Which is most efficient - snatch block or snatch ring?

[Music] so ever since four drivers have had winches we've also been using pulleys such as these snatch blocks to gain mechanical advantage or simply to redirect rope and that's the way it's been for many years but now these snatch blocks are being supplanted by these new snatch rings typified by this one from sabre and this one from factor 55. i've already put a video out explaining how to choose the best snap ring for you and this time i'm going to be looking at an important question efficiency so efficiency is how much energy you lose when you are using one or more pulleys so let's say that we've got our casualty stuck here and it's going to take a force of 2000 kilograms to shift it so we're going to do a double line pull we're going to run a winch line up around the snatch block and back down to the vehicle we're going to attach that snatch block to a winch anchor point and again that's going to take force of 2000 kilograms now in a perfect world we would have a force of a thousand kilos on each one of these lines however it's not going to be perfect reason being that there is going to be friction in the snatch block and that rope is going to form and deform as it goes around so it's going to take energy to turn it and it's that amount of energy which is the efficiency we're interested in so let's say that it takes a thousand kilograms exactly it's not going to be the case that would be 100 if it takes 100 2050 we could call that 95 percent efficient or a five percent loss eleven hundred we could call that ninety percent now another way to look at is mechanical advantage if we had a thousand kilograms here then that would be an exact two to one mechanical advantage and that's actually how i explain this stuff i pretend that there's no friction loss in it because it makes life easier and for a conceptual understanding that works fine but this is reality we're talking about now now if we had a 1050 force here that would actually be a 1.9 to 1 mechanical advantage and 1100 would be 1.81 mechanical advantage so that's what we talk about when we mean efficiency which is the friction loss in the pulley okay this is how i set up the test rig so again we've got our casualty here winch line and then that's our winch rope when you connect it to a load cell in blue here and then would take a winch extension rope and run that round the snatch block and back down to the vehicle and anchor at the top but we put a load cell at the top there as well now what this allows us to do is take a look at the total force required to move the vehicle which is on the top load cell here and the force required by the winch which is this one and you can only really do that with two load cells because we're not really that interested in the total force it's more what we're interested in is the ratio between this one and that one now if you do it with one load cell what you could do is just first of all winched the carp a couple of times and then take a measurement and then put your load sold in and take a measurement again i found that to be less accurate the reason is that in the real world with four wheel driving it's it's hard to get an exact measurement consistently every time you winch across a given track um you know the winch right might go on the drum slightly differently or there might be a little stone in the way there's all sorts of variables there but if we do it this way using two load cells then that variable is removed because you're simply looking at the percentage between each two of them now another complication with rigging was this load cell here normally when you run a double line pull you just take your windship out round the pulley and back down to the vehicle easily couldn't do that in this case because we had the load cell underway and the load cells obviously only go around the pulley and we don't want it to because we're actually trying to measure the force in this line and then the complicating factor is that this is a two to one mechanical advantage so for every meter this moves forwards this vehicle moves forwards two meters come in so it ends up looking like this and the snatch block travels from there to there and you can see there's hardly any winch line um left and that's not a huge amount of distance so we had to get start the load cell as close to the snatch block as possible now the way i did that was just run the winch line out put the load cell there then use a winch extension rope across the snatch block and down now winch extension ropes don't go into a drum so you've got to vary their length and i did that using an x locks which you'll see in the videos round air shorten it and it worked so here's how the load cells work that's the cell itself and it's connected by two 12 ton shackles to whatever load you want to put in i've only put one 12 ton shackle in there at the moment now the load is measured and that is sent by bluetooth to an app on a phone such as this you can see it's reading naught kilograms at the moment and if i was to pull that you can see that we're actually generating some force there only just a little bit now that's logging every second and what i can then do is actually generate it into a report so here's a report i created earlier on so we go here this example some of the previous load testing done so we just go into this one and you can see there that that's