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velotux
08-21-2010, 02:20 PM
Hi AZ Krew!

I was looking for inspiration on the web today and was googling away, when I came across a link to Popular Mechanics magazine Apr. 1969 on Google books. It contains plans and construction information for a great looking LWB bent called the Ground Hugger, with a clever, and rather neat method of steering in my opinion. Even if you don't build the bike, it may inspire, or be helpfull to all you great zombies out there. I thought I must share my good fortune with you all.

Here is the link.

http://books.google.com/books?id=KtgDAAAAMBAJ&lpg=PA192&ots=SnLZpmio4l&dq=popular%20mechanics%20Ground%20Hugger&pg=PA192#v=onepage&q=popular%20mechanics%20Ground%20Hugger&f=false

Enjoy.

All the very best.

Tim

Wingman
08-21-2010, 03:52 PM
Velotux,

You may be interested in the update to that bike, the Ground Hugger XR2. Robert Q. Riley was in on the development of the original GH and came out with this version about 11 years ago (hard to believe it's been that long ago). You may also get a charge out of his other creations, including his XR3 Hybrid Car. http://www.rqriley.com/

Wingman

Odd Man Out
08-21-2010, 04:22 PM
The steering mechanism was found to be sloppy and did not give a good tight accurate steering feeling since there was play in it. Somewhere deep in the forum this design has been descussed and pooh poohed...

tree
08-21-2010, 04:55 PM
I do like the 'ball grabber' braking system. ;)

It's clever though. The steering may work better with a CV joint instead of a universal joint. I think you can get smallish CVs for ATVs possibly?

Radical Brad
08-21-2010, 05:06 PM
My favorite JQR creation is that submersible thing that has the extending pontoon wings. I think that was shown in PM back in the 60's as well.

I agree, U-Joint steering has huge slack. I even tried a wrench joint once, but it just didn't feel right. A stiff spring joint might work if you could find a way to fasten it. Like the weedwacker drive system.

Brad

John Lewis
08-22-2010, 03:02 AM
We discussed Uni joint steering some time back. A friend has it on one of his bents and it is perfectly acceptable. I think from memory it came from a small car. Doesn't seem to have any slop.

He did mention the orientation of the joint was critical to the way it handled. Can't recall which way it had to be. I have a photo somewhere and will post it when I find it.

A South Australian school built a Groundhugger XR3 and entered it in the Solar Challenge from Darwin to Adelaide. Schools only did part of the course I think. They placed very high but of course at night when the solar cars stopped I think they just kept pedalling.

There is a link to the article on the Riley site.

John

imamedik
08-22-2010, 10:30 AM
..... the orientation of the joint was critical to the way it handled. Can't recall which way it had to be.John

I remember reading about it, it said that the uni-joint should be rotated to 45 degree then installed. That way the joint has taken up all the slop since we normally will only turn the wheels 40 degrees either way. The slop occurs when the joint transitions from/through 90 degrees.

velotux
08-22-2010, 11:33 AM
Hi all.

I like the idea. I can see that using a cheap UJ or using it at the wrong angle could be an issue. I have a Britool UJ that comes apart with allen bolts. It seems quite snug and tight in its movement. I will give it a try on a mock up on my bench. If all else fails I can turn up some new pins on the lathe at work, and clock them up to make them almost interference fit, then harden them. I think it is worth persevering. It has intrigued me now so I must investigate.

All the best.

Tim

Radical Brad
08-22-2010, 12:45 PM
A small car steering joint would be good as it has that rubber flange to stop the play.

The ones I tried that did not work were, a socket wrench joint, a V45 Magna drive shaft joint, and one from McMaster.

Brad

velotux
08-22-2010, 12:53 PM
Thank you for the tips Brad.

Much obliged.

All the very best.

Tim

savarin
08-22-2010, 11:40 PM
I think the reason why U'J's dont work as well as expected is the non-linear rotation speed they transmit as they go through the range of motion.
If we assume an angle between the two shafts then the transmission of power has a surge component as the joint slows and accelerates through a complete turn. CV joints do not have this discrepancy hence their term - "Constant Velocity"
I believe if the UJ is positioned at a 45' rotation angle then the discrepancies in rotational speed will even each other out.
If that makes sense.

mausball
08-23-2010, 12:26 AM
There's something I've used in the past for things like no-slop steering and shift linkages on racecars that I think might work well here:

http://www.pegasusautoracing.com/productselection.asp?Product=1490

velotux
08-23-2010, 03:55 PM
Hi all.

