Receiver Hitch on back of Trailer frame

[bobhenry]

Actually about 30 or so do allow what they refer to as triple towing (3 vehicles , tow vehicle and 2 trailers) in some manner or another.

Washington oregon and most of the eastern atlantic states DO NOT.

Looks like to be legal in Indiana I need to install a break away switch (but yet they do not mention having brakes go figure )

If you want to drive yourself crazy try figuring this mess out.

http://www.towingworld.com/articles/TowingLaws.htm

For the footnotes definition click on "footnote" at the bottom of the chart

[ssrjim]

Indiana is the only state I am aware of that allows someone to tow 2 trailers, even when both are bumper pull trailers.

There was a double trailer in Parker last December.

[Cliffmeister2000]

Indiana is the only state I am aware of that allows someone to tow 2 trailers, even when both are bumper pull trailers.

There was a double trailer in Parker last December.

Arizona requires the first trailer to be a 5th wheel, as does California.

[dh]

Never could see thier thinking behind that law anyway. I saw a guy towing two fithwheels, the second on a dolly (Professional trailer mover) I would think in theory, the dolly would count as a third trailer even though it was little more than a tongue, axle and a 5th wheel hitch. I've seen the big riggs tripple trailer in Colorado, anybody know the law up there?

[Hillmann]

Just want to respond to Steve_Cox who said that a 5/16 bolt has a tinsel strength of 120,000 lbs, but tinsel strength refers to the material being a full square inch so a 5/16 bolt can only hold 2187lbs when being stretched and 1312 lbs when being sheared (those are the breaking points not what they can safely hold)

Here is the math

A 5/16 bolt has a diameter of .270 after the threads are cut.
That means the radius is .135.

To get the area use Pi X R squared.
Which gives you .018225.

You would then multiply that by the tinsel strength, which is 120,000lbs.

Then you end up with the strength of the bolt, 2187lbs
and if you want shear strength you would multiply the strength by 60% giving you 1312lbs.



I just felt it should be pointed out cause if you are using a bolt that you think is 100 times stronger than it really is it could get you in trouble. Although even one single 5/16 bolt is strong enough to carry the weight of an entire tear so no need to go way over board either.

[Aaron Coffee]

Have thought about putting a receiver on #1 so I could pull both in parades.

[kennyrayandersen]

Just want to respond to Steve_Cox who said that a 5/16 bolt has a tinsel strength of 120,000 lbs, but tinsel strength refers to the material being a full square inch so a 5/16 bolt can only hold 2187lbs when being stretched and 1312 lbs when being sheared (those are the breaking points not what they can safely hold)

Here is the math

A 5/16 bolt has a diameter of .270 after the threads are cut.
That means the radius is .135.

To get the area use Pi X R squared.
Which gives you .018225.

You would then multiply that by the tinsel strength, which is 120,000lbs.

Then you end up with the strength of the bolt, 2187lbs
and if you want shear strength you would multiply the strength by 60% giving you 1312lbs.



I just felt it should be pointed out cause if you are using a bolt that you think is 100 times stronger than it really is it could get you in trouble. Although even one single 5/16 bolt is strong enough to carry the weight of an entire tear so no need to go way over board either.

I'm not sure on the Dia of the bolt since I don't have the spec, but using your numbers:

Stress = P/A

P allowable = Stress * A = Stress *pi*d^2/4

Stress allowable = 120,000

P allowable = (120,000)((pi).270^2)/4 = 6871 Lb

The associated shear allowables are usually published for high-strength bolts, but your .6 factor seems to be pretty close to the aircraft-grade bolts that I usually use.

I thought that load seemed a little low for a 5/16 fastener, but most of the bolts we use are 160Ksi tension, 95Ksi shear. It looks like you left off pi! Still, even at 120Ksi, that's still a pretty strong bolt and like you said -- tears don't weigh that much!