Tirfor style winch as a zip wire for logs

[cornish wood burner]

I am similarly intruiged by the figures - a 1:25 sag indicates a pretty high cable tension to me - if anything CWB figures are low so would be interested to see the figures you have for a 50Kg weight suspended halfway across a 50m span with total 1m sag?

 

Even if the figures are acceptable a 6mm wire will not last long at all in this application.

 

It is an interesting discussion since I have a similar problem involving soft rather than steep ground.

 

Without wishing to raise difficulties one issue that will arise is the effort of lifting the timber high enough to get it on to the travelling block while having the cableway high enough to ensure the load does not bottom out partway down.

 

Cheers

mac

I make it 625 to lift 50kg. Remember the tension provides lift from both directions.

[Johnpl315]

I have been following this thread with interest.

 

I don't know if this is feasible or not.

 

If you had to pully blocks. On at the top, one at the bottom. I would set the tirfor at the top so it's well out of the firing line. Get one very long rope and thread it through the pulley blocks. Tie the two ends together and create a loop. Also tie a loop in the center of the rope. Pull the setup tight.

 

Now when one loop is at the bottom the other will be at the top. I would be looking at modifying a pair of timber tongs for small timber so you don't have to strop every log.

When you send a log down the other loop will come back up, the guy at the bottom can unhook the log and you can send the next one down.

 

What does everyone think?

 

The only downside I can see is if the tension required to stop it sagging is such it prevents the rope from running freely through the pulleys

[cornish wood burner]

Here's the start of an idea for you guys to think about.

If you need the run your logs down hill it is going to take time to retrieve the pulley.

So have two lines, then when a log is sent down line one it pulls the retrieval rope of line two pulley around a pulley to bring it to the top.

[muldonach]

I make it 625 to lift 50kg. Remember the tension provides lift from both directions.

 

 

I make it 738 to lift 50Kg (allowing 9kg for wire weight) Whatever - it is asking a lot of a 6mm wire - there is a misunderstanding or mis-interpretation somewhere

 

Cheers

mac

[cornish wood burner]

I make it 738 to lift 50Kg (allowing 9kg for wire weight) Whatever - it is asking a lot of a 6mm wire - there is a misunderstanding or mis-interpretation somewhere

 

Cheers

mac

Agreed its 738 for 50 kg

My mistake I never included wire weight. I presume 9kg is a proportion of the total cable weight.

As you say bit much for 6mm.

[muldonach]

I have been following this thread with interest.

 

I don't know if this is feasible or not.

 

If you had to pully blocks. On at the top, one at the bottom. I would set the tirfor at the top so it's well out of the firing line. Get one very long rope and thread it through the pulley blocks. Tie the two ends together and create a loop. Also tie a loop in the center of the rope. Pull the setup tight.

 

Now when one loop is at the bottom the other will be at the top. I would be looking at modifying a pair of timber tongs for small timber so you don't have to strop every log.

When you send a log down the other loop will come back up, the guy at the bottom can unhook the log and you can send the next one down.

 

What does everyone think?

 

The only downside I can see is if the tension required to stop it sagging is such it prevents the rope from running freely through the pulleys

 

You won a coconut! In order to keep the rope from sagging (under load) you need a pretty high tension - much higher than the actual weight of the load, since you have equal tension on both lines it will not run freely.

 

Cheers

mac

[cornish wood burner]

I make it 738 to lift 50Kg (allowing 9kg for wire weight) Whatever - it is asking a lot of a 6mm wire - there is a misunderstanding or mis-interpretation somewhere

 

Cheers

mac

 

Not that it matters but I believe 50 M of 6 mm is only 7kg. Also only a proportion of that needs adding into our calculations. When we get to the heavier cable then obviously it will be more significant.

[scbk]

Gonna give it a bash using a 800kg tirfor copy, which is 8.3mm wire, and an 80m length of cable.

Do you think that'll take my weight? It's no fun if I don't get to ride down it myself

[cornish wood burner]

Gonna give it a bash using a 800kg tirfor copy, which is 8.3mm wire, and an 80m length of cable.

Do you think that'll take my weight? It's no fun if I don't get to ride down it myself

So will the cable be 8 mm all the way?

Remember the heavier the load the more sag you need otherwise the tension will be too high. If you are a featherweight then at least 3M of sag to keep within the SWL( assuming 8 mm cable.

Do not tension then put a heavy weight on it. Other way around to give you a guide of the tension.

Most IMPORTANT have someone looking on ready to scrape you off a tree or pick up the pieces if the tirfor or cable breaks.