One thing people get wrong with snatch blocks - explained
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- Опубликовано: 3 сен 2020
- #snatchblock #winch #doublelinepull #recovery
One of the biggest difficulties people have in understanding winching loads is how a snatch block can double the force on an anchor. How, they ask, can you "create weight" ? I used to explain this with a whiteboard, but there was always one or two people who refused to believe the numbers. So I put together a little kit to physically demonstrate the point using scales and a volunteers from the audience. Nobody argued with the point then, and it was mildly amusing to see their mental cogs shifting without a clutch!
Anyway watch for the answer. Also includes information about how to calculate load on a slope.
Post questions as comments!
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This is so interesting because it shows how common sense needs to be learned / experienced. My opinion: Very well done!
Thanks! Please share etc
None better explanation out there Robert in spoken word and demonstration. Thanks again.
Very welcome, thank you!
ruclips.net/video/ra5KqnESPOo/видео.html
Well demonstrated and you made it easy to understand. Good job Robert !
Like A BOSS !!!! ...this is , precisely, why I watch your videos . Simple explanations , physics applied . No nonsense , straight to the point. Thank you 🤓
Thanks, please share :-)
Ha ha love it 👍 so many people think they know facts when they don’t, love your work, what you explained is basic engineering that most people can’t comprehend, I get it every day, good work 👍
I really liked physics as a kid at school. This is the point that really used to se
crew with my logic.Still does some times. Very well demonstrated Rob. Thank you
It screws with everyone. That's why I started to use physical weights and scales when I ran classes. Otherwise, someone would refuse to believe. And no amount of whiteboarding would convince.
This is what RUclips is for ...LEARNING. I move bales of cardboard onto a utility trailer with a winch. This information is what I need. I'm reading all the comments and I know that I'm among well qualified people who know what they're doing and talking about. #Respect
Thank you!! Always good to hear from non-4x4 industries so we can all learn!
Fantastic demonstration! In the arboriculture world, we use a sling with twice as much capacity as our rigging line whenever we are lowering pieces out of the tree.
Very good points, a lot of people have a hard time with this type of winching, lifting or otherwise similar actions. I learned in my apprenticeship on rigging and lifting very heavy loads just this very important knowledge.
That is so counterintuitive. I needed to see it to believe it!
The last minute is gold!
Lol. I had to watch this like three times to believe what I was seeing, and I even studied this at university. It has been more than a few years...
Did you believe it in the end?
@@L2SFBC Ha. Yes. If you draw out the "free body diagram" like you did, it works out. Makes me want to take a closer look at some of the replicas of those old massive sail powered warships - all lines and pulleys and winches and the like.
Great demo. It shows where the loads are multiplied and need higher rated gear.
Just found your video series. Very impressed! Practical demonstrations making this very easy to understand.
The deepest part of his rather inane remark has not been tackled. Why do you not have more views???????🤣😂 Because this stuff is cool!!! You need to figure a way to add a snatch block to the RUclips algorithm.
i don,t understand why the weight increases, great video.
Excellent... I have told this to countless people over the years, but I'm not sure they get it. I explain by saying that, not connecting back to the vehicle means that, the cable is basically still a single line pull with a bend in it and if is creating resistance friction. Only when it is connected back to the vehicle, can the returned line contribute to carrying the weight. They say " I little knowledge is dangerous" I think in this case, at least detrimental to the task. Your demonstration is excellent. thank you...
Thanks! And agreed 👍
Robert, thanks for the videos! I just want you to know that I personally get rather excited watching your videos, especially the snatch box ones😉
Good to hear and pleased my work creates that sort of emotion...few are excited by what I do, perhaps more satisfied with the learning.
Maybe you need to watch more videos as I explain snatch blocks - snatch boxes are indeed an interest but not a subject I'll explore on this channel 👍
The stupidity of some people knows no bounds. Your information is so helpful and I'm grateful not only for your content but also that you don't let the pompous idiots distract you from putting out great content.
