Thank you so much for posting this lesson. I’m getting ready to use a block and tackle to hoist 2 x 184kg concrete lintels for a DIY garage build. Luckily I’ve gained a few pounds over the last year so I should manage the pull on my own... 😂 Cheers!
What I would like to know is how to determine how much the coefficient of friction is going to be with the pins. I know that the coefficient of friction is multiplied by the weight to increase the amount of force to be over come.
With 500 lbs of total weight, there is 250 lbs. on each pulley pin, not 500. We have two parallel sets of two in series. So, if friction is 10% for each pulley, total friction added to the system is 4 x 25 lbs, or 100, ...not 200.
Billy Stanley -- it also stuck me that there's not 500 pounds of weight on each pully and that total weight should be divided. I don't know beans about physics...just trying to learn...
Nope, the weight is not mysteriously split (in the typical system), it’s continuous on the entire system due to gravity. All force is transmitted to the anchored portion(s) of the system. His split up diagram is not the actual setup - he showed that earlier is it being a pair of 2shiv blocks, and only one is anchored.
Makingnewnamesisdumb it's just an arbitrary number. In reality, the coefficient of friction would likely be calculated after observing the additional force required to lift the load. I imagine it would be fairly difficult to know that exact number unless through experience with a particular setup.
I think for the scenario, you can assume 10% as the extra force needed to overcome the axle/pulley friction. Of course, if you have greased bearings or other types of low friction bearings, other than a metal pin axle stuck through a pulley. I don't think it would BE 10% as most of the time the axles are free to rotate as well as the pulley....but that's just speculation. 10% would be a bad-case scenario.
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Thank you so much for posting this lesson. I’m getting ready to use a block and tackle to hoist 2 x 184kg concrete lintels for a DIY garage build. Luckily I’ve gained a few pounds over the last year so I should manage the pull on my own... 😂 Cheers!
take a sip of beer EVERY time he says "take" .. you'll NEVER finish the video .. that's MY "take"
thanks for the info, helped me understand what I needed better
What I would like to know is how to determine how much the coefficient of friction is going to be with the pins. I know that the coefficient of friction is multiplied by the weight to increase the amount of force to be over come.
With 500 lbs of total weight, there is 250 lbs. on each pulley pin, not 500. We have two parallel sets of two in series. So, if friction is 10% for each pulley, total friction added to the system is 4 x 25 lbs, or 100, ...not 200.
Billy Stanley -- it also stuck me that there's not 500 pounds of weight on each pully and that total weight should be divided. I don't know beans about physics...just trying to learn...
So 150 is the the additional force we will apply to lift the weight but not 175.
Nope, the weight is not mysteriously split (in the typical system), it’s continuous on the entire system due to gravity. All force is transmitted to the anchored portion(s) of the system. His split up diagram is not the actual setup - he showed that earlier is it being a pair of 2shiv blocks, and only one is anchored.
sir can u plz... give a video of loading and discharging in oil tanker. ... sir
10% sounds like lot of friction… wouldn’t the use of ball bearing sheaves cut that down much?
lol when he got the calculator out but otherwise great lesson
10% !!! could someone help us here,
How do you figure 10%?
Makingnewnamesisdumb it's just an arbitrary number. In reality, the coefficient of friction would likely be calculated after observing the additional force required to lift the load. I imagine it would be fairly difficult to know that exact number unless through experience with a particular setup.
I think for the scenario, you can assume 10% as the extra force needed to overcome the axle/pulley friction. Of course, if you have greased bearings or other types of low friction bearings, other than a metal pin axle stuck through a pulley. I don't think it would BE 10% as most of the time the axles are free to rotate as well as the pulley....but that's just speculation. 10% would be a bad-case scenario.
10 percent for synthetic rope while reeving also bearings and bushings to consider for friction lol