Static load of linear actuator

[bbq_build]

Hello, I measured an object using an electric scale. It is 5kg. I want to select a linear actuator such that when placed vertically, it can keep the object on hold at a fixed height. In this case, what static load (in lbs and Netwon) should the actuator be capable of handling? I am confused by different units listed by different manufacturers. Thanks.

 

[Tom.G]

Use Google. If you enter: convert 5kg it will show hints for what to convert it to (pounds, grams, Newtons, stones)

 

[bbq_build]

I know how to do conversion using google. The confusion I have is whether the manufacturers and the electric scale take gravity into consideration when showing the numbers. For example:

When I measured the weight of the object using a scale, it reads 5kg. So, in Newton, it is 5kg*9.81m/s2 ~= 50N. However, objects are under gravity. So, the electric scale measured the object under gravity. Shouldn't that 5kg has already included an increased scale factor of 9.81? Does the electric scale takes gravity into consideration when showing weight in kg?

When manufacturers state the static load, I am not sure if they have taken gravity into consideration. For example, if the stated static load of a motor is 100N, does that mean it can hold an object of about 10kg? Similarly, if a company states that their motor has a static load of 500 lbs, does that mean it can hold an object of about 227kg. (If the object is put on an electric scale, it gives 227kg?) 227kg is the value given by a calculator I found using google. Seem to be too large.

 

[Tom.G]

Does the electric scale takes gravity into consideration when showing weight in kg?

Yes. Electric (or electronic) scales are glorified spring scales, you are measuring Grams of Force (due to gravity). If you take that scale and 5kg weight to the Moon, the scale will read about 0.83kg. That's because gravity on the Moon is about 1/6 of Earths gravity. If you want to measure Mass, you use a Balance and put the unknown mass in one pan and put various known masses in the other until the scale "balances." Then you will get the same readings whether you are on Earth, the Moon or Jupiter.

Addendum: The classical way of measuring mass is to find the force required (in Newtons) to accelerate the mass at 1 meter per second, per second. The answer is the mass in kilograms. That works anywhere, on any planet or even in space. (because that is the definition of a Newton)

So just keep things sorted out in your mind: Weight is grams, pounds, stones, etc, of force on an object due to gravity; Mass is measured by how much force it takes to accelerate that object to 1m/S².

Enjoy!
Tom

 

[bbq_build]

Thanks Tom. Sometimes manufactures use lbs as the unit of the static load. For most google unit conversions , they use pounds. Are they the same thing? In other words, is 1 lbs = 1 pound? lbs does not sound like an abbreviation of pound.

 

[Tom.G]

Are they the same thing? In other words, is 1 lbs = 1 pound?

Yes, the same, isn't English weird?
According to wikipedia, lb is from the ancient Roman libra, from the Hellenic system, which was built on the Egyptians, who were influenced by the Mesopotamians!

Here is the link to wikipedia:
https://en.wikipedia.org/wiki/Pound_(mass)