Tilter mk3

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I'm not so sure Emiel. It's hard to tell from such little pictures but the basic principle looks the same and he's also inspired by Alan Maurer's trike. That one makes what I'd see as an error in placing the main beam above the crossbeam. If the main beam goes below then you get the centre of gravity lower in relation to the central pivot which equals less effort to get upright as he found. Again, with the tiny pictures, I can't see the crossbeam bearings very well but it looks like he's using acetal which is not going to help matters in getting upright either. This thing really needs proper bearings IMO so all your effort goes where you want it. Steering input can help in getting it back upright and I suspect acetal bearings are going to make that harder. Whilst one handlebar is enough to apply steering it's very limiting in leaning and un-leaning, having two for lift up / push down is absolutely vital IMO. I suspect he was always intending to add the other later in the build but we never got to see that. Lastly he's copied Alan's minor "design flaw" and has to pull the handlebar(s) back to resist braking or would do if he ever got it finished. It seems much better to push to resist seeing as you're sliding that way anyway. That was a great find Paul.
 
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Now you say it. It is hard to see.
I think that he wanted a higher seat.
Balance thing depends on where the weight is to the rotation point. You can move the weight up, but it will mot balance it self. By riding it will be easier to balance, just like an upright. But I think that this height difference is still to low, to get that working good.
 
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Hi both

Just go on and ask if you can see bigger pictures and discuss the problems they found ?

I have done that before on both there and a Finish forum with good results.

Paul
 
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Got the 16mm holes drilled for the crossbeam to main beam mount. A new 16mm drill went through surprisingly easy. It's almost aligned but will need a wiggle with the drill to bring into perfect alignment which won't be any issue once welded in. My seat is down the road at Dewsbury UPS depot so hopefully will be with me Monday

 
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Didn't see it before, but what Popshot is building is different. The steering doesn't happen by turning the wheels, but by changing the angle of the uprights where the wheels are mounted on.

But that looks as something of a tilting system what someone I follow on YouTube is building.
 
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The link I gave had this to say about tilting and steering :-

The most important point when you go to "driver induced force tilt" a vehicle mass is the steer angle position of the front wheel/s at any given moment as the tilt action is occuring...[assume front wheel steer]..
..........any steer angle produces a curved steered path ....... ANY curved steered path will produce centrifugal force tending to tilt the vehicle mass in the wrong direction ... [like a car]...... SO..... you don't want to steer before you tilt...... You don't even want to steer AS you tilt, because , if the steer angle gets "in front" of the tilt angle for any given speed, it will restrain the tilt, or even prevent it.. , or worse ,overcome any positive driver applied tilt and send the mass in the wrong tilt direction...or, just as bad if the steer lags too much and sends the mass too far in the right direction!!!...

"For any given tilt angle as the tilt is occuring....and speed ,there will be a neutral steer angle which will not be tending to apply more or less tilt." This means that at any given moment the centrifugal force is being balanced by the gravity force acting on the inclined mass.

This neutral point must exist at ANY GIVEN INSTANT DURING THE TILT ACTION during any manouver or speed .. IT MUST DO THIS.... or the vehicle will be a pig.
So..... if you want to use hydraulics to tilt the mass and you want a perfect result, you MUST maintain the steer angle in the optimum position at ALL TIMES..... and trust me.... you DO want hydraulics [or some other servo power] because thats the only effective control at low speeds [when a motorcycle falls over\\].................... sounds like a job for a "super computer".?..... not really!!!
A freely castoring wheel [or wheel set] does it..and does it in style!!!! [see my patent] [F.T.C.]\par
And so the requirement to steer and to tilt as seperate actions is gone, and now its just a simple steer control of the tilt to produce the appropriate steered path at all speeds....... its simple


I am not sure all of this applies to our low speed vehicles ?
He does not explain F.T.C on the page and the Patent link appear to be dead ?

WO2005075278
US2008238005


Paul
 
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He is primarily talking about a relatively heavy tilting car where the only input the driver has is via the controls. As such he does not need to consider any shift in rider weight to control matters. Indeed driver weight shift is ruled out. For our purposes the rider can add a huge amount of control to a mechanism just as we do on a bike. That extra input should be or become instinctive just as it is on a two wheeler. There's no need for a perfect mechanical system as the rider is as much a part of it as the mechanical bits and doesn't add extra to the complexity or weight.
 
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Sitting on it wheels now.



A major issue arose. With the planned bolts tying the crossbeam to the main beam there was a lot of lateral movement in the crossbeam - a couple of inches fore and aft at the wheels. I had enough height difference to chop them down and still allow enough tilt. I chopped them down by 40mm from this...



to this.....



...and that has solved the issue. Despite being 8.8 high tensile bolts they simply had too much give in them and that extra length was a lever on the stainless main tube. Lesson for anyone following me - keep the distance between tubes as short as possible. The tubes now touch at a 32 degree lean angle which I expect to be enough. I can always get a bit more lean by winding the rod ends up though again that'll increase flex.

