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Old 07-20-2005, 20:01   #1 (permalink)
Nehmo
Guest
 
Posts: n/a
5th Wheel Hich Position?

A fifth-wheel trailer is one that has a hitch that connects to the
towing vehicle at a point above the rear axle of the towing vehicle -
not at a point on the rear of the vehicle as with a pull-behind trailer.
For example, this is a 5th wheel:
http://www.theironworker.com/Fifth%2...%20Trailer.jpg

My question concerns position of the point of attachment, let's say, the
position of the king pin. For normal pulling of the trailer, where is
the best point to have the king pin? Should it be directly over the axle
of the towing vehicle or should it be ahead of the axle? If ahead, by
how much? In what ways does handling change if the position of the king
pin is changed?

This page http://www.etrailer.com/faq/fifthwheelfaq.asp discusses using
a slider arrangement to move the king pin for maneuverability. It doesn'
t discuss the optimum position for towing.

Instructions that came with a hitch say to mount 0 to 6 inches ahead of
the axle, but provides no further information.

--
|||||||||||||||| Nehmo Sergheyev ||||||||||||||||

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Old 07-20-2005, 20:01   #2 (permalink)
RAM^3
Guest
 
Posts: n/a
Re: 5th Wheel Hich Position?

"Nehmo" <nehmo54@hotmail.com> wrote in message
news:cAvDe.5$8g.3@tornado.rdc-kc.rr.com...
>A fifth-wheel trailer is one that has a hitch that connects to the
> towing vehicle at a point above the rear axle of the towing vehicle -
> not at a point on the rear of the vehicle as with a pull-behind trailer.
> For example, this is a 5th wheel:
> http://www.theironworker.com/Fifth%2...%20Trailer.jpg
>
> My question concerns position of the point of attachment, let's say, the
> position of the king pin. For normal pulling of the trailer, where is
> the best point to have the king pin? Should it be directly over the axle
> of the towing vehicle or should it be ahead of the axle? If ahead, by
> how much? In what ways does handling change if the position of the king
> pin is changed?


Each truck's manufacturer has their own specifications as to the proper
location. Many say to position the center 2" - 4" forward of the rear axle
while others specify a position directly over the axle.

You may wish to peruse the installation instructions on the Reese website
for hitch rails similar to the ones you are interested in on the make and
model truck that you have.

http://www.reeseprod.com/support/sup...shtml#5thwheel will take
you directly to their support page.

The reason for the placement of the hitch centerpoint above or very slightly
ahead of the rear axle is to allow that portion of the weight of the trailer
that rests upon the hitch to be transferred to the rear axle without
disturbing the balance of the truck. If the point of weight transfer falls
behind the rear axle then the front (steering!) wheels are levered upwards
with a corresponding reduction in vehicle control.

Doing a wheelie down the highway while pulling a trailer will attract LOTS
of unwelcome attention! <G>

>
> This page http://www.etrailer.com/faq/fifthwheelfaq.asp discusses using
> a slider arrangement to move the king pin for maneuverability. It doesn'
> t discuss the optimum position for towing.


The sliding hitch mount is intended to provide adequate clearance, during
tight turns, between the rear of the cab and the front of the trailer when a
short (6' or less bed) wheelbase truck is used as a tow vehicle.

>
> Instructions that came with a hitch say to mount 0 to 6 inches ahead of
> the axle, but provides no further information.
>
> --
> |||||||||||||||| Nehmo Sergheyev ||||||||||||||||
>



  Reply With Quote
Old 07-20-2005, 20:01   #3 (permalink)
Jonathan Race
Guest
 
Posts: n/a
Re: 5th Wheel Hich Position?

Greetings,

Different vehicle manufacturers (as well as the hitch manufacturers) will
have varying recommendations. You are going to have to read your owner's
manual as well as the help and installation pages from the hitch
manufacturer's web sites for the best information for the set-up you have.