Thank you
I am going to be using a pulley system in my rocket now, your video along with SmarterEveryDay's video greatly helped me. Thanks a ton for these great videos!
Rocket??? Tell me more...
You have an excellent channel with a very bright future! Keep it up.
Thank you so much!
The mechanical advantage works against you. Mechanical disadvantage, because the way the pulley is set up. Cool video and thanks for showing it in such a clear way.
Excellent demo and info without all the fluff. Love it.👍🤠🇦🇺
Thanks 👍
Great demonstration !
Lots of opportunity for confusion in pulleys because of exceptions to the rules. This one is a good example. It breaks the rule…….only moving pulleys provide mechanical advantage.
Exception: when the haul line power source is attached to (or part of) the load.
Fantastic information Robert, Thank you very much!!
Thanks please share etc!
I find it interesting that most folks know you can double the force on a moving object with a dual line.... But they cannot comprehend that it applyings double the load on the stationary object that's doing the levering. For every action ...
Nicely put!
People are confusing line tension with force on the pulley.
Such great info!
I hope that " Commenter " paid attention here . I understood the first time it was explained in the Winching Video .
Ever applied force requires an Equal counter-force to remain in balance . Basic Newtonian Physics .
Well, that freaked me out. I gotta sit down and think that through!! 😁😁
Well that's better than the people who say "no, that is wrong, it's trickery" !!!
Anchor points increasing load was the biggest issue for me to wrap my head around.
Eventually, I just had to accept my common sense was incorrect and re-train my brain to take this into account.
Thanks for being open-minded. How could I have done better to explain?
Wow, nice explanation... Now i know why my rope breaks, because i use wrong configuration... I am subscribing now, very nice info, i use this when i play my RC and using winch...
Brilliant! This is what RUclips is all about!
Yes I'm sure it's exactly what the founders had in mind :-)
Nicely demoed.
LEGO fixes everything. 👍
Very interesting well done
well demonstrated Sir.
thanks please share!
i know my comment is way too late... but it is a cool demonstration never the less..
well done & thx you
Not too late! I appreciate it! Please share 👍
Good presentation!
Glad you liked it!
I think my head is about to burst, especially when you put the lego car in a slope
Please subscribe before your head bursts
You'll have to make new content then because i just watched thru all your pulley clips. Almost like being on a whole day seminar 🙈😀 👍🏻👍🏻 learned a lot //32 year old plumber
Stay tuned...
damn, I knew force doubles because of the 180 change in direction of the force vectors but I would have assumed that in both causes it would double! So in redirect situation, one can pull a much heavier vehicle without anchoring your vehicle as long as the heavier vehicle is not less than twice the weight of your vehicle. It makes sense that the pulling weight at the snatch block would double since one point is fixed and you have an action and reaction forces that add up. you have the 1000 kg force traveling from the 1000kg truck all the way to the fixed point on the ground, cable tension = 1000 kg BUT around the snatch point it changes direction, thats where it adds up. Just mind boggling to think you are creating double the force from nothing, right? I don't blame the lady 🙂. With double line since both the fixed points are on the truck itself, the weight of the truck is split equally and the tension the line feels is 1/2. Here you are basically doubling its capacity at the expense of speed.
I'm trying to wrap my head around how the weight doubles.
The simplest way I was taught if the block moves there is a mechanical advantage and in simple terms the number of lines coming out if the moving block is your mechanical advantage.
No, you can have MA if the block doesn't move, and it's the number of lines supporting the load, not coming out of the block.
@@L2SFBC The amount by which the pull on the hauling part is multiplied by the tackle is called its mechanical advantage (M.A.) and, if friction is disregarded, this is equal to the number of parts of the fall at the moving block.
@@L2SFBC the better phrasing would be if the block moves in relation to the other components in the rig.
Very good!
Well said
Thank you please share
So the redirect pulls are more strenuous on the winch than the double line back to vehicle pulls. Interesting. I think I'll get another pulley to carry.
