Has any one used YATES Pulley's?

Just wondering if any wall rats out there have experiance with yates paulley's. This one specifically:

And for further refernce, here is the Yates site for climbing pulley's here:

yatesgear.com/climbing/hard…

After about 15 minutes of searching I could not find any reviews, or the efficiency ratings. Any help would be much appreciated.

Thanks,

Danger-Russ

Danger-Russ Gordon wrote:Just wondering if any wall rats out there have experiance with yates paulley's. This one specifically: And for further refernce, here is the Yates site for climbing pulley's here: yatesgear.com/climbing/hard… After about 15 minutes of searching I could not find any reviews, or the efficiency ratings. Any help would be much appreciated. Thanks, Danger-Russ

I have not used that pulley; however, it has a bushing as opposed to a bearing so it is not going to rake in an impressive efficiency value. What do you intend to use it for?

Apostrophes indicate possession:

"What is the pulley's phone number?"

"Where did the pulley's dog run off to?"

The addition of the letter "s" indicates that you are referring to more than one pulley:

"The pulleys are all dancing in the club."

I hope you have enjoyed this experience. (Not "experiance")

Dylan Weldin wrote:Apostrophes indicate possession: "What is the pulley's phone number?" "Where did the pulley's dog run off to?" The addition of the letter "s" indicates that you are referring to more than one pulley: "The pulleys are all dancing in the club." I hope you have enjoyed this experience. (Not "experiance")

You forgot one. "The pulleys' union released a statement on Monday stating that they oppose harsh working conditions that involve frequent safe working load violations."

Looking at other similar products you´ll probably be on around 90-92% efficient depending on the rope. Bearing blocks are bigger, heavier and more expensive which is the downside of better efficiency.
The Yates blocks are made by ISC in Wales, you could ask them direct.

Jim Titt wrote:90-92% efficient

So 90-92% efficient, but is that linear regardless of tension? I use 2.25" triple pulleys in my slackline system to create a total of 14:1 mechanical advantage to tension my line. My front pulleys are ball bearing and my rear pulleys have bushings. As the load approaches 2,500 lbf, the rear sheaves start to become "sticky." The bushing creaks as the sheave spins, and at low speeds the sheaves act erratic. It is clear to me that as the load increases the bushings start to provide more and more resistance making it harder and harder to increase the load in reference to the tension I am pulling on the rope. The ball bearing pulleys dont do that nearly as much which makes them well suited to high loading scenarios such as slacklining. This implies that the true efficiency of a bushing pulley is not leaner through it's entire load carrying capability range.

The first problem is there isn´t a standard way of measuring block efficiency, or rather there are several ways. So the numbers you see quoted have a lot of variation. The efficiency I gave is for a typical 9mm or so dynamic rope with bodyweight. Change the rope and the load and you get completely different numbers.
Then there is the static or dynamic efficiency which of course are considerably different for bushed systems.
And then the different types of bushing react differently under load, bronze bushes friction drops and then rises again under increasing load, oilite bushes decrease in friction as the load increases to a certain point and then their self-lubrication fails and they seize up.
Most blocks are rated with a working load about 1/5th of the breaking load for this reason.
The block the OP posted is rated for 35kN and it is fairly inconcievable that anyone using it for its intended purpose as a wall hauler is going to be hauling 1400kg or so.
The only way to get the efficiency of a pulley system is to test it, certainly I´m suprised at the lack of initiative shown by the big wallers in this respect since it is very easy and cheap to do.

Jim Titt wrote:The first problem is there isn´t a standard way of measuring block efficiency, or rather there are several ways. So the numbers you see quoted have a lot of variation. The efficiency I gave is for a typical 9mm or so dynamic rope with bodyweight. Change the rope and the load and you get completely different numbers. Then there is the static or dynamic efficiency which of course are considerably different for bushed systems. And then the different types of bushing react differently under load, bronze bushes friction drops and then rises again under increasing load, oilite bushes decrease in friction as the load increases to a certain point and then their self-lubrication fails and they seize up. Most blocks are rated with a working load about 1/5th of the breaking load for this reason. The block the OP posted is rated for 35kN and it is fairly inconcievable that anyone using it for its intended purpose as a wall hauler is going to be hauling 1400kg or so. The only way to get the efficiency of a pulley system is to test it, certainly I´m suprised at the lack of initiative shown by the big wallers in this respect since it is very easy and cheap to do.

So I assume that larger diameter ropes will increase efficiency as they would increase the effective sheave size by placing the load further away from the center, is that correct?

No, completely the opposite.

Jim Titt wrote:No, completely the opposite.

Why? Smaller diameter ropes will place the load closer to the center, so how is that be beneficial? The entire point of a larger sheave is to provide more mechanical advantage to overcome the friction of the bushing. I would envision that placing the load further from the center would effectively create a larger sheave.

The thicker the rope the more resistant to bending it is as you move the moment of inertia outwards from the neutral axis. The more resistance to bending the more inefficient the system. The blocks efficiency remains the same since the bearing friction is unchanged (and unchangeable).
The rule of thumb in boatbuilding is the absolute minimum sheave diameter should be 4 X rope diameter but normally you go for at least 8 X. Generally the yacht industry use braid on braid rope construction in this application as well as it is more flexible.