As for handling, the farther forward the king pin is in front of the rear
axle, the more weight is transfered forward to the front wheels. Admittedly
6" may not sound like a whole lot, but the only way to determine what feels
best to you when towing your particular combination is trial and error,
which is much easier with a sliding set-up.. A change of an inch or two
could make your steering feel heavier or lighter, or give you too much rear
end "squirm". If you go to a newsgroup like alt.rv I can almost guarantee
that the folks there will have more than a few things to say about this!

Depending on the length of the bed it most likely effect your turning radius
as well. This is especially important with a short-bed truck. The last
thing you want is to have the front corner of the trailer crush your back
window and back edge of your roof while you are taking a tight turn. This
is why you see so many forward-offset kingpin setups on the larger 5th wheel
trailers these days.

Cheers - Jonathan

"Nehmo" <nehmo54@hotmail.com> wrote in message
news:cAvDe.5$8g.3@tornado.rdc-kc.rr.com...
>A fifth-wheel trailer is one that has a hitch that connects to the
> towing vehicle at a point above the rear axle of the towing vehicle -
> not at a point on the rear of the vehicle as with a pull-behind trailer.
> For example, this is a 5th wheel:
> http://www.theironworker.com/Fifth%2...%20Trailer.jpg
>
> My question concerns position of the point of attachment, let's say, the
> position of the king pin. For normal pulling of the trailer, where is
> the best point to have the king pin? Should it be directly over the axle
> of the towing vehicle or should it be ahead of the axle? If ahead, by
> how much? In what ways does handling change if the position of the king
> pin is changed?
>
> This page http://www.etrailer.com/faq/fifthwheelfaq.asp discusses using
> a slider arrangement to move the king pin for maneuverability. It doesn'
> t discuss the optimum position for towing.
>
> Instructions that came with a hitch say to mount 0 to 6 inches ahead of
> the axle, but provides no further information.
>
> --
> |||||||||||||||| Nehmo Sergheyev ||||||||||||||||
>



  Reply With Quote
Old 07-20-2005, 20:01   #4 (permalink)
nehmo54@hotmail.com
Guest
 
Posts: n/a
Re: 5th Wheel Hich Position?

[This is a repeat of the original post so that I can add news:alt.rv .]

A fifth-wheel trailer is one that has a hitch that connects to the
towing vehicle at a point above the rear axle of the towing vehicle -
not at a point on the rear of the vehicle as with a pull-behind
trailer.
For example, this is a 5th wheel:
http://www.theironworker.com/F ifth%20Wheel%20Trailer.jpg

My question concerns position of the point of attachment, let's say,
the
position of the king pin. For normal pulling of a trailer, where is
the best point to have the king pin? Should it be directly over the
axle
of the towing vehicle or should it be ahead of the axle? If ahead, by
how much? In what ways does handling change if the position of the king
pin is changed?

This page http://www.etrailer.com/faq/fi fthwheelfaq.asp discusses
using
a slider arrangement to move the king pin for maneuverability. It
doesn't discuss the optimum position for towing.

Instructions that came with a hitch say to mount from 0 to 6 inches
ahead of
the axle, but provides no further information.

[crossposted: news:alt.autos.dodge.trucks news:alt.trucks.chevy
news:alt.trucks.ford news:rec.crafts.metalworking news:alt.rv ]

--
|||||||||||||||| Nehmo Sergheyev ||||||||||||||||

  Reply With Quote
Old 07-20-2005, 20:01   #5 (permalink)
Mellowed
Guest
 
Posts: n/a
Re: 5th Wheel Hich Position?

My hitch is directly over the rear axle. Vehicle is a '99 F350 CC 4x4
8' bed. Hitch weight is 2300 lbs. Handling is transparent. With the
5th wheel attached, the truck is level. 5th wheel axles have been
reversed to match the truck.