If you look at the distance the vehicle moves, its exactly the same as the amount of rope taken in. No mechanical ad.
And yes, you do need a moving pulley
l2sfbc.com/you-can-get-mechanical-advantage-from-a-snatch-block-that-doesnt-move/
The difference between force and mass! You add no mass to the line, but double the pulling force!
Don't worry Robert, I am a complete noob with snatch blocks these types of things and all the terminologies..
But physics are physics.. It's not "weight" it's force applied.
Just because it is not obvious to the mystery complainer watching it, doesn't mean the teacher is wrong, it means their understanding is not complete yet.
Sadly he is going to be incorrect forever if he has declared he is not going to watch another video.
It's prob one of the reasons he is so wrong in the first place.. He never stuck around long enough to be taught correctly..
He is now going to go to another video about another subject and tell them they are wrong and he will stop watching their videos also..
If you wanted to help visualise it even more, you could add a weighing scale to the "stump" too, and show there is a force pulling it towards the snatch block.
Yep, could do that too...but I'm trying to balance my videos (and content) with accuracy vs brevity and ease of understanding. So I use kilograms rather than newtons, and often talk of 'drive' to wheels rather than torque.
Always welcome feedback as to how I can get the balance right 80% of the time for 80% of the people.
I find the people who know the difference between mass and weight for example don't need any explanations!!!
I see a risk of people getting this wrong. If you are pulling external load attached to snatch block, other end don't need to be attached on solid object. It can be attached to the vehicle and the force is still doubled. Of course if you use solid object, you vehicle needs only half of the force to anchor it into place.
LEGEND.
fantastic
Thank you so much 😀
Best setup is to attach the snatch block to the vehicle being recovered and run a buddy's winch through it to an anchor.
Why is that best?
@@L2SFBC All of the wear and tear is on his equipment!
Joking aside, the force applied to the anchor is half of that that would be applied by attaching the snatch block to the anchor and running the cable back to the vehicle being recovered. I prefer to have the pull capacity of the winch to be the weakest link. That way I don't have to worry about cables snapping, shackles breaking etc. I don't exceed the working load limits of these components (I can't because the winch capacity is less than the working load limit). The problem is that I have yet to find a tree with the working load limit posted on it. So if I can figure out a way to halve the load on the tree, I think that is better. You can also use another vehicle as the anchor point, using recovery points on it whose working load limit exceeds the capacity of the winch.
Exactly I explain that in my winch rig videos and also the one I did with Mad Matt recently
@@L2SFBC Mad Matt has some really good videos. For those that use snatch straps, watching the videos he did with Matt Winder in Utah using the ropes is rather eye opening.
Another good set of videos to watch is the ones where Ron Pratt and his father recovered a U-Haul van from a fire road in a National Forest using the 3000 lb winch on his father's Polaris Ranger side by side. Ron does a lot of work with a rotator tow truck, including a lot of overhead work. He is highly trained and very safety conscious. Watching his rigging and his techniques for moving something the way you want it to go is very educational.
Your video was excellent also -- it puts some real world data into it. I never appreciated how much the load on the cable can vary during the recovery and how fast it can change. It is those fast changes that could result in the failure of a component, even though the actual load on the component does not exceed its rating.
Lesson learned: take it very slow and easy when working at the limits of the capacity of your equipment.
As far as vehicle winching, this video seems to miss the crucial point. The point of winching the vehicle with a snatch block back to itself is to reduce the load on the winch. And you've shown that the load on the winch is indeed halved. In fact, you've demonstrated that you should not winch from the vehicle to a second static object, because you are towing twice as hard on your winch point in front of you. So if it's a tree it's taking twice as much load as it needs to and the load on the winch is the same. Instead you want to winch from the vehicle to the snatch block at the tree back to the vehicle.
Now if you're trying to tow a stuck vehicle in front of you you would absolutely benefit by going from your vehicle to the stuck vehicle to a solid tree.
The point of the video is to explain exactly what you describe. See the other ones for more general explanations. I am not sure what your point is?
@@L2SFBC Sorry, it felt to me like you were discouraging winching with a return to the bumper. I've watched your other videos and see that you meant this more as an add on. You have a great series and thank you for the excellent videos!
Hi, yes I can understand that if you watched that in isolation. That was to address a specific point which comes up time and again - that merely adding a snatch block does not necessarily give 2:1 MA. It's been a popular video so far glad it's helping, and thank you for the comment!
👍🏼👍🏼 funny thing is if you didn’t have visual add most of these naysayers wouldn’t know what you’re talking about. 🤯
True!
Great point. Goes to show how easy it is for people to believe what they want to believe and why it can be so hard to change their minds. Indeed it can be difficult to make a solid case and present it as clear as this example.
These modern thinkers (woke type) are now even questioning the scientific method, etc... making it literally a10000% chance you will not be able to change minds because without it they wipe out the independent standards so nothing can be proven... scary!
Mega important to keep the pulley bearings greased. The old boys said you loose 5% on every pulley, which is a legit good guess due to friction. They also said that pulling a machine up 45 degree slope is pretty much the same pull as it’s mass. (After 45 the drag is gradually swapped for dead lift)
Here's the efficiency loss -> ruclips.net/video/rdlRRAbzCzA/видео.html
@@L2SFBC the old boys knew right then :o) I wonder if a roller bearing snatch block does better? (Up until the bearing gets rusty)
Watch the video..all explained and more tests on the way 👍
buying stronger snatch blocks now
I know nothing about blocks and such and interesting. I'm trying to get my head around . Does the wight /force change on the scales if you change the angle point angle ?
Yes. The examples shown are a 180 degree direction change. For a smaller direction change, less effect. See here ruclips.net/video/GXk4xCPkeco/видео.html
Strange that some people think otherwise. People are not paying attention on their high school experiments on forces I guess. The pulley there could be the culprit. People got conditioned on its "mechanical advantage".
You also didn’t explain that the increased force (weight) can only be achieved if the object being pulled upon is the source of the pulling force/ location of winch...
What I don’t understand - Why this is so? The distance between the two anchor points is on 1cm at most.
Don't understand what?
Excellent videos! Could I use a 4500 lb rated winch for my Ram 1500 crew cab with snatch block?
You could, but I'd go for at least a 9500lb if not 12,000
@@L2SFBC 👍 thank you 🇨🇦 thought I could save some money with lower rated winch with a good set of snatch blocks. Thank you for you quick reply. I’m a new sub 👍🇨🇦
Bueno!🎉🎉
any advice on avoiding twists in the line when using a snatch block?
take your time and re-rig as required
Wow...
So which would be easier on a winch, to connect both points to the vehicle, or have one attached to an anchor (tree)?
No difference
This is great thank you. I watch a lot of your videos and try to study them....given this logic it makes me wonder, why bother doing a redirect if you're not getting a mechanical advantage? Why not just hook right to the first anchor point? I suppose it could help to get to lower levels of the rope which produces more power from the winch.
Good question and there's no point unless you need to change the direction of the pull.
Very interesting. You see people often using snatch blocks and seperate anchor points claiming it provides and mechanical advantage but these seems to disprove that. Other than getting more line out of the winch and working a lower layer it just doesn't seem worth it unless you can hook back to the vehicle
Depends if you are winching or being winched
Good point , I'm always thinking of self recovery but now that makes sense, if involving another vehicle
How would the weight change on the pulley if the rope was anchored 90° from it? Would it see 50% less weight?
A 90 degree change of direction adds 141% of the load onto the anchor point, as opposed to 200% if that helps? So yes a reduction.
If the block has lock to prevent it turning around, the load is just one time the weigth?
Sorry don't understand the question?
Weight still was not created. Anchor point, or reference, merely changed. In either case, there is still equal weight on each line.
Exactly!
LEGO. Not just a kids toy.
