Talk:Block and tackle

.           The pronunciation of tackle varies from region to region. Both tack le and take le are correct.

Pronunciation
Not being a regular wikipedia editor, i wanted to check with someone before i did this. Is it proper to put pronunciation in an article? The correct pronunciation of this is "block and take-el" not "block and tackle" as one might expect. The spelling is fine, but the pronunciation is wierd.
 * Sure, for oddball cases like this. Stan 13:36, 5 January 2006 (UTC)
 * Maybe this should be phrased as the "official" pronunciation. Block and tackle is pronunced the expected way quite often.  I've never heard the take-el version. ChrisLawson 19:11, 14 June 2006 (UTC)
 * It probably depends on your background. The pronunciation in the article as highlighted by the unsigned message at the top of this page seems to be from the Royal Navy.  If I had a citation for it I would add it.  If you have strong feelings about it you may wish to highlight the pronunciation you are used to and the one in this article as the different versions.  Language moves.  Look at what Michael Crawford did in the UK for the word "harassment" Fiddle Faddle 19:33, 14 June 2006 (UTC)

Captain Daniel Moreland is one of the most respected sailing ship masters at sea today. An internationally recognized authority on square-rig and traditional sailing ships, he started his career sailing in the West Indies in island schooners, brigantines, and passenger windjammers. He says while many people pronounce it both ways, 'tackle' relates to fishing or football; a piece of line rove through a block is pronounced 'take-el'. — Preceding unsigned comment added by PictonCastle (talk • contribs) 11:46, 21 September 2017 (UTC)

Rescue Technician textbook reference
Rescue Technician textbook reference added. For the record, I am an EMT and took the Heavy Rescue Technician course at the Bergen County EMS academy in Paramus, NJ, where this book was used as a textbook. Also for the record, this was the textbook used during the period of the 9-11-2001 terrorist incident, so that many of the rope rescue teams from New Jersey utilized the skills taught by this book in the work of rescue and mostly recovery operations at the former World Trade Center site. Other books of value that go into even more detail come under the heading of Technical Rigging, several of which are published by Elvesier and Jones and Bartlett Publishers. People looking to utilize these skills in the outdoors should look for the sites covering wilderness EMT, and whitewater rescue. -- Joe 02:36, 22 June 2006 (UTC)

Advantage/Disadvantage
I want to mention that the diagrams showing the various configurations state that they are all "Rigged to advantage", but in fact, according to the definitions lower on the page, if you read them carefully, these are all "Rigged to Disadvantage". I use these configurations myself in lifting loads, and it's clear why, from a practical point of view, the "Disadvantage" method is usually more convenient, with the pulling rope going first through the fixed block, even though it does give slightly less mechanical advantage. Since I am not a regular editor I will leave it to the rest of you to make any changes if you agree. —Preceding unsigned comment added by 66.245.148.208 (talk) 09:03, 27 December 2009 (UTC)


 * Corrected this in the article. Fiddle Faddle (talk) 11:59, 27 December 2009 (UTC)

In the "Rigging Methods" section, why is roving to advantage described as "obviously the most efficient use of equipment and resources"? As the comment above in this section of the discussion states, if you are lifting a load from the ground, you pretty obviously want to rove to disadvantage, i.e. to be able to pull down in order to make the load go up. I'm not any kind of rigging expert, so I haven't changed the article on the basis that I may be missing something, but I think this claim almost certainly needs further explanation, &/or a citation, &/or removal, if it is simply wrong. Bmju (talk) 23:03, 21 August 2011 (UTC)
 * Google gave 93 results for the exact phrase "roving to advantage". Apart from a few sports pages, they all had the same line: "While roving to advantage is obviously the most efficient use of equipment and resources, there are several situations ..." I'll try to add a bit to clarify. Don't have a source for it though, don't know if this would be considered original research.  81.165.78.108 (talk) 15:17, 28 August 2011 (UTC)


 * I am sorry, but I did not read this discussion before jumping in and making an edit to the section on rigging methods. I agree with the statements here, and I did similar searches to determine the source of the preference for reeving to advantage.  There is a probably apocryphal story about Archimedes using a block and tackle to haul an entire ship ashore, I suspect he rove the block and tackle to advantage.  However, when lifting a heavy load reeving to disadvantage just makes sense. Prof McCarthy (talk) 06:11, 3 September 2011 (UTC)

--108.21.218.188 (talk) 22:12, 8 November 2013 (UTC)gamine

Rove to Advantage
This is interesting. A colleague has edited this article to state that the block and tackle has a mechanical advantage of one greater, if the blocks are reeved to advantage as oppose to reeving them to disadvantage. Because the mechanical advantage can be determined by the number of ropes connected to the moving block this has to be the same whether the pulling rope passes over the fixed block (rove to disadvantage) or not (rove to advantage). Since use of block and tackles comes with a lot of tradition, it really is not clear if we are talking about the same thing. Prof McCarthy (talk) 04:58, 13 September 2011 (UTC)

In order to have the mechanical advantage of a block and tackle system be one greater when rove to advantage as compared to rove to disadvantage, we must focus on which block the start of the rope is connected. Because the number of ropes passing through the moving block is the mechanical advantage, it is clear that if one of these is the attachment of the start of the rope, then the mechanical advantage is greater by one, than if the start is not mounted to the moving pulley. From this viewpoint, rove to advantage does not refer to how the rope is threaded (reeved) through the block and tackle, but rather whether the start of the rope is attached to the moving block or not. Prof McCarthy (talk) 05:20, 13 September 2011 (UTC)