"Nehmo" <nehmo54@hotmail.com> wrote in message
news:cAvDe.5$8g.3@tornado.rdc-kc.rr.com...
: A fifth-wheel trailer is one that has a hitch that connects to the
: towing vehicle at a point above the rear axle of the towing vehicle -
: not at a point on the rear of the vehicle as with a pull-behind
trailer.
: For example, this is a 5th wheel:
: http://www.theironworker.com/Fifth%2...%20Trailer.jpg
:
: My question concerns position of the point of attachment, let's say,
the
: position of the king pin. For normal pulling of the trailer, where is
: the best point to have the king pin? Should it be directly over the
axle
: of the towing vehicle or should it be ahead of the axle? If ahead, by
: how much? In what ways does handling change if the position of the
king
: pin is changed?
:
: This page http://www.etrailer.com/faq/fifthwheelfaq.asp discusses
using
: a slider arrangement to move the king pin for maneuverability. It
doesn'
: t discuss the optimum position for towing.
:
: Instructions that came with a hitch say to mount 0 to 6 inches ahead
of
: the axle, but provides no further information.
:
: --
: |||||||||||||||| Nehmo Sergheyev ||||||||||||||||
:


  Reply With Quote
Old 07-20-2005, 20:01   #6 (permalink)
William Boyd
Guest
 
Posts: n/a
Re: 5th Wheel Hich Position?

RAM^3 wrote:
> "Nehmo" <nehmo54@hotmail.com> wrote in message
> news:cAvDe.5$8g.3@tornado.rdc-kc.rr.com...
>
>>A fifth-wheel trailer is one that has a hitch that connects to the
>>towing vehicle at a point above the rear axle of the towing vehicle -
>>not at a point on the rear of the vehicle as with a pull-behind trailer.
>>For example, this is a 5th wheel:
>>http://www.theironworker.com/Fifth%2...%20Trailer.jpg
>>
>>My question concerns position of the point of attachment, let's say, the
>>position of the king pin. For normal pulling of the trailer, where is
>>the best point to have the king pin? Should it be directly over the axle
>>of the towing vehicle or should it be ahead of the axle? If ahead, by
>>how much? In what ways does handling change if the position of the king
>>pin is changed?

>
>
> Each truck's manufacturer has their own specifications as to the proper
> location. Many say to position the center 2" - 4" forward of the rear axle
> while others specify a position directly over the axle.
>
> You may wish to peruse the installation instructions on the Reese website
> for hitch rails similar to the ones you are interested in on the make and
> model truck that you have.
>
> http://www.reeseprod.com/support/sup...shtml#5thwheel will take
> you directly to their support page.
>
> The reason for the placement of the hitch centerpoint above or very slightly
> ahead of the rear axle is to allow that portion of the weight of the trailer
> that rests upon the hitch to be transferred to the rear axle without
> disturbing the balance of the truck. If the point of weight transfer falls
> behind the rear axle then the front (steering!) wheels are levered upwards
> with a corresponding reduction in vehicle control.
>
> Doing a wheelie down the highway while pulling a trailer will attract LOTS
> of unwelcome attention! <G>
>
>>This page http://www.etrailer.com/faq/fifthwheelfaq.asp discusses using
>>a slider arrangement to move the king pin for maneuverability. It doesn'
>>t discuss the optimum position for towing.

>
>
> The sliding hitch mount is intended to provide adequate clearance, during
> tight turns, between the rear of the cab and the front of the trailer when a
> short (6' or less bed) wheelbase truck is used as a tow vehicle.
>
>
>>Instructions that came with a hitch say to mount 0 to 6 inches ahead of
>>the axle, but provides no further information.
>>
>>--
>>|||||||||||||||| Nehmo Sergheyev ||||||||||||||||
>>

>
>
>

I would think that the weight of the engine would be one of the
considering factors for hitch location. Such as the Ram hitch is over
the axle, but my 94 GMC with a 350 gas engine is 3" forward. Both trucks
are almost the same length and wheel base.
The Ram clearance is 37" (pin to cab) but the 5th wheel is quite a bit
wider. I do not know what the turn angle is, but it will be far less
than 90deg.
I might consider on installing a slider so I can gain cab clearance of
a couple of inches at 90deg, that would be aproximately 11" plus the
desired clearance. My rig is 96" wide, pin location is aproximately 1"
forward of front cap. I know the Cumins engine is heavy but I dont think
I would consider runnig down the road with the pin slid back.