Savarin.

I think what you suggest may well be correct if the UJ is mounted at 45 degrees, and the rotation remains less than 90 degrees, The pins of the UJ should be in line with the steering tube vertically and horizontally with the handle bars and wheel straight, and as long as you do not exceed 45 degrees rotation of the steering I think it should be ok. I am making up a trial rig at work. I will report back.

Mausball

Nice piece of kit. Many thanks for the link and your valued input. Looks like its fit for the job. Shame they are so expensive though. I will have to investigate and exhaust cheaper, more accessible routes first, before having a go with them. Much obliged.

All the best.

Tim

mausball
08-24-2010, 02:39 PM
Tim-

Yeah, Apex universals are pretty much the best around, but man, you DO get what you pay for. :jester:

tree
08-24-2010, 04:14 PM
I think the reason why U'J's dont work as well as expected is the non-linear rotation speed they transmit as they go through the range of motion.
If we assume an angle between the two shafts then the transmission of power has a surge component as the joint slows and accelerates through a complete turn. CV joints do not have this discrepancy hence their term - "Constant Velocity"
I believe if the UJ is positioned at a 45' rotation angle then the discrepancies in rotational speed will even each other out.
If that makes sense.

If anyone knows this stuff already, I apologize. If not, here goes.

The optimum angle for a SINGLE UJ is 0 degrees - anything more and you will get vibration/speed change to some degree. For a steering linkage, you can get away with a somewhat dramatic angle without noticing it too much - automotive steering columns are single-cardan I believe.

Automotive propeller shafts use TWO universal joints, mounted inline with each other. In doing this, the change in speed of the two joints cancel each other out. You can mount two UJs right next to each other to get the same cancelling effect and a smoothly-rotating joint. This is called a 'double cardan'.

This page was enlightening: http://www.4x4wire.com/toyota/tech/driveline/

Still, for bike steering systems, even one UJ would probably have a bit of slop unless you paid a fortune for it - two would have smoother action but even more slop.

velotux
08-24-2010, 05:03 PM
Hi Krew.

Mausball.

No doubt there, in many cases.

Tree.

Many thanks for the usefull information.

Because I am an AZ I ain't giving up yet! If all else fails I have an angle grinder and a welder, and Brad's Meridian style steering, and will have bits of UJ dust everywhere to remind me of the error of my ways. On the other hand I may well create something radical. Either way, sparks will fly, so I don't mind and I will have fun. Nothing is impossible. Some things are more improbable. Until someone makes it possible. Bring it on!

Many thanks.

Tim

John Lewis
08-25-2010, 01:32 AM
Here is the promised photo of Stan's uni joint steering.
This works perfectly. Notice the orientation of the hinge points. This was according to Stan the critical thing and with other orientations the steering becomes very different.
John
http://i254.photobucket.com/albums/hh98/lew2au/Uni.jpg

velotux
08-25-2010, 01:18 PM
Hi John.

Many thanks for getting back with the picture of the UJ steering. Very use full. This appears to be the orientation described in the ground hugger drawings and information as well. I have not had a chance to rig anything up yet but I will by the weekend for sure.

All the best.

Tim

savarin
08-25-2010, 11:01 PM
Its very interesting reading the 69 issue those plans are in as it makes you realise how long ago it was.
I can remember seeing those plans and thought they were way cool even then but would never have put the age as 40 years ago.
Reading the adverts and seeing the fashions in the pictures really hammers it home.

KoolKat
08-25-2010, 11:03 PM
Because I am an AZ I ain't giving up yet! If all else fails I have an angle grinder and a welder, and Brad's Meridian style steering, and will have bits of UJ dust everywhere to remind me of the error of my ways. On the other hand I may well create something radical. Either way, sparks will fly, so I don't mind and I will have fun. Nothing is impossible. Some things are more improbable. Until someone makes it possible. Bring it on!

Many thanks.

Tim

That's the spirit, Tim! :punk:

PeterT
08-26-2010, 06:03 AM
Velotux,

Have a good look through the local motor parts shop ...

You can get these types of flexishafts/UJ/goosenecks
http://farm5.static.flickr.com/4078/4929020824_f21f7ca39a_m.jpg

http://farm5.static.flickr.com/4134/4928428279_279f759960_m.jpg

PeterT

velotux
08-26-2010, 01:10 PM
Hi all.

It' great isn't it savarin.

Thanks Kat.

They look very pretty Peter. I will have to investigate. Many thanks.

All the best.

Tim