Synthetic winch rope

[SEREvince]

When you place a thimble, or any other device in or on the line, you will reduce the ultimate tensile strength of the "system".

According to Samson a spliced end loop executed in accordance with their guidance retains 90-100% of the original "new rope" breaking strength.

So; with a 13,000 lb "LAB" strength for the line, you may have an actual "working" strength of 7,000 - 10,000 lbs.

Your figures puts the synthetic ropes working load on par with the OEM wire ropes breaking strength. This means instead of destroying your $1200 8274-50 or ripping off a piece of your truck you break a $200 piece of rope.

More isn't always better.

One more thing to consider. If you are winching your vehicle up a rough spot, or out of the mud, the force necessary to move the vehicle, can easily be 2x or 3x the weight of the vehicle. An 8000lb winch won't be enough for a Tacoma. Luckily, we only need a "boost", most of the time,

Commonly quoted numbers, that I have luckily never seen in field conditions. I have witnessed crappy 8000lb winches make multiple pulls of Tacomas and larger vehicles over near verticle obstacles and while heavily mired in mud. Remember that this 6000lb vehicle is on wheels, I can generally push it around pretty easily over a flat surface, even uphill with a friend or two. (and Superman I am not!).

Basically this line of thinking says that the surface area of the components below the surface of the mud are generating 2-3 times more drag than the total weight of the vehicle being hoisted in the air? Maybe if you just burried some 49" Iroks up to the frame I could see this.

I'm not saying that it's not possible to generate 24,000lbs of drag with a 6,000lbs vehicle on wheels.


At that point you need heavy equipment, or maybe just a shovel.
http://www.4wheeloffroad.com/whoops/131_0604_ultra_4x4_whoops/photo_04.html

Here's what we use to unstuck things.
http://www.olive-drab.com/idphoto/id_photos_wrecker_hemtt_m984.php

By all accounts it shouldn't be able to recover its self let alone a tank.

 

[charlieaarons]

"One more thing to consider. If you are winching your vehicle up a rough spot, or out of the mud, the force necessary to move the vehicle, can easily be 2x or 3x the weight of the vehicle. An 8000lb winch won't be enough for a Tacoma. Luckily, we only need a "boost", most of the time, and the winch does the job. But, when you REALLY need it, the little winch might not be able to get the job done. You might need another vehicle with a winch to assist, or a High-Lift to get your axles out of the mud first, then pull, etc"

I've seen this allegation before. How does one explain that a typical "5 ton" military vehicle that has a GVW of 27000 lbs come equipped with a 20000 lb hydraulic winch? Do all the armies of the world not know what they are doing? Perhaps an explanation is that a hydraulic winch near its' pull limit will pull just as fast and efficiently (with little heat buildup) as with no load. Whereas an electric near its' limit slows down to almost nothing, emits screaming noises and draws immense amperage and builds up potentially fatal amounts of heat quickly because electrics have a thermo-electric efficiency of 10-20%, which is easily provable by looking at the the charts of pull/linespeed vs pull/amperage and doing a simple calculation (linespeed X pull in lbs /55,000 = hp output; amperage X 12V /.747 = hp input).
So although a 5000 lb rig may need an 8000 lb electric winch, a 27000 lb Unimog does fine with 15-20000 lb hydraulic winches. Paticularly if you pick a gear in the crawler range (55.7:1 additional reduction) to match tire speed to winch speed. Recreational electric winches are over-rated IMHO.
Nobody puts 65000 lb hydraulic winches that weigh 1500 lb on 25000 lb trucks. Check Jane's Military Vehicles, any edition, if you don't believe me.

Charlie

 

[p1michaud]

Don't forget the pulley block/snatch block.

One more thing to consider. If you are winching your vehicle up a rough spot, or out of the mud, the force necessary to move the vehicle, can easily be 2x or 3x the weight of the vehicle. An 8000lb winch won't be enough for a Tacoma. Luckily, we only need a "boost", most of the time, and the winch does the job. But, when you REALLY need it, the little winch might not be able to get the job done. You might need another vehicle with a winch to assist, or a High-Lift to get your axles out of the mud first, then pull, etc...

Excellent point. Don't forget the use of a snatch/pulley block that would double your pulling power (minus friction losses say 8%). That is nearly 15360 lbs for an 8000 lb winch.
Now if we take a very heavy Tacoma say Scott's for example at 6000 lbs (extreme case IMO) it could push you over the winch capacity depending on how stuck you were.

For example:
Good stuck but not on the frame rails: 2 x 6000 = 12 000 lbs thus you would be fine with a 8000 lb winch.
Completely burried stuck: 3 x 6000 = 18 000 lbs now you may be in trouble with an 8000 lb winch. There are other things you could do at this point as you have previously mentionnned (Hi-Lift, other vehicle helping, dig out under stuck vehicle, etc...).

Great discussion!
Cheers,
P

)..

 

[SEREvince]

I must be living in denial!:sport_box

I'll never believe that my Tacoma requires a 25,000 winch.

I always thought a pulley decreased the effort required to move a load? Does it double the output?

Does it really turn a 8,000lb winch into a 16,000 winch? Does a second pully make it a 32,000lb winch?

Give me two pullies and I'll be hoisting Mogs into the air like feathers!

So many questions!

 

[charlieaarons]

Archimedes said:
"Give me a lever and I will move the Earth".
Two pulleys gives 3 lines, so total pulling force is tripled, MINUS frictional losses. The winch is still what it is, the net winching speed is reduced by a factor equal to the number of lines.

Charlie

 

[ntsqd]

Archimedes said:
"Give me a lever and I will move the Earth".
Two pulleys gives 3 lines, so total pulling force is tripled, MINUS frictional losses. The winch is still what it is, the net winching speed is reduced by a factor equal to the number of lines.

Charlie

The thing that gives a lot of people trouble is accepting that the tension in the line remains the same. That is the case though. One way to look at is that each line is effectively another winch line hooked to the vehicle.

A snatch block or two is also a really good way to do very delicate or exact positioning work with a winch that has a high line speed, like an 8274 or similar.