Recumbent tadpole trike: Posts on Velomobilforum p.8

Hello Hein, Titan Wolf, trike like (Martin?) and Stephan (shs2_de)

It has been a couple of weeks since I was able to remark on what I have been doing with the idea of a tilting space frame trike and I have some things to share. I have built another new prototype of a tilting mechanism and have already come up with a new version. Interestingly enough my newest designs bears a great resemblance to what Stephan (shs2_de) worked on with his suspension system at the beginning of this forum file. It may be interesting to Stephan and others to see a modification of that suspension system. I have also spent a considerable time with my husband and a friend remodeling our 2 bathrooms as well as working overtime… Sigh real life… enough said on that subject.

Before I much go on I want to address a couple of comments from Wolf. I read your comment on obstacles in the road and thought about that in terms of tilting and locking the tilt mechanism. First I think that a tilting trike (1^st test geometry) will actually stay more level for the rider with holes and bumps than a nontilting trike.

This is not to say it will be any more of smooth ride without shocks but rather I believe it will not tilt the rider but lift them up and down due to the tilt geometry. The effect is is counter intuitive but I believe it to be true. The effect on steering will be no more than what would happen with a bicycle. Though I will admit it will be different than a nontilting trike. Second, I believe you are correct that depending on a locking mechanism entirely for stability of the tilt would be at best a poor idea. I really didn’t mean to give you the impression that a tilt lock was the only stabilizing mechanism I had in mind. I can see how that was my impression though. I have for some time known the suspension would need some sort of active system for creating a roughly centered riding stance on a straight road. The active system I have in mind is a triangle of shock absorbers and springs. This mechanism would tend to make for an upright stance on a straight ride. Last but of most importance, how does one stop leaning the wrong way in a curve. I think part of the answer is the shocks and springs but I do not want to depend on that alone. I believe that tilting does need a direct control from the rider for tilting, not just a tilt lock, and I have been working on that and looking around for that solution. I think I have found that solution and I believe that the XYZ frame is well fitted for this particular solution.

At this point I want to insert a disclaimer. I have no really original ideas in this area of endeavor but I am assembling those designs of others using my own thoughts on how they should work. Hopefully this will get a tilting trike to work. I do not claim these devices as my original work but rather stand on others shoulders to reach my top shelf (LOL… to turn a phrase).

I inserting that disclaimer because I have found what looks to me like an original and fairly brilliant idea by Martin Hill from Australia. You can view his work on You Tube while it is available at https://www.youtube.com/watch?v=koADanl4-vo . In short he appears to have solved the issue of how to mechanically control a tilting trike while steering. Martin has several video pieces on his EATSRHPV trike that are very educational! I will not attempt to print pictures nor make drawings of his prototype. I really don’t think I can do it justice. I will leave the viewing and analysis of that information to those readers who wish to do so. I will rather talk about the application of his idea and how I think it might work in an XYZ spaceframe.

So I realize that I have not yet stated exactly what composes this marvelous idea of Martin’s, therefore; if You Tube hasn’t let the cat out of the bag I will get to that in this paragraph. Martin has connected the steering to the tilting in a single handle bar package. Sounds a bit odd I am sure but that is exactly what he did. By connecting the handlebars to the tilting mechanism the handle bars tilt at the same time as the wheels. He used what Trike Like called “steering with push rods” to control the wheel steering attached onto the tilting handle bars. In this way he can control the tilt and the turning at the same time since they are one system in his hands. Wolf this is literally using muscle power to stabilize and control the tilt *not a brake*. It is not a direct proportional tilt to cornering ratio but rather using muscle, memory, and judgment to determine tilt. Direct proportional tilt would not work since the degree of tilt changes depending on speed (originally I had in mind to do a locked proportional tilt). So we use the most sophisticated computer on the planet to control the trike… a person. The tilt can be more or less depending on speed and degree of turn. It ends up being a meta-stable system like a bicycle. The faster it goes the more stable it will be. The slower it goes the less stable and thus why a tilt lock is probably necessary. With a tilt lock, in a snap, the whole trike can becomes nontiltable. The rest of the time at “normal” slow cruise it will be stable. If you doubt me look at the videos! I believe his trike is even stable at a stop but I am being a bit conservative in my judgment until I have built one.

Hein, yes the tilt may in fact need to be locked in very tight turns if it could not be held by muscle in the correct alignment on the curve. No flipping over please!

I am attaching some pictures of my last prototype that was based on a trike called Tripendo and a surprising number of other trikes. The model has the common geometry to them all. It allows the turnbuckles I pictured to be changed to shock absorbers and springs in order to allow tilting and a full suspension ride (the turnbuckles are not tight enough so the tilt is not equal).

I am also attaching a couple of sketches. The first should show the linking mechanism between the tilting wheels and the steering column in a XYZ trike. The second sketch should show how the tilting steering column and the paddle/joystick steering (push rod steering) works together in a general sort of way. 

I have not attempted to illustrate how the linkages work. If you wish to see those linkages at work go to You Tube. Unfortunately I have bathrooms to rebuild. Ta ta for now Ceeann

P.s. Just to be on the record the brackets for tilting in the diagram above are clumsy and probably nonfunctional if built. These will be revised but are sufficient to convey the idea in terms of the 2nd geometry of tilting pictured above. I suspect something welded as Martin has done on his trike will be absolutely required at the point where the shocks and springs are attached to the steering column.