Snatch block placement

[Darby1]

Who carries snatch blocks/pulleys? If your going to carry 1, I think you should actually carry 2. Was reading that drama crap between kaptainkraker and those guys he was threatening. they pointed out that little pulley on his winch line and it got me thinking.

Mechanical advantage- a stationary pulley (mounted on a tree) provides no mechanical advantage, only a change of direction which decreases line speed and adds friction. In order for a pulley to increase your winch's pulling power it must be moving tawards your direction of pull. If you put your 1 pulley on someone elses truck to pull THEM out then you have a mechanical advantage, a 2-1. If you have 2 pulleys and need to pull yourself out then one is placed on you anchor, route the line back to your truck through another pulley on your bumper, then route the line back to the anchor, this would give you a 3-1. A three to one would cut your line speed down a lot, but you should be cautious. If your using a 9k winch you are now pulling with 27,000 pounds of pulling power. This is way more than your winch line is rated for and could easily tear your truck apart. Should only be used for extreme circumstances, like recovery.

I still see dudes with a pulley that insist their winch would only pull them out after they ran it to a tree in front of them, I even see it in the magazines.
Also, what do they think is gonna happen when they drape a tshirt over the middle of the line? I doubt a shirt or a jacket is going to absorb much energy if that line snaps.

My .02cents. Any different thoughts? Lets debate it.

 

[nevada]

when were in a group...noone carries more than 1. or atleast several ppl carry them..

it was a good thing too. a few years ago, when i ended up...upside down. my snatch block was IN my bed mounted truck box. well, luckily we had another block with us. used it, and MY winch, against another truck, to flop mine back over.

i guess i COULD have opened the lid. but..that thing is stuffed to the top, would have been a hell of a mess.
as far as im concerned, you shouldnt even have a winch, unless youve got atleast 1 snatch block. the damn things SHOULD come with one.

 

[Lokey]

I carry one SB in the rig and have used it on occasion to get my self out of a jamb not to mention trail work.

As for increasing your mechanical advatage I agree that you need to be very aware of how you use the SB as you can over load you line quickly. Knowing how much your winch can pull on which wrap of the drum is very important also.

Honestly I think that an SB is of more important when used for a change of direction. It is really hard to put your rig back on its wheels with out a SB when space is limited.

Link is to the Warn winch techniques and saftey guide
http://www.warn.com/corporate/images/90/TechGuide_PN62885-A2.pdf

 

[irishman]

sb

I actually carry 2

 

[bigiron]

I carry several blocks.... Plus around 300ft of 1 1/2 synthetic shiprope,(looped with wear protection both loops and 1 movable sleeve) 4 4" wide 30ft straps and D rings to tie it all together..... You can realy screw up a rig when you start multiplying the strenght of your winch. All my recovery points(D-dring mounts) are 1" plate with 3/8" plate frame reinforcements.

 

[LWB Samurai Joe]

I carry three, and I actually had to use all three once to get a guy who was stuck to his axles in mud.

 

[Broken Again]

Table for SB placement and machanical advantage.

At 0* and a factor 2 an 8000# (Edit: load on the block) will double to 16000# so long as the hook is not attached to the winch vehicle, but something next to it like a tree.
More edit....If the hook is attached to the winch vehicle to pull will double.*


Angle Factor
0 ----2
10----1.99
20 ---1.97
30 ---1.93
40 ---1.87
50 ---1.81
60 ---1.73
70 ---1.64
80 ---1.53
90 ---1.41
100---1.29
110 ---1.15
120 ---1
130 ---0.84
135 ---0.76
140 ---0.68
150 ---0.52
160 ---0.35
170 ---0.17
180 ---0


Just sayin is all.


*special thanks to benw for pointing out my mis-statement.:awesomework:

 

[Spanaway Mudder]

I hear the little pulley/snatch block off of a come along works just fine:haha: :fawkdancesmiley:








j/k

 

[boxboy]

At 0* and a factor 2 an 8000# pull will double to 16000# so long as the hook is not attached to the winch vehicle, but something next to it like a tree.

I guess I don't understand what you are trying to say here but if at some point you do not connect the line back to the stuck vehicle a second or more times you do not get the doubling or more effect.

 

[benw1]

Table for SB placement and machanical advantage.

At 0* and a factor 2 an 8000# pull will double to 16000# so long as the hook is not attached to the winch vehicle, but something next to it like a tree.

