Group 21 - Jeep® Wrangler Power Wheels 1 - Gate 2
Project Management: Preliminary Project Review
The work plan for Group 21 (which can be viewed in Gate 1) outlined how the group anticipated to carry out the disassembly process of the Jeep. Contrary to original plan, the actual disassembly took place on two dates: Wednesday, October 13th as well as Tuesday, October 26th. The initial reverse engineering and process documentation was done on the 13th while additional photo documentation of miscellaneous parts was done on the 26th.
The group actually over estimated the amount of tools needed for deconstruction of the Jeep. The collection of tools solely consisted of a P2 Phillips head screwdriver, a 1/8" flathead screwdriver, and an assembly wrench that is included with the product. No power drill was needed. The amount of time anticipated to disassemble the Jeep, roughly two and a half hours, was also accurate. The group decided on that amount of time by planning ahead and thinking about the encountering a problem with difficult disassembly. One reason the disassembly might be difficult is the fact that the product in question was made for children. This prediction that there would be problems with disassembly that would extend the disassembly time proved to be true. Red safety caps on each of the wheels were not meant to be removed. However, removal of these were necessary to move forward with deconstruction, which took much effort. The extra time for disassembly could have made it difficult to finish on time, but by planning ahead Group 21 was able to avoid problems completing the assignment on time.
Opportunities for Improvement
Although physical disassembly went rather smoothly, the initial documentation of the step-by-step deconstruction process was performed at an insufficient level. Multiple members simultaneously began disassembling different components of the Jeep. This resulted in the steps being recorded in the incorrect order. The camera used for photo documentation of components was also of lesser than expected quality resulting in pictures that could not be used in the final product. To compensate for these setbacks, another session in the lab was needed for correction. Had this procedure been done correctly during the first attempt, an entire second lab session would not have been necessary. To avoid this in the future, there will be better communication between members, especially when recording information is necessary.
The management plan for Group 21 (which can also be viewed in Gate 1) has for the most part been successful thus far into the project. As of now the group meets weekly at 5:00 P.M. EST on Wednesday in Capen Library directly following MAE 277 lecture. Additionally, when it is necessary to meet in the lab and physically work on the product, the group has agreed to convene there at 10:00 A.M. EST on Mondays. Although some group member's time at these lab sessions are limited due to conflicting class schedules, it allows for all members to meet for at the least an hour to go over and execute the priority tasks.
At this point in time Group 21 has experienced no conflicts with group members that would result in the need of corrective action. This is partially because the group leader sends out emails making sure members know what needs to get done, and by when. Group members have been completing the work that is expected of them, and there have been no personality conflicts. If this scenario does in fact occur, the student in question will receive a warning email stating the problem this person is posing for the rest of the group as well as how this problem can be resolved. If this problem continues to persist, further action will be taken. Further action would consist of an email to the same person as well as the instructor of the course describing how and why the person in question is detrimental to the group's progress. Furthermore, docking of points would occur when it came time for the peer review.
One of the most beneficial qualities that attribute to the groups success thus far is the ability of the group to work as a team as well as individuals. The group's mentality is that it is best to brainstorm as a whole on the broad goals of each assignment. After everyone has achieved a general understanding of what is to be expected and what methods should be taken to complete the tasks, the work is then delegated evenly among the members. For example, during Gate 1, each subcategory of the Product Archaeology was initially discussed and reviewed. The sections were then broken up into much smaller segments allowing each member to have optimal time to focus all effort into completing one small subcategory. Afterwards the group reconvened reviewed the individual sections. Final drafts of each subcategory were finally combined into one coherent piece.
Opportunities for Improvement
One of the most important qualities a functional group can have is good communication. This is one aspect that Group 21 lacks. Members of the group often find themselves unable to contact one another at any given time. The last few days before a major gate of the project is due is when this fault affects the group the most. During this time interval is when communication is the most crucial as the individual sections of each member's work must be consolidated into one final product. Despite the importance of communication, this is the time where emails go unanswered and phone calls unreturned. In retrospect of Gate 1, this lack of communication resulted in the final product being pieced together merely hours before its actual due date. The obvious solution to this problem is that every group member exchange phone numbers with one another, instead of just the group leader having them all. Another way to improve this situation would be for all members to make a special effort to check their emails multiple times a day to decrease any chance of a missed message or delayed assignment.
Product Archaeology: Product Dissection
Ease of Disassembly
The difficulty of the disassembly of each of the individual components of the Jeep varied. In order to define the difficulty of disassembly scale, the ease of removing the part was considered. Whether or not the part was meant to be removed was also considered. If the part was not meant to be removed, then extra force/effort was required to remove it. If a tool is required to remove the component, the process is considered to be more difficult than a process that requires no tools. A rating scale of 1-5 was created and used to describe the difficulty of each step in the disassembly process. This scale can be viewed below in Table 1.