Any suggestions?

--
BILL P.

2004, 2500 SLT Quad Cab, Dodge Ram,
SLT, SWB, 2WD,
5.9 HO Turbo Diesel, 48RE Auto Trans,
Anti-Spin 3.73 Dif.Rhino Liner,
Husky 16K. Voyager Controller
2005, 27RL Wildcat, DT/PC Wi-Fi.
Dual EU2000i Hondas
Just Me and Dog
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Old 07-20-2005, 23:01   #7 (permalink)
Jimbo
Guest
 
Posts: n/a
Re: 5th Wheel Hich Position?

I towed a 30' fifth wheel with a RAM 2500 with an 8' bed for ten
years. The hitch was positioned so that the king pin was directly
over the rear axle and the handling was great. The trailer weight
was ~8,000 lbs.

--



PcolaPhil


To <Reply> Remove -SPAMNOT-


24 hours in a day ... 24 beers in a case...coincidence?



"Nehmo" <nehmo54@hotmail.com> wrote in message
news:cAvDe.5$8g.3@tornado.rdc-kc.rr.com...
|A fifth-wheel trailer is one that has a hitch that connects to the
| towing vehicle at a point above the rear axle of the towing
vehicle -
| not at a point on the rear of the vehicle as with a pull-behind
trailer.
| For example, this is a 5th wheel:
| http://www.theironworker.com/Fifth%2...%20Trailer.jpg
|
| My question concerns position of the point of attachment, let's
say, the
| position of the king pin. For normal pulling of the trailer, where
is
| the best point to have the king pin? Should it be directly over
the axle
| of the towing vehicle or should it be ahead of the axle? If ahead,
by
| how much? In what ways does handling change if the position of the
king
| pin is changed?
|
| This page http://www.etrailer.com/faq/fifthwheelfaq.asp discusses
using
| a slider arrangement to move the king pin for maneuverability. It
doesn'
| t discuss the optimum position for towing.
|
| Instructions that came with a hitch say to mount 0 to 6 inches
ahead of
| the axle, but provides no further information.
|
| --
||||||||||||||||| Nehmo Sergheyev ||||||||||||||||
|

  Reply With Quote
Old 07-21-2005, 04:01   #8 (permalink)
Roger & Lorraine Martin
Guest
 
Posts: n/a
Re: 5th Wheel Hich Position?

There is a formula which can be used to accurately calculate
the position of the fifth wheel, but you need to have a few
details about the trailer and tow vehicle.

You need to know how much weight is transferred onto the
fifth wheel when laden by the trailer.

You need to know the unladen weight of the towing vehicle
and the unladen weight on each axle. You also need to know
the maximum weight allowed on each axle.

You need to know the wheelbase of the towing vehicle.

Loadbase is the distance from the fifth wheel to the front axle

The formula is

weight transferred onto front axle =

(wheelbase / loadbase)* weight transferred onto the fifth wheel

You can the play around with the "loadbase" number to achieve
the optimum weight distribution onto the front and rear axles.
Ideally you want to have weight transferred onto the front and
rear axles in the same ratio as the manufacturer's maximum gross
weights. eg max weight on steer of 3 tonnes and 6 tonnes on
the rear indicates a 1:2 ratio.

We used extensions of this basic formula to achieve maximum
loading on B Double fuel tankers with 8 compartments with
varying fuel density to ensure we max loaded to legal limts every
load.

