Log Arch Design Critique

[Jjoness4]

 I am in the process of building a log arch.  The rough design is shown below:

 

My questions are:
(1) The fabricator has some 2" by 4" by 1/4" thick box for the arch itself.  Is that too beefy and will it be too heavy an arch?
(2)  The arch is going to mount on a 21 foot deck over trailer. The trailer has a 4 foot dove tail on the back.  Where along the dovetail should we mount the pivot for the arch.
(3)  What sort of connection points on the top of the arch do I need for the winch cable and chain going down to the log.
(4) Any advice on the pivot design is also needed.  Thinking of using 1/2" plate and a 1 1/4"  pin for this construction.

I have seen some great designs on FF and have looked at some YouTube videos at some in action.   Just wanted to get your expertise before we start welding.  Any suggestions as always are greatly appreciated. 
JJ

[fishfighter]

That tubing will be great to use. Add some plating at the angles. That will help the arch from twisting.

On mine, I bought a tackle bock from Harbor Freight that is rated at 20,000 lbs. Was like $20, on sale. I have mine hanging with a 1/2" chain. For your's, I would have a loop welded on top, then pass a chain thru that to hang a tackle box.

My arch is 6' high. I have it set from the back of the trailer to were when it is down at a 45 drg angle, that cable from the winch hands right at the back of the trailer.

I use 1/4" plating were my arch swivels with 5/8", grade 8 nuts and bolts.

Here is mine.



 

I have some cables ran from the corners, front and back. Really don't need them. I had the cable, why not use it.



 

Once the log is on the deck, I drop the arch down and unhook the winch cable from the tackle block. Then just pull the log the rest of the way on the trailer. My winch is rated at 12,000lbs.



 

Hope this helps.

Oh, I would for sure some cables from the back of the trailer to each corner of the back side, top of the arch. That keeps the arch from over swinging forward when loading a logs and slamming everything down at once.

[fishfighter]

Forgot something else. You will need a way to block the very back of your trailer. The weight of a good size log can bend or even snap loose the trailer hitch. Beware of that. I have a set of screw jacks that work good for me.

[Kbeitz]

Sounds a lot like the tubing that i used...



 

[Jjoness4]

Thanks Fishfighter and Kbeitz for your responses.

Fishfighter
How critical is it that when the arch is at a 45 degree angle that the winch cable is at the rear of the trailer.  Also,  some of the YouTube videos show the arches hooked solid to the winch cable and then a chain down to the log hooked solid at the top of the arch.  They are not using a pulley.  Do you ever use this configuration.  Please forgive my greenness on this.
JJ

[Kbeitz]

I like the cable instead of a chain.
This way I can pull a log that's 30 feet from the arch
and load it with out unhooking anything.
Also with the block on the arch I can drop the cable
and pull the log all the way to the front again without
any unhooking anything. saves time.

[Jjoness4]

I like the cable instead of a chain.
This way I can pull a log that's 30 feet from the arch
and load it with out unhooking anything.
Also with the block on the arch I can drop the cable
and pull the log all the way to the front again without
any unhooking anything. saves time.

Makes sense.  You keep your arch in a fixed supported position so that it doesn't rotate with the pull, correct? 

[fishfighter]

Pulling the log to the trailer will keep the log away from the decking as you lift the log. Myself, I get about 3' of the log on the deck. Then I unhook the block tackle, and use the winch to just pull it aboard.

I guess it all depends on the size winch one has. I'm using a 12 k one. ;D

Another note. Winches have a duty time. That means one has X amount of run time per the load on the winch.

Unloading, I use my backhoe. If you don't have support equipment, a second tackle block, chain off to a tree, then having the cable ran thru it back to a log would be the trick to unload it.

[Kbeitz]

I like the cable instead of a chain.
This way I can pull a log that's 30 feet from the arch
and load it with out unhooking anything.
Also with the block on the arch I can drop the cable
and pull the log all the way to the front again without
any unhooking anything. saves time.

Makes sense.  You keep your arch in a fixed supported position so that it doesn't rotate with the pull, correct?

No... My arch does rotate. I would think that it would have to.
First it picks the log up until it hits the arch. Then the arch
rotates forward up and over the trailer and drops the log onto
the decking. At that point I unhook the cable off the pulley
so the cable can continue to pull the log forward. Chains let
the arch go only so far each way.



 

[Jjoness4]

Thanks guys for your responses.  Fishfighter/Kbeitz do either of you have pictures in your gallery that show the attachment configurations at top of your arch.  The welder guy says he can put anything I want there.  Would two parallel plates with holes for a pin and clevis, a closed stout loop etc etc.  Do I need to put connection points either side of center to allow for pulling logs to one side of the trailer or the other?  I am not an experienced winch rigger so I need help.  Using a 12000 lb winch by the way.  Any help or advice is appreciated.
JJ

[Kbeitz]

I just welded a 1/2" x 3" x 6" steel plate to put a clevis on.



 

[KirkD]

I was thinking a tractor draw bar, the type that goes between the lower 3 point arms not the hitch type would work good welded up there then you could set your clevis offset if you needed. You can get them for 20 or 30$ new. I bet KB has a pile of them ;)

[Kbeitz]

I would check to see if it's hard steel if your thinking of
welding it. Hardened steel does not take to welding very
good. You could always bolt it on.

[KirkD]

Yes slip it and pin it on.

[fishfighter]

I am using a chain due to the fact that the arch is made out of house trailer framing. I have a hole cut in the center that a chain passes thru that the tackle block hangs from. Built it out of what I had on hand. Going with box tubing, I would of did what K did. If you box the angles with some 1/4" plating each side, I would add some off sets like K has. One would just move the tackle box to the outside to load logs to the side.

[Jjoness4]

I was thinking a tractor draw bar, the type that goes between the lower 3 point arms not the hitch type would work good welded up there then you could set your clevis offset if you needed. You can get them for 20 or 30$ new. I bet KB has a pile of them ;)

I have an old "swinging drawbar" that I don't use.  I may incorporate it in to the design.  Good idea!!.  I won't weld it just provide two brackets and pin it like you would on lift arms on tractor.  I will definitely put holes in the diagonal braces to mount a clevis both sides

I am using a chain due to the fact that the arch is made out of house trailer framing. I have a hole cut in the center that a chain passes thru that the tackle block hangs from. Built it out of what I had on hand. Going with box tubing, I would of did what K did. If you box the angles with some 1/4" plating each side, I would add some off sets like K has. One would just move the tackle box to the outside to load logs to the side.

es of center.  I am taking the trailer to the welder this week.  I will take pictures and post when we finish.  Thanks for all the good advice.

[bags]

In your drawing it looks like you have the arch mounted almost on the end of the trailer. Your arch mount should be a couple feet back from the tail end of the trailer so you get more lift on the log and travel with the winch line. You can see on the other two trailers that the arch is mounted forward .



 

[Jjoness4]

In your drawing it looks like you have the arch mounted almost on the end of the trailer. Your arch mount should be a couple feet back from the tail end of the trailer so you get more lift on the log and travel with the winch line. You can see on the other two trailers that the arch is mounted forward .



 

Thanks.  Yes I modified the design to put the arch connection forward to the intersection of dove tail and main deck.  It will be a much stronger weld point.  You have a good eye!
Jj