Table 1: Difficulty Rating Scale
Note that no step in this process received a difficulty rating of 5, meaning every component was able to be disassembled. However, this does not imply that all components were meant to be disassembled. Phase 1, 2 and 3, shown below, are all intended to be disassembled. This is known because all the steps involve removing screws with ease and removing basic portions of the structure. Also when the Jeep is received by the consumer all these portions come disassembled and therefore the consumer must put this together. Phase 4 is not intended to be disassembled and this is shown by steps 2, 3, 4. When doing these steps one is almost always going to damage to plastic casing which they are trying to remove. This is because needle nose pliers and flat head screw drivers are needed to pry the part off. These steps will warp and damage the plastic covering and therefore is not intended to be removed. Phase 5 also consists of removing the same plastic covering but now in the center of the wheels. Therefore the wheels are not intended to be disassembled by the consumer. Phase 6 requires taking apart the gearbox. This is very easy to disassemble because it is only held together by two screws. This is not intended to be taken apart by the consumer because removal of the wheels is necessary prior to this. However if the gears needed to be lubricated or fixed it could be done with ease by a professional. Phase 7, which is the removal of the motor, is also very simple. The motor protector can be opened with ease and the motor removed. Once again this is not intended to be done by the consumer because removal of the wheels prior is necessary, however a professional could remove the motor with ease need be.
Table 2: Process and Difficultly of Disassembly
Connection of Subsystems
FIgure One below shows the flow of energy through the Jeep to accomplish the task of transporting a child. As seen in Figure 2, there are two subsystems that contribute to transportation, which are steering and motion. “Motion” refers to the subsystem that converts human energy when the foot pedal is pressed to forward or reverse motion of the Jeep. First the pedal is pressed, which completes a circuit and sends a signal to the battery. The pedal does this by converting the human energy to electrical energy. Then the battery takes the electric signal and converts chemical energy inside it to electrical energy, which it sends to the motor. The motor converts that electrical energy to rotational mechanical energy, and sends that to the gears. The gears rotate, transferring the energy to the wheels, which rotate and move the whole Jeep. "Steering" refers to the subsystem that converts human energy when the steering wheel is turned into rotational mechanical energy. This turns the front axle, which turns the front wheels and allows the Jeep to move in the desired direction. The steering and motion subsystems are connected primarily by the steering column. The steering column uses locknuts to link the steering wheel to the front axle. When the motion system is implemented and the wheels begin to move then steering comes into play. The steering and motion systems are all joined together with the rigid plastic frame, or "body" of the Jeep. They are connected because the wheels are the components that rotate and move the entire Jeep. Without a way to steer the Jeep, the wheels would only move in a straight line. To be able to turn, the steering wheel has to be connected to the wheels, which are part of the motion subsystem.
Figure 1: Functional Model of System
Arrangement of Subsystems
The overall function of both subsystems is to obtain motion of the vehicle in a desired direction. At the beginning the system is started with the human signal of engaging the pedal. This action sends a signal to the battery which sends its stored electrical energy to the motor. The battery and motor are located in different parts of the Jeep because they are the heaviest parts. The weight needs to be distributed so the Jeep does not tip over. The battery is in the front because it can not be supported by only an axle, like the motor and gearbox. Once the electrical energy has reached the motor it converts it to mechanical energy and then is send to the gears. The gears now send the rotational energy to the wheels which in turn make the vehicle move. In the second level of subsystems human energy is applied to the steering wheel and allows control of the motion given by the first function. The subsystems are in an order in which the motion comes first and the steering comes second. This is shown as the rear left wheel is connected to the gears and is the only wheel being powered by the motor. After this energy is used to move the wheel the front axle can be pivoted by simply turning the steering wheel, which turns the front wheels in the desired direction.
Connection of Subsystems
The steering subsystem is utilized by the connection between the steering wheel and the front axle. This is done through the steering column which is connected to the steering wheel and the axle through locknuts. This enables the steering wheel to physically turn the wheels. The subsystems are also connected by the plastic body of the Jeep, which holds all of the components together. The components in the motion subsystem is connected through wires and gears. The electrical energy is transported to the motor from the battery through wires. From there the motor is directly connected to the gearbox next to the axle. This is held together by screws that connect the motor to the gearbox. From there the gearbox is physically connected to the wheel which causes the wheel to spin and causes motion of the Jeep. The subsystems that cannot be adjacent are functions such as steering and motor operation. In no way are the two related directly. The human energy put into turning the wheel cannot make the motor spin.
Concerns Influencing the Connection
Shown in Table 3 are the global, societal, economical, and environmental concerns of this connective body (the steering and motion subsystems). The subsystems are connected by plastic and metal. These are materials that are available in most places, including the USA and Mexico, which is where the Jeep is mainly produced and sold. This means the materials would be easy to obtain, and were chosen partially due to this reason. The impact of mining the natural resources needed to create the plastic influenced how much plastic was used to connect the subsystems. Some metal was used, like for the steering column, so the Jeep was not completely made of plastic, and to reduce the amount of resources that needed to be mined. However, plastic is the most cost effective material, so that was mainly used. By using a material with a low cost, Fisher-Price was able to create an affordable product for the consumer. The low price meant more Jeeps would be sold. A plastic was chosen that was safe for the child using the product. The products were tested to meet safety regulations, so the consumer will be willing to buy the product. The product was also tested to make sure it did what it was supposed to do, e.g. hold fifty pounds, drive at 2.5 mph, and last for the operating life of the product. Fisher-Price also thought about how hazardous plastic was to make compared to other materials and how will the Jeep be disposed of. The Jeep will probably just be thrown out when the consumer no longer wants or needs it, which is not good for the environment. Taking all of these issues into consideration, plastic and metal were chosen as the materials, because the pros of each outweighed the cons.
Table 3: Concerns and Performance of Connective Body
All information gathered in this Gate of the project was obtained from the physical disassembly of the Jeep Wrangler Power Wheels.