Angle Factor
0 ----2
10----1.99
20 ---1.97
30 ---1.93
40 ---1.87
50 ---1.81
60 ---1.73
70 ---1.64
80 ---1.53
90 ---1.41
100---1.29
110 ---1.15
120 ---1
130 ---0.84
135 ---0.76
140 ---0.68
150 ---0.52
160 ---0.35
170 ---0.17
180 ---0


Just sayin is all.

You should have actually read the page you copied and pasted that table from. The pull does not double unless the line is attached back to the vehicle. If the line is attached to a tree next to the vehicle the load on the block is doubled, but the pull is not.

http://www.dodgepowerwagon.com/glovebox/snatch.html

 

[Broken Again]

You should have actually read the page you copied and pasted that table from. The pull does not double unless the line is attached back to the vehicle. If the line is attached to a tree next to the vehicle the load on the block is doubled, but the pull is not.

http://www.dodgepowerwagon.com/glovebox/snatch.html

Your right I mis-stated it..the load on the block is doubled...


But I did read the page.:fawkdancesmiley:

 

[KarlVP]

I carry two snatch blocks in my rig.

One is the ARB job that I think is rated for 20,000lbs.

The other is one I got from the shipyard that was used on a crane to lift steel. Don't know the rating but it's a hell of a lot beefier than my ARB block.

 

[Lokey]

Something else to remember.

Never use a SB with rope that has previously been used with cable. The pully gets burrs on it from the cable which will damage a rope.

 

[bigiron]

Something else to remember.

Never use a SB with rope that has previously been used with cable. The pully gets burrs on it from the cable which will damage a rope.

I priced a synthetic line with masterpull that would hold up to my rig.....I about fell over when they said 689.00 plus tax and shipping......I will break a lot of wire rope before pony up that for a rope:haha:

 

[Drone637]

We usually carry 1 block per rig. So far the only reason to use it has been to change the direction of the pull.

I have been looking at changing to a lighter snatch block, as the one I currently use is normally used for hauling logs out. A little heavy duty for my SJ.

 

[Boonie Buster]

I think this theory is wrong...:fawkdancesmiley: :haha:


even on the pulley, isn't it only getting say. 18,000lb of force on that individual pulley? even if you have two SB's in the equation? the first will have 18,000lb and the second the same...

I just think the pulleys are not getting that kind of force on them... or the cable...:stirpot:

 

[zukkev]

I have been looking at changing to a lighter snatch block, as the one I currently use is normally used for hauling logs out. A little heavy duty for my SJ.

X2! Mine's also one used for logging---drops the rearend a half inch!!:redneck:

 

[nevada]

I think this theory is wrong...:fawkdancesmiley: :haha:


even on the pulley, isn't it only getting say. 18,000lb of force on that individual pulley? even if you have two SB's in the equation? the first will have 18,000lb and the second the same...

I just think the pulleys are not getting that kind of force on them... or the cable...:stirpot:

they'll only get the MAX weight on them, if you're trying to pull the MAX weight.

if ur pulling a 6,000lbs, with an 8k winch and double up...ur not doubling what the winch IS pulling(not 12k), only whats its CAPABLE of pulling. but since its only 6k, thats ALL your pulling.

also, double line...you would divide the weight by each block. so 6k with 2 blocks. each block is only seeing 3k. BUT the line is still seeing the same total weight.

 

[Boonie Buster]

they'll only get the MAX weight on them, if you're trying to pull the MAX weight.

if ur pulling a 6,000lbs, with an 8k winch and double up...ur not doubling what the winch IS pulling(not 12k), only whats its CAPABLE of pulling. but since its only 6k, thats ALL your pulling.

also, double line...you would divide the weight by each block. so 6k with 2 blocks. each block is only seeing 3k. BUT the line is still seeing the same total weight.

thanks i think you said what i was trying to say. It's not like doubling the line makes the line force more than whats actually being pulled (ie. 6'000lb rig stuck in mud)

 

[Money Mark]

I don't have an opinion on all the mathmatical forces :; But I will show you what I use.

You can get one from here: http://www.baileysonline.com/itemdetail.asp?item=RP110&CAT=

I use it because I'm NOT toting around a big ass one.......that will rarely see use. And I have used it with success for flops, stucks, etc. No bending or twisting. It's rated at 7000lbs.......good enough.

The only time I now use to use a snatch block is when a straight pull isn't an option. Doubling my winches power is not something I view as necessary for self recovery. I'm not winching "you" out.....:fawkdancesmiley: