Group 6 - Mini-Bike

Revision as of 17:36, 2 November 2009

Mini-Bike Side View

Group Members

• Jeffrey Becker - Communication Liaison
• Stephen Harris - Group Leader/Wiki Manager
• Eric Jongsma - Solid Model Creator
• Garth Lester - Technical/Mechanical Expert
• Eddie Morales - Technical/Mechanical Expert

Executive Summary

The objective of this project is to better understand the product through dismantling, modeling and reassembly. The product is a min-bike not yet out on the market. It is designed only for recreational uses. Its top speed is approximately 10 mph. It stands up well without any external support and with its wide tires and low center of gravity is very stable even at very low speeds. The throttle is in the very convenient position of the right handlebar grip. The throttle signals the fuel air mixture flow mass flow rate to increase converting chemical energy to reciprocating mechanical energy and waste thermal energy in the combustion chamber then the reciprocating mechanical energy is turned into rotational mechanical energy by the clutch and transferred through the chain to the rear axle where the rear wheel in combination with the surface it rests on turns that rotary motion into linear motion.

Work Proposal

Based on a surface inspection of the mini-bike it seems that it is held together entirely by hex bolts. We will be needing a socket set and ratchet as well as a set of end-wrenches for when more torque is required. Having not seen inside the engine we can’t accurately determine exactly what tools will be necessary, but I would guess we’d need a razor blade or some other kind of scraper to remove any gaskets, a flat-head screwdriver in case anything needs to be pried open and a pan and funnel for the engine oil. I’ve also found a magnet and needle-nosed pliers are always handy just in case a nut falls somewhere inaccessible.

In taking it apart, we’d first remove the frame from the engine. This would mean loosening the chain tensioner and removing the chain, disconnecting the engine mounts and throttle control and we’d probably have to remove the seat or disassemble part of the frame to get the engine out.

Before opening up the engine, we’d have to properly drain all of the fluids, so as not to spill them all over the lab creating a safety hazard. Since there is no gas in the tank, no coolant system, no transmission and the brake system does not use any fluid, we should only have to drain the engine oil.

When taking apart an engine it is a good practice to replace any gaskets or seals you remove, rather than reusing the old ones, but due to the nature of our project we don’t have that option. Since the mini-bike is fairly new there shouldn’t be much existing wear and tear on the gaskets and seals but we will still have to be careful not to cause any damage in their removal.

I would assume this engine will have a timing chain, or similar mechanism, so we will have to observe it carefully as we take it apart. That way we don’t risk destroying any of the valves when we start the engine back up.

Besides the aforementioned gaskets and seal removal the disassemle should be a fairly straightforward process of removing one piece at a time, although it is hard to tell until we actually open it up. An experienced mechanic could probably disassemble it in as little as half an hour to an hour, but I would estimate we need at least an hour for us. We need to be taking detailed notes and measurements as we disassemble the mini-bike so that we can reconstruct it in a solid modeling program later. Given that, I’d say disassemble will take three to five hours just to be on the safe side.

As far as the experience level of our group members we aren’t too bad off. Eric mentioned that he has worked on bicycles before. Eddie has a motorcycle and seems mechanically inclined; I don’t know if he’s ever taken it apart, but I’m sure he at least has a working knowledge of how the engine runs. I have decent mechanical experience, having worked extensively on my car the past two summers, although the frequency with which it breaks down is alarming. Stephen has been on a robotics team for the past six years so he is experienced with most of the tools that will be used. The other members of the team do not apparently have any mechanical experience beyond the average person. All in all, the engine on our mini-bike is pretty simple as engines go, and I’m confident that our group has the necessary skills to disassemble and reassemble it successfully.

Management Proposal

Group six consists of five individuals with a variety of strengths and weaknesses that complement each other. The work for the project shall be evenly divided between its five members which each person responsible for a different main function and additional ancillary functions distributed in whatever manner results in the best project. Stephen Harris shall be the Project Manager and Wiki Manager. He will ensure all tasks proceed as planned and lend a helping hand when needed. He is responsible for the overall direction of the project and should help the group members when they are confused as to what task to proceed to. For example, Stephen should tell the group if they are dissecting the mini bike in an incorrect fashion, and give instruction on how to do it correctly. Finally Stephen will collect all individual assignments done by the group, proofread them and add them to the Wiki. Stephen’s leadership will be essential in the timely completion of all five gates.

Jeffrey Becker will be the Organization Expert and Communication Liaison. As Organization Expert he will ensure the dissection of the product is done in a precise and orderly manner. This will be important in finishing gates two and four, in which the product will be taken apart and re-assembled. Jeffrey will be expected to make sure all parts of the engine are organized and easy to find. He will also take notes when necessary and make sure everyone in the group is on the same page. To facilitate this task Jeffrey will be head of communications. As head of communications he will compile and rout all information and make sure it gets to the entire group.

