Towbar Incident Report

[stumps]

I wonder what changed between 1972 and 1994.

Possibly the towbars? MWO's?

Why would they have ommited the speed limit in the later TM?

The '84 manual says the maximum tow speed is specified in the '10 for the towing vehicle.

-Chuck

 

[73m819]

Does your insurance cover you to tow?

More importantly, have you gotten it patched up yet? How is that old girl doing?

I can tow for pleasure , not for hirer
I just got the front U-bolts, waiting for the rain to quit, then I can put it on rubber so I can jack up the motor to replace the front cover/motor mount
This will be a slow repair due to monetary restraints

 

[mudguppy]

The '84 manual says the maximum tow speed is specified in the '10 for the towing vehicle. ...

that's what i read, too.


and the -10 manual says............<drumroll>...................................

 

[doghead]

I'd still suggest that the 84 TM is superseded by the 1994 TM, unless there is a newer version than that, that's the one I would base my use on.

 

[doghead]

Angus, do you have towbar TM info for the new bars you sell?

 

[Tow4]

Having done a lot of destructive testing on large bolts, pins, and other hardware I would say it's more likely that the saftly pin failed and allowed the 1 inch pin to come out.

The Towbar manual that was posted (4910_496_10_towbar) did not mention safety chains. What we have learned here is proper rigging and safety chain use prevented a mishap.

The OP has a lot of experience and it paid off. Thanks for posting.

 

[73m819]

my tm-260-10 said nothing about speed, ect, with tow baring, refered to fm-20-22 (1990 is on mine) vehicle recovery operations, it says very little about flat towing. so ???????????

 

[3dAngus]

AngusT, do you have towbar TM info for the new bars you sell?

Yes, I posted the original .pdf file here back in Sept. I believe, for all to see and download. (If you mean the MRAP towbars. )

I guess the single most important thing I wanted to get across here is maintenance of these pins. The only way to maintain them is to change them out after use. I can tell you from my experience in towing a trailer in La. to Ft. Polk, I would change out the pins and discard them after a single tow. The up/down motion of the roads and bridges, whether rural or interstate is unlike anything I have experienced in this country. And I have driven from coast to coast. And while I may use the same pins for a lifetime in Miss. Ala. or Ga. I would not hesitate after that one trip to Ft. Polk. The bumper action will lift a truck up and down and this stress in felt thousands of times in a single trip. And while some in the state can testify they have NEVER had any trouble, I would stick to my maintenance using my own common sense.

Pins need maintenance. They suffer a great deal of stress. It is not limited to stop and go. So if on other state roads, I may do my maintenance based on visual inspection for burrs, there are instances where once you bouce your head off the roof a number of times, these things should be taken into consideration. Nothing last forever.

BTW, I have a 83000 pound capacity towbar that is bent. These bugars are tough, but anything can take a hit.

 

[3dAngus]

Having done a lot of destructive testing on large bolts, pins, and other hardware I would say it's more likely that the saftly pin failed and allowed the 1 inch pin to come out.

The Towbar manual that was posted (4910_496_10_towbar) did not mention safety chains. What we have learned here is proper rigging and safety chain use prevented a mishap.

The OP has a lot of experience and it paid off. Thanks for posting.

TOW4, you do realize of course most destruct testing is done on new material, not well used material that has already been through a great deal of stress.

You have to do a reverse engineering of a broken device to determine cause. i

I am thinking what we have here based on the OP's comments is this was a well used pin. So where every well used pin would suffer different levels of fatigue, I am not sure we can say conclusively the pin did not shear.

I do agree with you the simplest answer is usually the best.

Anyway, I've said enough on the matter. Just be careful out there guys.

Over and out.

 

[docfarmall]

If you saw these chains you would no why . They are heavy

 

[Tow4]

TOW4, you do realize of course most destruct testing is done on new material, not well used material that has already been through a great deal of stress.

You have to do a reverse engineering of a broken device to determine cause. i

I am thinking what we have here based on the OP's comments is this was a well used pin. So where every well used pin would suffer different levels of fatigue, I am not sure we can say conclusively the pin did not shear.

I do agree with you the simplest answer is usually the best.

Anyway, I've said enough on the matter. Just be careful out there guys.

Over and out.

I'm very familiar with failure analysis 3dAngus. The whole point of engineering is to make something that will just barely not fail.

And yes, we tested new hardware. You probably know the government also requires accelerated wear testing and we had machines that we used for that purpose. I've tested many beat up shackles, tie down straps, etcetera. They have to pass the load test the same as a new part.

All of this is beside the point since we will probably never know what happened. The point I was making is the OP performed the proper rigging and took appropriate safety precautions and that avoided a bad situation. We should learn for his experience.

Cheers

 

[3dAngus]

Thanks tow4. Completely agree. He did good, under the circumstances.

 

[Recovry4x4]

So, anyone selling off their "rated at the speed of desert rat" towbars? Unlike Gimpy, I only have 3 towbars.

Doghead, none of that "use the classified" crap, this is a public service announcement dealing with slowbars.

 

[gimpyrobb]

Hey gang, I figured I'd post it here rather than answer 15 PMs, I am sorry to say, I don't have any tow bar pins. I had an extra and sent it to Ferro so he would have a spare. All the pins I have left are for tow bars I am trying to build. Sorry to let you down.

 

[Speddmon]

I wish i had a towbar

 

[gimpyrobb]

I wish i had a towbar

Did I miss something?

 

[Speddmon]

no, I just wanted to get in on all of this arguing back and forth about how fast you can or should tow a vehicle.

I see RV's going down the highway all the time doing 65 and 70 pulling their little SUV's and foreign cars behind them on towbars that aren't build nearly as well as the military ones. The ones they use don't look like they'll safely tow 200 pounds let alone 2000.

 

[SCSG-G4]

Tom,
Maybe maddog still has some of the heavy towbars. Only problems with them is they use 1.5 inch pins, and you need soldier A, B, and C to hook them up and lift the lunette while soldier D backs up the towing vehicle.

 

[Speddmon]

Mike,

I have one thanks to the towbar b*tch...Gimpy (we did a little horse trading a while back). I was just screwing around. I hope to never have to use it, but I got it just in case.

 

[swbradley1]

After going through this entire thread I have come to one conclusion, I'm glad nothing happened to a; my friend, b; Angie, c; anyone else.

sw