Just curious about something... I have 6 blocks that I am working on rigging up in the same line. One is direction changing and the other 5 are running the load - 2 fixed/3 moving.

I have 2 options with connecting all the blocks - use them all as separate blocks through a big shackle in sets of 3 fixed on top and 3 moving on the bottom. Or I can take all the blocks apart, get longer bolts, and put the 5 blocks together as two units with 2 sheaves on one and 3 sheaves on the other (6th block isn't the same as the other 5) - sort of like this:
http://www.byrnerentals.com/Crane-Blk-1843SHA.gif

I am well within the capacity of the blocks, even a single one, the goal is to make moving the load a lot easier, not more load. I tried with a 2:1 ratio without any luck, went to a 4:1 and I got the set up to work, but it was way hard. So now I'm up to a 6:1.

If I stack the blocks that would hold them, and the cable, together a lot better (not spaghetti as much) when not in use, but I am thinking that being locked together may bind up the cable - the the first sheave closest to the winch would pull towards the winch and leave the last sheave would be further out = angled pull, not straight with the load. Thoughts?

 

How much weight are you trying to move? It's amazing what I've dragged with a double blocked 1.5 ton chain block or 2 of them double blocked. The last big pull I was part of we had 5 blocks attached right to the piece of equip we were pulling each were double blocked into the wall across from the equip. Starts to become a rats nest...

How far do you have to pull?

 

Block travel is about 2ft under load. Weight-wise, maybe 1000lbs on the rig.

Right now all the blocks are individual but Id like to keep things less of a tangled mess.

 

Ya, the last pull we did 5 x double blocked, was a mess, had to slowly bring up tension and someone had to get in there to keep the cable/blocks/heavy cable straight, becomes a safety issue.

That link you posted is interesting, I never used anything like that...

 

Here is what I've got going, just the rigging part of it. The red ellipse is the top/fixed end and the blue is the moving/bottom end.

 

I wonder if you could get a 1/4 inch steel plate, maybe 1.5/2 foot long, cut holes every 4-6 inches and mount a block at each hole, would hold them apart and keep the cable from tangling? Then install your clevis on the opposite side of the blocks?

 

Something like this link shows, the ones Ive seen have a bigger spacing between holes, so it holds your blocks further apart, which helps with tangling.


Stainless Steel NFPA Rigging Plate

 

Thanks for the idea. I know what you're talking about, and I thought about something similar. However, that isn't getting me around the "loose blocks" syndrome. They would all still be able to swing freely. It may be a wasted effort anyway because the loose cable is going to flop around on its own regardless, its just the blocks seemed to make the tangling worse.

When it is all set up in use and tension is on the line it is fine - no tangling issues there, although I could relocate the fixed end as one of the cable clamps always seems to ride on the block next to it and the cable passing through. When its not set up is when it gets tangled.

 

All my rigging experience is from working underground, if we need to mount something we just drill a hole and install a rated eye bolt/mounting beam/lifting lug, lol, pretty easy we can space them out, etc.

Only other thing I could think of is maybe beefing up to a ratchet chain block or something so you could get away with using one block or none...?

 

At some point I am going to get an electric winch. That would make things a ton easier. Until then I am making do. I think the extra 2 blocks I added today will do the trick to ease up the effort, it just turns in to a mess quick. I used to store that winch with one block. I could crank the cable all the way in like how you lock up a power winch for storage, but I think if I do that now all the windings through the stacked blocks will set a permanent bend in the cable and kink it.

The original power source was a come-along, but it fell apart after 2 uses. The crank winch holds up better. It is a ton easier to lower the load also. It just doesnt have the "power" the come-along did with the lever. With a 4:1 reduction I could raise the load ok. Lowering was another issue as the pawl had to be reset with each drop of the cable to control it. With the crank winch I crank backwards to lower, no pawl to release.

Ive never used a chain hoist. That may be another route. A power winch would be a lot easier than the rest of the options, though.

 

I have used chain hoists, wire hoists, and, block and tackles (4" and 5" sheaves with 5/8" rope) to lift and lower electrical transformers up and down utility poles in back yards (can't get a boom truck back there). I have not used multiple blocks separately in a 4:1, 5:1 or 6:1 application, but, I would think using them separately could spin each sheave to where the cable could bind up (IDK). If it were me, I would get longer bolts and make the blocks in 2 units.

5:1 or 6:1 is right at the peak, before diminishing return. Loss of mechanical advantage.

My info is about using rope. Same size ropes, but, different manufacturers have different strength ratings. 5/8" Esterline rope is good for 1000 lbs. working load limit, and, 7/8" esterline rope is good for 2000 lbs. working load limit. If you need more block travel, just get a longer rope (same strength rating). The blocks will need to accommodate the rope sizes. I imagine you could get longer cable wire.

You may know this already (I'm just sharing some info), but, in the picture, your set-up is only as strong as your weakest link in your configuration. You have different sized shackles, the carabineer, the wire rope size, the blocks with the hooks, and your winch. So take a look at your ratings for each item and the one with the lowest strength rating, that is what your whole set-up is going to be worth (strength-wise).

These are my set-ups away from work:



On my block & tackle: rope and sheaves are good for 400, hooks are good for 2000 lbs., snaps are good for 750, 1/4" shackle is good for 1000 lbs., and 1/4" quick link is 880 lbs. But, my whole set-up is only good for 400 lbs.

My chain hoist (that I found at a flea market for $40 bucks): is good for 1 ton.


Chain hoists are great, but, are limited to a specific distance before you have to re-rig. Yes, a power winch is the best is you can use it in your application.

Hope this helped you out with a little info,

 

Steve,

What'd you end up doing with your blocks set-up?

How'd it work out?

Just Curious,