Our lead Solid Modeler will be Eric Jongsma. Jongsma having a great deal of experience with CAD software will make gate three easy to finish on time. He also has experience in a bike shop, and is expected to provide technical knowledge as to how the bike works. This will be helpful in gates two and four when we take apart and re-assemble the bike engine.

Technical/Mechanical Experts Eddie Valentin and Garth Lester will both be mechanics for this project. While Jeff, Eric, and Steve will help plan disassembly, Eddie and Garth will be actually dissecting the engine. Garth has experience with tools and will primarily take things apart. Eddie has knowledge as to how engines work and will handle the individual parts of the engine. Both are expected to take the engine apart without breaking it by using the correct tools and safety precautions. They will also re-assemble it, again using care and safety. This will help make gates two and four go smoothly.

Together, all five students will blend their knowledge and successfully meet all the project deadlines. As the project progresses work shall be assigned. The group will meet in 621 Furnas after every Wednesday class at Five PM, to discuss and work on the project. Additional work time will be scheduled by Steve. To contact Group Six, please email Jeffrey at jbecker6@buffalo.edu <mailto:jbecker6@buffalo.edu>.

Initial Product Assessment

The product for the assignment given to group 3 was the mini-bike. It is a small, one person unit capable of providing transportation over short distances at relatively low speeds (no more that 10 mph). Given its low power output the product should only be viewed as a recreational vehicle and not used for any professional purposes. Other than for the transport of a single person from one point to another, the mini bike serves no other purpose in its design and should be recognized as just that. The mini bike uses a simple gasoline engine from which all the power necessary for it to function is generated. Simply put, the chemical energy from the combustibles (gasoline and oxygen) is transformed inside the engine is into mechanical energy that causes the mini bike to move. While the mini bike does still work, it was discovered that if any time was wasted between turning the bike on and giving it throttle, the bike would choke up and shut itself off. Any speculation as to why this happens is currently unfounded; a reason for the malfunction is still an open question. The product in itself is of a very simple design, it consists of a simple aluminum frame with a gas tank, an engine, and a chain, all of that, with the obvious addition of a seat, handle bars and wheels consist of the product completely. It is more complex than a non-powered bicycle but significantly less complex than a motorcycle. From a simple initial overview of the product, it is obvious that aluminum, rubber, and plastic are the main components of the mini bike. If one were to think more, it would be logical to assume that copper wiring would be used in the system to pass on electrical systems from the throttle to the engine, from the ignition switch to the engine, etc. The product’s appeal resides in its simplicity, the fact that it is easy to use with minimal training required beforehand. It is relatively comfortable although upon riding it, it is easily noticed that the bike was designed for someone younger/lighter than the members of the group. As for maintenance, the only real issues with that would be making sure that the moving parts are well lubricated as needed, that there is gas in the tank, and that the necessary switches such as the choke and ignition are well maintained and not loose. In terms of other alternatives, a motor scooter or perhaps a dirt bike would be possible, all depending on whether u want more power, distance and mobility from your product. A scooter would be the closest thing to our current product in every cat4egory ranging from power given to distance to price, the advantage of a scooter would probably be the maneuverability provided, considering that it’s not as cumbersome as the mini bike, while the disadvantages would be comfort, since while some motor scooters provide seats, they would not be as comfortable as the mini bike’s.

Causes for Corrective Action

Our group’s system of management and our work proposal require several upgrades to fit the current work situation. One of the major issues not dealt with in the original planning and execution of the first gate was the matter of specific timelines for completion of the gates of the project. In order to correct this oversight, a Gantt chart has been added to the wiki page explaining our projected completion dates. This chart demonstrates amended work schedules that represent a more realistic yet timely set of goals that must be met in order to successfully complete the gates. Another concern that needed to be addressed was the weekly team meetings. It was previously agreed that group 6 was to meet Wednesday evenings. Having had more opportunity to scrutinize our schedules, we have discovered that Thursday during lab hours (3:30-6:30) is the optimum time for our group to meet. A problem not originally addressed in the management and work proposal but discovered during the actual work process is the structure of said weekly meetings. Future weekly team meetings shall begin with each member reporting how much progress they have made on their long term projects and if any roadblocks have been encountered. If so we will proceed to work towards solutions of those blocks, then continue by proof reading of all written assignments as a group. Finally, we will end each meeting by assigning new tasks based on past performance and total workload of group members. Something we did not expect was the fact that disappearing parts have become an issue in the past couple of weeks, with both the gas cap and the muffler of our mini-bike going missing. We have also found that larger parts, such as the front wheel assembly, have been moved around the lab in our absence. Due to Group 6’s specific project, we do not have the option of storing it in another location. Currently, to minimize the risk, we will move the large parts of our product farther away from the trash can area and take all the smaller parts out of the lab. This should curtail the threat somewhat, although we have no way of completely preventing the theft and/or vandalism that is occurring. Finally, while personal conflict has yet to occur within group 6, the work ethic as well as attendance of group meetings has been poor lately. The new structure of our group meetings should hold members more accountable to their fair share of the work. On the off chance that any personal issues arise however, a plan for dealing with them has been devised to manage said issues depending on the severity and the type of the conflict. In the case of a verbal altercation over work load or quality, the group members not involved in the argument shall determine who was in the right and take whatever corrective action they deem necessary. This egalitarian process allows for a fairer and easier going working environment and will hopefully minimize any resentment. However, if the group cannot come to a consensus, the final decision will go to the group leader. In the case of a non work related verbal altercation, the members involved shall be told to refrain from such unprofessional behavior and be kept away from each other if necessary. If said problem persists to the point where it is affecting our project, it will then be dealt with as a work related problem. Finally, any physical altercation shall be reported to campus police and dealt with by the proper authorities.