To undertand the forces here think about this.
Attach the snatch block to the rear of a Towing Car (Car A).
Don't Actualy Do This, Only In Your Head. You will FAST understand why.
If both ropes are connected to the car being towed then the setup is the same as a single line pull (Car B)
Energy Needed to move Car B 1kmh = 1 x E
Now connect one rope to a Tree next to Car B
If Car A travels at 0.5kmh then Car B will travel 1kmh
Or if Car A travels at 1kmh then Car B will travel 2kmh and Car B will be getting 2 x E. Also here the Tree is also working at 2 x E
And Car A and Car B will combine to become the latest viral video.
So if Car A wants to stop Car B from reversing, Car A now needs 2 x E brakes to stop Car B reversing
Because Like the Winch setup, (Car B has a Winch) and now only needs half the Energy to pull Car A in reverse.
Car A = Car B + Tree
The Pulley on the Ramp is giving the Toy Car a 2:1 advantage to pull on the Scale with so the scale reads 2 x Toy Car.
And this is how to better understand what E=MC2 Actualy means.
E = Speed of light, M = Car B, C2 = Winch Wired to a Dwalf Star Held inside a TARDIS.
What if the winch connected to the car's bumper (to itself)?
Explained here:
ruclips.net/video/oBYa28i_K9Q/видео.html
So a redirect has a mechanical advantage if the anchor at the top is your mate that your trying to pull out of the muck
Yes...but then it's not really a redirect. But you've hit on a really important point - the same rig works differently for MA depending on whether you're pulling someone, or pulling yourself.
Not so much a mechanical advantage in winch rate, but an advantage in that you have effectively halved the pull on the recovery vehicle while keeping full pull on the recovered.
@@johnsullivan6709 if you use the snatch block as the stuck vehicle, this is a very good way to phrase the demonstration.
You for got to explain that the further your two lines are apart reduces the mechanical advantage proportionally. I realize that you know that
Good point shpuld have added that! But, only so much some minds can take at one go :-)
Just basics we learn at school.
Not everyone
When you know your s*** you know it
30” degree plus shackle might be the key to lighter weight.
Sorry don't get that?
@@L2SFBC Im trying to reason as my explanation. 30” angle elevation might be reason why vehicle might be lighter to winch with also the use of a ball-bearing snatch .
Your commenter is right. The issue is that you're confusing weight and force. The reason (I suspect) is because of the imperial system measuring force in lbs.
Anyway, to make clear the difference, something still has a mass when you're lifting it, even when it's not putting any force on the ground, and a vehicle doesn't double its weight when you run a double line pull, or half when you split a double line pull between the vehicle and an anchor.
Anyway, I really enjoy your videos and hope that helps.
Sorry I don't get the context of this? Yes mass doesn't change like weight, agree with your comment but don't quite see the relevance to the video? A double-line pull halves the effort (I prefer to say that rather than doubles the pulling power)
@@L2SFBCthe commenter is quite correct. Weight is the force applied by gravity on an object. You can't change the weight of an object by doing anything other than changing gravity.
A double line pull doubles the force, the weight remains the same. A scale is a force gauge, it's designed for the application of measuring weight and hence its units reflect that, but in the applications you've used it it's measuring force in an incorrect unit, not measuring weight.
I know all that...maybe I used the wrong terms in the video. Which would have been intentional, I find if I talk newtons nobody gets it, so I use kg. Which isn't correct. But the people that know the difference tend not to need the explanation..hard balance to keep it simple vs accurate, and always looking for feedback to improve!
I feel sorry for those who need to be explaned...
Thts not how i would put in use
Attach block to the load
Attach one end of rope,cable. To anchor
Applly force to other end
You will travel twice as gar as load but half the effort 😮
I'm not getting the point of what you're saying because (I guess) I'm stupid. But I thought the point of using a snatch block is to make your winch not have to work as hard. So why are we focused on the amount of pull against the tree? In other words, why is the meter where it is instead of measuring the tension in the piece of rope connected to the winch? If I'm in a stuck car, I'd want to know if what I'm doing is making the winch's job easier or not.
