CCKW TIDBIT

joel gopan · Post by **joel gopan** » Mon Dec 19, 2005 8:27 pm

The technical term for the steering method your CCKW uses is "Ackerman Steering," a system in wigh the individual front wheels pivot at the knuckles and are connected by a tierod so that the wheels rotate together about their pivots.
The Horse and buggy which the CCKWs had recently replaced used a "fifth wheel" method in which the entire front axle pivoted from a central point.

Barry Churcher · Post by **Barry Churcher** » Mon Dec 19, 2005 10:56 pm

Here is a good page for understanding the Ackerman principle. You can turn the wheels and see what happens. Do you know the optimum ratio for steering arm angle to wheelbase?
Cheers,
Barry

http://www.compgoparts.com/technical/001/Ackerman.asp

joel gopan · Post by **joel gopan** » Mon Dec 19, 2005 11:20 pm

Neat.
The inner wheel turns at a sharper angle to enable the vehicle to turn with the least possible radius. If it were not using the Ackerman Principal, it would take forever to complete a turn.

armydriver · Post by **armydriver** » Tue Dec 20, 2005 11:28 am

Thanks Barry, that is interesting.

dr deuce · Post by **dr deuce** » Tue Dec 20, 2005 8:47 pm

With this type of steering, if you draw a line thru the center of the two knuckle bearings towards the ground, it will pass through the center of the tire at the point of contact with the ground. If it dod not do this it would be much harder to steer.

joel gopan · Post by **joel gopan** » Tue Dec 20, 2005 9:13 pm

I think someone forgot about Caster.

dr deuce · Post by **dr deuce** » Tue Dec 20, 2005 9:43 pm

Yes, caster would make the contact point a little forward of the actual point of contact.

It would however still be in the center of the tread. Caster is sometimes called steering axis inclination. That is what keeps the wheels going straight while you are going forward and the same thing that makes the steering wheel want to go to the lock right or left when in reverse.

joel gopan · Post by **joel gopan** » Tue Dec 20, 2005 10:32 pm

Without caster the steering would be very difficult and shimmy would be chronic.

Barry Churcher · Post by **Barry Churcher** » Tue Dec 20, 2005 10:49 pm

The easy way to figure caster is look at bicycle forks. A bicycle has lots of positive (+) caster. You can easily ride a bike with no hands, right?

Now turn the forks around backwards to give you lots of negative (-) caster. Betcha have a brute of a time riding it with no hands now!

Cheers,
Barry

dr deuce · Post by **dr deuce** » Tue Dec 20, 2005 11:02 pm

Do I have caster on my Unicycle...

joel gopan · Post by **joel gopan** » Tue Dec 20, 2005 11:26 pm

When you assume the caster attitude, on your Unicycle you will be about to fall on your ass. Caster is not a good thing on a Uniclcle. It would be neat to be able to ride one, but I gotta feeling that I should forget the idea.