a time stamp of um the exact time zero kilometer zero kilograms and you can see the light sort of building up there as well then what i do is i export that into excel then i can analyze the data build graph submit create averages do formula calculations etc and that's how the load cell testing is done before i did any tests i wanted to calibrate the cells now they're already calibrated at the factory then they're shipped over from the uk to the australian distributor and they checked and calibrated them again and then they gave them to me and that's the test certificate now i've got i've got two of them one for each one but i wanted to do my own as well and this is what it looked like so i took um the cells and i connected them in a sequence to a tree and then just um pulled on them and made sure that day basically read the same so you can see there that's the first cell went up to about 3 300 kilograms pool there and then that's the second cell and then there's a very close overlap there now it's interesting that to some extent it's actually slightly time offset um that's because obviously the cell nearest the vehicle took up the load first then faction afterwards the second one what that does tell me though is that you're just going to be wary of that and it's only per second it's not per tenth of a second or something like but nevertheless i think this shows that the two cells read identically so therefore the results are valid so we've got nine units on test and representing the snatch rings they are the sabre factor drifter george 4x4 camp boss red winches and from the snatch blocks we've got this red rider which i bought especially for the test an arb one which i've owned for many many years and this one here and i forget even who made this one um but um it's even older and i've actually gone and deliberately left out in the rain so it just gets as rusty and as inefficient as possible so we got one load cell on the anchor one load cell on the winch line and both of those run all the way back to the test vehicle which has got a shortened winch light extension attached to it and there is in action now for this test we just left a patrol in drive but we didn't give it any extra revs so the winch is doing the bulk of the work here's our data logging setup as you can see we're well out of the way of any potential problems with the winch rope snapping now in these shots of the various pulleys you can see that the load varies and that says the car goes up a hard bit more difficult bit etc and that's just normal for full drive winching so i wanted to just replicate that and just see what sort of results came out now one problem we had with throughout the testing was that sometimes a rig would be made and then the load cell would drag on the ground and that was okay initially but needed to get off the ground and stay there so that the dragon of the load cell didn't have an effect because that was obviously another variable it didn't want in the equation so it took a bit of rigging to get out of the way so here's to first results i'm not going to run through every single combination of snatch block and snatch ring i'm going to summarize that at the end but i'm going to show you the results of each test using the arb snatch block which is representative so this blue line here represents the total load on the anchor and the green one represents exactly half of that or a perfect two to one mechanical advantage pull the orange line represents the actual force on the uh winch line and you can see it tracks very closely indeed and difference between the green and the orange is the friction or the efficiency now you also noticed on this it's really quite jagged and that's kind of the reality or for drive winching it's not a smooth operation when you start to look at the loads there many different reasons for that obviously the terrain itself makes a big difference even just a small little pebble just half the size of my fist can actually increase or decrease the load you've got rut you've got where the steering was turned you've got different levels of voltage amps going to going to the winch to which rope going on the drum lots of factors make a change to the load and that's what you see here it's not a particularly consistent load nevertheless these purple areas here i was able to analyze those as which was rested there and have a closer look at that and that allowed me to to start to generate some numbers to figure out the efficiency so for the next test i selected an easier simpler hill a bit shorter as you can see here still enough that the ranger lost traction trying to get up it so it's still a reasonable test and i winched this one with the car in neutral not driving it at all so the pool for the second test anchor point tree trunk protector going over those logs and i'll explain why they're there in a moment there's the load cell for the measuring the anchor force and there's a all the cells and so all of the rings and everything on test there's the second load cell measuring the winch load and then it runs back to the vehicle and you can see down the left i've shortened the winch extension rope to to suit now those logs are there to lift the whole rope and extension off the ground because i don't want it dragging on the ground because that will throw the load cell results off and to be honest it's pretty good practice anyway you can see there that