Which direction parking jack.

[Breytie]

Doing the rough layout of the chassis, a few things are threatening to cause analyses paralysis.

Firstly - the positioning of parking jacks.
What is better, pointing in from the sides, at an angle from the corner or forward from the back?
Moving the last interior cross member back a bit should form the 3rd mounting point for the jacks. For the side facing version, 2 longerons of 2x2 tubing should do the trick.

And then, what is the best spot to attach the A-frame to the chassis? Ending on a cross member, before or beyond it?

I need to get it all ready for welding by Wednesday to make my new timetable for first camp in December.

[Dale M.]

My preferred placement for jacks is at a 45 degree angle to frame members (at corner), this braces rear of frame/trailer is both directions....

Dale

[angib]

And then, what is the best spot to attach the A-frame to the chassis? Ending on a cross member, before or beyond it?

There is no structural reason to end the A-frame at a cross-member, though some people do seem to think it looks 'right'.

The biggest overlap of the A-frame and main frame reduces the load on the A-frame welds (though it also shortens the exposed A-frame a bit).

I think it is best to put the end of the A-frame away from a cross-member since that means there is better access to make the weld properly.

[KCStudly]

I concur with both replies. +1 +1.

[Breytie]

Thanks people - that one is now SORTED!

Jack at an angle like the one on the left in the pic.
A-Frame as long as possible, cross under first cross member to terminate on the side rail. Longitudinal welds only at front frame member and first cross member, full welds the end on the side rail.

(edited to apply corrections)

[angib]

A-Frame as long as possible, cross over first cross member to terminate on the side rail. 4 full welds at each crossing point.

Yeah, lots of people thinks lots of weld is good, but it isn't - just enough weld is the best amount, not too much, as all that does is induce stresses that can cause cracking in time.

Where the A-frame crosses the front cross-member, the Australians (who have lots of washboard dirt roads that are about as bad as roads can get for trailers) say that the joint should not be welded at all and just left in metal-to-metal contact. I think a more realistic plan is to make only the longitudinal welds along the A-frame and not the transverse ones across the A-frame tubes. Those transverse ones are just crack generators after a few years.

I found an old illustration of this, looking up at the blue main frame and red A-frame (so the coupler is off to the right). The green welds are the ones that do the good.

[KCStudly]

Actually, you only want to weld along the long axis of the tongue where it crosses the front xmbr (unlike me ). Flexing between the relatively flexible tongue and the relatively rigid main frame can create cracking issues with welds running across wise. Better to leave the front and rear of the front xmbr unwelded; just weld along the sides of the tongue members where they cross the front xmbr.

I see Angib beat me to it.

[Breytie]

Making only longitudinal welds makes sense! Weld can (do?) cause a lot of stress in the steel and providing a full "tear along this line" may not be the best idea. The changes were applied to the solution. I will talk to the welder to keep that in mind.

Thanks again