Ok probable a bad title.

I'll keep numbers simple here.

9000# winch 3/8 cable

3/8 cable will break ~14,400#'s

Ok the less wraps on the drum = more availible pulling power

So let's assume that we are on the 1st layer of the drum(we have 8 wraps on the 1st layer on the drum).

So we can pull 9000# without stalling the winch.

Ok if we run the cable thru a snatch block back to a tree
to the side of the Isuzu <img src="/forums/images/graemlins/smile.gif" alt="" />(Isuzu content).

Same number of wraps etc on the same 1st layer etc.

I remember from school something about a 2 to 1 ratio. does this mean we can pull 16,000# before stalling the winch?(this is a numbers game here folks)

Ok I guess the question is:

How much pressure/tension is the cable under?We very often use a snatchblock to change directions etc.

Does changing directions make a difference on pressure/tension of rope?
Or does the cable have to be attached to the same vehicle that the winch is attached to to affect the pressure/tension of the rope?

Bottom line :
If the above winchrope is attached thru a snatchblock back to the vehicle (assume the stuck vehicle wieghs 8000#,taking into account friction etc) will this situation actually exceed the breaking strenght of the rope?or will the actual pressure/tension be less since we are using a snatch block?

I hope this ? make since.

Bansil

According to specs , they say with a snatch block you can double your winch pull and shouldn't have any problems.I don't know if you want to try pulling 16,000 pounds though with your trooper , if it doesn't yank your trooper towards what your pulling , your gonna snap something , the winch bolts , or worse , do what a guy I know did , he tried pulling a full size tree , it pulled so hard on his truck , full size chev , it snapped an axle <img src="/forums/images/graemlins/scared.gif" alt="" /> he did move the tree though , must have weighed a good 27,000 pounds <img src="/forums/images/graemlins/kewl.gif" alt="" />

It makes perfect sense to me Doug <img src="/forums/images/graemlins/smile.gif" alt="" />. Let's see if this does:

If you are winching your own vehicle, the weight you are pulling will be the same weight carried by the line, no mater what snatch block configuration you use. Since it's the fixed end of the line running through the block, and it does not move through the block.

If your vehicle is stationary, you could, concevibaly, connect the snatch block to the vehicle being winched. That should cut the force carried by the line in half.

Force=Mass x Acceleration

You would be moving the vehicle at half the speed you're pulling in line.

Now, I have never seen a snatch block attached to a vehicle, so I'm not recomending it. But, conceptually it would work. But then again, it's early, and it's been a while since physics class <img src="/forums/images/graemlins/scared.gif" alt="" />

<img src="/forums/images/graemlins/cheers.gif" alt="" />Andre

Andre is correct. Here are some visuals to go along with this discussion....

typical winching (w/o snatch block), you're pulling the entire load directly, and thus the line and the winch absorb the full weight of the load.



however, when you introduce a snatch block attached, you effectively half the force required for your winch to pull. you also split the load across the line too, so the cable is only absorbing 1/2 the total load. But like Andre said, you cut your speed in half.





So to answer your question, yes, a winch rated for 8000lbs can pull 16,000lbs load with the use of a snatch block and without the need to upgrade the cable diameter.

-Rob

Thanks guys's <img src="/forums/images/graemlins/cheers.gif" alt="" />.

Andre in the military we have attached snatch blocks to vehiles because of how heavy they were it's alot of cable to pull tho' <img src="/forums/images/graemlins/shiner.gif" alt="" />

It's not uncommon for us to have to attach the zu to a tree our another vehicle to keep us stationary......and that's with the tires chocked.....

Bansil

Just my two cents worth.If the cables are parallel then the force would be equal in each leg,any deviation from parallel and the forces in each leg would increase.So yes changing directions will make a difference on pressure/tension of the rope.

In the case of rigid items, you would be correct in the assumption that the forces would not be equal, but in the case of a cable, the force on the cable does not change with angles. The cable is primarily loaded in tension. There are different forces on the front of the vehicle. You will have the tension component of the force, but you will also have some lateral components, which depending on the angle of the cable, may be trying to lift the rig, pull it sideways, pull it down, etc. But in the case of the cable, you will not have more than the force of the tension, unless you applied some lateral load to the cable somewhere along the length of the cable, then the tension in cable can increase. It can get complicated, but in general, the primary force on the cable is tension from the winch and will generally not be above the rated pull of winch. Bear in mind, you only double your pulling force if you reattach to the vehicle. If you run through a snatch block and hook the cable to a tree, you will only have the pulling force of the winch. If you are winching at an angle, you will have a component of the force pulling the vehicle sideways as well. A lot of winching damage occurs from lateral loads and poor cable practices. If you use a steel cable, always drape a jacket or something else over the cable. This helps absorb some of the energy if the cable breaks. The reason synthetic cables are so popular, they don't have the same ability to store potential energy like a steel cable. They don't have the mass, so even when they do snap, they don't do the same damage. I have snapped a winch cable, and it sent one of the hooks, right through the tailgate of my truck (we were being stupid and had some cables hooked together with only open hooks)! We were lucky that no one died! That cable would have easily gone through one of our heads!! <img src="/forums/images/graemlins/shiner.gif" alt="" />

Well put.I should have said that changing directions makes a difference in pressure/tension required to do the same job.As you said, winch/snatchblock/bumper versus winch/snatchblock/tree.