the ropes are pretty close to the ground and i don't want them rubbing on the ground that's why i've arranged those logs to lift them up and you can see that the load cell is now nicely into the air as the load is recorded so i put a few clips here of snatch rings and pulleys going from no load to full road and you can see that there's a fairly significant stretch on it which is just basically the inbuilt elasticity in the system of which there's always some and also the rope never really pops out of the snatch rings either which is fine um what i have been careful to do is take the slack out of the system before i start pulling it in and also you'll notice that there's a small pause um before i put full sort of force on it and that's because that's always good practice just to check whenever you're doing anything winching that once you've got a little bit of tension in the system it's all good then you can go for full tension and here's what a shackle looks like and the rope direction is set so it doesn't undo the pin not recommended i just was interested to see what efficiency it would be all right the second test same thing again you can see that's the total anchor load there and then that's exactly half of that that's our perfect two to one mechanical advantage pool and orange is the um load and winch load and then the purple is when i was winching resting the winch winching again resting an atmosphere lying down so i took those areas there as a nice consistent increase in decrease of load so for test three this is on the flat there's the anchor point there's the load cell measuring the anchor force there's a test unit which is not got a slap taken out of it yet that load cells measuring the winch force and then we go all the way over to my car and i've taken all the winch line off it so that i stress my winch at least and i've shortened the winch extension rack with this x locks as you can see there there is no it's glowing so that is connected to the vehicle and all i'm doing is you can see it's basically just locking the brakes and putting it in and that's what it looks like you can see the load starting to build up there and you can get over two tons of load pretty easily that way so so for this test what i did was just lock the brakes and pulled a car that generated a force of about two tons and i winched for about 38 seconds which gave me a solid 30 second run of just pure load and i could use that to compare [Music] efficiency so this is what a snatch ring looks like when you're putting some load on it you see it's gone from just complete slack to loading it if it hasn't fallen out it's really been fine so here's the george 4x4 ring which has got the shallowest flange and arguably that's the one which would have most risk of the rope coming out of the shave but as you can see it works just fine so this is why it's always a good reason to have lots of shackles and connector type things i don't want to put the soft shackle around that really sharp edge on the metal snatch block um so i've used that 4.75 ton shackle instead but that metal shackle won't go around a big 12-ton shackle on the load cell so i've used a soft shackle to connect the two okay third test now and again that's the total anchor load that's the perfect half load and that there is the representative load of a of the winch load and that's the area which i took as a example for calculating the efficiency purposes so what i've done here is i've summarized all of the results of the blocks and the rings in one go and that is across all three tests plus a couple more which i haven't detailed before i started doing those three main ones so the first one here that represents the perfect solution a two to one mechanical advantage which you'll never get but the idea is to get as close to that as you can now the most efficient was amazingly enough the crap block which i just left out in the rain and i've owned for over 20 years a surprise but there you go it just did consistently edge ahead the next most efficient very close was the arb um again i've owned that used that for quite a period of time but not give it giving it really any special maintenance and then the first of the rings came through and the george ring was actually the most efficient a bit of a drop from the two blocks but um yeah still still um quite quite up there and i've put the rings in blue and the blocks in yellow then um the ridge was actually less efficient and the ridge consistently was behind the other two blocks so i don't know if it's particularly representative but maybe it is maybe it isn't but i did just buy it off the shelf for this test and um so i'm glad to have it in there then the rest of the rings started to come through and you can see that they're all pretty much down there about and the shackle itself um actually quite a long way off compared to the rest now the interesting thing here is if i put this red line up that is actually the best and worst um there's not a massive difference between the very best performing and very worst performing and d numbers are down here so you can see that i've just actually rounded it to one decimal place which is why they look um identical but i think with the equipment i had one decimal places is going to be finer if there's any point going to three or four so you're looking about sort of one point eight one one one point nine um four d blocks and the rings