# Device to check tension in wire ropes

1. Jul 24, 2010

### caslor

Hi

i have 3 wire ropes that holding a weight and i want to have the same tension in all of them.

there are some devices all ready in the market bat costs a lot of money.. 500 dollars/euro and more

like this one

i was thinking to build my own device..
like this one :

screw with my Torque wrench until a specific distance in wire rope curve...
after that i move the device to the other wire rope and torgue it until i have the same distance/curve
see how much torque needed to have the same curve and adjust the tension of the wire rope...

what do you think?
that will work?
1. The problem statement, all variables and given/known data

2. Relevant equations

3. The attempt at a solution

Last edited by a moderator: Apr 18, 2017
2. Jul 25, 2010

### pongo38

You started by saying you had 3 wire ropes. Are they the same length, and can they be adjusted independently? If the holding device is such that tightening one rope causes a slack in the others, then the process is going to be more iterative. I didn't find your explanation clear enough.Are you applying the torque wrench to the rope or to the screw in your metallic device? When you speak of 'the other rope', which of the two remaining ropes are you speaking about? When you say 'distance/curve' do you mean for the rope or for the device? Have you considered the possibility of measuring the natural frequency of vibration? Whatever method you adopt, you need to think about the tolerances and accuracy of what you are doing. On the device, how will you measure lateral movement, and with what possible error (I prefer the word 'variation')?

3. Jul 25, 2010

### caslor

Thanks for the reply my friend..

the 3 wire ropes have the same length
they can be adjusted independently
i am going to apply the torque wrench to the screw in my metallic device
When i speak about the other ropes... i refer to the other 2 ropes...

i know that accuracy will not be so good... but until know i was doing that by hand... checked witch rope is more tightened than the others..

4. Jul 26, 2010

### pongo38

how long are your ropes? Long ones can have their tension assessed by the amount of extension. You didn't say if you had considered period of vibration, which you might achieve by counting with a stop watch of the period is long enough. A sketch of your system would help a fuller understanding.

5. Jul 26, 2010

### caslor

Hi my Friend..

the ropes are not standar in length .. depends from the building... is elevator ropes...

here is the system

having the same tension all ropes is critical for the life of the pulley that moves them.. thats why i want to make them having the same tension as more accurate i can

Thanks in Advance for the interesting

6. Jul 27, 2010

### pongo38

Here is a device we use in the laboratory to get three equal forces. In the figure, the verticals are cables and the horizontals are beams. Do you get it?

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7. Jul 27, 2010

### caslor

Yes i understand but i cant use this kind of connection in the elevators...

In Elevators/lifts hoisting have to made in a certain way that iso describes .
each wire rope should be connect to the frame of the car independent from the other wire ropes.. for safety

so thats is why i need a device to check the wire ropes tension... each wire rope has at the end a system with a big screw to connect them to the chassis...

so with the screw you can tight or loosen it in order to have the right tension..

8. Jul 28, 2010

### Staff: Mentor

(Thread moved to ME for more views)

9. Jul 28, 2010

### Mech_Engineer

Since this is a safety significant application, I would highly recommend you look into the laws governing safety requirements on elevator cables. I doubt a hodge-podged design like you're describing would be preferrable to a certified device designed for use on elevator cables specifically.

In addition, that tension measuring device you found is cheap compared to what it will cost your company to pay you to re-invent the wheel. Torque is a notoriously error-prone method for measuring bolt preload, which is why the device you found uses a load cell. Just suck it up and buy the thing.

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