempted but not archived do to technical difficulties. The issue set back the the Gate to be completed to four members. The Meeting Plan also states:

"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. "

" 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 together as a team to accomplish each goal. "

Communication between members is necessary to complete every part of the project and the group's research expert Sangjoon Bark communication skills prevented him from understanding current issues and task needed completed. Magnitude of this issue was not establish until work performance seemed to be affected by this barrier. The work produced by Sangjoon was small and complete revision was needed to properly apply to the Gate. This issue forced the Gate to be completed mostly by the other 3 members.

This conflicts created a big challenged in completing the Gate and the group was forced to use the "Group Conflict Plan of Action" established in the proposal and decided to speak to each member demonstrating problems to ensure that they informed of the issues presented and requested members to provide more effort in their contribution to diminish deadline rush and work stress on other members. To reassure that the conflicts wont repeat itself, group manager, Ryan Sans warned each member that work completed would be credited in the submission of the next Gates if conflict continues on Gate 3.


Author: Kevin Perez, Ryan Sans

Product Archaeology: Product Dissection

Details
Details of the disassembly are provided to inform the steps taken which will allow any individual to read and follow.
Level of Difficulty
The rate of difficulty is ranged from 1 to 10:
    1. Used no tools usually an easy pull or pull dissassembly of the part.
    2. Uses simple tools and required very little effort.
    3. Tools were required .
    4. Encounter obstacles but not too difficult to solve.
    5. Tools are mandatory and assembly requires some effort.
    6. Difficulty Disassembling part properly also time consuming.
    7. Difficulty understanding part and Disassembly step.
    8. Parts are delicate and require precision.
    9. Complex components that require several tries for disassembly.
    10. Most complicated part that requires most attention and time requiring extensive research.

Tools Used
The tools required for the disassembly:
    • Flathead Screwdrivers
    1/2 Sized Socket Wrench
    1/4 Sized Socket Wrench
    5/16 Sized Socket wrench
    3/8 Sized Socket Wrench
    7/16 Sized Socket Wrench


Pre-Disassembly:

    In order to conduct a disassembly an extensive research had to be conducted providing with information on parts and an exploded diagram of the engine this process reduces the amount of obstacles encountered but wont prevent them. Recording tools also were discussed and determine before the process in order to be prepare and have accurate data for further use and documentation.

Author(s): Matthew Whitman, Ryan Sans, Kevin Perez

Product Dissection

Tecumseh Engine Disassembly Procedure
Step # Detail Difficulty (1-10) Tools Used Image
1 Removal of gas tank from the engine:
In order to remove the gas tank, the group unbolted two hex-bolts located on the top of the gas tank. No additional parts holding the gas tank to the engine. Further dissection included removing the gas cap and the oil dipstick/cap.
2 Socket Wrench
Figure 1: Gas Tank
2 Removal of Engine Cover:
The removal of the Engine cover consisted of unbolting the hex-bolts that were holding the Engine cover to the engine.
2 Socket Wrench
Figure 2: Engine Cover
3 Remove air filter from engine:
The air filter was secured to the side of the engine nearest to the piston casing by a single Phillips-Head screw. Upon removal of the screw, the group was then able to open the lid to the air filter. The air filter contained the old foam filter along with a flat black cover.
2 Phillips-Head screwdriver
Figure 3: Air Filter
4 Remove carburetor from engine:
After removing the air filter, we were then able to turn our attention to the carburetor. The carburetor was held to the engine by two hex bolts. After we removed the bolts , we dissected the carburetor further. The carburetor was held together by one hex-bolt, however unlike the other bolts this one was very difficult to remove. After repeated attempts with a variety of wrench sizes and pliers, we were able to loosen and ultimately remove the bolt. As we opened the carburetor, a small piece of metal shot out. We recovered the piece and photographed the inside of the carburetor
4 Socket Wrench
Figure 4: Carburetor
5 Remove Recoil Starter:
The next step in our dissection was the removal and disassembly of the Recoil Starter. By using a socket wrench, we unbolted the 3 hex-bolts that anchored the Recoil Starter to the rest of the engine .
1 Socket Wrench
Figure 5: Recoil Starter
6 Take out Flywheel, magneton and Spark Plug:
After the removal of the Recoil Starter the Flywheel was able to be slid of the engine. The magneton had to be unbolted from the side of the engine with a socket wrench on two hex bolts and the Spark Plug that was attached to the engine was twisted off by hand. The Spark Plug was somewhat difficult to unscrew, however the rest of this step was routine wrench work.
3 Socket Wrench
Figure 6: Crankshaft
7 Take off oil filter and disassemble:
After removing the alternator, an orange filter was exposed. Inside the filter was some kind of metal shaving like pieces which we assumed were used to remove anything from the oil that could damage the piston. We unbolted the top piece with the black tube coming out of it by using a socket wrench to remove two bolts. The orange filter and the metal ring were simply pulled out of hole shown.
3 Socket Wrench
Figure 7: Oil Filter
8 Open Piston Case:
With the outer parts and subsystems removed, we turned our intention to the inner workings that occurred inside the crank case. By using a socket wrench, we removed the eight hex bolts that secured the lid to the crankcase. The bolts were in very tight and it required some effort to remove them. Once the lid came off we were able to see the head of the piston pictured below.
4 Socket Wrench
Figure 8: Open Piston Case
Figure 9: Case Cover and Cover
9 Removing and dissection of the piston:
The group was setback during this process as it was found difficult to access the inside of the engine to remove the piston. This was due to the lawn mower idler pulley that was stuck onto the end of the crankshaft. The group was able to overcome this challenge by reaching inside the engine and unscrewing two hex-bolts with the socket wrench to separate the piston from the crankshaft. The group then slid the piston through the cylinder and separated it from the overall engine.
8 Socket Wrench
Figure 10: Piston
10 Remove camshaft:
Once the piston was separated from the crankshaft, the crankcase was easily split open into two parts. This led to the removing process of the camshaft which was extremely easy as the camshaft was able to just slip right out of the crankcase.
1 None
Figure 11: Camshaft
11 Remove crankshaft:
After the camshaft was removed only three parts remained, they were the crankshaft, the stubborn pulley idler and the other side of the crankcase. This was the group’s most difficult setback as the group was unsure if the pulley was designed to be removed. After a little research it became apparent that the part was slid onto the shaft and used a woodruff key to set the flywheel’s position on the crankshaft. This meant that it should be removable, however due to the wear and tear of our product the pulley seemed to be jammed onto the crankshaft and it would take more than the tools in the lab to produce enough force to detach the part from the crankshaft. This was achieved by taking a walk to Jarvis Hall to use a tool called the wheel puller to disconnect the part and finish the disassembly process.
10 Wheel Puller
Figure 12: Crankshaft before separation from the crankcase

Author(s): Matthew Whitman, Ryan Sans, Kevin Perez

Ease of Disassembly:

How difficult is each step?

Each step of the disassembly process was very straight forward as most parts of the engine came off without any trouble. However, after the piston casing was taken off our group had trouble entering the gear box as the bottom of the engine was hard to maneuver.

Author: Ryan Sans

How can you define a meaningful scale to rate the difficulty?

A meaningful scale of disassembly can be broken down into the factors that make it a complex or simple process. As the more parts included in the disassembly process increases, the difficulty of the overall process will also increase. For example, a two-thousand piece puzzle is much more complex to disassemble and reassemble than a ten piece puzzle. Another factor contributing to the difficulty would be the amount of different parts included in the disassembly process. It is much harder to disassemble a product that has a variety of components keeping it together (nuts, bolts, screws, etc.) than a product that has only uses one type of component. It is these factors that differentiate the level of difficulty between each product.

Author: Ryan Sans

Is that part of the product intended to be disassembled?

Each part of the product that our group has disassembled was intended to be taken apart in case of repairs or maintenance of the product to aid it’s overall functionality. The fact that each part of the product is easily taken off with the use of basic tools while maintaining its original shape and function is a good sign that is was intended to be disassembled at one point or another. Also, each part did not need the aid of a more complex tool or device for disassembly such a welder or saw which would alter the overall material of our product.

Author: Ryan Sans

Document the connection of subsystems:

What subsystems are connected?

• Alternator
• Sparkplug
• Valves
• Piston
• Crankshaft

Functional Model

All of the components that make up our product work together in order to complete the product’s main function to eventually achieve the final goal of transmitting power from fuel. However, this process is more complicated than that as the system can be broken down into smaller subsystems. Each component is connected purposely based on each one of their functions. To explain further we can use the energy diagram shown to relate the process of how the engine works:


Step 1
Fuel is added to the gas tank
Parts Used
• Gas Tank,
Gasoline is physically added to the gas tank. This introduces the Chemical Energy that is later used during the combustion process.


Step 2
Human pulls the pull cord to create angular velocity,
Parts Used
• Pull Cord
• Flywheel
Both parts are physically connected and are used to transfer the human energy generated to mechanical energy or more specifically rotational energy.
Step 3
Angular velocity is used to rotate the alternator and generate a spark
Parts Used
• Flywheel
• Alternator
• Magneto
The flywheel is used to generate the rotational energy in step 2 through the alternator, as the alternator rotates it creates a high-voltage pulse. During this process the rotational energy from the flywheel is used along with the magnetic energy introduced by the magneto to generate electrical energy through the alternator. To learn more about the functionality of the magneto and how the spark is created Click Here.
Step 4
Ignition is created in the combustion chamber
Parts Used
• Spark Plug
• Camshaft
• Valves
• Piston
The piston is used to compress the air/gasoline mixture that is let in by the camshaft opening the intake valve. The fuel mixture is then ignited from the spark generated from the alternator forcing the piston down the cylinder. During this process the electrical energy generated from the alternator creates a spark that is able to jump across the engine’s spark plug and interact with the chemical energy introduced in step 1 to create both pneumatic energy in the piston and thermal energy that is expelled through the exhaust valve that the camshaft rotates to open. This process differs from a conventional 2-stroke engine in which the 4 main strokes are simplified to just two strokes
Step 5
Pneumatic motion is transferred to mechanical energy
Parts Used
• Piston
The piston is driven down the cylinder by the pressure created by the ignition process in step 4 and uses that pneumatic energy to transfer into translational energy
Step 6
Convert translational motion to rotational motion
Parts Used
• Piston
• Crankshaft
The piston is physically connected to the crankshaft and operates to create rotational energy through the crankshaft from the translational energy by the piston from step 5. In other words, as the piston is forced downward, the pistons up and down force is used by the crankshaft to physically rotate it accomplishing the engines goal of continuous rotational energy.
Step 7 (Optional)
Throttle increases rotational energy
Parts Used
• Throttle
• Valves
• Piston
• Camshaft
• Crankshaft
The throttle is activated by the user of the product to allow more air/gasoline mixture to enter the combustion chamber at a higher velocity this increases the rotational energy produced in the crankshaft.

Author: Ryan Sans

Four Factors for Engine Subsystems and Parts

Global
In different parts of the world the parts of the engine be unique to the setting around them. For instance somewhere in the mid-western United States, where there is a lot of farming, the parts of the lawn mower will be bigger due to bigger engine. Compared to somewhere such as Buffalo, where the use of the lawn mower is much more domestic. Or consider a place like Seattle, WA, they may use aluminum for the casing or for different parts this way in wont rust from all of the rain. These parts will differ globally due to the surroundings and environment they are in.;Societal: The engine and its parts may have been changed due to societal factors such as safety and lifestyle. As far as safety there are no open parts on the outside of the engine where someone could be injured. The flywheel, pistons and camshaft are all contained and surround by over laying parts which don’t allow the user to come in contact with moving parts and therefore not easily get injured. The engine was also designed to be small, for an everyday lifestyle. All of the parts are down sized from say a car engine, in order for the user to operate the engine.
Economical
Economically all of the parts have to be mass produced and cannot be expensive. The amount of engineering that goes into the engine and its parts are high, due to the complexity of an engine, however the parts need to be easily produced and cheap. Because of how cheap they can make the engine, replacement parts such as pistons, camshafts and flywheels are not highly available or may not be the best economic option. Instead of buying each individual part, one can just buy an entire new engine.
Environmental
Every part goes through a cycle from the time its manufactured to the death of the product. Most of the parts in the engine like the pistons, valves, camshaft, flywheel and screws are made of metals. The metal can be recycled along with the plastic gas tank. All the individual parts on the engine can be recycled and reused in the future. So environmentally this is a very good product, because the parts are not wasted which allows for the ideal situation of no disposal at all.

Author: Darroch Moorhead
Wiki Formatting: Kevin Perez

REFERENCES

http://science.howstuffworks.com/question375.htm

http://inventors.about.com/library/inventors/blinternalcombustion.htm

http://www.ehow.com/how-does_5008782_lawn-mower-engine-work.html