Group 29 - Yard Machines 139cc Push Mower

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Gate 1 Work Proposal

Introduction: The reverse engineering of an engine can become very complicated. As the majority of our product consists of an engine this will be the main challenge in our disassembly. The easiest way to organize the disassembly is to document and photograph every piece as it comes off the mower. Labeling pieces and making notes and diagrams will make reassembly a lot easier.

II) Project Management

a. This section outlines the work required and the timeline for our group project

b. 2.1 Work Proposal i. Plan for disassembly

1. Tools required to disassemble a lawnmower are a Phillips-head screwdriver, a Flat-head screwdriver, a box-wrench set, and pliers

2.Keeping all pieces organized making sure we remember the order of disassembly will be one of the more challenging parts of this project. Time in this project is limited and making everyone’s schedules fit together is another challenging aspect.

3.All members of the group are capable of using hand tools. The knowledge of small mowers is not very high and this makes the disassembly a big learning experience.

4.The biggest learning experience for the group will be how the inner mechanics of a small lawn mower engine work. c. Management Proposal d. The work put into this disassembly will display how this particular lawnmower is best suited for the people and uses it was designed for

III) Product Archaeology: Prep and Initial Assessment:

a.From the outside of the lawnmower you can tell that it was designed for simplicity and safety. The majority of operation is meant to be done from the push handle. The safety handle is present at the end where it is easy to grasp. The pull start cord is placed about two-thirds of the way up the push handle for easy reach as well as a choke plunger that can be pulled up to engage the choke. The safety mechanism that is obvious is the lever handle that is placed at the end of the push handle. In order to start the mower you must be holding this handle down. If you release the handle the mower will stop. This feature makes the mower much safer if someone was to trip and fall while using it or if there were an emergency and the mower needed to be shut off quickly. The four wheels are easy to move and keep the mower stable. There are larger wheels in the back and I am not sure if that serves a purpose or is aesthetic. An air intake and exhaust are easily visible and upon opening the air intake you find a filter, which connects to a carburetor. The carburetor is responsible for mixing fuel and air to the proper ratio. The exhaust as visible simply expels the exhaust gasses. A tank exists on top to fill with gasoline to power the mower and an oil fill are to pour in oil to lubricate the mower engine internals.

b. 3.1 Development Profile

Lawnmowers have been around for many decades but the modern lawnmower is different in the fact that it has a horizontal spinning blade compared to a spinning wheel of blades. An engine was attached to achieve an easier, more consistent cut. Adding an engine made the product more expensive but easier to use. The inclusion of a bagging system makes it possible to keep a neater lawn because grass clippings can be removed. This mower was meant to be sold in America based on the English writing on it and the fact that lawn cutting is part of American society. Keeping your lawn trimmed and green is something that not all countries do. This product is intended to simplify lawn maintenance as well as make it possible

c. 3.2 Usage Profile

This product is intended to cut lawns to a height determined by the user. The user is meant to be a homeowner or anyone who has a lawn that needs to be cut. If you want to use the mower to pick up leaves it is possible for them to be sucked up into the bag.

d. 3.3 Energy Profile

The lawnmower runs on gasoline and is lubricated by motor oil. A carburetor mixes fuel and air, which is ignited by a spark plug. This explosion causes expansion of gasses, which drives a piston that spins a shaft creating power.

e. 3.4 Complexity Profile

There are many different systems involved in the use of a lawnmower. An intake system and a fuel delivery system begin the process. Once the fuel and air are mixed they are transported into a combustion chamber where they are ignited and drive a piston to create power. Once the gasses have expanded they are pushed out of an exhaust pipe into the atmosphere. The power that is generated in this explosion turns a shaft connected to a blade that cuts the grass. The interactions between components in the engine are complex and each of these components are very complex with small moving parts.

f. 3.5 Material Profile

Many different materials can be seen upon first glance. A majority of parts are metal and make up the engine and cutting deck of the mower. A plastic cover exists on top of the engine to mask many moving parts and to make the mower look sleeker and more uniform Plastic wheels exist, which are light and durable. Most parts that encounter movement are made of metal to withstand many years of friction and use.

g. 3.6 User Interaction Profile

The user stands behind the mower and pushes it . A majority of the controls used for basic usage are placed on the push handle in order to give easy access to the user. The intended user does not have an extremely complex role but may require some training to use the mower. Some maintenance is required. Filling of gasoline is required to power the mower and changing oil is required to ensure proper lubrication of moving engine parts. Also, changing of the air filter would make the mower more efficient. Mower maintenance is not extremely difficult as it is meant to be done by any home owner.

h. 3.7 Product Alternative Profile

Other product alternatives are the ride on mower and commercial mowers. The advantages of these are durability and reliability. They cost more money and are larger but the larger cutting deck makes it possible to cut grass faster which is more economical. Comparing a commercial mower to a low-end home mower would show many differences in the products that are used for the same thing. Comparing a large ride on commercial mower to a home mower in price would show large differences. The most complex and expensive commercial mowers can extend in price range up to a few thousand dollars as compared to a residential push mower like the one we purchased for fifty dollars. A commercial mower may be required when mowing a large field or when owning a lawn maintenance business. Using a 21” diameter mower to mow a field would be ridiculous compared to a mower with a 4’ wide cutting path. This would play a role in societal factors because less noise would be generated because the mower would cut faster. Economically and environmentally more as would be consumed using a smaller mower for a longer time. However, the higher price of a large commercial mower may not be feasible for a homeowner nor necessary.

Some examples of alternative mowers that would be used as a commercial mower, which are referenced within this page are mowers similar to an ExMark Lazer DS-Series Zero Turn Mower [1]. These mowers are used in commercial operations because they are reliable, powerful, and are much larger than a single 21" push mower like the Yard Machines 139cc Mower.