Torque Calculation - Solar Tracker

Don't calculate it!

Measure it!
Attach a lever and some weights, that way you'll measure the actual value including the stiction etc.
By all means use calculations as a back up, or for working out the extra loading factors, safety factor etc.

But for pities sake measure it to make sure your calculations are of the right order of magnitude.
Del

yeah, measuring would help us.

we do not have facility to test or measure the torque required, so, I have to order for a new actuator.

if I buy a new actuator of high torque capacity, how do I go for measuring the torque??

If you find a fish scale and attach a lever to the structure you can measure the torque just like this. If it does not move or the scale bottoms out chose a longer lever and repeat. Or chose a long lever but mind the deflection.

I think you have the means to carry out the measurement.

Anyway it should just be friction from the bearing and overcoming the inertia from the structure if it is free standing.

Or a lever and weights.
A lever, a rule, a bag of stones and a scale on which to weigh them!

I had to measure the torque required to start a peristaltic pump.
I mounted a lever or the rotor (sticking out equally either side so it was balanced and not creating torque) I tied a plastic tray to the lever a known distance from the pivot and added M4 nuts into the tray until it moved the rotor.
I then weighed the tray plus nuts multiplied it by the distance and there I had torque!
It astounds me that someone can profess to 'calculate' the torque, yet they it seems they don't have the understanding to measure it.
Engineering is about understanding not calculation! (sorry, I have a bit of a bee in my bonnet about such stuff)

Del

yeah, your idea may work for small equipment. how can I apply in my case.

if someone can help in attaching images, I can explain you better.

thanks for the answer,,

If the ideas you have been given are insufficient, it is because you have not given enough information.

How big is this thing what does it weigh? Can you move it by hand with a long lever? If so then it can be moved with weights or a spring scale.

With a long enough lever I would think a 100kg spring scale would be able to apply enough force move it, or failing that a pile of bricks which could be weighed individually if necessary.
C'mon, the pyramids were build by sheer manpower without CAD.

Del (unsubscribes)

I agree with your point.

I have considered only the friction in my calculation.

what will be the starting friction coefficient for steel to steel for tracker applications ??

it's given 0.7 to 0.8 in some websites, but it seems to be large value.

Thanks for answering.

Me thinks you are missing a component there. How about an Axial Bearing? With the right bearing you can move things that weigh tons and tons and tons just with your bare hands.

I am going with Del.

He cat wait for me . . . . . . ..

Coefficient of friction comes in if you are dragging something. I hope you are using some type of bearings!

I'm facing problems in uploading the images,,,

Something like this?

http://www.physicsforums.com/showthread.php?t=673148

https://www.wpi.edu/Pubs/E-project/Available/E-project-121710-140419/unrestricted/Dual_Axis_Tracker_Final_Report.pdf

http://www.mecasolar.com/pub/doc/File/ingl/2-axis-tracker-mecasolar-catalog.pdf

hi,

the one you have shown is a dual axis tracker, supported by single leg.

i'm talking about a single axis tracker, in which three rows are interconnected to a single push-pull rod. you might have seen theose type of trackers.

--ntr

I understand, that, information was inadequate. i have tried to explain how my system should be working.

Our system is spread over area of 265.57 square meters. It consists of three rows of solar panels; panels are mounted to a torque tube. The torque tube and panels are placed on a leg member with the help of clevis arrangement.

Now I have attached an arm at the middle of torque tube (running horizontally), thus I have three torque arms. The three torque arms are interconnected through a push- pull rod (length = 10 m).

Now my drive point is at one end of the push- pull, by applying some force at the end of push-pull rod, i will be rotating the torque tube on which panels are rigidly placed. So I should be able to move or tilt the solar panels.

The total weight (weight of structure +weight of modules+ wind load) is 11691.4 Kgs.

The length of the torque arm is 500 mm.

In the following link I have that file,

http://files.engineering.com/getfile.aspx?folder=f76f567d-11d6-4517-92bc-9d210a24fa04&file=torque_calculation.PDF

http://www.smarttrak.in/single_axis_tracking.php

Imbalance in wind force on upper versus lower parts of the structure will be the most significant factor, and hardest to estimate closely.

Why is there metal sliding on metal? There should be rolling-element bearings that reduce friction coefficients to 0.05 or less.

i have suggested them to go for iglidur flange bearings.

decision is with the management, helpless.

Then you have our sympathies, condolences, prayers, thoughts, whatever....

hmmm,,

thanks

OK, so I didn't really unsubscribe, 'cos it's interesting.

BUT Three rows of panels.

The clue is there...

MEASURE IT FOR ONE PANEL, then do some simple arithmetic (with obvious allowances, safety factors etc, based on the "take a measurement and double it" principal.)
Build up a group of panels and then test them.
Do it slowly and methodically. The concept of designing something huge and complex on CAD, building it all at once and expecting it to work is bonkers. "Right first time" is a dangerous myth, which might apply to production, but hardy ever to design (IMO)

The watch word of any engineering should be simplicity.
Now I really have run out of useful input. But I will be watching, and any more silliness and I'll send you to the naughty step!

Del

Hmmm, thanks for being in the discussion.

yeah, i will try to measure it individually and then calculate for whole system.

When i calculated (not measured) for individual panel and converted it for a whole system, it is coming around 8.12 KNm. I feel it's very large value, because even SUVs will have around 600 Nm.

Do you think, the calculated torque is acceptable.

-- ntr

No!
I have no view on it's magnitude, I haven't seen the device I have no feel for irritating modern units like Newtons... it means nothing to me... a foot pound or a kg metre I can envisage... but I have no feel for a Joule or a Newton...
If I started measuring bow draw weights in Dels no one would have any idea what I was on about!
Now look you've started me ranting again

My view is it is easier to screw up a calculation than a measurement.
(hands up anyone who has been out by a factor of 10 or worse in a calculation.... Right that's everyone. You can all say behind and write out 100 times, "calculations are to support measurements not replace them". Unless you have a note from your Mum)
Given a choice I will always believe the measurement.
Del

You're talking about 6 million foot-pounds (in Yank terms)! What kind of bearings are supporting this and is it balanced (counter-weighted)?

8120 newton-meters = 5990 ft-lbs

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Sorry, you're right.

Have you thought about driving your solar panels with a worm and gear? The panels do not have to move very fast to track the sun and a worm gear, properly lubricated, will give you a high torque multiplication.

Yeah, in the present design we are using it.

Hello everyone,

Our soalr tracker is ready to enter operating mode. The worry is, I had oversized my actuator since i couldn't calculate the required torque for operation, now i need to validate the design for further implimentation. Any suggestions, How to measure the amount of torque being applied by the actuator while in operation.

-NTR

Calibrated strain Gauge and a PC + interface?