block/ pulley

[KevinS]

Can anyone tell me the difference between a block and a pulley?

I have a 2 1/2" cmi ... With a becket

 

[Tom Dunlap]

There are several definitions...and some people use the two terms interchangeably.

To me, a pulley has fixed cheeks and a fixed eye. A block has swivel cheeks and two sheaves.

YMMV ;0

 

[monkeylove]

I agree with Tom, now a days in most circles they get used to mean the same thing. The Maritime industries are the few that still keep to the traditional definition of....

"A pulley is a wheel on an axle that is designed to support movement and change of direction of a cable or belt along its circumference.
A block is a set of pulleys or "sheaves" mounted on a single axle. The assembly of two blocks with a rope threaded through the pulleys is called tackle"

Make sure what you are looking at does what you need it to do and is rated for the purpose at hand and then pay little attention to what the vendor is calling it.

 

[TreeLogic]

I was always under the impression that the difference was a block can be directly connected to a sling or rope, whereas a pulley (due to sharp edges and by design) needs a connecting device (i.e, carabiner) to connect it.

 

[TreeLogic]

http://www.treeservicesmagazine.com/article-585.aspx

Per the above article, "The obvious and most important difference between pulleys and blocks for arborist rigging applications is that a pulley lacks a bushing for sling attachment."

 

[KevinS]

Well I'm glad that question had a few answers makes me feel less silly for asking

 

[Treezybreez]

In my mind a block pulley is simply a type of pulley capable of handling a specified shock load. It makes it easy to tell a ground guy what you want.

 

[Tom Dunlap]

In sailing vernacular 'tackle' is sometimes pronounced 'tay-kle'

 

[chewbacca]

In my mind a block pulley is simply a type of pulley capable of handling a specified shock load. It makes it easy to tell a ground guy what you want.

This is how I've always thought of the two. A pulley is for changing the direction of a rope in motion. A block is capable of doing so while being aggressively shock loaded.

 

[wyoclimber]

I think pulleys like the Pinto force us to define that a little more carefully. Attachable to a sling and will handle a shock load, but definitely a pulley rather than a block. I tend to go with the definition of a single sheave for a pulley, two sheaves for a block.

 

[tomthetreeman]

In sailing vernacular 'tackle' is sometimes pronounced 'tay-kle'

And how would you pronounce 'Forecastle?'

 

[Tom Dunlap]

Fo'csle

 

[Tom Dunlap]

The pulley is the device that a rope, cable or belt is reaved around to change direction.

http://ep.yimg.com/ay/karst/petzl-p00a-ultralegere-pulley-10.gif

A block has cheek plates and pulley or pulleys between the cheek plates.

http://ems.imageg.net/graphics/product_images/pEMS1-7419478venh.jpg

Common usage of the terms pulley and block may mean different things to different people.

 

[oceans]

And how would you pronounce 'Forecastle?'

Folk-sull.

 

[treehumper]

It serves us to learn to standardize and define our terms especially where tools are concerned. Imagine a surgeon asking for a knife instead of a scalpel. Sure the assistant would figure it out but.....

 

[Treezybreez]

According to the ISA's glossary of Arboricultural terms (1) a block is a heavy duty pulley used in rigging. Designed for dynamic loading. (2) casing enclosing one or more parallel pulleys.

 

[treehumper]

^^ There goes my theory.....

 

[TreeLogic]

See, the pulley needs a connector.

But the block does not.


There ya go. That settles it.

 

[treehumper]

One less link in the chain.

 

[chewbacca]

So is this a block?