Product Dissection Plan

Product Dissection By Steps
Step	Description	Tool Required	Difficulty (1-5)	Photograph of Parts Involved
1	Removed the (4) screws from the bottom of the seat to disconnect it from the frame.	8 mm socket wrench	2	Seat highlight
2	Removed the handle grips, brake lever and throttle from the handlebars.	Phillips screwdriver and 10 mm socket wrench	3	handle bar mechanisms
3	Removed the front steering assembly	13 mm and 15 mm socket wrench	1	Steering assembly
4	Disengaged the chain from the wheel then removed the chain guard and chain tensioner.	6 mm Allen key	2	chain tensioner
5	Removed the rear fender by unscrewing the (2) bolts.	10 mm socket wrench	2	rear fender highlight
6	Removed the rear wheel and axle from the frame, by unscrewing the axle bolt.	16 mm socket wrench	2	rear axle assembly
7	Removed the engine and engine plate from the frame by unscrewing the (4) bolts on the bottom.	Hands	3	Engine picture
8	Removed the engine mounted gas tank.	10 mm socket wrench	3	gas tank highlight
9	Removed the muffler and muffler cage.	(2) 10 mm socket wrenches	3	muffler cage
10	Removed the pull starter from the side of the engine by unscrewing the single shaft bolt connected to the main shaft of the engine.	12 mm socket wrench	1	pull starter highlight
11	Removed the carburetor assembly from the engine.	6 mm socket wrenches	3	Carburetor assembly
12	Removed the magnetic ring on the engine shaft.	Pin spreader	4	Locking collar
13	Removed the top of the engine's combustion chamber by unscrewing the 6 bolts holding it to the engine block.	8 mm socket wrenches	2	Combustion Chamber
14	Removed the spark plug and timing mechanism	16 mm socket wrenches	1	spark plug and timing mechanism

Total dissection time: 3 hours.
*Note: the break down for the difficulty levels are as follows:

1 = easy, requiring no real thought or awkward positioning.
2 = medium, some awkward positioning to get to the part
3 = hard, requiring some very awkward positioning and thought.
4 = hard, requiring some thought multiple people wielding tools and a great deal of time.
5 = impossible with current tools and expertise.

Post-Dissection Analysis

Below are a few sample questions that address the purpose and methodology behind the drills design:

- Is the product intended to be taken apart easily?

The mini-bike is quite easy to take apart up until the engine. Standard tools such as metric wrenches and Phillips screwdrivers can disassemble the bike up until the transmission is reached. The transmission is press fit together which would require some kind of prying tool to get off and then some kind of press to reattach. Therefore the products engine is obviously not meant to be taken apart while as individual parts can be replaced on the frame of the bike.

-_Hurdles and Disappointments_

There were a few tough spots in this dissection. The first came when we lacked the proper tool to remove some springs. In order to combat this problem, Garth actually purchased a pin spanner tool in order to allow further dissection. The second major hurdle prevented taking the transmission apart. This was a major disappointment to the group as they all wanted to see the internals, including the clutch assembly. There were two parts that prevented the dissection. The first was a lock nut. The nut had teeth on the inner edge that prevented the nut from being turned counterclockwise. The group could not even nudge it even with all five members using their combined forces. The second part preventing assembly was a factory pressed part. It would be impossible to get off without using a factory press. There were thoughts of removing it with blunt force via a hammer. These thoughts were quickly quelled when it was realized that there would be no way to put the part back on without a press. The group spent two hours in addition to the three previous dissection hours trying to move forward. It was finally decided that there was nothing they could due given the circumstances, and we moved on to work on this report. This step is considered level five difficulty since it was impossible to complete with the current tools and expertise.

- What fasteners are used and why?

The fasteners used are:

metric bolts sizes 8mm, 10mm, 12mm, 13mm, 15mm and 16mm. These standard metric bolts are used for ease of replacement and removal
Phillips screws. These common screws are used for ease of replacement and removal
Locking collar. This is used to hold on the magnetic collar and is not so easy to replace or remove so that the magnetic ring stays in place even with all the vibration from the engine shaft it rest on.

- Are special tools required?

A Pin spreader was used to remove the locking collar holding on the magnetic ring.