4/23 Update

We are on the final phase of our project. We have fabricated most of our mechanisms and are in the process of assembling the fabricated parts. This semester, our focus was not only in the fail/safe development, but also in bogie design development and propulsion. Our team took the responsibility of the bogie fabrication because in developing the fail safe mechanisms our team had a better insights of the bogie's mechanics and its fabrication.  Our team lead, Cassie took the responsibility to waterjet the plates of the bogie. Currently, we are in the phase of welding bogie's parts and fail safe mechanisms. Also, our team is helping Alex to fabricate the parts of the guide-way. 

Upstop wheel

With respect to the design from the steering team, we found a way to add upstop wheel in the bogie. I've made a rough sketch. We even added the upstop wheel to last year's design in the solidworks for reference. We will be finalizing the dimensions of the upstop mechanism as the steering team finalizes their cad design.

progress

From the 1^st presentation we had 2 major initial designs for the fail-safe mechanisms.  upstop stop wheel and the safety wheel. The main purpose of the safety was to stabilize the bogie while traveling in an angle and the main purpose of the safety wheel was to provide a back up, if one of the load-wheel FALLS off the track.

After the first presentation we came up with two more significant designs of a fail-safe mechanisms. As well all know, the bogie will be traveling in an angle of 17 degree. A major fail-safe design is required to stop the bogie from rolling back, if there is a power failure during inclination. Obviously the pod will not fall from the track because we have the extra support of the upstop wheel. To stop the bogie from rolling back, we came up with the anti roll-back device. ARB

ARB is not a rocket science. It is a very simple mechanical design that has ratchet system and a pawl. As shown in the figure, its operation is very simple. It will prevent the bogie from rolling back incase of power failure while ascending in an angle.

Next, we decided to scratch  safety wheel from our design and instead add the third set bogie without any of these top wheels. This bogie will give more support to the whole system by evenly distributing the stress along the bar. Also it will hold the pawl that locks the bogie in the ratchet system.

Oct 7 update

Last week, we presented our presentation on fail safe mechanism . We went through our goals, background, possible failing scenarios, challenges, functional specification, and individual responsibilities. After the phase one of the semester, we are moving toward phase two, that is to design the fail safe mechanisms.
Since last meeting, I have been researching on roller-coaster's fundamentals and design of upstop wheel. Also, I have been reading previous reports on bogie design. 

Assignment 3: Update

During the meeting on 9/16/15, team members from fail safe team gathered around and share their ideas. Considering the fact that the design of the bogie be similar to existing bogie, we all came to an agreement that, addition of the upstop wheel (3rd wheel) is very logical, since the wheel will stabilize the bogie and will keel the bogie from falling. Next, the team is focused on other fail safe mechanisms. One of the main goal of this week is to come up with a failing scenarios under any circumstances. On 9/23, the team will be discussing on how reasonable is that scenario and hopefully come up with a solution.
Lastly, I have read chapter 6 of Safety and Emergency Operations of the Fundamentals of Rapid Transit. This chapter gave me an idea of possible failing scenarios and a way to solve it. On our next meeting, we will be comparing the list of the failing scenarios and come up with a possible solutions.  

bogie design: Fail/safe.

The current design of the bogie only consist of two sets of wheels, load wheel (the big one) and the guide wheels (the one on the side). Since one the main goal of this year is to traverse up and down in  slope, adding a upstop wheel (3rd wheel, underneath the track) is very much required. The addition of the third wheel will not only aid on traveling up and down on a guideway, but will also keep the bogie from falling off. Additional pressure will be exerted when it is traveling at 17 degree, the upstop wheels shall reduce the pressure and stabilize the bogie.

Post3: Fail/Safe

Braking system has not really been addressed thoroughly in the previous reports. Since I'm a part of fail/safe team, emergency braking system in the bogie design would be key if the system fails due to technical error or catastrophic events. The emergency braking should be triggered manually and is equipped with traditional mechanical system. For example, all the rotating wheels of the bogie be chained together in such a way that once the emergency brake is triggered, the stretched  chain  would stop the wheels from rotating any further. Installation of a damper would give fluency to the braking process.