Rigging Concepts in Tree Work Part 1: Compression, Vectors, Shock Load, Letting it Run...

hey what's up climber nation so today I want to take a look at a lot of the basics the underlying stuff behind the rigging systems that we use in tree works so I want to look at like compression versus tension forces versus vectors what a resultant vector is dynamic loading static loading shock loading letting it run just sort of all the underlying basic concepts that you need to understand before you can actually get up in a tree and get work done in a safe and efficient manner all right so let's dive right into that [Music] there's a be trapped in here okay so let's start with forces versus vectors okay I think everyone knows what a force is right so you know if you're pushing against something with 50 pounds that's a force right it doesn't it doesn't really describe things in in the real world pushing this way with 50 pounds is the same force as pushing in this direction or pushing down with 50 pounds do you know what I mean that's a force so a vector on the other hand is a force in three-dimensional space right it's a mathematical term a quantity represented by an arrow with both direction and magnitude yeah exactly yeah it's a force with both magnitude and direction in three-dimensional space so it it much more accurately describes the way that things work in the real you know three-dimensional world right so that's a vector versus a force okay the next thing is super important and tree work to understand is the difference between tension and compression okay so if we take a stick right and let's just pretend that this is a part of a tree that we're working on okay there are two ways to load that tree right you can load it in compression or tension okay so compression is by far by far the stronger way to load any piece of wood so compression is basically like you're not going to break this by pushing it in inwards on itself if that's compression okay tension on the other hand is bending right if we were to bend this right you can easily break it right and that's how you run into problems in tree work when you put a tension force on a stem or you're bending it that's how you snap reading points that's how you snap tie-in points for climbing it's super dangerous right so you need to understand that so the basic idea when you're designing rigging systems is you're always trying to design them in such a way that you're loading the stems in compression you're loading them so that they squeeze together on each other as opposed to bending apart from each other which makes them snap okay so that's the basic concept there you still with me okay so now that we understand tension verses compression and we understand the difference between a force and a vector we can look at the the next really important thing which is called a resultant vector okay so basically if you have a rope that's going in one direction over here and another direction over here right and it's through a rigging point the the the the vector that's being exerted on the tree is what we call the resultant vector and that will be halfway in between the two rope angles that are going into that reading point right now this is far far more easier to see when you're using a false crotch rigging point such as a block or a ring or whatever you're using as opposed to just natural crotch ringing it's just a lot easier to see so in this case like I have the rope is tied to the desk over here and then I'm pulling it in this direction okay so we have two vectors we have a force vector here on the rope and we have another one coming out of the rigging point but the resultant vector is somewhere half halfway in between and you can see it exactly in three-dimensional space by just looking at the rigging sling right though the sling will show you the exact direction that resultant vector is taking do you know what I mean so that is how the the stem here is being loaded it's being loaded in this direction right it's pulling it precisely this direction right so that's the resultant vector so as we're building our rigging points are rigging systems we're trying to figure out ways in which we can use you know the way use the structure of the tree and the ropes and the rigging points to tulo in such a way that we can load the stem as much as possible to be in compression again squeezing together as opposed to twisting you know or being being pulled apart right tension versus compression okay so that's the resultant vector that's a very important concept to understand for designing rating systems okay let's look at static loading so static loading is it's like the textbook perfect scenario in rigging it's like what we're going for all the time except in real tree work it's it's it's mostly unattainable but static loading would mean let's say we have a load here of five pounds and we're going we want to transfer that load into our rigging system okay in a static loading scenario it would be done very slowly very controlled right like that and that would be a perfect static load scenario and what it would mean that the rigging system would never experience more weight or more force than the load itself actually weighs so if this is a five pound load if I did it perfectly static the the rigging system would never experience more than five pounds okay now again that's a perfect textbook scenario highly usually unattainable in tree work okay so compare that to what we call dynamic loading which is more more you know what we can expect in tree work so dynamic loading involves things like swinging and you know it's it's more it's messy dynamic loading is