If you use pounds then use inches, if you use kilogrammes
use centimetres. Dont mix your avoirdupois with your metrics.


"Nehmo" <nehmo54@hotmail.com> wrote in message
news:cAvDe.5$8g.3@tornado.rdc-kc.rr.com...
> A fifth-wheel trailer is one that has a hitch that connects to the
> towing vehicle at a point above the rear axle of the towing vehicle -
> not at a point on the rear of the vehicle as with a pull-behind trailer.
> For example, this is a 5th wheel:
> http://www.theironworker.com/Fifth%2...%20Trailer.jpg
>
> My question concerns position of the point of attachment, let's say, the
> position of the king pin. For normal pulling of the trailer, where is
> the best point to have the king pin? Should it be directly over the axle
> of the towing vehicle or should it be ahead of the axle? If ahead, by
> how much? In what ways does handling change if the position of the king
> pin is changed?
>
> This page http://www.etrailer.com/faq/fifthwheelfaq.asp discusses using
> a slider arrangement to move the king pin for maneuverability. It doesn'
> t discuss the optimum position for towing.
>
> Instructions that came with a hitch say to mount 0 to 6 inches ahead of
> the axle, but provides no further information.
>
> --
> |||||||||||||||| Nehmo Sergheyev ||||||||||||||||
>



  Reply With Quote
Old 07-21-2005, 16:01   #9 (permalink)
Nehmo
Guest
 
Posts: n/a
Re: 5th Wheel Hich Position?

- Nehmo -
Fifth wheel load = The point load the tongue of the 5th wheel trailer
places on the frame of the towing vehicle while the vehicle and trailer
are attached to each other and at rest.

For the moment, leave aside the best place in terms of carrying fifth
wheel load. Is there any advantage one way or another for position of
the fifth wheel load in terms of steering or maneuverability.

Those with the fifth wheel load placed directly over the rear axle speak
approvingly of that position in terms of maneuverability.


- Roger & Lorraine Martin -
> There is a formula which can be used to accurately calculate
> the position of the fifth wheel, but you need to have a few
> details about the trailer and tow vehicle.
>
> You need to know how much weight is transferred onto the
> fifth wheel when laden by the trailer.
>
> You need to know the unladen weight of the towing vehicle
> and the unladen weight on each axle. You also need to know
> the maximum weight allowed on each axle.
>
> You need to know the wheelbase of the towing vehicle.
>
> Loadbase is the distance from the fifth wheel to the front axle
>
> The formula is
>
> weight transferred onto front axle =
>
> (wheelbase / loadbase)* weight transferred onto the fifth wheel
>
> You can the play around with the "loadbase" number to achieve
> the optimum weight distribution onto the front and rear axles.
> Ideally you want to have weight transferred onto the front and
> rear axles in the same ratio as the manufacturer's maximum gross
> weights. eg max weight on steer of 3 tonnes and 6 tonnes on
> the rear indicates a 1:2 ratio.
>
> We used extensions of this basic formula to achieve maximum
> loading on B Double fuel tankers with 8 compartments with
> varying fuel density to ensure we max loaded to legal limts every
> load.
>
> If you use pounds then use inches, if you use kilogrammes
> use centimetres. Dont mix your avoirdupois with your metrics.


-Nehmo -
> > A fifth-wheel trailer is one that has a hitch that connects to the
> > towing vehicle at a point above the rear axle of the towing

vehicle -
> > not at a point on the rear of the vehicle as with a pull-behind

trailer.
> > For example, this is a 5th wheel:
> > http://www.theironworker.com/Fifth%2...%20Trailer.jpg
> >
> > My question concerns position of the point of attachment, let's say,

the
> > position of the king pin. For normal pulling of the trailer, where

is
> > the best point to have the king pin? Should it be directly over the

axle
> > of the towing vehicle or should it be ahead of the axle? If ahead,

by
> > how much? In what ways does handling change if the position of the

king
> > pin is changed?
> >
> > This page http://www.etrailer.com/faq/fifthwheelfaq.asp discusses

using
> > a slider arrangement to move the king pin for maneuverability. It

doesn'
> > t discuss the optimum position for towing.
> >
> > Instructions that came with a hitch say to mount 0 to 6 inches ahead

of
> > the axle, but provides no further information.


