9/21-9/28

This week has been spent preparing for the first round of presentations, and working on CAD models. There are a lot of parts that need to be designed with how many changes are planned. It is our attempt to procure as many off the shelf parts as possible to avoid custom machined ones, however with the size of the bogie and the compact nature of it, it is turning out to be difficult. Figure 1 shows an early picture of the bogie thus far.

Figure 1. Bogie Structure

 From the picture, it can be seen that the largest change so far is that there will be three wheel instead of two wheels at the bottom of each bogie. This is in order to keep the bogie perpendicular to the track at all time, independent of one another.

Figure 2. Cross Section of members with thread inserts

Figure 2 shows the new design for mounting the support wheels on the bogie structure. Last year they used a threaded rod that went through the length of the member, this year we will mill threaded inserts that will be welded into place and the wheels will be on should bolts that will have some kind of bushing to allow for free spinning. 

Figure 3. Initial Joint design for Bogie Connection

Figure 3 is the initial design that has been done for the joint between the bogie uprights. It uses should bolts, brackets, a center shaft insert, and middle x joint to allow for 2 DOF for traveling up and around bends. 

Figure 4. Off the Sheld Bearing Unit

Figure 5. Start of Custom Bearing Unit for Main wheel

Figure 4 and 5, are an example of issues with off the shelve purchase parts I am currently having. I would like to be able to buy a full bearing unit for the main wheel, however, The ones available are too wide, and won't allow for the wheels to be aligned with the current track config. This means I need to design a custom one that will need to be machined. Not shown in figure 5, is addition bearing retaining plate that will also act to position the wheel in the correct location.  The bearing is required because Propulsion is planning on integrating the drivetrain onto the main wheels. This is going to make fitting everything difficult, so this is currently one of the top issues in my mind. 

Lots more work needs to be done.