My life with Python trikes Mk1 , Mk1.5 , Mk2 ?

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As the tilting part is on top of the fixed part you are always balanced on a knife-edge, I wonder what would be the effect of under-slinging the front section?
Interesting idea .

My take would be the knife edge means it's natural tendency is to want to leap to it's death either side rather than remain balanced ?
I assume by keeping it balanced I am expending some energy and brain power ? both of which are sadly lacking.

Your idea would in effect suspend me and the front end under the rear wheels thus naturally being balanced , only expending some energy when tilting and recovering ?] [ and no brain power involved Whew ]

However it would put the seat no longer over the elastomer/rod end bearing ? would that matter ?

As discussed, If there were 2 x Rod-ends and elastomers (tilt resistors) sandwiched between the fixed/tilting beams; would that work better?
not sure it will need 2 ? [ I know my idea ] thinking about it the whole affair will try to bend downwards at the single rod end thus forcing the elastomer into a compression mode ?
 
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If you invert the lean pivot it will move to the 6 o'clock position at rest so it would always want to move to upright. You may then need to fight it to create lean depending on a number of factors, one of which would be the vertical length of the pivot. The longer, the more stable but the harder to lean.
 
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If you invert the lean pivot it will move to the 6 o'clock position at rest so it would always want to move to upright. You may then need to fight it to create lean depending on a number of factors, one of which would be the vertical length of the pivot. The longer, the more stable but the harder to lean.
Need to draw it and thing about it ?
 
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So got a bit done yesterday:-



New handle bar mount , now 4 x M8 bolts clamping flat plate to box frame instead of 2 x M8 clamping round tube to box frame , should stop it moving.

Bit bigger now so don't thing it fit in same place as existing one.



However plenty of room between elastomer's or behind them.

Still awaiting steering dampers

Discussing with DannyC about changing vertical rod end for a pair of 90' pivots thus eliminating the Yaw axis :-



Pair of suspension pivots trimmed and could almost be welded together after paint removal.
Going to be a challenge to keep them @ 90' really need to think that through , ideas ?

Pink one would have bearings with M12 centre hole to rotate on existing bolt - tilt.
White would probably have the original plastic bush and fittings with some plates to bolt it to the sides of the frame ? - suspension
only fly in that ointment is it is wider than frame box section ?
If I start to trim it down existing parts won't fit.

Paul
 
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To get them at 90-degrees can you use a standard set-square to get the bottom one square to an edge of the bench and then clamp it there buy inserting a small clamp inside the tube and clamp it to the benchtop?
To put the top one square to that one use the other end of the bottom one, put a known square object on the end as a reference and use a second square off of that. Quick dab with the sparkle stick to follow.

This is where engineers V-Blocks or 1-2-3 blocks or similar are very useful.

Or, stand one on its end vertically, then place the other one on a bit of packing to get the correct height/alignment (automatically horizontal and square to the first one. Even easier and only clamps required. ;)
 
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I found a interesting way to make diy vibration dampers.


Watch between the 4th and 5th min. of the video.

Could it be used for a home made lean joint?
 
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I think that with only one pivot you will always get yaw as the elastomers resist the pivoting action at their end of the beam, moving the beam into the turn which when translated through the python pivot moves the front wheel in the opposite direction to the turn. Two pivots would mean elimination of yaw. The pivot position should be in the middle of the elastomer when measured vertically or viewed from the front or back IMO. This would give equal amounts of compression and tension on the elastomer and I suspect that the material is vastly harder to compress than stretch thus giving more resistance.



The top pair show the elastomer behaviour with the current pivot point. The elastomer is essentially pushed to one side with minimal compression. The bottom pair show the elastomer behaviour with a central pivot. One side gets substantially compressed. I'd expect this to give more resistance than the existing set-up and I'd expect the elastomers to have a longer life being subject to less stretching.
 
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I found a interesting way to make diy vibration dampers.


Watch between the 4th and 5th min. of the video.

Could it be used for a home made lean joint?
Great guy , always loved his Mochet inspired cycle car.

Paul
 
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If you want this underslung, then the rider's seat mountings need to be altered don't they?
I mean by this that the tilting part (including the front wheel & python-pivot) has to be on the lower tube, but the rider has to be seated above the upper tube.
So a seat mount would have to straddle the upper tube in a "V" perhaps?
Not at all impossible to do.
 
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Hi all

Stuff done , tick off wobbly bars fixed !



Standard kids bars welded to a plate with 4 x M8 bolts nice and secure.

Over long extensions fitted and brake levers left as is for testing again..



plate a bit to big to fix bars in front of forward elastomer , could maybe have done it if I had ground a curve into the plate so it wrapped around the elastomer.



It almost seemed like my knuckles were brushing the ground [ not again you say ? ] however the bars do not tilt so only mild peril.

Next up is to probably angle those extensions up a bit swap the levers around and add some rotary shifters left and right.

They will be the correct way around so reasonably easy to operate and will mean there is no need to take my eyes off the road whilst I locate a bar end shifter and puzzle out which direction to move it ?

So another short ride around the estate , felt a lot more in control decided to completely ignore the tilt unless I was in danger of hitting the ground with the pedals.

Yes I could turn/tilt that sharply !

So on to do list steering damper ?



As you can see there is a M6 tapped hole just above the upper pivot rod end bearing , steering damper is M8 however it is wider than the 2 strengthening ribs visible.

