Delta trike design - constraints and solutions ?

[stormbird]

Hi all

Last attempt to control these poorly designed wooden king pins , the whole think is just to floppy and inaccurate especially as some large oaf keeps sitting on it !
I think the short wood screws are working loose in the soft wood

So a M12 rod was put through the axle holes , which are M14 so there goes any accuracy !
A lock screw was inserted to try and stop unwanted angle changes and a pin inserted to declare 0' , theoretically now they can both be turned to the same angle ?
Sadly the Ackerman difference is so small that will have to be by the Mk1 eyeball.

At the same time I added a 1.5" spacer to get the main frame up to 11 from the ground to the underside , still need to do the back.

Needs taking outside and trying.

Next up jack shaft mount and rear suspension units , all wood of course to start with.

Paul

 

[stormbird]

Hi all

Turning radius and all that malarkey please don't read if you are easily bored [ I fell asleep twice writing it ]

DannyC of this parish is more a theoretical man and after some research found this picture and some equation or 2 he claimed he understood ?

He being a wiz at spreadsheets and me only being a wizard at claiming his don't do what I want produced this :-

So basically you can put a starting figure in for the w/b " and it will fill a page with these columns , I chose 30" as a starting point as I had no intention of going lower and I highlighted 34" my current w/b.
the graph shows a turning angle for the outer wheel in the left hand column 5 , 10 , 15 etc and then shows a Ackerman estimate for the inside wheel and a predicted turn radius in Inches. It is now easy to see at low turning angles & short w/b Ackerman could be ignored but angles above 15' Ackerman was getting serious.

The other useful think is now I don't have to keep building the quad with different w/b to see the effect I can look it up - IF the figures could be trusted ?

So it was my job to use my rickety mock-up to see if I could validate his figures , the might of Microsoft and a southern brain verses some wood and cable ties in the cold north !

I placed inside centre of rear wheel on a cross in the joints of my path [ point A ], one join heads to the house , the quad is lined up parallel to it , other joint goes at right angels to shed front corner where I placed a garden cane [ point B ].
So I could measure A to B and B to trike hub centre of the rear wheel add the two together divide by 2 for a approx value.

Angles tried Point A to B Point B to hub average Spreadsheet

35' & 48'	26"	30"	28"	49"
30' & 38'	36"	36"	36"	59"
25 & 30'	54"	55"	55"	73"
20' & 25'	69"	74"	72"	93"
15' & 17'	109"	114"	112"	127"
10' & 11'	148"	165"	157"	193"	[ actually ran out of garden ]	so A to B should be bigger

Now there is a discrepancy between the figures , when I asked Dans figures came from the centre of the outside front wheel shown in red on the first drawing
I was measuring from the inside of the rear wheel shown in green on the first drawing DOH

However I had an idea ?

I plotted them both on graph paper and it showed we had the same curve just a little bit out , so i think we are both happy.

This shows me achieving 35' outer wheel and an amazing 48' on the inner wheel [ nails are pointers to angle ]

At those angles the quad would look like this ! AND the inner wheel does not touch either me OR the frame !!!

So the challenge will be to find a steering mechanism that can achieve these angles

Paul

 

[stormbird]

So today some time was spent on the rear jack shaft and suspension cross member:-

beam in foreground is 40mm x 40mm and 30" long , the maximum width I want the rear to be [ it will be trimmed a little ]

Red hashed parts will be the suspension arms [ no pivots being shown here ] single sided wheels [ M14 axles ] and no brakes

So pivots on the back and drive on the front - part 1

This is for the right hand wheel , free wheel may/will drive rear wheel and pedals driving sprocket screwed to a home made adaptor.

I need to ensure I have enough clearance between the biggest sprocket and the cross beam , I need to swap the cassette for either a 32T or a 34T as i want a 1 x 8 transmission

Lots to do Paul

 

[Popshot]

The steering will have to come to a central position on the front axle and from there to the wheels. Tank steering could still be used. The main fore and aft rods comming to that central position. Equally a go kart type steering could be used. You'll then need a pivoting plate with the correct linear ratios between input, pivot and outputs. A little finnicky getting correct dimensions but simple enough to actually build.