Another stupid thing I'd like to contribute is: since the snatch block doesn't move then it only redirects, so how the heck is attaching the other end to an anchor contributing anything to the situation the vehicle is in? As I understand it, using a moving winch is when the advantage happens. Have I learned everything wrong?
Upon further reflection, maybe this is a demonstration of an incorrect setup. Because as I understand it, the moving winch needs to be attached to the stuck vehicle and this setup only pulls harder on the tree and does nothing to help the stuck vehicle.
You're not stupid. Understanding winching rigs means Understanding what not to do. And this is that, in response to a reader question. You can have a 2 to 1 advantages rig and thr block doesn't move check my other videos.
@@L2SFBC
Thanks for that. I was beginning to wonder if I had it all wrong. Now I'm curious about the 2:1 advantage without a moving snatch block. I'll look for your videos on that. By the way, in addition to full size equipment, I recently bought miniatures like you use to demo your setups, including a couple of weight meters. I plan on working out setups and learning more. I don't know why this fascinates me, but it does.
2:1 is when you run the return line back to the car. Block doesn't move, but car does.
You aren't increasing mass, you're increasing force. As in newtons, not kilograms
Probably what confused the viewer
Yes...should be newtons. But I use kg to make it more relateable
Your weight changed because you went from one line supporting the full load, to two lines supporting the full load, not because your angle changed. The correct test would be have an inline anchor not connected to vehicle.
Now if your test was to see if a vehicle mounted wench makes a difference, then yes the anchor on the vehicle matters.
this doesnt prove anything about increasing the pulling force of a winch. it only shows the distributed weight throughout the line.....
Newton third law
What’s confusing about your “explanation” is that you are not using the correct terms. The display of the digital scale is not showing weight , but force...it still only takes 5+ pounds of force to move a 5 pound object with a snatch block or off a single straight pull...the block just allows you to redirect it per convenient anchor point...
weight, force, mass, torque, power, load, work...these are all very specific terms engineers understand. The average person does not, so I often simplify.
Yes he is measuring load sharing across 2 lines which we see showing a 50% reduction in weight in both lines as they are sharing each of the total load. This doesn’t equate to a mechanical advantage it’s just a change of direction.
Yes, that commenter is wrong and the author of this channel is mechanically correct. They are still both semantically wrong. What is this "creating weight" nonsense? Weight is a measure of heaviness - it differs from planet to planet, even though an object has the same mass (which is a measure of inertness - in "weightlessness" objects are weightless but not "massless", but in most practical situations we tend to think of weight and mass as interchangeable, like speed and velocity). Pulley/block is one of "six simple machines" - a historic sign of civilization (along with "inventing the wheel"). To deny that pulleys provide mechanical advantage (aka "leverage") is to also deny wheel and axle, the lever, etc. And to deny human civilization. It is not "creating weight", or even changing it, it's merely splitting applied forces and sharing them across directions. Just like leverage. Words mean things, otherwise everything would be a dohickey or a whatchamajig.
You are confusing force at the pulley vs. mechanical advantage. I agree you have 6.2 Kg. But that is the force at the pulley. You have to have a moving pulley to have a mechanical advantage. The setup you show is simply a redirect.
This video was created to specifically explain that you don't always need a moving pulley to create MA...
l2sfbc.com/you-can-get-mechanical-advantage-from-a-snatch-block-that-doesnt-move/
Your physics is fine, Your terminology is a bit squiffy is all.
Squiffy!
Flat Earthers be like......🤨😵😮😰😱
Pulley Deniers 😥
@@L2SFBC Well played sir
witchcraft
Wizard you mean
@@L2SFBC t'was invented by no man
If you have the right mind set, these facts mean nothing. And at that point you can run
for governor, or prime minister, or president of the United States. In fact, you're qualified to
be a politician anywhere in the world.