you're looking at sort of one point seven one point in the shackles right down there at 1.5 basically what this says is that everything can do the job of being a pulley in a mechanical advantage situation when you are winching with the exception of the shackle which is too high friction but even in that that's not completely off to table however i do want to stress that having high efficiency is not quite the same as having a minimal wear and tear effect on your equipment and you know the soft shackle will get worn a bit by the ring over time that's not really going to happen so much of a snatch block and i do think that the rings treat the their soft shackles and their ropes differently regardless of efficiency so here's our average mechanical advantage what i've done in this one is i have again um said that's perfect two to one and i've taken the results of all the blocks and all put them together as one and all the rings and put them together as one so that's the average result of the blocks and that's the average result of the rings and there's the shackle and you can see there that um the average result for the blocks is 4.5 percent and average mechanical advantage 1.83 to the ridge one sort of dropped that down a bit um and for the rings at 7.5 percent average mechanical advantage 1.74 and the shackles 18 mechanical advantage of a bit under 1.5 so if you're doing calculations out in the field the figures i would use i would work on with a snatch block of a five percent efficiency loss or increase depending which way you're going to look at it and for a ring i'd go for 10 i think those numbers are easy to work with for mental math certainly for me anyway and i think that they also give you a fairly nice margin of error without being overly cautious or completely unrealistic so to put this in perspective what i've done here is i plotted on this red line a force going from 500 up to 5000 kilograms i've called out the stuck force now this green line is exactly half of that and that represents how much force you would need in a perfect two to one mechanical advantage where you are putting in half the force but it's going to take you twice the time this yellow line represents how much extra force you'd need with the block and you can see it's really not that much at all in the grand scheme of things and the blue line represents the extra force again with a ring so what that is saying that yes blocks are more efficient than rings but not so much that it's going to stop you using a ring and here's the numbers to go with that you can see that in with a thousand kilos um ideally you'd want a 500 kilogram force that's of zero friction with a block you're looking at more like 523 kilograms a ring 537 we go down to five feet let's say a 3 000 kilogram pool now that is a lot of force to an average four-wheel drive wearing three or four tons you'd rarely be winching with that amount um but that would be 1500 kilos perfect but 1568 river blocks so you're losing 68 kilograms or rather having to add an extra 68 kilograms worth of force um effort there 16-11 with with the ring so again that's not going to make the difference between you getting out or not getting out and if it does if you've got a snatch ring they're so cheap and and light and easy rig yourself a triple line pull if you're not sure how to do that have a look at my other videos so i had a look around to see who else has done this sort of testing and i found this study by the bush walkers wilderness rescue squad and it's a pdf fairly detailed and here's what they've done they've got an anchor and they've got a load 80 kilograms which represents a presumably injured bushwalker and then they're going to raise that using a pulley they're going to measure the efficiency of that pulley which is basically pretty much exactly what i'm doing just on a larger scale much greater than 80 kilograms now here's what they do 80 kilogram load and they raised at 5 meters per minute which i've calculated to be eight centimeters per second and here's what they tested all of these different blocks and pulleys and i've categorized them as pulleys with a bearing which is similar to our snatch blocks and a non-bearing pull it's a carabiner with a kind of a sheave around it which is kind of analogous to our soft shackle and rings and then they just use a plain old carabiner which is equivalent to to my shackle test so those are the three types which i've taken out of that lot there now the results were they found this to be a 1.81 ma armed up to be 1.7 and 1.5 and i've calculated that by going through their results and just averaging the whole lot there so basically what they found is that the non-bearing ones these um are sort of twice or half as efficient as the ones with bearings and ender pulley is is about a third is efficient again so that's pretty similar to what i found what i did notice is that i found the blocks to be more efficient than theirs and i think that's because the more load you put on it you almost kind of get an economy of scale if you imagine that you had a load of five grams either side well you might need to go to 10 or 15 grams to move anything but once it's moving then you actually get quite a good load so i think that's probably where it comes from but the sort of percentages they're getting relative to these three i think are pretty consistent with what i've found this test isn't directly