Tirfor style winch as a zip wire for logs

[cornish wood burner]

Some great ideas and suggestions

 

I like the idea of using a thinner cable, and I could then get a longer length to get further up the hill - 100m would be good! Although can't remember how many good trees there are to tie it off

 

 

Waterbouy, whereabouts in Argyll are you? Might be a good excuse for a trip in the van with the other half!

 

Obviously you will need to increase the tension for 100M or put up with more sag. If you need a different weight, tension or length its an easy calc.

[csservices]

With regards to your braking system could you attach your retrieval rope to the sling/pulley and capstan it off around suitable tree at the top of the bank this would give you a controlled descent and avoid needing to build in a braking system at bottom end.

[tree-fancier123]

here is a pulley, unfortunately US, if carriage and charges too dear, maybe there is a european supplier

 

MicroTrolley Stainless Steel Tandem Pulley by CMI, up to 1/2" diameter rope | SherrillTree.com

 

or this one, max speed 60mph!

CMI Comtrolley Companion Trolley Pulley

[waterbuoy]

Waterbouy, whereabouts in Argyll are you? Might be a good excuse for a trip in the van with the other half!

 

I'm based just south of Oban, but travel all over the UK - Northern Ireland via Glasgow and Coatbridge this week. If you have any contacts in these parts I can leave some cable with them for you to try. Sadly I chucked away some 150m lengths of 6mm a couple of weeks ago, but have a 65m length of 6mm sitting outside that I removed last week, and probably more if I rummage around.

 

The fuel costs are likely to be more than the cable is actually worth so it makes sense to try and collect from a mutually convenient mid point - I have to head up to Fort Bill in a few weeks time for example.

 

As others have advised, the sag will increase proportionally with span. However, my previous comments and calcs were based on a level cableway. If you are running your '30 kg' timber down a steepish slope then the sag will be less as there will not be a static load, which is what we use for our load tests when setting the cables.

[teepeeat]

sag will depend on incline of the wire as Waterbuoy has pointed out.

 

With regard to getting the logs down the hill I shifted a few tons by cunningly harnessing gravity by tossing them down the hill - simples

My braking system consisted of a level area about 10m wide at the bottom that seemed to stop most of the logs. The few bouncers that went beyond only went as far as a few dodgy hazel bushes and an old fence that needed some repair anyway. Didnt do any damage to the fence in the end.

 

To turn the question on its head, suggestions would be welcome on how to get similar logs UP the hill using simple rigging and a small powered winch ??

[justin131]

fr jones have a pulley for cable

24kn Petzl P21CAB Tandem cable

[cornish wood burner]

I'm based just south of Oban, but travel all over the UK - Northern Ireland via Glasgow and Coatbridge this week. If you have any contacts in these parts I can leave some cable with them for you to try. Sadly I chucked away some 150m lengths of 6mm a couple of weeks ago, but have a 65m length of 6mm sitting outside that I removed last week, and probably more if I rummage around.

 

The fuel costs are likely to be more than the cable is actually worth so it makes sense to try and collect from a mutually convenient mid point - I have to head up to Fort Bill in a few weeks time for example.

 

As others have advised, the sag will increase proportionally with span. However, my previous comments and calcs were based on a level cableway. If you are running your '30 kg' timber down a steepish slope then the sag will be less as there will not be a static load, which is what we use for our load tests when setting the cables.

What is the SWL of your 6mm cable? Its not so much the static load more the angle of the pull from the log. Cable inertia would be fairly insignificant, but the inertia of the log when travelling down the wire will increase the strain as it passes the maximum sag point so some

safety margin should be included. Anything other than a smooth travel will also increase stress.

[treequip]

fr jones have a pulley for cable

24kn Petzl P21CAB Tandem cable

 

See response 2 in this thread

 

The TANDEM CABLE is designed for smooth and efficient Tyrolean traverses on rope

[waterbuoy]

What is the SWL of your 6mm cable? Its not so much the static load more the angle of the pull from the log. Cable inertia would be fairly insignificant, but the inertia of the log when travelling down the wire will increase the strain as it passes the maximum sag point so some

safety margin should be included. Anything other than a smooth travel will also increase stress.

 

6mm galvanised (7 by 19 with a steel core) (ie not fibre) when new has a SWL of c. 500kg and a MBL of 2.5 tonnes; for stainless it is a little less than this. This gives a FoS against the quoted 30kg of significantly more than the 5 which is required by the various regs (ie LOLER and, in some cases, PUWER)

 

The 6mm is more than man enough for the job in hand. The only downside over using this instead of (say) 10mm is that whilst it will sit higher when not under load, it will stretch more when loaded. In this instance this should not pose a problem.

[waterbuoy]

To turn the question on its head, suggestions would be welcome on how to get similar logs UP the hill using simple rigging and a small powered winch ??

 

What type of powered winch do you have in mind?