People think pulleys increase pulling power.

#76
I think you’re measuring the wrong side of the pulley. Hard to tell the overall setup from the pictures, but if you’re measuring from the mark on the cable to the pulley, you need to be measuring from the winch side of the cable. The pulley moved one foot, the actual cable moved two.
The length of the cable does not change regardless of where you measure the cable. if you started a 30-foot cable you'll end with a 30-foot cable. If It Moves one foot over a pulley on one side it'll move one foot over the pulley on the other side the relationship or the where you gain mechanical advantage is how those two pulleys close together or separate way from each other that's the variable that's where things change.
 
#78
the pulley doesnt need to move, the load is moving towards the pulley, so relativly speaking, the pulley is thus moving towards the load.


the distance between the load and anchor are decreasing. this happens with any straight line pull.
however when you had a pulley and hook the winch back to the anchor, its the same as having two pullies move towards each other. as you need twice the winch line, so when its looped back the vehicle, if you spool in 6 inches of line, its technically 3 inches of line from each side the pulley, therefore 2:1,

when its a straight pull, 6 inches wound in, is 6 inches straight.
Test it
 

DaveInDenver

Expedition Leader
#79
Beautiful graphic showing fall line, return line and dead line. You gain advantage in this scenario because the left side is moving twice the amount of rope, both sides will get shorter and in effect the sheave is a second winch that's a reflection of the source.
I feel like this thread doesn't have enough graphics of trucks and pulleys and trees and lines... He's my contribution (though not my image)... this was the point I was trying to clarify way back on page 1:

View attachment 440428
 
#80
If I were 10 feet from a tree and I ran a cable to a tree with a pulley and back to the jeep I would have 10 feet of cable to the tree and 10 feet back to the jeep. If i pulled my Jeep 5 feet forward I would have five feet of cable to the tree and five foot of cable from the tree to the jeep. The cable moved the same on each side of the pulley. I pulled 10 feet or cable and moved so 5 feet so 2:1. If the cable is run back to the load wincing yourself you gain advantage. Wincing others you need the third pulley. Pic is right.

I did measure wrong but not on the wrong side, I needed to measure both sides.

A. True
B. False.

Thanks heading down this bumpy road with me but I was not trolling. everything changes when you're pulling force is within the system.
 
Last edited:

DaveInDenver

Expedition Leader
#81
Yes and the total pulled in by the winch would be 10 feet of rope length to move 5. If you had a single line pull you'd have pulled 5 feet of rope to move 5 feet. It's the circular equivalent of using a lever on a fulcrum that's twice a long. You have to move the side gaining advantage farther as the length grows.
 
#84
FFS...nothing...can...ever...surpass...the...global...warming...thread!
the problem we may run into increasing mechanical advantage is if we have to pull the cable longer we're going to have to run our vehicles longer so we don't kill our batteries. The extra exhaust will accelerate global warming.
 

dwh

Tail-End Charlie
#85
the problem we may run into increasing mechanical advantage is if we have to pull the cable longer we're going to have to run our vehicles longer so we don't kill our batteries. The extra exhaust will accelerate global warming.
But you're only putting half the load on the winch.
 
#90
What helps me in understanding this phenomenon of Work and Load with pulleys and in what scenario are you providing mechanical advantage.

When you have 25 feet of line going to an anchor 25 feet away. The vehicle will move forward 1 inch for every 1 inch of line pulled in by the pulley.

When you have 50 feet of line going to an pulley anchor 25 feet away, and then back again to the an anchor on the vehicle. The vehicle will move forward half an inch for every inch of line pulled by the pulley. Whenever this is the scenario there is mechanical advantage created.
 
Top