--
|||||||||||||||| Nehmo Sergheyev ||||||||||||||||

  Reply With Quote
Old 07-22-2005, 03:01   #10 (permalink)
TBone
Guest
 
Posts: n/a
Re: 5th Wheel Hich Position?


"Nehmo" <nehmo54@hotmail.com> wrote in message
news:R3SDe.107$8g.48@tornado.rdc-kc.rr.com...
> - Nehmo -
> Fifth wheel load = The point load the tongue of the 5th wheel trailer
> places on the frame of the towing vehicle while the vehicle and trailer
> are attached to each other and at rest.
>
> For the moment, leave aside the best place in terms of carrying fifth
> wheel load. Is there any advantage one way or another for position of
> the fifth wheel load in terms of steering or maneuverability.
>
> Those with the fifth wheel load placed directly over the rear axle speak
> approvingly of that position in terms of maneuverability.
>
>
> - Roger & Lorraine Martin -
> > There is a formula which can be used to accurately calculate
> > the position of the fifth wheel, but you need to have a few
> > details about the trailer and tow vehicle.
> >
> > You need to know how much weight is transferred onto the
> > fifth wheel when laden by the trailer.
> >
> > You need to know the unladen weight of the towing vehicle
> > and the unladen weight on each axle. You also need to know
> > the maximum weight allowed on each axle.
> >
> > You need to know the wheelbase of the towing vehicle.
> >
> > Loadbase is the distance from the fifth wheel to the front axle
> >
> > The formula is
> >
> > weight transferred onto front axle =
> >
> > (wheelbase / loadbase)* weight transferred onto the fifth wheel
> >
> > You can the play around with the "loadbase" number to achieve
> > the optimum weight distribution onto the front and rear axles.
> > Ideally you want to have weight transferred onto the front and
> > rear axles in the same ratio as the manufacturer's maximum gross
> > weights. eg max weight on steer of 3 tonnes and 6 tonnes on
> > the rear indicates a 1:2 ratio.
> >
> > We used extensions of this basic formula to achieve maximum
> > loading on B Double fuel tankers with 8 compartments with
> > varying fuel density to ensure we max loaded to legal limts every
> > load.
> >
> > If you use pounds then use inches, if you use kilogrammes
> > use centimetres. Dont mix your avoirdupois with your metrics.

>
> -Nehmo -
> > > A fifth-wheel trailer is one that has a hitch that connects to the
> > > towing vehicle at a point above the rear axle of the towing

> vehicle -
> > > not at a point on the rear of the vehicle as with a pull-behind

> trailer.
> > > For example, this is a 5th wheel:
> > > http://www.theironworker.com/Fifth%2...%20Trailer.jpg
> > >
> > > My question concerns position of the point of attachment, let's say,

> the
> > > position of the king pin. For normal pulling of the trailer, where

> is
> > > the best point to have the king pin? Should it be directly over the

> axle
> > > of the towing vehicle or should it be ahead of the axle? If ahead,

> by
> > > how much? In what ways does handling change if the position of the

> king
> > > pin is changed?
> > >
> > > This page http://www.etrailer.com/faq/fifthwheelfaq.asp discusses

> using
> > > a slider arrangement to move the king pin for maneuverability. It

> doesn'
> > > t discuss the optimum position for towing.
> > >
> > > Instructions that came with a hitch say to mount 0 to 6 inches ahead

> of
> > > the axle, but provides no further information.

>
> --
> |||||||||||||||| Nehmo Sergheyev ||||||||||||||||
>



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