Two Design questions...

[Rezarf <><]

Two questions here and I would love your opinions.



1. I have recently built a rear tire carrier that I love. However, as I look into hooking up a scratch built trailer my pintle hook will not open without hitting my rear tire carrier "bumper.

Do you think that spacing the pintle out with a steel block, or heavy wall tubing and then bolting up the pintel would be safe?I am thinking of 3x4" tubing with 1/4" wall with the sides boxed and bolted up to the crossmember and into the pintle, with seperate bolts.The cross member is barely 3/16" thick. Will the forces increase that much to not consider this as a viable, safe option?Billet steel is another option but hard to find in thick chunks.



2. Frame design. On the m101 can and m416 trailers the A-arm drawbars are both tied into the front shackle hanger mounts. Stregnth is increased in this design because the chasis can be tied into the leading edge of the trailer as well, just like the m416's. However, do you think the losses in strength would outweigh the gain in useable space of connecting the drawbars to the front corners of the trailer. By connecting the drawbars to the corners of the front edge of the trailer I can pick up nearly 1.5' of extra surface area to strap things down onto it. Strong welds are not the issue, either option will be properly TIG welded. What would you do and why?

Clear as mud? thanks for your opinions.

Rezarf <><

 

[big sky trapper]

If I understand you ??? about the pintle .... you are using one of the 4 bolt, bolt on style that would bolt into a slide in type reciver hitch, Or even one of the direct frame bolt on pintle's. ???

If so then I would say yes that is acceptable mounting option. 3x4 or 3x5 both x 1/4 would be plenty strong esp if your are only needing a 3-5 inch extension.
I would make your adapter block as wide as the mounting pad. and weld the bolts heads/nuts to the inside (watch your heat esp with the tig...) then box the sides as needed.

I ve run almost the same thing for many years of some of my rigs and never had a problem. That is assuming we are talking smaller offroad utillity type trailers ect you should be fine.

the trailer ??? Im not understanding quite what your describing so ill defer to some one else......

any one else???

 

[Rezarf <><]

Yep, that is what I am using for a pintle.

Small m416 style trailer.

Thanks for the tips.

 

[Rezarf <><]

Maybe this will stir up some discussion?...

Would this work?

 

[Rezarf <><]

Which would you run? The first or the second?...

The first one has better triangulation of the chasis, at the cost of a useable platform in front of the "box."

 

[PhulesAU]

I'd vote for #2. 1st that corner looks like a great place to get hung-up. 2nd as light as the trailer is going to be "I" wouldn't think there would be loss of needed frame strength.

 

[Grim Reaper]

Since you are scratch building the frame #2. You can notch the frame and pull it in without fully cutting it. Just have to do the math to make the notch at the correct angle to meet up

 

[DaveInDenver]

Heya Drew.

I have two thoughts for you. First is on the second, your trailer. I would say either way could be fine, but my first blush is the second one with gussets would work well.

Now, about that pintle spacer. I would not just space out the pintle with a 4" block and really long bolts. If that was only for the trailer, it would probably be fine, but a pintle (really any tow point) serves us as recovery points. Technically a tow point isn't really a proper recovery point. The most common one is a class III tow point, which is only rated to 5000 or 6000 lbs (I forget which). Anyway, even my little Hilux fully loaded easily blows way past 5300 lbs curb weight, which means in a dynamic recovery that actual force on the recovery point is much higher, easily twice that. We get by because most tow points are built beyond their minimum rating. So you are using 5-ton pintle or something? This rating assumes a surface mounting and you'll probably be using four grade 10.9 14mm bolts (or maybe grade 8 1/2"). By spacing the pintle 4" away from the surface, you have significantly changed the loading on the tow point and bolts, particularly in an off axis recovery.

So I think personally I would do it like a good wheel spacer. Bolt the plate to the rear frame member and then a second set of bolts to the spacer. I would use a solid piece of stock and counter bore four holes to mount to the frame and offset the four counter bored holes for the pintle lower or higher whichever works best. Just my $0.02.

 

[Sgt Grunt]

I extended mine like your drawing #1. The reason I did it that way was so I could jackknife the pull vehicle a little more than 90 degrees to the trailer, so I wanted to keep it narrow up front to avoid contact with my bumper and spare tire. I hope that makes sense... I was going to put a tool box up front, but decided to put the propane bottles instead.

 

[FourbangerYJ]

Which would you run? The first or the second?...

The first one has better triangulation of the chasis, at the cost of a useable platform in front of the "box."

#2 is what I have in mind for mine,when I get around to building it. I plan to add another cross brace between the pintel and your box. Then triagulate (sp) 2 more from the center of the box out to the edge of the new crossmember. |<| kinda like that. IF it makes sense?

#1 would work better if you put the drawbars under the box. That way you can use the area in front of the box for storage.

 

[Rezarf <><]

Thanks for the replies... still wrestling over this one. For the weight of this thing it may be overkill to mull on this too long, but I want to do this only once, and get it right at that.

Drew

 

[ntsqd]

As you increase the length of the spacer you give the trailer more leverage to tear the spacer off the frame. A proportionately larger bolt pattern for the spacer to frame join is highly recommended.

Trailer tongue design No.2 is specifically warned against in M. M. Smith's books (Vol. 1 and Vol. 2) on designing & building trailers. I only have Vol. 2, so it must be in that one. The basic argument against has to do with the Bending Moment that exists at the point where the tongue joins the rest of the frame.

 

[Rezarf <><]

Thanks I appreciate the reply. My space will only be 3" off the crossmember... if I go that route.

Thanks!

Drew

 

[FEF]

As I found out, pulling a trailer on Black Bear, you will likely need to jack-knife.

If you plan to pull on some tough trails, I recommend designing it the tongue such that there's one piece of box iron (maybe 3x3, or 4x4) as the tongue, and it's only as long as 1/2 the width of the tow vehicle.

My small trailer is setup such that there's a 2" receiver in the trailer tongue. On the hiway, I have a 3' section with a ball hitch, and at the trail head, I take the section off, and put on the pintle ring. It pulls like a dream on the road, and I can see it well when backing, because it's longer.

The down side to my configuration is that I can't have a rotating pintle on the truck due to the 2" receiver, and it's a few extra minutes at the trail head. The plus is that both conditions are accounted for. There's no question, it works.

Maybe I should get pictures...

Your trailer looks a bit heaver then mine. It's still possible, but the size of the metal is important. Man, I wish I studied ME, rather then EE, and music.

It always easy on paper.

 

[ntsqd]

The TrailBlazer I posted about being loaned in that thread has it's new frame built such that the tongue telescopes. The "receiver" tube runs from the very front of the rigid tongue part of the frame clear to the rear & sticks out a scosh so that there is a socket on the rear of the trailer too. (Battery cabling was run so that a receiver winch can pull on the trailer from the rear.)

2nd on the pictures, I should do that too.