canted wheels on a trailer?

M-gineering Wrote:
Gary Young wrote:
I'm building my own trailer, of a design similar to this one:

http://drumbent.com/trailer.html

I've noticed that some commercial trailers (and racing wheelchairs)
have
the wheels canted toward each other at the top. It's said to improve
handling, but I don't understand why. Can someone explain the
thinking and
whether it's a good idea for a cargo trailer?

reduces width for equal track, reduces sideload on wheel during
cornering, increases tyre traction during cornering

--
/Marten

info(apestaartje)m-gineering(punt)nl


The tradeoff for the above is increased rolling resistance due the
camber steer of the right tire attempting to turn left and the left
tire attempting to turn right. The thinner the tire and larger the
diameter, the milder the penalties.


--
meb

meb wrote:

M-gineering Wrote:

reduces width for equal track, reduces sideload on wheel during
cornering, increases tyre traction during cornering

The tradeoff for the above is increased rolling resistance due the
camber steer of the right tire attempting to turn left and the left
tire attempting to turn right. The thinner the tire and larger the
diameter, the milder the penalties.

I thought that this was addressed by means of corresponding toe-out.

Chalo

own a vehicle? if the toe and or camber is adjusted to postive or
negative with tape and chalk-you'll get a feel for the effects!

if the wheels are leaned in at the top on a solid non-turning axle,
the leaning provides a simple solution to different travel lengths and
speed travel rates for the different radii of inside and outside
wheel.
the outside contact surface grips while the inside pivots on less
contact surface than the outside. Knot as effective as one wheel at
the rear or more complex and expensive suspensions.
make a model with a straw and two donuts.

On Sun, 26 Aug 2007 08:20:11 +1000, meb
wrote:


M-gineering Wrote:
Gary Young wrote:
I'm building my own trailer, of a design similar to this one:

http://drumbent.com/trailer.html

I've noticed that some commercial trailers (and racing wheelchairs)
have
the wheels canted toward each other at the top. It's said to improve
handling, but I don't understand why. Can someone explain the
thinking and
whether it's a good idea for a cargo trailer?

reduces width for equal track, reduces sideload on wheel during
cornering, increases tyre traction during cornering

--
/Marten

info(apestaartje)m-gineering(punt)nl


The tradeoff for the above is increased rolling resistance due the
camber steer of the right tire attempting to turn left and the left
tire attempting to turn right. The thinner the tire and larger the
diameter, the milder the penalties.
And this can be totally corrected for by adjusting toe.

--
Posted via a free Usenet account from http://www.teranews.com

true but what's the golden hammer toe adjustment mechanism for home
brew bike trailers?
one wheel rearward seems easier, effective, and more reliable.

On Sun, 26 Aug 2007 14:46:53 -0400, clare at snyder.on.ca wrote:

On Sun, 26 Aug 2007 08:20:11 +1000, meb
wrote:


M-gineering Wrote:
Gary Young wrote:
I'm building my own trailer, of a design similar to this one:

http://drumbent.com/trailer.html

I've noticed that some commercial trailers (and racing wheelchairs)
have
the wheels canted toward each other at the top. It's said to improve
handling, but I don't understand why. Can someone explain the
thinking and
whether it's a good idea for a cargo trailer?

reduces width for equal track, reduces sideload on wheel during
cornering, increases tyre traction during cornering

--
/Marten

info(apestaartje)m-gineering(punt)nl


The tradeoff for the above is increased rolling resistance due the
camber steer of the right tire attempting to turn left and the left
tire attempting to turn right. The thinner the tire and larger the
diameter, the milder the penalties.
And this can be totally corrected for by adjusting toe.


Is there any formula (or rule of thumb) for determining the proper camber
and toe-out? I'll be using 700C front wheels set a little over two feet
apart.

