I have learned a little about Slider hitches and  Extended Pin Boxes and would like to share my findings.

There seems to be a lot of questions regarding Slider Hitches and Extended Pin Boxes on 5th Wheels and if both are really needed.

The King Pin on a 5th wheel is much like the ball on a standard hitch, except it is mounted on the trailer rather than the tow vehicle and is upside down.  It is attached to the 5th wheel by a 'Pin Box'.  Pin boxes are made of very heavy gauge metal and some are now adjustable to accommodate the various heights of tow vehicles.

With the increase in popularity of short bed trucks, there has been a need to keep the 5th wheel further from the cab of the tow vehicle.  The Extended Pin Box will help.  The standard (non-extended) pin box will place the king pin flush or slightly behind the front most portion of the 5th wheel.  The Extended Pin can move the King Pin 6-12" ahead of the front most portion of the 5th wheel.  This increases the turning capabilities of the 5th wheel in respect to the angle of the truck.  But it doesnt eliminate the possibility of contact.

The only way to assure clearance between the truck cab and 5th wheel is a slider hitch.  When in the tow position, the slider hitch is designed to place the king pin weight over or slightly ahead of the rear axle.  This is the recommended and desirable location for 5th wheel towing.  With the short bed trucks and the pin in this position, there is insufficient distance when turning sharply between the tow vehicle cab and the front of the 5th wheel resulting in contact causing damage to either or both.

Slider hitches come in two styles of operation: manual and automatic.  The manual are least expensive.  They require a lever to be moved to release the slide mechanism when changing from tow to maneuver or maneuver to tow.  This must be done while the vehicle is stopped.  Usually when entering driveways for filling stations it is not a problem.  The problem is most likely to occur when the tow vehicle is backing into a campsite space or other tight maneuvering.

The automatic slider hitches will adjust the distance from the king pin to the cab as the angle between the tow vehicle and trailer is reduced (assuming the angle when towing straight is 180 degrees) and automatically re-adjust to the normal towing position.  This process happens continuously with the driver giving any thought to the action.

Both style hitches will usually allow for the tow vehicle and trailer to reach an angle of 90 degrees (although not recommended due to stress on the 5th wheel tires, axles and bearings).

The manual models like Reese(R) will cost about $650.00.  The automatic slider like SuperGlide(R) may run $2300.00.  These are the hitch costs and do not include installation fees.

Hitching up with the Reese(R)
If you look at the shape of the pin it becomes apparent that the jaws must wrap around the pin, above the bottom collar and below the upper collar.  This is best accomplished by sliding the pin into the jaws with the jaws at the right elevation - which is accomplished by the plates 'kissing' during hitching.

The 3 key points with the 14/15/16 and 20K Reese is:
1 - Release handle 'IN' and lock/hasp open
2 - Pin plate approx 1/2" lower than hitch plate
3 - Release handle extends fully while hitching and snaps back to the lock position (hasp lockable).

It seems the most common problem with hitching up with a Reese(R) is the trailer/pinbox being too high relative to the plate on the Reese hitch.

HitchProcess001.jpg

The pin extends approx 4" below the plate on the pinbox.  The reason for this is the hitch jaws are also recessed in the hitch.  This means that proper elevation is relative to the plate on the pinbox and the plate on the hitch.  The plate on the pinbox should be approx 1/2" lower than the hitch plate when hooking up properly.

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Standard and slider hitches:

Reese Hitch w/slider
http://www.reeseprod.com
http://www.hitch-web.com
http://www.reesehitch.com

B&W/Companion hitch no slider
http://turnoverball.com/companion/

Valley Industries
http://www.valleyindustries.com/fifth_wheel_hitches.html
http://www.valleyindustries.com/new_products.html
http://www.valleyorders.com/public/applookup.html << with power roller base

Husky Hitch w/slider
http://www.bobstravelcenter.com/catalog/husky_ez_roller_16_000_lb__5th_wheel_hitch_1121881.htm

Hijacker
http://www.hijacker.com/

RBW/Li'l Rocker
No website - just search for dealers

Hidden Hitch
http://www.hiddenhitch.com/Home/

Pull-Rite
http://www.pullrite.com/

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Auto-slider hitches:
SuperGlide
http://www.pull-rite.com or http://www.pullrite.com
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Just a quick brief description of what I know about the SuperGlide:

The king pin plate requires a small modification that incorporates a 'rudder' like piece sitting behind the kingpin.  This is stationary in relationship to the kingpin.  The rudder provides the hitch feedback as to the relative position to the hitch which is stationary in the truck.  As the truck and trailer angle changes, this causes the rudder to push a cam operated mechanism (like a worm gear) to move the hitch forward or backwards - whichever is required.

This prohibits the 5th wheel from being used on a standard hitch - I understand this plate w/rudder can be removed in less than 1 minute - kingpin is std to both.

You can send away for a free video from Pull-Rite that may help explain more.

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Air Hitch:
http://www.advancedairhitch.com/
Craig Keplenski - President
Uses Reese 22K head
Has slide eliminator - 2 plates with multiple holes - moves king pin behind axle

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TrailAir air ride Pin box:
http://www.trailair.com/pinbox.asp

Email Bruce  : bruce.wittmeier@cox.net

Email Carolyn: carolyn.wittmeier@cox.net