relevant for driving but i thought it'd be pretty interesting anyway so i've got the arb block and i've got the fact 55 ring and i've done this for all of them and i've just hung identical weights off either side five kilos five kilos five kilos five kilos and i've got a bucket here at either end and then i'm just going to take this water jug and fill these buckets until such point there's a counterbalance here and then the rope starts to move down so let's see what happens so that's an interesting difference between the two with the blocks what we find is that once it reaches that tipping point it sort of goes bang and it very quickly sort of moves down there's nothing and then all of a sudden it will balance whereas with the rings and factor 55 is representative here there isn't that immediacy what happens is that it will start to move down and start to move down very very slowly and it won't really speed up so here's the results of the water test and interestingly the most efficient was the george which only required about 1.1 kilograms of water before it started to move and ended drifter then the saber the red and what you notice here is that these are all the snatch rings and they soon to be outperforming the blocks in this case which is really quite interesting um and then again the old crap block just came steaming through there then the arb and the camp boss and in the region in the fact 55 was the least now obviously this is not a particularly relevant four-wheel drive test because it's only 10 kilograms of weight i'm really including it here because i thought it was interesting to to do so hopefully you find it interesting as well i also find it interesting the way that those two moved and that the snatch blocks moved very slowly first was the blocks just really well straight down all right so a few conclusions to work for at the end of this um the first one is that rings are half as efficient as block order batch which sounds terrible but to be honest the difference is so small that in practice it really doesn't make that much of a difference and rings have advantages they're a lot cheaper lighter and less bulky so i think they really are a good way to go for using pulleys when you're winch rigging efficiency is not the same as soft shackle where i think that you might be able to have a fairly efficient ring yet it has a relatively large effect on soft shackle again it's based on on on the testing that i've done there probably need to explore this a little bit more in in further detail and the rings do where the shaft shackles but that doesn't seem to be a problem for recreational stuff we just don't do enough heavy duty winching for that to be a problem there and finally the reported issue of rope falling out of the rings hasn't really happened i think if you just take your usual care when you're doing winch rigging and make sure everything's tight before you start to pull it in and then do a final check after you put a little bit of tension in before you start really starting to apply that that load you're going to be fine so you can never do enough testing and i still have questions i'm sure you do drop them in the comments and we'll see what i can do to answer them but things like does the soft shackle make a difference i kind of feel not because based on the testing so if i've used the different ones there didn't really see a massive difference between the shackles but i haven't tested it specifically does it change over time well definitely the soft shackle changes over time but i don't think the efficiency changes because the early tests i did even before the three that i showed i did more before that it's kind of test tests um that hasn't really changed the results over time does the diameter of the right you know 8 10 12 mil make a difference um it would do but i don't think i've got the equipment sensitive enough to really measure it uh triple line pull this is something i'm going to look at there i'm interested to see the efficiency using uh two or more pulleys as opposed to just one and also the effect of mud dirt and wet and i'm going to find some good leaded mud probably and immerse them in mud and see what difference that makes both the efficiency is definitely going to go down for sure um but will the block be more affected by the ring i don't know so look um i will get into more of this later on if you've got any views comments what you'd like to see um please put them in the comments so thanks for watching hope you found this video useful and i'm going to be doing a fair bit more of it so please continue to subscribe like patreon etc so i try and sort of put some science and facts and research into full driving and rather than just sort of rely on what people have said down the ages

Channel: L2SFBC - Robert Pepper - auto journo

Views: 60,956

Rating: 4.8742394 out of 5

Keywords: 4WD, 4X4, offroad, snatch blocks, snatch rings, recovery rings, snatch ring efficiency, pulley efficiency, factor 55 rrp, saber recovery ring, drifta recovery, red winches recovery ring, george 4x4, snatch block test, winching techniques, snatch block vs snatch ring, snatch block, winching safety, snatch blocks explained, off road winching techniques, double line pull, snatch ring, factor 55, winching tips and tricks, soft shackle, snatch block mechanical advantage

Id: rdlRRAbzCzA

Length: 29min 17sec (1757 seconds)

Published: Wed Jan 20 2021