cargo lift, hyraulic cylinder
cargo lift, hyraulic cylinder
(OP)
i just commissioned a cargo lift with a 3 kw motor , 2400 rpm motor but while working there is a huge sound like a humming sound which seems to come from the cylinder. clueless
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cargo lift, hyraulic cylinder
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RE: cargo lift, hyraulic cylinder
It could also be that your motor speed is close to the natural frequency of the cylinder. In which case, you'll need to either change the motor speed, get a new cylinder with a different natural frequency or do something drastic to stiffen the cylinder up to move its natural frequency away from the motor speed.
Hpost
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
The cylinder supplier probably wont help you much, it's not their fault that the cylinder's natural frequency is close to the motor speed.
That is a very slender cylinder, not surprising it's signing. Can you brace it at all in the middle at all?
Does the noise change as the cylinder extends...does it get any more noisy or less noisy?
RE: cargo lift, hyraulic cylinder
The natural frequency of the system should be calculated.
On page 2/27 there is the formula for natural frequency.
http://deltamotion.com/peter/Mathcad/Mathcad%20-%2...
The pdf file shows how I can simulate the cylinder with changing load or disturbances and how the closed loop control will react.
My suspicions is that the mechanics are vibrating.
Peter Nachtwey
Delta Computer Systems
http://www.deltamotion.com
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
The pulsations or ripple from the pump are being transmitted to the cylinder via the oil. The frequency of the vibrations is, as stated, close to the resonant or natural frequency of the cylinder. As the issue is more about noise than actual movement, it suggests that it will not take much to reduce the noise.
I think that you best bet is to change the cylinder mass or stiffness. Maybe up, may be down...???
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
Lowering the speed might push it towards the resonance point. Likewise, going up in speed could do the same. Without knowing the natural frequency of the cylinder, it's impossible to know which way to go.
Given the size and shape of the cylinder, my guess would be to go slower.
Slowing the motor down will decrease the flow. You'll need to get a bigger displacement pump to keep the cylinder speed the same.
RE: cargo lift, hyraulic cylinder
or shall i go ahead with changing the piston rod with a more thicker one like from 35 mm to 45 or 50 mm?
RE: cargo lift, hyraulic cylinder
There is no guarantee of success here. you'll have to try it and see what you get.
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
Any air in the system will find its way to the under side of the piston head in the cylinder. Air will give you what you are seeing.
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
Lower the cylinder to approx 2" from the bottom position.
Crack the fitting at the bottom of the cylinder, then force cylinder down. It is the air under the piston head that is causing the problem and it sounds like you have bled the top of the cylinder.
It might be messy.
Needless to say, you need to get all of the air out. Otherwise you will have a bouncy cylinder.
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
In that case, I would suggest letting the cylinder down to the bottom. Crack the fitting at the base and then try to lift the cylinder.
I am sure you will find that the bottom side is the pressure side and the top side is just there to drain away any oil that gets over the seal.
The lift falls under gravity right???
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
It's a single acting cylinder, the load is raised and lowered by pumping oil into a releasing oil from under the piston head.
It can't be as you say, have another look.
Can you sketch out your understanding of how this thing works???
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
1) How do you think the lift goes up?
2) What do you think stops the lift falling under gravity?
Please remember, I am trying to help you here. I am not taking the "P"
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder
So, just do the same, but at the other end of the cylinder. The air will accumulate at the top fluid port.
Just to be clear, when you say rope, do mean steel rope?
If it's not steel rope, there will be loads of compliance which could explain why you get this unwanted effect.
RE: cargo lift, hyraulic cylinder
RE: cargo lift, hyraulic cylinder