 

[stormbird]

The main fore and aft rods comming to that central position.

I think they need to run parallel to the main boom and as close as possible to it ?

Equally a go kart type steering could be used.

What this that you speak of ?

Paul

 

[stormbird]

So onward.

New rear end does not yet have the transmission however it needs trying to see if it fit's etc
I figured for the gears etc I can set a dummy rear cross beam on the workmate figure it all out and then transfer it to the mock-up as even with the seat on access is easy.

As I was taking the seat off I though ' I bet the new rear comes close to this front seat mount '
yep as close as it can and I still have a 34" w/b [ actually 34.25" however that's not on Dans table ]

Not really strong enough to sit on now , so I added to legs to the rear of the main boom , with a bit of packing the gap is 3mm so now when I sit on it it stops sagging when the
gap has closed up and then it is stable.
I need to sit on it to investigate arms/steering etc later on.

Paul

 

[jonrev]

I've been a bit confused with the maths and the close-up shots of sections of this design for a while now. I'm still not up to the maths but now I can see the layout clearly in the last few pics I really like the look of your machine Paul. Hope you get to the metal bashing stage so I can see it in the flesh and on the road.

John

 

[Popshot]

I think they need to run parallel to the main boom and as close as possible to it ?


What this that you speak of ?

Paul

The levers need to be at your side but they can be built so the rods run close to the middle.

By go kart I just mean a central steering column with a plate at the end attached to the rods going to the wheels. This would affect getting on and off though.

Whatever system you use will have to be central to the front axle as the wheels themselves will want the space of any other system with that amount of lock.

 

[stormbird]

I've been a bit confused with the maths and the close-up shots of sections of this design for a while now. I'm still not up to the maths

Me to that is why I keep DannyC under the stairs so I don't have to worry , although he eats to much for my liking ....

but now I can see the layout clearly in the last few pics I really like the look of your machine Paul. Hope you get to the metal bashing stage so I can see it in the flesh and on the road.

John

Thanks muchly , as you say hopefully it will get turned into steel.
In the past I have followed someone else's design just tweaked for my inside leg and seat preferences , as this is clear water I though it better to build an easily changeable mock-up and so far it seems to have worked.

Paul

 

[stormbird]

The levers need to be at your side but they can be built so the rods run close to the middle.

I was worried the levers would be sat out in space with no where to mount them , it now looks like they can go on the beam carrying the drive components , rear wheels and seat handy !

By go kart I just mean a central steering column with a plate at the end attached to the rods going to the wheels. This would affect getting on and off though.

Ok it is my preferred choice as the rotation of a column [ I believe ] has less angle restrictions than straight bell cranks however I don't think I am far enough away from the position of the wheel steering arms to get it in.
I did envisage a telescoping steering wheel to aid getting in and out.

Whatever system you use will have to be central to the front axle as the wheels themselves will want the space of any other system with that amount of lock.

Yes from the wheels it will all have to come backwards towards the seat else the legs will collide with it.

Paul

 

[stormbird]

Ok so I built a mock up of the mock up so I work at bench height and not kneeling on the floor.

In this view the front of the quad is at the bottom of the picture and the rear of the quad at the top of the picture.
The bearings and jack shaft are just balanced on some scrap wood however it is almost central to the 40mm boom , the red line on the left is where the chain needs to go to drive the right rear wheel so there needs to be something on the jack shaft to achieve that and it needs to be further over to the left.

I am looking for room to get the 34T cassette close to the cross boom , otherwise the 4 [ or more ] pillars that the shaft bearings will sit on will have to be very long ?

here I cut all the way through the main boom [ 40mm ] and attached another 40mm piece around the back across the hole , I did not get the piece at the back long enough it needs to be further under the boom out of the picture on the right.

I need to refer to the mock up it is possible I won't have to do this IF the cassette is not to far in front of the seat.

