Can an ARB tree saver strap be used as a bridle between 2 recovery points? (1 Viewer)
- Thread starter Sverige
- Start date
This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.
Josie'sLandCruiser
Stop calling it a "FJ."
Hi All,
Sverige, I can't think of any reasons why this would not be perfectly safe to do.
Regards,
Alan
Sverige, I can't think of any reasons why this would not be perfectly safe to do.
Regards,
Alan
Mark W
Yep, it's true. I just don't care that much.
How long is it? You can create a tremendous amount of force pulling the two attachment points together unless you have a long "bridle". Generally speaking you are better of to use a single attachment point.
Mark...
Mark...
yup, gut feeling is that if the angle made by the bridle at the tip of the triangle it forms -where you'd attach the pulling cable to the bridle- is more than 90deg, IOW if it's "short", the force pulling the 2 recovery points (frame?) together will be more than the axial pulling force, and the force / stress in the bridle itself more than than the 2 of them. So if you were to pull axially with a force equal to the nominal "break load" of the bridle, it'd be exceeded in the bridle with possibly nasty results. (I'd go and do a force diagram to double check all that armwaving, but it's too late at night here... 
)
)I've been wondering the same thing. The 100's are heavy beasts and I've been contemplating ways to reduce stress on frame componants and recovery points. A long bridle seemed like a good idea to me but I couldn't find much information anywhere about the pros and cons of using them.
With a 16' strap, 8' on each leg, and with a recovery point spacing of about 3' that makes the angle at the hook between 20 and 21 deg's.
It seems that this would lessen the load on each recovery point even though they are being pulled together slightly.
Consider the load on the frame and especially the recovery point bolts when you are doing a hard side pull when using only one recovery point. I would think sharing the load over two recovery points would be a better way to go as long as the frame is braced so it can't compress together and a long enough strap is used?
What do you think about the 20 deg. angle as far as strap load?
I'm not sure how to compute that.
One more question about using a strap for this purpose. Do you think a trianglar steel ring (not sure what they are called) slid on the strap to hook on to would help protect the strap as it would then be just a smooth straight line bend for the strap rather then a crumpled sort of bend as would happen running it through a hook or shackle?
Thanks and sorry for the Hi-Jack
cp
With a 16' strap, 8' on each leg, and with a recovery point spacing of about 3' that makes the angle at the hook between 20 and 21 deg's.
It seems that this would lessen the load on each recovery point even though they are being pulled together slightly.
Consider the load on the frame and especially the recovery point bolts when you are doing a hard side pull when using only one recovery point. I would think sharing the load over two recovery points would be a better way to go as long as the frame is braced so it can't compress together and a long enough strap is used?
What do you think about the 20 deg. angle as far as strap load?
I'm not sure how to compute that.
One more question about using a strap for this purpose. Do you think a trianglar steel ring (not sure what they are called) slid on the strap to hook on to would help protect the strap as it would then be just a smooth straight line bend for the strap rather then a crumpled sort of bend as would happen running it through a hook or shackle?
Thanks and sorry for the Hi-Jack
cp
The angle formed between the two lines should not exceed 120 degrees (see attached). There probably isn't a huge argument for not using the tree strap per the OP's question assuming the strap is in good condition and rated for the task.
However a "basket" type sling arrangement would be more typical for this type of usage or two individual straps.
I'd use a suitably sized and rated D-type shackle with the bow portion interfacing with the sling/sling loop ends.
As I've suggested countless times: For about $20 everyone should buy, read and understand Jerry Klinke's "Rigging Handbook" (now in its 4th edition). A worthy investment for everyone's safety.
http://www.amazon.com/Rigging-Handb...d=1363624192&sr=8-1&keywords=rigging+handbook
However a "basket" type sling arrangement would be more typical for this type of usage or two individual straps.
I'd use a suitably sized and rated D-type shackle with the bow portion interfacing with the sling/sling loop ends.
As I've suggested countless times: For about $20 everyone should buy, read and understand Jerry Klinke's "Rigging Handbook" (now in its 4th edition). A worthy investment for everyone's safety.
http://www.amazon.com/Rigging-Handb...d=1363624192&sr=8-1&keywords=rigging+handbook
Last edited:
Tapage
Club 4X4 Panamá
the first think blinking on my mind it's what happen if the force ( as it used to be ) it's not perfectly applied over the 2 recovery points .. I mean we are seen the triangle with the force being applied with no angle .. but most of cases ( if not all ) force can't and won't be perfectly aligned ..
Then we will have one recovery point under more stress than the other one .. I honestly will keep the idea of using one recovery point at time and picking the best one angle wise ..
Then we will have one recovery point under more stress than the other one .. I honestly will keep the idea of using one recovery point at time and picking the best one angle wise ..
^ this is why the "basket" method works better for this application. Just pay attention to how the tree saver/strap interfaces with the screw shackles attached to the recovery points on the rig. If the strap rests near the anchor screw it can be abraded...this would be a good application for a rated ring, attached to the screw shackles, to smooth out the transition/movement of the sling relative to the screw shackle.
