grcs tips?
- Thread starter RANDY10
- Start date
AmericanArborist
Participating member
- Location
- Omaha, NE
http://www.youtube.com/watch?v=b5JCezOemM8&list=UUo038fESSLb4Cma_eTVCANQ&feature=c4-overview
This is a video from a few years ago of us lifting a hackberry tree that split onto a roof. We got the trunk vertical and then cut it and lowered it back down. The rigging line I believe was a 5/8" line and went to a block for a 2:1 ratio.
Most all of the GRCS applications are going to be at least a 2:1 ratio since you are using it to lift with a block. 3:1 ratio you would put the block on the trunk and the limb and back to the trunk again. Hope this helps. Good luck on the storm work.
This is a video from a few years ago of us lifting a hackberry tree that split onto a roof. We got the trunk vertical and then cut it and lowered it back down. The rigging line I believe was a 5/8" line and went to a block for a 2:1 ratio.
Most all of the GRCS applications are going to be at least a 2:1 ratio since you are using it to lift with a block. 3:1 ratio you would put the block on the trunk and the limb and back to the trunk again. Hope this helps. Good luck on the storm work.
SRTsteve860
New member
- Location
- North West Connecticut
[ QUOTE ]
Most all of the GRCS applications are going to be at least a 2:1 ratio since you are using it to lift with a block.
[/ QUOTE ]
In normal orientation, GRCS on trunk, line up to a block in the tree, then line back down tied to a limb, piece of wood, etc, there is no MA from the block system, it is 1:1 with the only mechanical power coming from the gearing in the winch. In this orientation the block merely acts as a redirect.
-Steven
Most all of the GRCS applications are going to be at least a 2:1 ratio since you are using it to lift with a block.
[/ QUOTE ]
In normal orientation, GRCS on trunk, line up to a block in the tree, then line back down tied to a limb, piece of wood, etc, there is no MA from the block system, it is 1:1 with the only mechanical power coming from the gearing in the winch. In this orientation the block merely acts as a redirect.
-Steven
SRTsteve860
New member
- Location
- North West Connecticut
A 2:1 ratio would be the GRCS on a tree, line running up to the block, down to the piece to be lifted where it runs through another pulley, back up to the high block and either tied off up in the tree, or redirected down to the ground where its tied off near the GRCS.
AmericanArborist
Participating member
- Location
- Omaha, NE
My mistake. You are right about the ratio.
treehumper
Carpal tunnel level member
- Location
- Ridgefield, NJ
And this is why they teach applied mathematics and physics to arborists. When adding complex systems together you need to be really on top of breaking strength of your gear and how many cycles have been put on them, as well as green log weight. Do a rough calculation of the load to make sure it's within the capacity of whatever you have connecting it to the system and anchoring the system. While the GRCS strap is strong this is where slipping occurs if it's not set securely. Have at it but do your numbers first.
SRTsteve860
New member
- Location
- North West Connecticut
[ QUOTE ]
And this is why they teach applied mathematics and physics to arborists.
[/ QUOTE ]
Same physics as applied to structural engineering. Its amazing how so much of my education is applied to treework, and it is a great way to explain "unseen forces" to people who cant recognize those principals first hand.
-Steven
And this is why they teach applied mathematics and physics to arborists.
[/ QUOTE ]
Same physics as applied to structural engineering. Its amazing how so much of my education is applied to treework, and it is a great way to explain "unseen forces" to people who cant recognize those principals first hand.
-Steven
Norm_Hall
New member
- Location
- Wauconda, (Chicago),IL,USA
[ QUOTE ]
Thanks guys! Yes , 2to1 even 3to 1 applications for lifting and securing large pieces. Storm work has brought out more creative rigging situations, than ever before with the grcs.
[/ QUOTE ]
Here is a 2 to 1 MA system with the running rope at the anchor at an approx. 60 degree angle. The forces will increase as that rope angle decreases.
Thanks guys! Yes , 2to1 even 3to 1 applications for lifting and securing large pieces. Storm work has brought out more creative rigging situations, than ever before with the grcs.
[/ QUOTE ]
Here is a 2 to 1 MA system with the running rope at the anchor at an approx. 60 degree angle. The forces will increase as that rope angle decreases.
- Location
- Portland, Or
I usually set up a redirect on the tree I am working to another tree that is not being worked on. Usually because we are taking bigger pieces and I like the idea of the grcs or people not being in the impact zone. Also tip tying on codominate stems so if it gets snagged up you don't have to operate underneath it.
[ QUOTE ]
I usually set up a redirect on the tree I am working to another tree that is not being worked on. Usually because we are taking bigger pieces and I like the idea of the grcs or people not being in the impact zone. Also tip tying on codominate stems so if it gets snagged up you don't have to operate underneath it.
[/ QUOTE ]
Super solid advice. Anytime you can do that you should.
I usually set up a redirect on the tree I am working to another tree that is not being worked on. Usually because we are taking bigger pieces and I like the idea of the grcs or people not being in the impact zone. Also tip tying on codominate stems so if it gets snagged up you don't have to operate underneath it.
[/ QUOTE ]
Super solid advice. Anytime you can do that you should.
SRTsteve860
New member
- Location
- North West Connecticut
[ QUOTE ]
I usually set up a redirect on the tree I am working to another tree that is not being worked on. Usually because we are taking bigger pieces and I like the idea of the grcs or people not being in the impact zone..
[/ QUOTE ]
Be careful when you do this, as the redirect can bring alot of laterial loading onto a tree trunk, both off your redirect spar as well as the terminal rigging point on the tree thats being worked on. A trunk can take a huge amount of weight when loaded along its length, in line with the trunk. But it will take a much smaller load to cause problematic loading when perpendicular to the trunk, if there are any weak spots in the trunk between the blocks an the GRCS failure can occur, or because of leverage forces, the whole redirect tree could possibly fail depending on root plate condition, something that can be very hard, or impossible to judge on day to day jobs. If real big pieces are being taken, guy lines would be a good idea to sure up that redirect pole from any major deflection.
just something to watch out for!
-Steven
I usually set up a redirect on the tree I am working to another tree that is not being worked on. Usually because we are taking bigger pieces and I like the idea of the grcs or people not being in the impact zone..
[/ QUOTE ]
Be careful when you do this, as the redirect can bring alot of laterial loading onto a tree trunk, both off your redirect spar as well as the terminal rigging point on the tree thats being worked on. A trunk can take a huge amount of weight when loaded along its length, in line with the trunk. But it will take a much smaller load to cause problematic loading when perpendicular to the trunk, if there are any weak spots in the trunk between the blocks an the GRCS failure can occur, or because of leverage forces, the whole redirect tree could possibly fail depending on root plate condition, something that can be very hard, or impossible to judge on day to day jobs. If real big pieces are being taken, guy lines would be a good idea to sure up that redirect pole from any major deflection.
just something to watch out for!
-Steven
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