D shackle nut vibrates off of bolt - video

[Jon]

From the excellent Safety Engineering Network. D shackle without a safety pin - nut vibrates off of bolt. Bolt turns in one direction, nut turns in the other.

0:51 video:

Previously:

wing snaps off plane, whole-plane parachute deploys safely
Lathe safety/stupidity accident video
Combustible wood dust explosion safety video
SAFE-SAW miter saw safety modification

[Ralphxyz]

But the cable had no tension on it so it did not demonstrate a live load.

Ralph

[hemmjo]

Depending on the application, that cable may very well not be under tension at all time. I used to race a small high performance sail boat, Hobie 16, in my younger years. On most points of sail at least one mast shroud sometimes two out of the three would be loose. The wind and tension from the main, or jib sheets took all of the load off of the shrouds. We learned very quickly to tie the shackle pins in place. Fortunately we saw the loose shroud swinging free and were able to reattach it before changing tack.

Safety pins or wires are always necessary.

[Ralphxyz]

re: "Safety pins or wires are always necessary."

Absolutely, I just wonder also how tight the nut was to begin with, there are different factors to every situation.
It is a great video!

Ralph

[Frank S]

The video was made to be an educational tool to demonstrate the need for safety pin/ wires. Had there been tension on the cable the video would have been as exciting as watching paint dry. The ultimate result would have been the same just over a much longer time lapse. Tightening the nut on these type shackles will not help since when the cable is under tension the shackle will distort slightly lessening the torque on the nut. Many shackles are threaded and do not use a nut on the pin those have a taper which the pin torques against but even at that they can and will under the right (wrong) conditions become loose. Most Shackles on sail boats are of the threaded shackle type but will have a hole in the thumb screw type head for a safety wire.

[ranald]

I once lost an expensive anchor when anchored in a very strong current around 3 knots when the tide changed but was lucky enough to be awake at the time and save the vessel. I learnt to tie d shackles then (about 1980). New laws in Oz are addressing trailer d shackles and banning the common d shackle, so many accidents must have occurred when safety chains were not properly fixed to the vehicles. inproper walk around?

[Frank S]

Accidents resulting from a trailer becoming disconnected from the tow vehicle can be summed up in 2 words. Human error. A properly loaded trailer with sufficient tongue weight with a properly latched and secured quality coupling will never come loose under even rough road conditions. Worn or loose hitch balls mounted on a cheesy factory bumper or most of the dealer installed receiver hitches damaged or worn couplings are factors which will lead to failure but these are not the cause. the person who is behind the steering wheel is the ultimate weak link. For not knowing their equipment is faulty, and not conducting a proper connection inspection.

[Mi Tasol]

The person who is behind the steering wheel is the ultimate weak link. For not knowing their equipment is faulty, and not conducting a proper connection inspection.

Or for not having a clue on what they are doing.

Two examples.

I was following a heavy tail dragging two axle caravan that was all over the road and doing only 50km/hr on the open hiway. I did not pass, and nor did anyone else, even when there were passing lanes. Eventually he pulled over just after we reached the next town. As I passed I noticed that the caravan was loaded so that the rear of the car was way above the rear wheels. Obviously there was insufficient weight on the rear wheels which is why he had minimal control.

Twice I have seen the reverse - too much weight on the tow-bar. In the first the car was all over the road approaching me with it's wheels dancing on and off the road.
The second was in a parking lot at a shopping centre. A Ford F-250 with an empty tray and a covered single axle trailer that was depressing the tow bar so hard that the front wheels were almost leaving the ground when there was no-one in the cab. I raced in to buy a cheap camera to get a photo of the "Public servant and proud" of it bumper sticker across the front of the bonnet/hood but it was gone when I came out.

I will not call them complete idiots because they are missing too many brain cells.

[ranald]

Definately, ignorance is no excuse. Maintenance:- I often receive comments on how old my smaller box trailer's (7 by 4) number plate is (about 1972 for memory) but times have seen repairs & replacements as well as the ever important greasing/adjusting bearings. Carrying very green (fresh) manure has resulted in about twenty gal floors: overloading/ rust has required 4 dray bars: 2 carcases from manure, and 3 towball hitches=1 from 1 3/4 inch to 50mm and 1 from the lock-down not looking really reliable even with "r" clip. It doesn't take much to carry around a pair of pliars to tighten the d shackles.Unfortunately I had a few stolen so leave them on trailer safety chains when not in use and keep a couple of spares under the floor. one day when i clean out my shed I may post a pic of a pintle hook that could scare the daylights from viewers. I just wonder what the driver of the truck was thinking at the moment it broke=looked like a flaw in the metal to me but I'm a novice.

Regards, Ranald

[ranald]

Yes, that kind of "power steering" is scarey. What was the driver focussed on: definately not on driving and resolving the distribution issues. The worst I know of is a 1968 Toyota Corolla (very small vehicle like a "Getz" or "Swift" towing a car removal trailer loaded with a full load of heavy hardwood.