Tuesday, May 09, 2006 at 21:33
You may be interested in a couple of
test results on some recovery hooks that were carried out last week. A
test mounting was made up and several brands of hooks bolted down to simulate being mounted on a vehicle. They were taken to a commercial testing rig and pulled to destruction. We did this as we want all recovery hooks used by our club members to fail by unwinding and not snapping. If a hook unwinds and lets the strap go at least you only have a strap flying through the air. If the hook breaks then you will get a chunk of metal flying through the air - not good ! We demand forged not cast hooks but it is often hard to tell how a hook is manufactured.
A hook from SuperCheap (painted black) with 4,500 kg stamped on the side reached its limit ok but when it did fail it snapped and metal flew !!
A Black Rat hook (also painted black) with 10,000 lb stamped on it also reached its rated value before failure but then it also snapped and metal flew again.
The other brands we tested unwound (or straightened out) and released the rope.
Lucky these
test rigs use a safety cage.
We also tested (straight pull) a couple of pintal hooks to
WELL over 10,000 lb's - no problems. I will let interested people know the exact results if they want them.
By the way, the tow ball we tested sheared as expected and really flew into the safety cage.
FollowupID:
427303