recovery points

[Ben-e-boy]

hi all.

My ute has no decent recovery points on the th rear. So I have decided to fab up my own

This morning I took off my tow bar as I am using the centre mounting holes.
I used a piece of 100x10 flat bar for the base which was cut at 130mm long. For the eye I used a piece of 100x12 flat bar cut at 60mm long. In this I drilled a 30mm hole for the eye.

I heavilly shamphered the end of the eye piece before welding it to the base plate. To ensure full weld penetration I did a "3 row fillet weld" (first time I have tried a 3 row fillet).

Once the eye is attached to the base, I cut 4 gussetts and welded them to the base and eye

Tomorrow I'll clean up the spatter, give it a lick of paint and install. hopefully I wont need to test it anytime soon

Cheers
Benny

[Bigrig]

Top effort old mate - certainly looks string enough .... well done!!

[Silver]

I don't have a trade or engineering background, but it looks well made to me, Benny.

Has that cross member stood up to a recovery before?

There's that Kiwi site that tested a Pintle hitch - stood up to lots of tonnes once the bolt dia was increased. I put the info on this forum before under one of the Recovery Point threads.

[Ben-e-boy]

I don't have a trade or engineering background, but it looks well made to me, Benny.

Has that cross member stood up to a recovery before?

There's that Kiwi site that tested a Pintle hitch - stood up to lots of tonnes once the bolt dia was increased. I put the info on this forum before under one of the Recovery Point threads.

I have been thinking about the strength of the crossmember.I think I need to fiqure out a way to strengthen it.
I've been told by a boilermaker that roughy an inch of weld = a tonnne of weight. there is over 20 inches of weld on that recovery point. ATM the chassis is the weak point and I dont want to bend that. I'm thinking that I should gussett the chassis and make the mounting bolts the week point

[YNOT]

Making the bolts the weak point has the potential to turn the recovery point into a missile.

Tony

[Ben-e-boy]

Making the bolts the weak point has the potential to turn the recovery point into a missile.

Tony
I agree with that I thought about it just after posting I may have to redesign

[the evil twin]

Making the bolts the weak point has the potential to turn the recovery point into a missile.

Tony


I agree with that I thought about it just after posting I may have to redesign

You guys are correct in that any 'chain' must have a weakest link so something will fail before anything else but I reckon the bolts or hitch are the least of the issues.

As far as "what will fail first" if you design the Bolts to be the weakest point then, Yes, metal will fly... BUT... if you use say M12 10.9 Hi tensile bolts the force to 'fail' the fastener is around 80 kN.

You will need a phenomonally large Snatch Strap (EG one from the Mines that they use on the Haulpaks) or a chain of about 20 Tonnes WLL to hit 80 kN. For example a Grade 70 3/8" link Drag Chain has a rating of 3 Tonnes WLL and a Breaking Strain of approx 20 kN and a lot of the Chinnee Drag Chains available in the 4X world will be a sight less than Grade 70.

In other words the Chain, Wire Rope or Strap used by any sane person in a 4WD recovery will break at about 1/10th to 1/4 the force required to take out an M12 Hi Tensile Bolt.

Or, conversely, looking at the Construction of that hitch I'd guess you will need about a M25 Bolt before the Hitch will fail before the bolt and you still end up with metal flying.

[GUte]

Make the snatch strap the weakest link, just be sure to use a dampener

[patch697]

You'll pull a house down with that mate especially on a Patrol...lol...... Love your work.

I tend to agree with ET with the bolts but as Tony said it would make one hell of a missile....

How would you go plating behind your mounting point & using The bolts at ET recommended as well???

Your thought Tony?

[Ben-e-boy]

You'll pull a house down with that mate especially on a Patrol...lol...... Love your work.

I tend to agree with ET with the bolts but as Tony said it would make one hell of a missile....

How would you go plating behind your mounting point & using The bolts at ET recommended as well???

Your thought Tony?

I could up the tensile strength of the bolts. I was also thinking about the 2 pieces of flat bar that run from a crossmember to the rear of the chassis as shown in the photo, I could add 2 more either side of the hitch to stop the chassis bending

[Ben-e-boy]

Make the snatch strap the weakest link, just be sure to use a dampener

That would be the ultimate goal I think

[Dhuck]

Why dont you just buy a haymen reese ( or make something better ) and a recovery hitch. Hard work done.

[Ben-e-boy]

Why dont you just buy a haymen reese ( or make something better ) and a recovery hitch. Hard work done.

I just had an urge to fabricate something and thats what I came up with

[Bigrig]

I just had an urge to fabricate something and thats what I came up with

Bloody good to ... as you said, some gussetting/plating on the chassis mount should make it plenty strong enough ... appreciate something 'can' always break, but if it's over engineered on yours, that's going to mean it'll happen to a lot of manufacturer built gear before it ever does to yours ...

[Pete's GU3]

you should be able to pull tree stumps with that mate.....looks ballsy.....................!!!

[portal pat]

Knocked this up for mine.
http://i961.photobucket.com/albums/ae100/slowzuki/2011_0723trekka20001.jpg
http://i961.photobucket.com/albums/ae100/slowzuki/2011_0723trekka20002.jpg
Makes for a simple, fast hookup.

[patch697]

Knocked this up for mine.
http://i961.photobucket.com/albums/ae100/slowzuki/2011_0723trekka20001.jpg
http://i961.photobucket.com/albums/ae100/slowzuki/2011_0723trekka20002.jpg
Makes for a simple, fast hookup.

Love your work Pat.......... How simple is that & a cheaper alternative to others out there.........

Cheers for the post.

[TimE]

Knocked this up for mine.
http://i961.photobucket.com/albums/ae100/slowzuki/2011_0723trekka20001.jpg
http://i961.photobucket.com/albums/ae100/slowzuki/2011_0723trekka20002.jpg
Makes for a simple, fast hookup.

A mate of mine did some interesting "snatch" tests while doing his engineering degree.

You may be interested in the following figures resulting from "snatching" experiments. Shock load of 8 tonne about 14 km/hr, around 13 tonne at about 21 km/hr. Exceeded the SWL of 2x rating at about 27 km/hr.

Need to ask yourself if your welds could handle these sort of loads.

[Dhuck]

Would be as solid as if the bar goes all the way through (which I am guessing is)

[portal pat]

Yes, it does. The weld is only to stop the bar from falling out. We are relying on shear strength with this unit.

[Finly Owner]

Knocked this up for mine.
http://i961.photobucket.com/albums/ae100/slowzuki/2011_0723trekka20001.jpg
http://i961.photobucket.com/albums/ae100/slowzuki/2011_0723trekka20002.jpg
Makes for a simple, fast hookup.
Very interesting, I have looked closely at the pics, and am wondering what sort of steel is the pin? Rated? Billet? Mild?

I realise the strongest points are the closest to the "block", so therefore should snatch most light to medium bogs. And if this "pin" failed it would become airbourne, but, I suspect more likely to go either outwards ur upwards, not towards the vehicle being snatched, unlike a bow shackle on the end of a snatch strap.


Tim

[portal pat]

The pin that secures the attachment to the SHS is the Hayman Reese pin. The round bar that the strap wraps around is 20mm. stock.