This seamanship reference is specific that rove to advantage increases the mechanical advantage by one. While it is not described very clearly, there is an example that shows that rove to advantage has the start of the rope tied to the becket of the moving block. Notice that if this is the case, which is my vote, then it does not matter whether the hauling part of the rope is threaded over the fixed block or not, and it does not matter the direction of hauling, because the mechanical advantage will be the same, which is one greater than if the blocks were reversed. Prof McCarthy (talk) 05:43, 13 September 2011 (UTC)

One last point on this topic. If the fixed and moving blocks have the same number of pulleys, then when the start of the rope is attached to the moving block (rove to advantage) all the pulleys in the fixed block are used and the hauling rope can only be pulled in the direction of the moving pulley. In order to reverse the direction of the hauling rope in this case, an additional pulley is needed in the fixed block or another stand alone pulley. Prof McCarthy (talk) 05:56, 13 September 2011 (UTC)

All right, now I get it. Sorry, for one last comment. A block and tackle system will generally be constructed from blocks with the same number of pulleys or blocks that differ by one pulley. For example, a double whip has two blocks with one pulley each, a luff has a block with one pulley and a block with two pulleys, a two fold purchase and three fold purchase have pairs of blocks with two and three pulleys respectively. In order to thread the rope properly, the start must be attached to the block with less pulleys, if there is one. In order to have the maximum mechanical advantage, we have two cases: Thank you for your patience with this. Prof McCarthy (talk) 06:18, 13 September 2011 (UTC)
 * If both blocks have the same number of pulleys, then the maximum mechanical advantage is obtained when the start of the rope is attached to the moving block, in which case the hauling rope is in the direction of the moving load because there are no additional pulleys on the fixed block;
 * If one block has one more pulley than the other, then the maximum mechanical advantage is obtained when this larger block is used as the moving block and the smaller block which has the start of rope attached is mounted as the fixed block; this means that again the hauling rope is in the direction of the moving load.

Moment of inertia
I understand the thought that the moment of inertia of the pulleys must affect the analysis of mechanical advantage, because the larger the moment of inertia the larger the torque needed to accelerate the pulley. However, mechanical advantage is a static analysis, we assume there is no acceleration. The application of the forces exists without the system accelerating. Therefore the inertia properties of the pulleys do not change the mechanical advantage. Prof McCarthy (talk) 05:15, 23 March 2012 (UTC)

Reeve
The verb "reeve" is not familiar to most people. Here is how the American Heritage diction defines this term: reeve 2 (rēv) tr.v.reeved or rove(rōv), reev·ing, reeves Nautical 1. To pass (a rope or rod) through a hole, ring, pulley, or block. 2. To fasten by passing through or around. 3. To pass a rope or rod through (a hole, ring, pulley, or block). I hope this helps. Prof McCarthy (talk) 19:36, 1 June 2012 (UTC)

Threefold purchase, run of tackle
I removed this section for two reasons apart from the obvious total lack of citation, an overwhelming reason in itself. Fiddle Faddle (talk) 23:21, 19 November 2012 (UTC)
 * 1) it was unclear
 * 2) it was inaccurate. A threefold purchase may be rove without crossing points and with no special considerations for 9o degree setting of the blocks

The quoted data appears wrong, and if so will massively understate the efficiency of blocks and tackles (if that's the correct plural form!) using rolling-element bearings
The article states, "Typical K values are 1.04 for roller bearing sheaves". I doubt it. I think there's a nought missing. It's more likely to be around 1.004 (I just did a quick calc using bearing coefficient-of-friction data from NSK). I could be wrong here, because I'm in a rush, but I'm a pretty decent mechanical engineer...

For a pulley that is twice the diameter of that of its ball bearing, and for a bearing coefficient of friction of, say, 0.002 (and this can be significantly less if sealed and oil-filled, but it can also be more when bearings are not in 'proper' condition), the tension in one leg of the rope only has to be 0.002 (0.2%) more than that in the other leg. That's an efficiency loss of ~0.2% for one sheave, although it does "compound" over more than one sheave (as covered by the formula in the article)... So I suspect 1.004 for K is more likely... I'm happy to be corrected though.

Addenda: the above is from a perspective of dealing with a high-load, small system in which cable losses are likely to be smaller than in larger rigs, and chain and sprockets also might be considered. I can see how cable/rope bending losses (friction between fibres), exposed bearings, ropes rubbing the sides of sheaves etc may add to losses...

Addenda: also, isn't S = N? 86.147.100.122 (talk) 22:34, 29 April 2013 (UTC)
 * Please make the revisions that you feel are appropriate. This section predated my efforts, and would benefit from your experience. Prof McCarthy (talk) 01:19, 30 April 2013 (UTC)

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History?
There really ought to be a history section here, tracing it from at least Archimedes to today. I'm having a heck of a time finding any online history, especially of use in sailing ship rigging. Dismalscholar (talk) 03:02, 18 December 2018 (UTC)
 * Agreed. Do what you can. &middot; &middot; &middot; Peter (Southwood) (talk):

Nested pulleys
I don't see nested pulleys described. There's a nice demonstration of them at https://www.youtube.com/watch?v=M2w3NZzPwOM&t=577s. You get a LOT more mechanical advantage using them. David Spector (talk) 00:50, 23 September 2022 (UTC)