5th Wheel Position And Backing

So.. quick question. Does the positioning of the 5th wheel affect turning radius and how the trailer backs?

So.. quick question. Does the positioning of the 5th wheel affect turning radius and how the trailer backs?

A little bit, although in the vaaaaaast majority of situations you'll never move your fifth wheel. Since the vehicles are articulated any shift in position of your linkage point would affect your backing.

A rule of thumb... good place to start is the hole for the kingpin should be centered between the drive axles. Any further back will take too much weight off the steer axle and create a very bouncy ride quality. Minimum of 11,000lbs on the steer axle with full tanks and a loaded trailer. Balance.

So.. quick question. Does the positioning of the 5th wheel affect turning radius and how the trailer backs?

Not much on turning radius or backing, mostly moving the kingpin is for balancing the weight by axle. Most people run it a couple holes back as 2 back seems to be the most aerodynamic putting less space between the tractor and trailer thereby reducing wind drag. It can be moved forward or backward if needed if a load won't weigh legal after moving the trailer axle to a legal place. It can move weight off or on steer tire axle/drive axle. I have never had to move the kingpin in 2 years though. It should be a rare event if you need to.

Mikey suggests:

Most people run it a couple holes back as 2 back seems to be the most aerodynamic putting less space between the tractor and trailer thereby reducing wind drag.

Yes, but ....

When students are taking their CDL exam, they must state that there needs to be sufficient clearance between the landing gear and the back of the tractor so sharp turns can be made.

Moving the fifth wheel too far forward for that aerodynamic saving may cause damage between the landing gear and the mud flap bar in a sharp turn maneuver. After they get their CDL, they can do whatever they want.

Mikey suggests:

Most people run it a couple holes back as 2 back seems to be the most aerodynamic putting less space between the tractor and trailer thereby reducing wind drag.

Yes, but ....

When students are taking their CDL exam, they must state that there needs to be sufficient clearance between the landing gear and the back of the tractor so sharp turns can be made.

Moving the fifth wheel too far forward for that aerodynamic saving may cause damage between the landing gear and the mud flap bar in a sharp turn maneuver. After they get their CDL, they can do whatever they want.

Yep, they can put it all the way back if they want or all the way forward if they so chose. I recommend they place it wherever you think is best.

If their company truck has the option to move it.

A few companies I've been with have had it bolted in a standard location, so no adjustments were possible.