Good info here...including WLL reduction with off-90 degree rigging.
http://www.fdlake.com/rig-slng.html
Good info here...including WLL reduction with off-90 degree rigging.
http://www.fdlake.com/rig-slng.html
Mark W
Yep, it's true. I just don't care that much.
Actually a basket hitch is usually a poor choice for vehicle recovery.
The "leg" of the strap that runs between the two attachment points will add the full power of the pull to pulling the two points inward toward each other. In addition to whatever inward force the angle of the legs creates.
Looping the bridle is not what you want to do.
Use it to form two separate legs if you use it at all.
If you allow the attachment point of the winch line to float... To slide along the bridle instead of securing it somehow in the middle, it will self adjust and compensate for odd angle pulls maintaining equal force on each leg.
Unless you are forced to use inappropriately weak attachment points, a bridle is seldom needed or beneficial for a winch recovery. And is almost never a good idea for a dynamic/inertia/snatch recovery.
Mark...
The "leg" of the strap that runs between the two attachment points will add the full power of the pull to pulling the two points inward toward each other. In addition to whatever inward force the angle of the legs creates.
Looping the bridle is not what you want to do.
Use it to form two separate legs if you use it at all.
If you allow the attachment point of the winch line to float... To slide along the bridle instead of securing it somehow in the middle, it will self adjust and compensate for odd angle pulls maintaining equal force on each leg.
Unless you are forced to use inappropriately weak attachment points, a bridle is seldom needed or beneficial for a winch recovery. And is almost never a good idea for a dynamic/inertia/snatch recovery.
Mark...
You're right on that one.. We use this as a climbing anchor that self adjusts for angle and minimizes the forces during side loading.. many climbs zig/zag if you will, and you are all over the face (within reason, say 4-6 feet off center). it helps to centralized the load over two anchors.. or three or whatever number you use.
A basket hitch would be fine. You NEVER thread any sling, steel or synthetic through the attachment point. NEVER NEVER NEVER.
A basket hitch would entail one sling with the two eyes each attached to the anchor points of the vehicle and the recovery line attached onto the middle of the sling.
A "bridle" is two slings attached at one end with a ring or shackle. Basically the same as the basket, but there are two slings attached at one end forming a third attachment point.
If using wire rope slings in a basket hitch you have to take into account the D/d ratio also. I am assuming you are using synthetic though so i won't confuse you too much....
Angles need to be specified, are you talking about the included angle ( the inside angle where the two slings come together) or the leg angle ( angle from the horizontal to the single leg?
As was stated before it is a good idea for anyone doing winching and recovery to read a rigging handbook. They even come in pocket size. There are many factors and variables in rigging. There is nothing that will replace experience and training. But a good rigging handbook would be a good place to start.
A basket hitch would entail one sling with the two eyes each attached to the anchor points of the vehicle and the recovery line attached onto the middle of the sling.
A "bridle" is two slings attached at one end with a ring or shackle. Basically the same as the basket, but there are two slings attached at one end forming a third attachment point.
If using wire rope slings in a basket hitch you have to take into account the D/d ratio also. I am assuming you are using synthetic though so i won't confuse you too much....
Angles need to be specified, are you talking about the included angle ( the inside angle where the two slings come together) or the leg angle ( angle from the horizontal to the single leg?
As was stated before it is a good idea for anyone doing winching and recovery to read a rigging handbook. They even come in pocket size. There are many factors and variables in rigging. There is nothing that will replace experience and training. But a good rigging handbook would be a good place to start.
This is on the right track here, but the depiction and wording are wrong. I don't know if this came out of a rigging handbook or not, but i have never seen the angles referred to like this.
The angle we are talking about is the "included angle" the other side of the arrow. Which is 60 degrees. Better referred to as the lift angle.
So for example:
60 deg angle 1000 lb load each leg will see 575 lbs
45 deg angle 1000 lb load each leg will see 705 lbs
30 deg angle 1000 lb load each leg will see 1000 lbs
30 deg is the obvious angle you do not want to exceed, forces increase greatly below this
5 deg angle 1000 lb load each leg will see 5735 lbs.
While 30 degrees is the do not cross line good rigging practice dictates not exceeding a 60 degree lift angle.
Clear as mud?
Of course we are only talking about the load on the slings, not the recovery point on the vehicle. But with a properly rated sling and nothing less than 60 degrees, you should be fine.
If you want any more explanations feel free to ask. Got my handbooks handy, and I have been rigging and hoisting and come-a-longing etc for more than a few years. Been on a few 100 ton + lifts.
Mark W
Yep, it's true. I just don't care that much.
Yep, in agreement with this.
However it seemed to me that when it surfaced in this discussion, the term "basket hitch" was being used to mean one strap threaded through two attachment points and back to the winch hook. Bad bad ideas, as we have both said.
