New Bearing Design for Morphing Joints - Similar to Mountain Bikes

[From Graham Butler July 2 2010]

Here are some screen shots of what I have been working on.  I think that we can make the seat fold back using a push pin system as shown.  It is simple.

Images also show how the bearings will be assembled.  Bearings will press in, and then be screwed into the frame using a shoulder bolt.  All we will need is to thread the frame.  There is also a spacer on the inside to keep the bearing the correct distance from the frame.

Images also show the upper linkage arm with the steel subframe bolted to it.  It is a lot of hardware, but I think that we are going to need a lot of small hardware to hold it in place.  A couple of larger bolts will just bend the aluminum arm.

Discussion of Locking Mechanism and Rear Linkage Arms

[From Graham Butler May 14, 2010]

I just wanted to give you an update....


I have gone through the CAD and started sourcing most of the tubing for the prototype.  Some material has already arrived, some is on order but hasn't arrived yet, and there are still some parts that I am figuring out.

In terms of materials selection I think that the linkage arms (upper and lower) can be made out of aluminum.  The mechanism for adjusting the gas shock on the upper linkage, needs to be made of steel for strength, but I think that there is a way to mount it to the an aluminum linkage arm.  The rear frame and lower fork should be made from cromoly for strength.  The upper fork, crank piece, seat sub frame, and main frame can all be aluminum to save weight.

Fairing has some good double butted teardrop sections that should work well for the linkage arms.

The locking gas shocks are on order from Germany, but it will probably be a month before we hear anything from them.  I still haven't received the shocks from George.

Locking Mechanism:

I have been thinking a little about designs for a safety locking mechanism, to secure the handcycle in low rider mode for longer rides and for safety.  For the lock to be fail safe, it needs to be extremely simple  The simplest solutions are either a simple pin through the frame, or a strong hook around a frame member.

There are also other possibilities, including spring loaded pins, over center latches (similar to the one on morph 2) etc, but the issue I see with a more sophisticated latch is the it has a greater potential to come unlatched and to wear out.

What do you guys think about this.

Next steps:

Once we nail down our prefered locking mechanism and get the rest of the materials in, I should be able to start making parts.  This should happen early next week.

Photos of Test Rig: Morph lift system update

[From Graham Butler April 9, 2010]

I have modified the test fixture and done some initial testing with non-locking gas springs (because that is what we can get quickly)

I have attached a series of pictures showing the current state. With 2 riders.... me at 130lbs and Josey at 245 lbs.   It turns out the the adjustment system works pretty well.  It allows us to adjust the force without changing the shock; but the lift characteristics are not ideal.  There are several reasons for this..... the geometry of the test fixture is slightly different from the CAD model.  What this means is that we are loosing mechanical advantage in low rider mode, so it is hard to morph up.

Josey in low rider mode.
Note that gas shocks meet the upper linkage arm about 2 1/2 inches from the upper rear joint. Notice later that the meeting position is changed for Graham.
The tester uses two separate adjusters, one for each gas shock. On the finished machine, a single adjuster will move both shocks.
Graham in high rider. Notice how much further back the gas shocks hit the upper linkage arm.

Test Rig: Update 2

[From Graham Butler April 9, 2010]

We have changed the geometry to be as close to the new design as possible (as close as possible without having to rebuild the whole fixture.  The results are awesome.  We got the fixture lifting 250 - 130 lbs with out changing the shocks.  The adjustment is fairly quick (30 seconds or less) The morphing action is smooth, and relatively easy.  I have a couple of comments on it:

Initiating an upwards morph is not at seamless as it was in morph 2.  I think the reason is that you are now down lower than you were in morph 2, so it takes more to get the morph started.  This said, it doesn't take much, and it feels great.

Morphing down is awesome.  It feels smooth, and natural both for the heavy guy (josey) and me.  The shocks that we used were 250 lb shocks.

I have attached pictures of the test including the new geometry, I have also taken some video which I will upload to the FTP site over the weekend for you to check out.

In other news.... I talked with easy lift this afternoon, and they indicated that they could get the locking gas shocks to us faster than their usual lead time of 5 weeks.  I explained the problem of not being able to test the product and they said that we should be able to get a single pair fairly quickly to test.

I will send an email tomorrow as soon as I have had a change to get the videos off of the camera onto the FTP site

Powerpoint and Spreadsheet: Shock location and variable weight riders

[From Graham Butler February 26, 2010]

I think I have a handle on shock position. I have extended the slide show to include most of the process that I went through. There are some things that we can just talk about at 2.

Updated Powerpoint with more information on forces

Spreadsheet showing force calculations for lift system.