Trailer tongue question

[KevinP]

I started rebuilding the front of the frame of my trailer last night (my neighbors enjoyed the "light show" from the grinder and welder) and have the main frame back together. The next task is adding the tongue back to it. I originally chose 2"x2"x.125 wall square tubing and was going to make the tongue ~ 32" long. After doing some readin and calculating I found out this was not going to be strong enough if I done a single tongue However, if I done an A-frame tongue it should be more than adequate for a tongue on paper. I'm wondering if I should put aside the tubing and try to locate some 2"x3"x.125 wall thick tubing?

Specs of the trailer are 5'x10' and highballing the weight of 2000lbs loaded.

For those who have built a larger TD what did you use for the tongue?

thanks......Kevin

[Dale M.]

I used single 3x3 inch .120 (1/8 wall) steel tubing...... And it catches the first three frame cross members and is secured with triangle gussets at all contact points.... Forget length but I know its long enough the if I jackknife rig, bumper of truck does not hit front of trailer....

Dale

[eamarquardt]

I'd go for the A frame style as it spreads the load over a greater area, can be welded to more frame members, and is connected closer to the corners of the frame where the frame is stronger. I've heard of single type tongues failing but never an A frame! My frame uses a combination of A Frame and central post and is overbuilt for sure. I wanted the rails on the outside and some support for a deck on the foretriangle. Also bored a hole in the central post and put the tongue jack right through it.



Hope this helps.

Cheers,

Gus

[KevinP]

Thanks for the replies. I was planning on going back to where the second cross beam was (had to replace; twisted from the wreck) and form the A-frame at the hitch.

Gus....could I get a closer photo of where your A-frame intersects please? What hitch did you use? Was looking @ Tractor Supply during lunchand they had hitches for A-frame tongues @ $30 each when they had regular ones for $10.

[wattsworth]

Don't use the 2x2. It's probably not strong enough and may fatigue and crack after a while. Also, most couplers are more than 2" deep so your 2x2 tongue would swim inside the hitch coupler. The vertical dimension of the tongue increases strength in that direction as a cubic of the vertical measurement of the beam.

Your 2x2x.125 square tube is a only third the strength of 2x3x.125 on edge. It's also about a sixth the strength of a 2x4x.125 on edge. (for the engineers out there, this is from comparing the moment of inertia of the beam cross-sections).

A single 2x3 or 2x4 is easily stronger than two 2x2s used in an A-frame in the vertical, load carrying direction. Is either strong enough? For that, do some calculating using angib's page to guide you: http://www.angib.pwp.blueyonder.co.uk/t ... tear84.htm

An A-frame or Y-frame tongue is stronger than a properly sized single beam only in the side direction -- ie if you had the trailer all hitched and pushed horizontally in the middle of the tongue. As far as tongue vertical loads, they are only as strong as putting your two tongue beams side by side. Since most failures happen due to vertical loads (weight on the trailer over bumps, dips, and washboard), a rectangular tube can easily be stonger in the direction that matters -- you'll have to do some calculating to find out.

Nobody wants to see their trailer go flying off the road due to a broken tongue. If you're going down hill at the time it fails, your trailer can really come back to haunt you.

[bobhenry]

I really like the way this one was built that "c" channel will hold what ever is thrown at it !



Pretty sure it's Planovet's frame.

[planovet]

Yep, that's my frame. It's definitely a solid frame. Actually they overbuilt it but what could I do after the fact. They added some things that I didn't request because they thought I needed it. They had never built a trailer dedicated for a teardrop before. All in all it's a great frame and I'm glad how it turned out.

[KevinP]

Don't use the 2x2. It's probably not strong enough and may fatigue and crack after a while. Also, most couplers are more than 2" deep so your 2x2 tongue would swim inside the hitch coupler. The vertical dimension of the tongue increases strength in that direction as a cubic of the vertical measurement of the beam.

Your 2x2x.125 square tube is a only third the strength of 2x3x.125 on edge. It's also about a sixth the strength of a 2x4x.125 on edge. (for the engineers out there, this is from comparing the moment of inertia of the beam cross-sections).

A single 2x3 or 2x4 is easily stronger than two 2x2s used in an A-frame in the vertical, load carrying direction. Is either strong enough? For that, do some calculating using angib's page to guide you: http://www.angib.pwp.blueyonder.co.uk/t ... tear84.htm

An A-frame or Y-frame tongue is stronger than a properly sized single beam only in the side direction -- ie if you had the trailer all hitched and pushed horizontally in the middle of the tongue. As far as tongue vertical loads, they are only as strong as putting your two tongue beams side by side. Since most failures happen due to vertical loads (weight on the trailer over bumps, dips, and washboard), a rectangular tube can easily be stonger in the direction that matters -- you'll have to do some calculating to find out.

Nobody wants to see their trailer go flying off the road due to a broken tongue. If you're going down hill at the time it fails, your trailer can really come back to haunt you.

This is what I've been thinking and calculating since. I actually studies this prior and curretly to see what I should actually use for the tounge. From looking at the chart I will either use the 2"x3" channel in an A-frame or go up to 2.5"x2.5"x.250 wall tubing as a single tongue. Short wee at work and won't be able to order anything til next week....

[wattsworth]

Beam strength in bending doesn't go up very much for having thick-wall tube, but it does get a lot heavier. You might want to use 2x3 or 2x4 instead of the square 2.5x2.5x.25 just to save weight & cost. 3/16" wall makes stick welding easier. 1/8" wall is about the minimum if you are pretty good at stick welding.

[angib]

Your 2x2x.125 square tube is a only third the strength of 2x3x.125 on edge. (for the engineers out there, this is from comparing the moment of inertia of the beam cross-sections).

You're exaggerating the effect - I think you've only remembered half the formula for beam strength. It's not moment of inertia that determines strength but section modulus (that's moment of inertia divided by the maximum distance from the neutral axis - commonly abbreviated to I/y = Z).

So a 2x3x1/8 is 1.8 times as strong as a 2x2x1/8, not three times as strong.

A single 2x3 or 2x4 is easily stronger than two 2x2s used in an A-frame in the vertical, load carrying direction.

A single 2x3 is not quite as strong as two 2x2s. But, yeah, a 4x2 is stronger, by about 40%.

Andrew

[wattsworth]

I should have carried the calculations further in my spreadsheet ... angib is right.

[asianflava]

I used 2x2x1/8 but felt that it wasn't strong enough, I ended up lopping 18in off for a little bit of insurance.

When I moved from TX to ATL, the trailer was loaded more than normal but still within my axle and tire limits. When I hit a rough section of road with bad expansion joints, the tongue broke. I had it towed to a trailer repair place and I wanted 2x3x3/16 installed instead. No one in town had any so they used 2x4x3/16. Way overkill but at least I don't have to worry about it anymore. I also had them put the 18in back when they put the new tongue on.

[eamarquardt]

Just noticed the request for a better picture of my tongue. Here it is. Hope this helps.

Cheers,

Gus