What your refer to as a basket would be functionally the same as what you call a bridle, with the added benefit of maintaining equal loading on each attachment point if the angle of the pull changes.
Regardless, it comes down to, never never loop, keep the legs of the bridle or basket as closer to parallel as you can, and if you can, stick with simple rigging and a single attachment point.
Mark...
- Joined
- Nov 6, 2006
- Threads
- 62
- Messages
- 1,595
- Location
- Boulder County, Colorado
- Website
- www.adventuretoolcompany.com
Excellent read...thanks
Ok...I don't see the inherit problem with using a suitably rated and rigged sling as a choker or basket sling in a static type recovery event between two rigs and/or 1-anchor and a rig where the connected points are: Between the recovery line and two frame or bumper mounted rated recovery anchor points on the recovery vehicle (assumes <30 degree included rigging angle and suitable attachment rings at the bumper side). The need for this type of rigging assumes the forces are great enough to warrant spreading the load to more than one anchor point. In reality, based upon most if not all the recovery situations I've been involved in this extra step, if you will, is not warranted. So this question is more theoretical...
The advantage would be spreading the load between two anchor points of the frame...which seems to be a good approach rather than isolating the stress at one frame anchor point. And maintaining equal tension on each leg of the hitch along with maintaing a consistent included angle at the winch side.
^, like most recovery situations, this isn't a universal panacea but yet another tool in your recovery tool box if the need arises.
Note: I'm not 'arguing'...just trying to better understand.
Agreed: Measuring the included angle (keep to <30 degrees) might be simpler and potentially more accurate than measuring the wider angle created between the bumper and the recovery line when a sling is utilized. Either way: Its the same angle measured at a different reference point.
This is also a good link to bookmark: http://www.pirate4x4.com/tech/billavista/Recovery/index.html
The advantage would be spreading the load between two anchor points of the frame...which seems to be a good approach rather than isolating the stress at one frame anchor point. And maintaining equal tension on each leg of the hitch along with maintaing a consistent included angle at the winch side.
^, like most recovery situations, this isn't a universal panacea but yet another tool in your recovery tool box if the need arises.
Note: I'm not 'arguing'...just trying to better understand.
Agreed: Measuring the included angle (keep to <30 degrees) might be simpler and potentially more accurate than measuring the wider angle created between the bumper and the recovery line when a sling is utilized. Either way: Its the same angle measured at a different reference point.
This is also a good link to bookmark: http://www.pirate4x4.com/tech/billavista/Recovery/index.html
Last edited:
Correct. You are distributing the load. You are also able to use a smaller sling in a properly rigged basket or bridle then you would have to use in a single leg.
For example:
A typical nylon sling 1" wide A typical nylon sling 2" wide
vertical 1100 lbs vertical 2200 lbs
choker 880 lbs choker 1760 lbs
basket 2200 lbs basket 4400 lbs
As far as the angle and where to measure.....Like I said earlier you weren't necessarily wrong. In fact you were right.
Something like this just needs a standard way of measuring and relating, that way people don't get confused. Neither way would really be anymore accurate, both angles are correct as they are inverses of each other in regards to the horizontal plain. We just need a standard. Some rigging books I have seen and used refer to the angle at the top of the triangle. Mostly older books. In the newer books and in general practice the lift angle( angle from horizontal to the lift leg, inside the triangle if a two point lift) is used.
Just want to keep everyone on the same page and lesson confusion. (I may need to start using diagrams and tables if this goes any farther)
This is a fun thread! I hope no one takes offense or gets their panties in a bunch.
I am by know means the absolute authority on rigging, but every now and then a topic comes up that someone knows a great deal about, has extensive experience in, and is somewhat passionate about. I am only trying to be helpful and informative, and valid arguments are welcome!!!!!
I like and now prefer to measure the included angle as you fabriwelder pointed out. This method automatically accounts for non-centered winch/pulling side angles of the sling.
Yes...very good and valuable discussions here!
Yes...very good and valuable discussions here!
Ok - had the same question as the OP and decided to start looking for a bridle when I came across this thread.
If I understand correctly:
I'll update this post per the feedback/critiques since it may be useful for others who happen upon it.
FYI - Based on numerous searches today, it would appear that "bridles" are more popularly used and sold "down under" vs. N.A. A somewhat subjective assessment. Also appreciate the tips and advice in this thread.
If I understand correctly:
- Bridles are another tool in the extraction/recovery arsenal.
- However, they should only be used properly (e.g. < 30 degrees included angle, assuming all other components in the extraction are appropriately rated for use).
I'll update this post per the feedback/critiques since it may be useful for others who happen upon it.
FYI - Based on numerous searches today, it would appear that "bridles" are more popularly used and sold "down under" vs. N.A. A somewhat subjective assessment. Also appreciate the tips and advice in this thread.
Last edited:
You don't have to buy a bridle. The same thing can be accomplished with two equal length straps and a shackle. Example: two six foot chokers (straps), one attached at each tow hook and then the both of those married together with a shackle. No point in spending the money in a bridle.