Speaking of flex that weld of the main pivot to the crossbeam will need some reinforcement. On a perfect road it'd be fine but a pothole at one end only will impart enough force on the crossbeam which will act as a lever on that weld to destroy it. Like Alan I'll add the same type of reinforcement there.

You can see the outer wheel leans more than the inner one.



This is a function of the lower arms having two inboard pivot points versus one on the top. The inner wheel is turning a tighter circle so extra lean is useful. The uprights were originally made to a length to support the longer pivot bolts. The main tube now rides higher and the control arms now have a higher mount in the middle than the outside. I was going to shorten the uprights to match but changed my mind.

With the original bolts the arms were parallel with the crossbeam and the inner mount set to match the outer at 22.5 degrees caster which is bang in the middle of the 0 to 45 degree max range for the steering. The control arms have to swing on the outer mount to steer at various levels whilst the inner mount is fixed. This means the effective length changes which in it's original long bolt form means that if you set camber to zero at 22.5 degrees steering you get increasing positive camber as you move from that central point in either direction. Now in short bolt form there's more movement away from the 22.5 setting as you take steering out but less movement away as you add more steering on. This is a better scenario I believe as the smaller geometry changes will occur at more extreme steering where I'll expect to appreciate the smaller movement more. I'll set it at 22.5 degrees with some negative camber with a view to only coming to zero camber as it's at zero caster.

Realistically I need the seat to do much more on it.
 
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Looking good Popshot you make it look great.
I can"t wait, till the seat is on and you added the steering arms.

In an ideal world, the wheels should point to the same point on the ground as they tilt. You never get that perfect, but you can come close.
The distance of the mounting on the inside, makes how much the tilting difference is, between the 2 wheels. Wider gives a bigger difference, where as they come closer, they become more parallel.

Are now all parallel? As I see the 2 bottom booms in the first image, they look like to be higher in the center.
Last image they look more parallel. But image can make it look different.
 
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The inner bottom mounts are now higher than the outer ones. They were originally the same height with the longer bolts in the middle. I decided to keep it that way because as the steering is applied the track changes less.
 
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Still no seat so limited in where I can go 'till it arrives - damn UPS who've tracked it to Dewsbury (3 miles away), lost it and then found it back in Poland!

Bracing added to cross tube.

 
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Popshot

Have you found this ?

BROL discussion on tilting trikes

there is a lot of input from the designer of the Jetrike whpthomas which is interesting...

However he goes on to talk about Alan's trike and a serious problem it has with braking ? [ page 3 ]

regards Paul
 
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I hadn't seen it Paul but the braking problem is well understood and known about. It is this reason that I am altering the control rods so that the force is braced against by pushing on your arms rather than Alan's pulling. Seeing as braking has the tendency to have your body moving forwards you only need to lock your arms and your weight does the rest. Alan has to be pulling back on the bars whilst sliding forward to resist the force which must be much harder. I've yet to see any tilting tadpole that doesn't have some issue or compromise. By comparison a delta is much simpler to lean. My Mk2 has the steering geometry all over the place as the suspension moves and it needs very wide bars as they move counter to the lean. Alan's has what I consider to be one of the smaller foibles or at least appears so on paper. I'll know better once I can ride it.

If I'm kind to whpthomas then he's somewhat muddled in his statement:-
"The big problem with Alan's trike is that all the brake torque is transferred to the tilt trim controls, which has the effect of straightening up the steering under hard braking. So if you brake hard on a tight corner you will over steer and overshoot the corner."
The effect, if unchecked, is to increase steering and in extremis that increase will then turn to a decrease if the upright goes beyond 45 degrees. Given there's no point in allowing the steering beyond 45 degrees it makes sense to have a stop there so any unchecked braking effect then becomes solely to try to increase steering, the exact opposite of what he said. Also if you do oversteer you undershoot the corner. Again the opposite.
 
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Popshot

whpthomas assessments are interesting as to the best of my knowledge no one has ridden as far on a tilting trike in the real world [ racing does not count ;) ] however all his riding has been on his Jetrike , although 4000+ miles at the time of his putting his thoughts onto paper is impressive.

His circumstances do not require a high seat nor narrower track than 30" so do not cover what I am trying to do.

Still onwards and ever upwards.

Paul
 
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The break steering is a known problem, but it also depends on the use of the trike. It will never be great in breaking in a corner, but I don't see that as a problem.

The trikes whpthomas builds are nice and there are several version riding around, using that system. Nice system and I lokked ad it, because you can make a similar design trike as a mosquito. Also is the construction a bit less complicated as on a mosquito.
 
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Experience is a great asset but you need to be able to articulate it if it is to benefit others.
 
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