Local lad killed by towball

its a tragic thing to have happened and as has been said before it stresses the use for common sence , rated recovery gear and points , i like to winch rather than snatch unless all that is needed is a gentle pull like a tow , also making sure there is nobody in close proximity to whats going on especially inside the car besides the 2 drivers.. i suppose hindsight is a wonderful thing. but things like this happening are going to quickly destroy whatever privilages we have left as offroad enthusiests im sure many will agree.. Just my 2 cents. Dan.

Tas Fire service taught (if feasible) raising the bonnet on the Toyota if the line is out the front and the vehicle is occupied.
cheers

Still no one has mentioned that (generally) the most useful piece of recovery gear is a shovel/spade and a bit of time spent digging. We continually see a hopelessly bogged 4WD try to be recovered by a big 'snatch' without any work to lessen the load.

Years ago I would regularly be recovering trucks, we used to tell the crew of the stuck vehicle to get on the end of a shovel while we made our way out to their location, and if they hadn't done enough digging sit there and wait while they did a whole lot more.


Martyn

Hi,
a U.S. Army manual I read (pdf on line) stated that a vehicle up to the sills in mud could require > 10x the vehicle weight to move it.
One could say 'that sucks'!
cheers

Quote:

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Originally Posted by austastar

Hi,
a U.S. Army manual I read (pdf on line) stated that a vehicle up to the sills in mud could require > 10x the vehicle weight to move it.
One could say 'that sucks'!
cheers

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Say for example my Rangie is up to its sills in mud and isn't going to go anywhere easily, suggesting as per US Army manual it will need approx 18T of force to remove from the hole

Snatch strap is attached to my Rangie and recovery vehicle with a 3500kg bow shackles.

If the recovery vehicle moves at walking pace and my maths are correct you will apply the following force on your gear.

For the sake of the argument, my Rangie is an immovable object and we are ignoring any other outside forces.

Mass = Recovery vehicle = 2000kg

Velocity = walking pace = 3km/h = 0.833333m/s

F = X KG

X= M*V

= 2000*0.83333 = 1666.66

Force = 1666.66KG

So not too much, but to overload the bow shackles we only need 3500kg of force;

F = 3500

M = 2000

V = F/M

3500/2000

1.75m/s = 6.3KM/H

So again if my maths are correct, you need to be doing 6.3km/h to overload a 3.5 T Bow shackle, however you are not likely to break it due to its safety factor which is IIRC 500% so 17.5T

Not much IMHO

Now say the Reece hitch was fully welded, and rule of thumb is 1 inch of weld will hold 1000kg then:

Reece hitch is 50x50mm = 8 inches of weld = 8000kg breaking strain, were not looking at a great deal of speed to create a lethal object.

If anything, make sure you pack your shovel next time so you can do the walking pace recoverys rather than trying warp speed to 'pop' it out of the bog

So condolences out to the victims family and hopefully it wakes us all up when on the tracks

Quote:

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Originally Posted by Bushie

Still no one has mentioned that (generally) the most useful piece of recovery gear is a shovel/spade and a bit of time spent digging. We continually see a hopelessly bogged 4WD try to be recovered by a big 'snatch' without any work to lessen the load.

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Well said Bushie. I have bogged vehicles in sand and recovered on my hands and knees - clearing the sand by hand.

Using a shovel also lets you have a look at the situation, catch some fresh air (;)) and inspect the vehicle. The vehicle is often "hung up" by a rock, log, root etc. YOu can get an idea what is getting stuck (diff, gearbox, skid plate, etc) and whether something will be damaged in the snatch - including humans.

Thanks for the update Andy-M - it would have gone bad so very quickly :(

Quote:

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Originally Posted by austastar

Hi,
a U.S. Army manual I read (pdf on line) stated that a vehicle up to the sills in mud could require > 10x the vehicle weight to move it.
One could say 'that sucks'!
cheers

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Read this,

http://www.aulro.com/afvb/general-ch...-formulas.html

Quote:

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Originally Posted by p38arover

When I was in the Toyota LC Club in Sydney, that is how I was taught to do a snatch recovery ......

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The Suzuki 4wd club teaches the exact opposite. The most appropriate use of a snatch strap is where a vehicle is lightly stuck or has lost traction. The first attempt at recovery should have the tension taken up on the strap gently, then a constant tension used to tow the vehicle in the chosen direction while the driver drives out. If this fails to assist the bogged vehicle, only then should the second attempt use kinetic energy to extract the vehicle, and with as little "snatch" as necessary. This places the minimum stresses on components of both vehicles.

I remember at a 4wd Jamboree many years ago, I had bogged my Suzuki LJ50 (weighing a massive 900kg) and the duty recovery Landcruiser used the "Take off at max throttle with slack snatch strap" method. Not only did the LJ un-bog, it was nearly airborne and bent the front crossmember of the chassis. I very nearly got whiplash. I was ****ing furious and wanted to massage the Cruiser's driver with a pick handle. It would have been possible to have driven out of the mud with the assistance of 2 people pushing.

As others have said, if the vehicle is more heavily bogged, put away the snatch strap and use a Shovel, Tirfor or Winch.

Quote:

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Originally Posted by 303gunner

The Suzuki 4wd club teaches the exact opposite. The most appropriate use of a snatch strap is where a vehicle is lightly stuck or has lost traction. The first attempt at recovery should have the tension taken up on the strap gently, then a constant tension used to tow the vehicle in the chosen direction while the driver drives out. If this fails to assist the bogged vehicle, only then should the second attempt use kinetic energy to extract the vehicle, and with as little "snatch" as necessary. This places the minimum stresses on components of both vehicles.

I remember at a 4wd Jamboree many years ago, I had bogged my Suzuki LJ50 (weighing a massive 900kg) and the duty recovery Landcruiser used the "Take off at max throttle with slack snatch strap" method. Not only did the LJ un-bog, it was nearly airborne and bent the front crossmember of the chassis. I very nearly got whiplash. I was ****ing furious and wanted to massage the Cruiser's driver with a pick handle. It would have been possible to have driven out of the mud with the assistance of 2 people pushing.

As others have said, if the vehicle is more heavily bogged, put away the snatch strap and use a Shovel, Tirfor or Winch.

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Just goes to show that not even the 4WD clubs teach/use the correct techniques.

refering back to whitakerb's maths I think the correct formula for force imparted by moving objects is in fact mass x velocity^2.

ie it is the square of the velocity which makes this even more nasty. Doubling the speed of the snatcher increases the force by 4 times.

Little steps are required going from no slack to small amount of slack in small increments. There are no medals for getting out of a bog on the first try.

Sometimes it is very difficult to stop people from going for it straight away though, and sometimes the onlookers don't help either. I got bogged once (out of many times) and breif the snatcher to take up the slack and then drive off gently as you would normally and some bogun half wit piped up saying "no mate, you want a decent run up and full noise". Thankfully the guy pulling maintained focus on me. Got me out with the most gentlist of pulss and I was up to the rails in river mud.