messy you know what I mean and the end result of the messiness of it is that quite often the rigging system experiences more of a load than what the than what the piece actually weighs the piece that we're transferring into the rigging system okay so that's dynamic loading and you know again that is more typical of what we actually experience in day-to-day tree work okay and then if we look at overhead slash positive rigging basically all that means is when we have a load we have an overhead rigging point right it's it's above the load to be to be put into the rigging what that means when it's above it means that we can preload the rigging system we can take the slack out of the rope and we can get everything ready before we make that cut and the result of that is that there's less dynamic loading and there's less less shock going into the system right so the the system is still probably going to experience a bit more of a load than what the weight what the piece actually weighs but not not a crazy amount more right so in general whenever we're designing rigging systems we always design them we always favor the overhead or positive rigging scenario rather than the negative rating scenario okay so negative rigging on the other hand is basically we only use it really when we have to you know when there's no other way to do it okay so we use it for instance when we're blocking down the stem you know if we can't just freefall chunks of the stem to the ground we use negative ringing okay so negative rigging simply means that the rigging point is below the piece to be cut right so if I had a block down here let's say a block or a rings or whatever and I'm cutting this piece it's going to freefall right it's all slack it's free falling and then and then it goes into the rigging system and the rigging experiences that load okay so that's negative rigging and so again it's it's severe dynamic loading negative rigging is and what it means is that the rigging system is going to experience a lot more of a load than what the piece actually weighs okay so contrast that with shock loading what we call shock loading is like it's the most severe form of dynamic loading and again that means it's negative rigging okay it's negative rigging pieces falling free-falling with slack right it's gonna fall and it's gonna be caught into the ring and so there's been a lot of studies about negative rigging and you know there's a lot of published numbers that say as much as ten times or maybe even more that 10 times the the weight of the load of the piece being taken in a shock load scenario more than ten times is actually experienced in the rigging system meaning that you know if we were negative rigging a 100 pound piece of wood and shock loading it into our system the Rope and the rigging slings and hardware are going to experience up to 10 times or more of that load so so if that's 100 pound piece your rigging system could experience a thousand pound load okay and that is why we don't mess around with with- ringing and shock loading that's why we need to know what we're doing before we get into these scenarios and and that's why we need to take it easy you know what I mean and if it's a choice between taking a huge piece or two smaller pieces you know I'm always going to be in favor of taking smaller pieces in a negative Rigney scenario and then the last thing that I want to look at is the concept of letting it run okay and so basically when I say let it let it run when I'm when I'm rigging a piece and I tell my whoever's on the ground to let it run what I mean is I mean let it let the piece come off and move freely okay and then somewhere between where it's being cut and the ground somewhere being in between there you're gonna need to cushion it and bring it to a gradual stop okay that's that's a proper that's properly letting it run as opposed like it's not enough to just let it come off and go fast and then slam it to a halt down further further down the stem that's not properly letting it run that's still a severe shock load any time you bring something you know to a quick sudden stop a short drop in a sudden stop yeah right that's what stock load is okay bringing something to a quick sudden stop is shock loading and you know and it's wearing out your your rigging components but more importantly what you're really worried about is the tree itself you don't want to break your rigging points ever in a tree that's the most dangerous thing that you can do obviously okay so again letting it run the way that I think about letting it run is just imagine the piece that you're rigging imagine that it's an egg okay and if you were to drop an egg right the only way to catch it without breaking it is to cushion it right you got a cushion you got to catch the egg okay so that's what I mean when I say let it run I mean let it move naturally and then catch the egg it's good good sale it back okay so that's just a very brief overview of you know these basic ideas hopefully that makes sense hopefully you can get some value out of that and you know the next time you're in a tree you can think about these basic concepts and see how they apply and how they work and and and why they matter so much in in rigging in tree work all right so until next time Patrick [Music] [Applause]

Channel: EducatedClimber

Views: 58,227

Rating: 4.9093566 out of 5

Keywords: arborist, tree, work, climbing, chainsaw, rope, knots, ropes, knot, trees, arb, rigging, roping, educated climber, climbing arborist, srt, tree climbing, tree work, drt climbing, ddrt climbing

Id: aiZOp9qNsgs

Length: 12min 54sec (774 seconds)

Published: Sun Jun 21 2020