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Strewth, not another receiver!
- Thread starter Chris
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nivapilot
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- Apr 6, 2011
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Cheers lads....I did think about a receiver extension from e-bay.
Found this one and it has dimensions on it......result.....item no 180666381507
12" reciever hitch extension......my thought would be to cut it in half, use the larger piece to form the reciever on the towbar, and the smaller end to make the tow hitch.
Found this one and it has dimensions on it......result.....item no 180666381507
12" reciever hitch extension......my thought would be to cut it in half, use the larger piece to form the reciever on the towbar, and the smaller end to make the tow hitch.
What's the minimum length of receiver hitch needed for safety? The one I want to build for my 120 will be welded to a 5mm plate bent or welded and drilled to mount to the 6 OEM holes in the rear cross member. It won't go through the cross member. The mount plate 'may' be a 'U' shaped unit to go under the cross member and have bolts go right through, like an upside-down clamshell design. I think 3" should be ok - but will 4" be better?
Intended use - recovery point primarily with a drop-plate and ball for extremely infrequent towing
Cheers
Intended use - recovery point primarily with a drop-plate and ball for extremely infrequent towing
Cheers
There may one day be a proper off-road trailer of lol 2m and width same as vehicle track. Weight will be about 1500kg all-in.
The other tow option is a small caravan - very unlikely
Most likely tow option is a water bowser for some of the triathlon events that Lothian 4x4 Response support - and that's heavy at about 2.5 metric tons !! Right on my maximum tow weight I think.
The other tow option is a small caravan - very unlikely
Most likely tow option is a water bowser for some of the triathlon events that Lothian 4x4 Response support - and that's heavy at about 2.5 metric tons !! Right on my maximum tow weight I think.
Gary, the length depends on the thickness. The pin is essentially a shear pin. Two sliding sections locked together. The force when pulling in a perfectly straight line are all across the face of the pin and the mating wall of the hole. Obviously any yaw in the tube adds friction (in a good way). The thinner the tube section, the higher the force on the mating faces. If the box is too thin it will tear. But I think that we are talking huge forces here more in line with a snatch recovery using a static rather than dynamic rope.
(as a minimum based on my experience not an engineering calculation) If you had 4mm wall thickness in both the receiver and the attachment and a 12 mm pin with at least an inch of metal past the hole into which the pin would tear, you'd be fine. I make mine thicker than that generally and I also tend to make the attachment from two pieces of 50mm x 25 box. That way it has a third double thickness internal wall to prevent the pin from buckling when in the tube. When I made one for Andrew recently, I also welded a tube insert into the hole where the shackle goes. This means that there is no knife edge shear effect if you follow me.
You can go for a solid attachment ie 50mm bar. But the truth is that the shear point is no different really. I would go with several inches past the pin hole and probably 5mm wall for the box section. (my desc above was a MIN build) So far after some hard recoveries, I have never seen any elongation of any of the holes in any of my receivers. I have some spare 120 towbar clamshell bits if you want to play around with them or indeed have two towbars.
Chris
(as a minimum based on my experience not an engineering calculation) If you had 4mm wall thickness in both the receiver and the attachment and a 12 mm pin with at least an inch of metal past the hole into which the pin would tear, you'd be fine. I make mine thicker than that generally and I also tend to make the attachment from two pieces of 50mm x 25 box. That way it has a third double thickness internal wall to prevent the pin from buckling when in the tube. When I made one for Andrew recently, I also welded a tube insert into the hole where the shackle goes. This means that there is no knife edge shear effect if you follow me.
You can go for a solid attachment ie 50mm bar. But the truth is that the shear point is no different really. I would go with several inches past the pin hole and probably 5mm wall for the box section. (my desc above was a MIN build) So far after some hard recoveries, I have never seen any elongation of any of the holes in any of my receivers. I have some spare 120 towbar clamshell bits if you want to play around with them or indeed have two towbars.
Chris
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Thanks Chris. The only real bit I'm left wondering about now is whether I run the receiver under the rear cross member, welded along it's length to the 'U' bracket, or out the face of the bracket to give (slightly) better departure angle clearance. I suspect, after a chat with Gav, that it should go under the 'U' bracket. I'll fire up Google Sketchup on the weekend for a play.
I've still got my clamshell bits I took off, so I'm good for that, thanks!
Cheers
I've still got my clamshell bits I took off, so I'm good for that, thanks!
Cheers
Or cut a square hole and go through the steel plate so that it can be fully welded both sides with webs too. If that's possible. The hole doesn't have to be neat, it's something to weld into. Drilled holes joined up with an angle grinder or simply bashed up with a hammer works fine.
Chris
Chris
