A bit more specific information is needed but I will try.
Tractor is Kenworth T2000 with sleeper:
Wheel base 222"
Rear Axle spacing 52"
Kingpin location +10" (10" rearward from center of rear axles)
Front wheel cut 54°
Tractor-only turning radius 359.2" (30')
Trailer is 53'x102" with 41' kingpin (distance from center of rear axles to kingpin is at 41')
In theory the tractor, remaining perpendicular to the trailer can pivot the trailer about the center of the rear axles (making the turning radius for the trailer equal to the kingpin dimension plus half the width of the tractor or 45'.)
In practice the two together would be better limited to the keeping the tractor at an angle to the trailer where the tractor rear axle group and trailer axle group are creating two points of the circle, and the tractor front wheel cut is tangent to this while at the 54° maximum. This results in a 984" (82') turning radius.
We usually specify a radius of 1143.1" (95.3') when laying out a parking area, gives a bit more room...this is from a three point circle of the tractor front axle, tractor rear axle group, and trailer axle group.
This is fairly absurd. There is no mention of what kind of vehicles we are talking about.
We don't even know if it is a semi-trailer or not. The length of a semi-trailer is not really relavant to turnig radius, as it will generally go as sharp as the tow vehicle.
Many hitch type trailers also turn as sharp as the tow vehicle.
But again, we don't even know what type of tow vehicle it is.
The use of the term "King Pin" with respect to the tractor and trailer specs given is a dead give away that we are dealing with a tractor/semi trailer rig here.
Fabrico - draw a picture of a semi going round a corner with no scrub. get back to us with the geometrical relationship between the 3 axles of importance, assuming that the kingpin is over the middle axle.
Cheers
Greg Locock
Please see FAQ731-376 for tips on how to make the best use of Eng-Tips.
RMW
Here is the entire question from ashesc:
"ashesc (Aeronautics)
What is the turning radius for a 54 foot long trailier and truck"?
That's it, period. Please point out where ashesc ever mentioned "King Pin".
Greg,
Please excuse my ignorance for not knowing scrub was part of the question (even though trailers scrub all the time) or that ashesc was talking about a 3 axle truck-tractor.
FWIW, a 3 axle tractor will not out-turn most trailers. At 45 feet combined length, that's a pretty short semi-trailer. Assuming nothing more than the tow vehicle being something larger than a Volkswagon. A 20-25 foot semi-trailer will easily turn as sharp as any normal tow vehicle.
