Under performing winch,Cable does matter

Submitted: Tuesday, Jul 26, 2005 at 00:28

ThreadID: 25056 Views:3137 Replies:6 FollowUps:10

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Member - Davoe (Widgiemooltha)

Tried Using My winch a few weeks back with a 10m pull and no dice. I have since aquired a snatch block which allows me to run out much more cable (I have 50m of cable) So I tested it again with a short pull and found it had the grunt to tow my 4by along with all 4 wheels locked up in low 4 1st, Until it got to 5m (10m of line pull) proving to me that the less line on the drum the better the pull

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Reply By: Kiwi Ray - Tuesday, Jul 26, 2005 at 06:56

Reply By: G-wizz - Tuesday, Jul 26, 2005 at 07:55

Tuesday, Jul 26, 2005 at 07:55

You do know that the snatch block is a pulley and that it reduces the load on the winch don't you? A snatch block can actually double the pulling power of a winch if used correctly.

AnswerID: 122058

Follow Up By: F4Phantom - Tuesday, Jul 26, 2005 at 10:23

Tuesday, Jul 26, 2005 at 10:23

if you use a snatch block you will get double the power from the winch and the winch cable will be under half the tension. thats if the block is running the cable approx 180 degrees.

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Follow Up By: Member - Davoe (Widgiemooltha) - Tuesday, Jul 26, 2005 at 11:04

Tuesday, Jul 26, 2005 at 11:04

yea know that although I cant wotk out the physics involved. interestingly it still stalled out about 5m from the tree. In a real situation I would be better off selecting a tree about 20m away giving me 40m of cable out and working on the bottom layers of the winch

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Follow Up By: F4Phantom - Tuesday, Jul 26, 2005 at 15:57

Tuesday, Jul 26, 2005 at 15:57

The physics is as follows as you may have already guessed.

the snatch block is a pulley. If you use the normal winch speed you have normal power and normal speed, if you half the winch speed via pulley you double the power and half the amount of tension on the cable. It is a fairly simple calculation of power vs speed and even easier than acceleration calculations which include rate of change becuase the winch is linear. The amazing thing about all this to me is the halving of tension on the cable, my dynamics teacher went over that point with me several times cause i just wouldnt believe it, but apparently it is true, so good news if you want to ease the wear and tear on expensive equipment.

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Follow Up By: Member - Davoe (Widgiemooltha) - Tuesday, Jul 26, 2005 at 16:10

Tuesday, Jul 26, 2005 at 16:10

I am sure your explanation is correct but you have confirmed to me why i dont understand the physics, Still its like alot of things I dont have to know how they work - just how to use em, great for dumb people like me:)

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Follow Up By: Member - Tonester (VIC) - Thursday, Jul 28, 2005 at 13:50

Thursday, Jul 28, 2005 at 13:50

Davoe, consider hanging from a branch with your two hands. Pretty easy right. Try and let go with one hand and hang on - it feels twice as heavy. Nothing to do with speed, its just that two cables pulling wieght share it b/w them (eg. half each), instead of a single cable handling load. Ever done a sheep shank on a rope to tie something off? Same principle applies.

FollowupID: 377703

Reply By: AT4WD ADVENTURES - Tuesday, Jul 26, 2005 at 13:23

Tuesday, Jul 26, 2005 at 13:23

Davoe,

Even better still hook up two snatch blocks to lessen the effort again on all equipment. Cables runs from winch to first block mounted off pull point back to car snatch block then back to pull point. Enable more cable to be spooled off winch in a short distance. Slower, stronger pull but less effort on equipment.

IMHO I would not use a winch without a snatch block in any case as the single line pulls with off the shelf unmodified winches exerts substantial stress on the equipment after the rated layer is filled.

My two bobs anyway.

Stuart

AnswerID: 122114

Follow Up By: Member - Davoe (Widgiemooltha) - Tuesday, Jul 26, 2005 at 16:15

Tuesday, Jul 26, 2005 at 16:15

hear ya but in most of the winch pulls i have done are on salt lakes where doubling back isnt an option and extension straps are needed. My last atempt at winching could have benifited from what you speak of but in the end prob the highlift and reversing back were prob the best solution. Like any recovery it is a matter of assesing the situation and seeing what you have then (hopefully) picking the right option

FollowupID: 377308

Follow Up By: F4Phantom - Tuesday, Jul 26, 2005 at 17:32

Tuesday, Jul 26, 2005 at 17:32

what kind of salt lakes mate? i once saw a few driving from kalgoorlie to esperance, i walked up to one and broke the salt surface, underneath was the stickiest and STINKIEST mud ever. The smell would not leave my shoe and really made me feel sick, driving through that would be utter madness and you would be bogged within 1 meter of salt.

FollowupID: 377322

Follow Up By: Member - Davoe (Widgiemooltha) - Thursday, Jul 28, 2005 at 12:14

Thursday, Jul 28, 2005 at 12:14

Not ones that bad F4 we were wrrking large areas in dense bush SE of Norseman Most of the areas we wanted to check out were around saltlakes. The saltlakes in the area are often long and thin and we would attempt to drive the sandy beaches as a better option to straight bush bashing. at times it was best to skirt the edges of the lakes (Never accross that is just suicide) most of the time the edges were firm but every now and again we had to make use of vegetation along the lake edge for winch recovery