Group 28 gate 2

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In this section of the project, the group must review their work proposal and managements plans. Any corrective actions and variations in the plan are included in this gate. The group must also describe the overall product dissection process and create a detailed list of the individual steps taken during dissection. All of the gate two information is available on this page.


Group 28 main page:

http://gicl.cs.drexel.edu/wiki/Group_28_-_Pressure_Washer


Contents

Causes for Corrective Action

Our group's task was to dissect the engine of a power washer. Our dissection plan was split into two separate days of work; the first day’s plan was to take off all the parts and systems directly attached to the engine (exhaust, air intake, compressor unit). On the second day we planned to disassemble the engine unit itself. Our method was to follow our dissection plan by taking off one part at a time, taking its picture and noting where on the engine assembly it belongs.

Below we review our management plan and address changes made to it.

Plan Reassessment

To split the work up evenly we had each person assigned to a specific job to keep everything organized. One member was primarily responsible for finding the correct tools needed to take off the part we were on. Another member’s job was to actually take off the part and set it aside .The third person would then take a picture of the part. The last member’s responsibility was to write up a detailed note card for each part specifying the part name, location, tool used for removal, and in what order the part was removed from the engine.

Our plan worked very well. We had almost no problem with the disassembly process. The plan was successful due to a few key factors. Our group communicated very well concerning the general plan, group member’s roles, and when meeting times were. We communicated through use of email and cell phone. This communication allowed us to have a very good picture of what needed to be done and how it would happen. When dissecting, we had a fairly clear idea of what every component was for, and how to remove each part. Splitting up our tasks also worked very well, allowing for a smooth process of disassembly and documentation.

Plan Revisions

During the dissection of the engine, our group ran into very little trouble. We finished the dissection of the engine in the time we allotted. One problem we encountered was the tightness of some of the nuts and bolts, which led to difficulty getting many of them off. Another problem we encountered was trying to take the crank shaft out of the engine block. The way it was attached made it so it could not be removed without the use of a special tool which our group did not have. This did not present any problems because this was the only piece that could not be taken off and did not stop us from taking apart the rest of the engine.

Product Dissection Plan

This chart below provides a detailed guide to disassembling this power washer engine. This product is not meant to be disassembled entirely. Many users may take apart small sections of the product for regular maintenance or to replace parts. For example, the air filter cover must be removed in order to replace the filter itself. However, the original designers probably did not intend for users to remove the crankshaft which is pressed tightly into a bearing connected to the engine block.

To make documenting and reassembling easier, group 28 grouped all of the parts removed from the same system together. This way bolts, nuts, and other small parts would stay with the main component they came from. For example the gas tank was removed with two nuts and a bolt so those items were grouped together so that they can be easily identified later.

Dissection Procedure
Step # Process Tools Required** Difficulty Level* Image of Step
1 Remove the four bolts to detach the compressor from the engine. 10mm wrench 3
Group28Step1.jpg
2 Remove the four bolts, nuts and washers from the bottom of the frame to detach the engine. 1/2 inch socket wrench; pipe to increase torque applied to bolts 5 (Bolts are very tight and require a large amount of torque)
Group28Step2.jpg
3 Remove two bolts from the bottom of the frame to detach the fuel pump. 8mm socket wrench 2
Group28Step3.jpg
4 Detach the exhaust assembly located above the engine block next to the fuel tank by removing two nuts and washers. Then remove the metal gasket separating the engine and exhaust assembly. 1/2 inch socket wrench 4
Group28Step4.jpg
5 Remove one wing nut to detach the intake cover. Remove a second wing nut to detach the filter. Next remove one flat head screw, one round head screw and two screw caps. Then slide off the air filter body, throttle body, and carburetor from the screws. P1 Philips head screw driver; P2 Philips head screw driver; 10mm socket wrench 1
Group28Step5.jpg
6 Remove two nuts and then one bolt from the underside of the large red gas tank. Then detach the fuel line from the tank. 10mm socket wrench; 5/16 inch wrench 2
Group28Step6.jpg
7 Remove two bolts from the throttle assembly that is attached to the cylinder block near the intake. Then remove the nut with the rectangular bolt and cotter pin. Then detach the spring to pull off the assembly. 5/16 inch wrench; 10mm wrench; cotter pin puller 2
Group28Step7.jpg
8 Remove the spark plug near the cylinder block. 13/16 inch spark plug socket wrench 2
Step8.jpg
9 Remove the electrical wiring connected the starter to the pull start assembly. Then remove the four bolts from the pull start assembly shroud. Remove the pull start assembly to expose the magneto and flywheel. The magneto is press-fit on the flywheel and was not removed for this reason. 5/15 inch wrench 3
Group28Step9.jpg
10 Remove the electrical wiring and two bolts connected to the engine near the flywheel. 5/16 inch socket wrench 2
Group28Step10.jpg
11 Remove the four bolts from the metal shroud covering the cylinder block. 5/16 inch socket wrench 2
Group28Step11.jpg
12 Remove six bolts from the engine block on the side opposite the flywheel. Then pull off the cover to expose the gears. 10mm socket wrench 3
Step12.jpg
13 Remove two bolts to detach the cooling fins' cover 10mm socket wrench 2
Group28Step13.jpg
14 Remove four bolts from the top of the cylinder block. Then pull off the top cover to expose the valve assembly. Then remove the metal head gasket. 12mm socket wrench; pipe to increase torque applied to bolts 5 (Bolts are very tight and require a large amount of torque)
Group28Step14.jpg
15 To disassemble the valve assembly, start with the intake valve. First remove the nut. Next slide off the spacer nut, then remove the rocker and pull out the push rod. Then detach the cap to remove the spring and valve from the internal screw. Repeat this process for the exhaust valve. 10mm socket wrench 1
Group28Step15.jpg
16 With the flywheel side of the engine block facing down, pull up on the main cam gear located near the center of the engine block to remove it. Then slide out the inlet and outlet valves located on the inner wall of the engine block near the original position of the cam gear. N/A 1
Group28Step16.jpg
17 Remove the two bolts on the piston that lock it to the crankshaft. Then slide out the piston from the cylinder block. 10mm socket wrench 4
Group28Step17.jpg
18 Some gears remain inside the engine around the crankshaft. They will not be removed due to an uncertainty in being able to reassemble them. N/A N/A
Group28Step18.jpg

'*'A difficulty level of 1 refers to a simple task that can be easily completed with one attempt. A difficulty level of 5 refers to a task that is difficult and may require multiple attempts. The easiest task was unscrewing the wing nuts to remove the air filter which was taken off by hand. The more difficult tasks required a lot of force from the user or were in tight spaces where it is difficult to attain a good position for working. These levels of difficulty would be a 4 or 5. A 2 or 3 implies basic understanding of how the tool being used works and a non-strenuous amount of force.

'**' The tools are mentioned in what order they are used to remove which part in the same section. If a nut and bolt are removed in the process section, and in the tool section it reads: 10mm wrench and 15/16 socket, then the wrench was used to remove a 10mm nut and the bolt was used to remove a 15/16 socket. All fraction measurements imply SAE inches. All numbers reading "mm" are metric. The tools used include a metric and SAE set of 6 point sockets with a 1/4 inch and 3/8inch ratcheting socket wrench, a p2 and p1 Philips head screw driver, a cotter pin puller, and a metric and SAE set of wrenches. A mechanical puller could be used to remove the flywheel. However, this step was not taken.