ridecamp@endurance.net: RE: Trailer Woes

RE: Trailer Woes

Mike Sofen (a-miksof@MICROSOFT.com)
Fri, 9 May 1997 08:24:12 -0700

While Joe's points are completely valid, the issue of bumper-pull
trailer stability/safety is a completely different subject. Gooseneck
rigs are inherently stable, bumper pulls are inherently instable -
tongue weight (the weight of the trailer that is applied to the rear end
of the vehicle at the hitch) presses the rear of the vehicle down and
lifts the front end.

If enough weight presses down on the rear, the front wheels start losing
their grip on the road. That's one problem, albeit correctable to a
certain extent with good trailer/truck setup.

What's not correctable is the ratio that Joe refers to - the trailer
length (from hitch to trailer wheels) versus the vehicle wheelbase. A
short vehicle wheelbase relative to the trailer length allows the
trailer to 'out muscle' the vehicle, because it can act like a lever.
The longer the vehicle wheelbase, with a bumper pull trailer, the safer
the rig. It's just physics.

Does that mean that a short wheelbase bumperpull rig is unsafe/unusable?
Nope. It does mean that someone driving a rig like that better be
driving slower (reduces the leverage via angular mass/velocity, that is,
the higher the speed, the more a given weight can exert a pull on the
trailer hitch in a direction that is not straight back), and have really
good brakes, and load the trailer so that weight shifts are minimized or
completely eliminated.

Goosenecks are clearly the way to go relative to safety and towability,
but we sacrifice a lot of other stuff (space, flexibility).

Mike Sofen
Redmond, WA

> -----Original Message-----
> From: Joe Long [SMTP:jlong@mti.net]
> Sent: Friday, May 09, 1997 8:02 AM
> To: ridecamp@endurance.net
> Subject: Re: Trailer Woes
>
> On Fri, 9 May 1997 07:34:56 -0700, "Kathy Myers" <kathy@nvolve.com>
> wrote:
>
> >Size? In here lies the rub doesn't it. The larger the vehicle, the
> >harder it is to park. But the smaller the vehicle, the less stable
> it
> >is for pulling horses.
>
> It's not that simple. Consider that 18-wheelers are more stable than
> most tow
> vehicle/horse trailer combos, yet the tractor is *much* smaller than
> the
> trailer. It has to do with the geometry of the whole package,
> particularly the
> relationship between wheelbase and the distance from rear axle to
> hitch.
> Ideally, the hitch should be slightly ahead of the rear axle. A
> gooseneck
> trailer towed by a short wheelbase truck will be more stable than a
> "bumper
> hitch" trailer towed by a long-wheelbase truck.
>
> Also, gooseneck trailers are easier to park and maneuver than
> equivalent size
> tag-along trailers.
>
> --
>
> Joe Long
> jlong@mti.net
> http://www.mti.net Business
> http://www.rnbw.com Personal

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