In article
,
Gary Young wrote:

On Sun, 26 Aug 2007 14:46:53 -0400, clare at snyder.on.ca wrote:

On Sun, 26 Aug 2007 08:20:11 +1000, meb
wrote:


M-gineering Wrote:
Gary Young wrote:
I'm building my own trailer, of a design similar to this one:

http://drumbent.com/trailer.html

I've noticed that some commercial trailers (and racing wheelchairs)
have
the wheels canted toward each other at the top. It's said to improve
handling, but I don't understand why. Can someone explain the
thinking and
whether it's a good idea for a cargo trailer?

reduces width for equal track, reduces sideload on wheel during
cornering, increases tyre traction during cornering

--
/Marten

info(apestaartje)m-gineering(punt)nl


The tradeoff for the above is increased rolling resistance due the
camber steer of the right tire attempting to turn left and the left
tire attempting to turn right. The thinner the tire and larger the
diameter, the milder the penalties.
And this can be totally corrected for by adjusting toe.


Is there any formula (or rule of thumb) for determining the proper camber
and toe-out? I'll be using 700C front wheels set a little over two feet
apart.

Not from me, not now. Non-holonomic constraints.
An intriguing project trying to calculate it.
Maybe ask the automobile engineers.
They've done everything.

--
Michael Press

In article
,
Gary Young wrote:

On Sun, 26 Aug 2007 14:46:53 -0400, clare at snyder.on.ca wrote:

On Sun, 26 Aug 2007 08:20:11 +1000, meb
wrote:


M-gineering Wrote:
Gary Young wrote:
I'm building my own trailer, of a design similar to this one:

http://drumbent.com/trailer.html

I've noticed that some commercial trailers (and racing wheelchairs)
have
the wheels canted toward each other at the top. It's said to improve
handling, but I don't understand why. Can someone explain the
thinking and
whether it's a good idea for a cargo trailer?

reduces width for equal track, reduces sideload on wheel during
cornering, increases tyre traction during cornering

--
/Marten

info(apestaartje)m-gineering(punt)nl


The tradeoff for the above is increased rolling resistance due the
camber steer of the right tire attempting to turn left and the left
tire attempting to turn right. The thinner the tire and larger the
diameter, the milder the penalties.
And this can be totally corrected for by adjusting toe.


Is there any formula (or rule of thumb) for determining the proper camber
and toe-out? I'll be using 700C front wheels set a little over two feet
apart.

I do not think toeing the wheel will compensate for a
cambered wheel. There will be tire scrub.

r = wheel radius
c = angle of camber
t = angle of toe.
s = distance the wheel wants to track without scrub.
R_c = the radius of curvature of the track of the cambered wheel.

The wheel axis strikes the ground at distance R_c = r/sin(c)
from the contact patch.
Draw the triangle. This is elementary trigonometry.

Following is a cheesy analysis. Actual research is called for.
I am interested in a full answer. Non-holonomic constraints
are `interesting.'

A cambered wheel wants to track a circle
tangent to the straight ahead line.
A toed wheel wants to track a straight line
deviating from the forward line by angle t.
The amount of scrub of a toed wheel is first order in ds.
The amount of scrub of a cambered wheel is second order in ds.

A second order effect cannot compensate for a first order effect.
There will necessarily be scrub.

--
Michael Press

Chalo Wrote:
meb wrote:

M-gineering Wrote:

reduces width for equal track, reduces sideload on wheel during
cornering, increases tyre traction during cornering

The tradeoff for the above is increased rolling resistance due the
camber steer of the right tire attempting to turn left and the left
tire attempting to turn right. The thinner the tire and larger the
diameter, the milder the penalties.

I thought that this was addressed by means of corresponding toe-out.

Chalo

Partially. There still is an intrawheel rolling resistance caused by
smallest diameter portion of the wheel contacting the road fighting the
largest diameter portion of the wheel contacting the wheel attempting to
turn different radii.


--
meb

meb wrote:

Chalo Wrote:

meb wrote:

The tradeoff for the above is increased rolling resistance due the
camber steer of the right tire attempting to turn left and the left
tire attempting to turn right. The thinner the tire and larger the
diameter, the milder the penalties.

I thought that this was addressed by means of corresponding toe-out.

Partially. There still is an intrawheel rolling resistance caused by
smallest diameter portion of the wheel contacting the road fighting the
largest diameter portion of the wheel contacting the wheel attempting to
turn different radii.

How different could this be from the left edge of the contact patch of
a plumb tire fighting the right edge, and both of them fighting the
center of the tread? There must always be some scrub; it's intrinsic
to an elliptically convex tire tread conforming to a flat surface as
it rolls.

Chalo