Any more stress on the cable than when using a block?Quote:
Originally Posted by Barefoot Dave
The kit is something you could work around, like a land anchor it is quick to use if you're in a competition but for the average person you could work out ways to get the recovery done without it.
I think he did.Quote:
Originally Posted by simmo
The RH rear wheel was turning anyway.
I cant think of a situation where 10 minutes of work with a pick and a bit of road building would not have achieved the same result.
Yes true.Quote:
Originally Posted by 123rover50
But...what if it was a concrete box culvert, and you didn't bring your jackhammer :D AND there had been a flood so the culvert and surrounds were void of any logs, sticks and mud :D. ... :confused: THEN this little beauty would be just what you needed to lift you up and over the square edge of the box culvert...
I'm gonna wait until the Bear Grylls authentic version is stocked at Ray's or BCF before I get one.
.
Any more stress on the cable than when using a block]
Yes, about 3-4 times. Roller radiusis 1/2-1/3 that of a block and the contact patch is only about 1/10th of a block. So all or the weight is concentrated on a much smaller radius multiplying the forces by an order of magnitude.
I agree that in THIS particular demonstration it is effective, but all of us know that you need a 6x6 mack following to have all of these well thought out but limited devices just in case.
A couple of bridging ladders will help just as much and be far more useful.
With all of these Gucci bits of equipment, I can't help but wonder how Len Beadell, the LRD patrols and we RFSU patrols did what we could.
Oh, wait. I remember now.
Reading a map and plotting a route, reading the terrain to avoid most issues, choosing an alternate route if needed, doing a little shifting of rocks and lastly a calm head and a good line.
If you want the ability to go anywhere without slowing down much get a helicopter or a Mog.
ck?[/I]
What is the radius through the eye of the winch hook or the roller on the fairlead or the winch drum down at the first layer ?Quote:
Originally Posted by Barefoot Dave
Chopper, You are not exactly comparing apples with apples.
What is the radius through the eye of the winch hook
Yes it is MUCH smaller, but the load is effectively static, though there is some movement. Yes it is a smaller diameter, BUT the cable is not moving,which deforms the cable and weakens it.
the roller on the fairlead
Have a look at the angle of the cable over the roller in the video.
Now have a look at the manufacturers guidlines for safe use of your winch. I think that you will find this device is operating at 2-3 X the recommended angle of incidence.
winch drum down at the first layer
If your winch drum is <80mm, then it is trouble waiting to happen.
Roller radius is 1/2-1/3 that of a block and the contact patch is only about 1/10th of a block. So all or the weight is concentrated on a much smaller radius multiplying the forces by an order of magnitude.
Correction: After taking a closer look at their other videos, it appears they are using the same roller as in a snatch block. So, no difference there, just in it's application.
This applies to the winch roller. Larger diameter plus greater support for the cable = the load is spread over a greater area. The same as running lower pressures in you tyres.
Perhaps this is why the manufacturer recommends NOT using the last lay of cable?! Because you have the roller diameter+ 2x the diameter of the cable= >100mm.
Seeing the pattern here?
..It obviously multiplies the power available...
No it isn't. It is a simple redirection of the applied force. The same as using a snatch block in a single line pull to apply force from an angle away from the path of Greatest resistance.
Now, the BIG questions are difficult ones.
Will the lifting of the vehicle and resultant lessening of drag offset the greater load of the redirection?? How does this redirect load compare to a flat plane redirection?
This can only be tested with a strain gauge as it will always be different. Half an hour of physics equations can establish a result in a perfect world but that won't help us, will it?
It comes down to the reccomended safe maximum angle of pull. This device exceeds it and offers a number of complications.
In the video, the front axle makes it over the step and is very close to the device. What do you do then?
The cable is still under load. These blokes don't seem to worry about stuff like that.
How do we stabilise the vehicle while we reset the system?
Solution: chock it up with a few rocks and logs maybe? wait a minute...that rings a bell :twisted:
As Burt Rutan says about Aerodynamics "If it looks right, then it will fly right".
This just doesn't look right.
I like the thinking, but a few rocks or a shovel would have done the trick. A snatch block looks a lot easer to carry also.
If your winch drum is <80mm, then it is trouble waiting to happen.
Warn 8000lb winch 64mm drum
In the video, the front axle makes it over the step and is very close to the device. What do you do then?
How do we stabilise the vehicle while we reset the system?
Solution: chock it up with a few rocks and logs maybe? wait a minute...that rings a bell
You could use the handbrake, if you think it will roll much , front wheels on a horizontal surface and rear wheels on a horizontal surface , which way will it roll.
Pretty sure the older Land Rover "How to 4WD" books had a very similar device usually made from 2 poles.
Martyn
No worries. I choose not to buy or use it.;)