Paul

 

[DannyC]

Paul,

Ref "King Pin Placement" and the difficulties of getting the head tubes located.
Here is a side-view of LOKI's round cross-beam mounted onto the square keel.
As the head-tubes are only notched onto the cross-beam they can resolve to any require angle for centre-point and other steering angles.
It also allows you to have the cross-boom go forwards and outwards in one sweep.
This "bending" was not done in any other way than slicing into the tube at various points, folding the slits closed and welding the slits up again.

 

[stormbird]

Dan

Thanks for this , very nice job there.

However you know round tubing is a step into the dark side ....[ certainly for me ]

Whilst you are right square tubing limits the angles you can achieve [ like right angles are best ] it must take some working out to achieve those off centre angles and know how much to cut out of the slits to achieve the objective ?

Paul

 

[DannyC]

Dan

Thanks for this , very nice job there.

However you know round tubing is a step into the dark side ....[ certainly for me ]

Whilst you are right square tubing limits the angles you can achieve [ like right angles are best ] it must take some working out to achieve those off centre angles and know how much to cut out of the slits to achieve the objective ?

Paul

Paul,
This was John Prices approach to it. What he did to achieve it was very clever. He made a "jig" out of angle iron that allowed him to do the cuts and capture the tube into the inside corner of the angle-iron with jubilee clips.
The angle-iron provided the backbone to keep everything straight and where he wanted it, and the slitting procedure allowed him to get the round tube to conform to the changes in direction required.

I think Ed has has employed a similar technique for Ed's Inferno and his Hot-Rod .

 

[stormbird]

So saps rising and a young mans mind turns to kingpins ?

The black triangle shows the area the wheel mounting hardware must stay inside for maximum turn radius , just visible in some pictures is a kingpin housing [ head tube ] underneath
the axle just to prove it is a no goer.

To marry a head tube to the current frame it would need to be mounted something like this , the trail will be taken care of by mounting the whole assembly @ 15' to the main boom
so not shown here for simplicity.

From above we have quite a bit of space..

Same from the rear looking forward

Next up then cut a fork down to go inside and attempt to find the centre point line for the kingpin inclination.
What can possibly go wrong

Paul

 

[stormbird]

Today was pedal car day !
Dalerider and I went to a 3 race meeting about 1 hours drive away , me to look at kingpins ! sad I know...

This car had the best lock however this was just a simple go kart style and did not bother with any of the technical complexities so not really for me.

This was a Royce car , very good engineering with the steering arm actually going inside the car and having a car type steering shaft very complex

Another version of the same idea

This may be smaller and lighter than a head tube/fork set up which nobody used except the commercial AZUB

The AZUB may have been a tadpole conversion ? it was hard to see as it had cloth body work , it was noticeable it was quite high.

The Apollo cars used bronze bushing , all very neat however beyond someone with a lathe.

There were multiple versions of both these cars a commercial AZUB quad and a few of the older cars being used by youngsters.
Looked to be great fun however :-

race 1 - 95 mins
race 2 - 110 mins
race 3 - 125 mins

You really needed to be a team of more than 2 ! else someone is doing a lot of pedalling !!!

Paul

 

[DannyC]

The Apollo cars used bronze bushing , all very neat however beyond someone with a lathe.

with a lathe? or without a lathe?

 

[stormbird]

with a lathe? or without a lathe?

well of course your with ...
and I'm without

Paul

 

[stormbird]

Ok another mock-up

The plywood is a bit thick [ 9mm ] I think it wants to ba a small plate maybe 4mm will be thick enough ?
The rod ends are staggered vertically for the 15' of kingpin inclination

And then the lower one is wound out of the plate and the upper one wound in [ plate limits how much centre point steering angle I can get ] currently 10'

Looks like this might work ?

Paul

 

[DannyC]

Ok another mock-up

The plywood is a bit thick [ 9mm ] I think it wants to ba a small plate maybe 4mm will be thick enough ?
The rod ends are staggered vertically for the 15' of kingpin inclination

And then the lower one is wound out of the plate and the upper one wound in [ plate limits how much centre point steering angle I can get ] currently 10'

Looks like this might work ?

Paul

If you use female rod-ends and M12 studding and nuts, can you not get increased angles?