I reckon if I drill it out to M8 and trim the damper down so it fits between the plates that may do as a fastening for the time being , just the got to find a way to mount it on the moving bit ?

Paul
 
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If you want this underslung, then the rider's seat mountings need to be altered don't they?
I mean by this that the tilting part (including the front wheel & python-pivot) has to be on the lower tube, but the rider has to be seated above the upper tube.
So a seat mount would have to straddle the upper tube in a "V" perhaps?
Not at all impossible to do.
Drawing in 10 min's , however imagine elastomer's and vertical rod end at the rear of the trike ?
 
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Dan

Like this ?



It will probably need the top frame coming out of the rear end at axle height however I still think it is do-able ?

With the weight trying to bend it in the middle the forces on the elastomer will mainly be compression so it should not rip that apart ?

Paul
 
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I think that with only one pivot you will always get yaw as the elastomers resist the pivoting action at their end of the beam, moving the beam into the turn which when translated through the python pivot moves the front wheel in the opposite direction to the turn. Two pivots would mean elimination of yaw. The pivot position should be in the middle of the elastomer when measured vertically or viewed from the front or back IMO. This would give equal amounts of compression and tension on the elastomer and I suspect that the material is vastly harder to compress than stretch thus giving more resistance.



The top pair show the elastomer behaviour with the current pivot point. The elastomer is essentially pushed to one side with minimal compression. The bottom pair show the elastomer behaviour with a central pivot. One side gets substantially compressed. I'd expect this to give more resistance than the existing set-up and I'd expect the elastomers to have a longer life being subject to less stretching.
All we need a a pivot with only 2 axis of movement , instead of the rod end bearings infinite possibility's ?

My view what slightly different ?



In the first example with the pivot below the elastomer my though was the full height of the elastomer was being bent ? maximising it's effectiveness ?

In the second example with the pivot in the centre of the elastomer my though was only the elastomer above the pivot was being used ? effectively halving it's height ?

All opinions listen to Paul
 
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In the second example with the pivot in the centre of the elastomer my though was only the elastomer above the pivot was being used ? effectively halving it's height ?
Not how it would work. It's only the top that actually moves but as far as the elastomer is concerned it could well as be the top that stays still and the bottom that moves or a bit of both. Think of holding the seat still and rotating the fixed part. The elastomer would be equally stressed above and below the pivot.
 
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So being completely underwhelmed by the current work in progress Flevo rear tilter I though I had the parts to tackle a iLean as well !

So out with the original frame and grab some bit's


The frame from the Mk1 Python that had been on the mule when testing the new front end had a height of 5" from the ground in normal use , so aiming for that I suspect 90' cranks will do that.

Found a 3 piece crank complete with a length of seat tube added a screw in BB

Got 2 kiddie cranks 140mm [ 5.6" ] IIRC cut off the single front ring and ground down the pedal end as they are covered in plastic and sprayed silver ?

Got one of my trailer wheels and added a M12 axle [ bit to much play in the bearing but needs must].

Got a SA drum braked wheel that's M12 of course , marked the crank arm for a M6 bolt to hold the SA back plate.

Using a SA brake means I will have to find some way of stopping it reversing the leading/trailing wheel not sure whether in the real world it would try to do that ? however it will damage the brake cable I suspect ?



Sleeved the seat tube to get it near the inside dimension of the 1.5" sq keel tube , just need 2 x M8 bolt holes through them both when I have added the seat and seen how far behind the iLean part needs to be to stop the leading wheel interfering with the seat or me.
This is why it won't stand on it's own at the moment the M8 bolts are missing , I need to determine how long it needs to be to stop them leading wheel hitting the seat ?

Will only give me 1 brake on the trailing wheel , need to get the front end swapped over and put the bars and controls back on the front.

Maybe 2 days work and it should be ridable.

This will be to narrow for luggage however it is only a mule , and I suspect more width may add stability ?

Went out again on the current set up after redoing the controls and tweaking the bars , still not sure whether I can live with it ?

So decided to lay the iLean to rest at the same time so I can compare the 2 ?

It also seems I am in an arms race with the soft southerner wus [ DannyC ] who is also pursuing this goal ?

Paul
 
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Looks good Paul.
It will certainly be a narrow-tracked machine indeed.
I think the police will want to have a word about different tyres on the same axle. Ha! Ha! ;)

Not an arms-race at all, I am just puttering along at my own sad pace. 1 step forwards and 2 steps back it seems.
The trailing arms affair just didn't "feel" right, so some changes have been made (probably all wrong still).

It turned out like this.

It IS i-Lean in principle, it isn't much more stable than the 2 trailing-arms and TBH, I hate it.
I think I will just chop it all up and do away with the forked front end and justr pythonise it for fun.






 
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Looks good Paul.
It will certainly be a narrow-tracked machine indeed.
Yes I would want to get a pannier between the wheels wide side across the frame , so more girth is required :whistle:;)

I think the police will want to have a word about different tyres on the same axle. Ha! Ha! ;)
Guilty as charged , at the moment....

Not an arms-race at all, I am just puttering along at my own sad pace. 1 step forwards and 2 steps back it seems.
The trailing arms affair just didn't "feel" right, so some changes have been made (probably all wrong still).
My attempts are just as wrong/disappointing in all honesty , there are so many dead ends to travel down just in case it goes further after the first bend :D

Paul
 
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