So this is gonna be a school project
I am making an elevator that has to be able to lift about 3 Kgs against the gravity of Earth upward to 10 meters and the problem that is stopping me is my very little knowledge about motors
So what kind do I need?
I know there are Stepper motors, Brushless motors and Servos
I was thinking servos are the right choice here since i am lifting heavy objects
Also I am focusing more on the torque as its speed doesn't need to be super fast as long as it is gonna complete the 10 meters distance in less than 5 minutes
Thanks in advance

 

For motor economy, choose a geared motor if speed is not an issue.
Max.

 

Where is your teacher?
Shouldn't they be "teaching" you?

At this point almost any motor can work.. Do you have more details? Does this elevator need to stop at different floors in response to buttons,etc..

Don't forget that with pulleys in different configurations you can really change how much weight your motors can lift..

 

10 meters?
Uh, who is going to construct a tower over 30 feet high for your little elevator?

 

10 meters?
Uh, who is going to construct a tower over 30 feet high for your little elevator?

It's a 3 story school!
Max.

 

A little knowledge is a good lubricant ... sometimes.
Here is a fundamental graph showing the principle of dc motors ... not stepper motors ... that is another topic.

At the left-most point on the speed axis is the maximum or locked rotor torque, of which a given motor is capable. The qualifying characteristic of the locked rotor torque is that the motor speed is zero ... The drive axle is not turning. The second point of interest on the speed axis is the no-load rpm, at the intersection point on the right. The no-load rpm is the maximum speed which the motor can produce. The draw-back of the no-load rpm is that it can deliver no torque to do any work.
So, you are required to have the motor perform somewhere on the diagonal line ... about half-way would deliver the maximum power.

The interesting thing is that the performance of a gear applied to the motor may be represented as a diagonal line that is super-imposed on the original, at different angles ... a steeper line means more torque, less speed ... and a line with less slope means more speed, less torque.

Here is one link to look at ...
http://lancet.mit.edu/motors/motors3.html#tscurve

 

MOD NOTE: Moved to Homework Help from General Electronics Chat.

 

So this is gonna be a school project
I am making an elevator that has to be able to lift about 3 Kgs against the gravity of Earth upward to 10 meters and the problem that is stopping me is my very little knowledge about motors
So what kind do I need?
I know there are Stepper motors, Brushless motors and Servos
I was thinking servos are the right choice here since i am lifting heavy objects
Also I am focusing more on the torque as its speed doesn't need to be super fast as long as it is gonna complete the 10 meters distance in less than 5 minutes
Thanks in advance

One of the first things you need to do is determine the ideal power you need. This is an absolute minimum -- any less than this is incapable to meeting your needs under any circumstances. Of course you will need to allow for friction and other losses, but you need a starting point.

You have all the information you need to determine this -- 3 kg through 10 m in Earth's gravity in under 300 seconds. How much power is that?

You should find that it is so low that you can expect friction in the system to be dominant.

Next consider how fast your final shaft needs to turn. Make an estimate of the diameter of your pulley/gear that will be interacting with the cable (assuming you are using a rope of some kind) and figure out how many times it needs to turn each minute to move something 30 m in 5 min. That will also let you figure out the ideal torque you need in order to exert the needed force of the cable.

Build in some good margin and these numbers establish the basic framework for your solution.

 

10 meters?
Uh, who is going to construct a tower over 30 feet high for your little elevator?

That was my first thought, too. But since that's only about three stories, it's very possible that the school has an area (some accessible part of the roof) that overlooks a 10 m drop from which they can rig up a boom that sticks out a foot or two from the building with a pulley pretty easily.

 

A little knowledge is a good lubricant ... sometimes.
At the left-most point on the speed axis is the maximum or locked rotor torque, of which a given motor is capable. The qualifying characteristic of the locked rotor torque is that the motor speed is zero ... The drive axle is not turning. The second point of interest on the speed axis is the no-load rpm, at the intersection point on the right. The no-load rpm is the maximum speed which the motor can produce. The draw-back of the no-load rpm is that it can deliver no torque to do any work.
So, you are required to have the motor perform somewhere on the diagonal line ... about half-way would deliver the maximum power.

That can be a bit misleading as the typical torque curve for all the various makes of servo motors I tend to use have fairly flat torque curves from 0 up to the rated torque.

Max.

 

For your small weight application a traction elevator would be ideal.
The motor is mounted to and moves with the elevator. The drive can either run on a geared rack or can operate a spool of suspension cable on a pulley type setup. You just anchor the cable at the top or install a toothed vertical rack for the motor to engage.

 

That can be a bit misleading as the typical torque curve for all the various makes of servo motors I tend to use have fairly flat torque curves from 0 up to the rated torque.
View attachment 126492
Max.

Presumably, you are using a newer, improved design motors At any rate, a motor performance curve can be approximated by obtaining the stall and the no-load operating points, at least for the purpose of estimating the minimum power required.

 

First is this project isn't for a lesson its for the science fair and it is supposed to be secret until the event
second I am not constructing towers for the elevator
I will put the lifting assembly just in the top floor and it is gonna stop between the ground and the top floor only
and I thought it is gonna be helpful in pulling large banners to hang for the event
that's why I have a strong feeling that it is gonna get the likes of the judges because we have points for the usefulness of the project

 

For your small weight application a traction elevator would be ideal.
The motor is mounted to and moves with the elevator. The drive can either run on a geared rack or can operate a spool of suspension cable on a pulley type setup. You just anchor the cable at the top or install a toothed vertical rack for the motor to engage.

I don't know how practical that is for this project. It's unlikely that they are going to have a suitable toothed track available or that the TS is expected to construct one. Also, for the motor to be mounted on the elevator car you have to get power and control signals to it, which might also not be very practical for this kind of school project. Even if you have the power source be batteries that are on the car, you still have to get control signals to it. Plus, the motor now has to lift not only the 3 kg payload and weight of a simple car, but now also the weight of the motor and batteries as well as a somewhat heavier car built with suitable mounting points and hardware.

But this is quite a bit of speculation -- it would be nice if the TS provided some info on the constraints they are operating under. As was asked earlier, is the goal simply to lift the weight that distance in that time with someone manually controlling when it starts and stops, or is it supposed to detect when to stop by itself? What safety features, if any, are expected? What is provided in the way of structure beyond the car and payload? Is building/modifying the car to meet their design even allowed?

 

I don't know how practical that is for this project. It's unlikely that they are going to have a suitable toothed track available or that the TS is expected to construct one. Also, for the motor to be mounted on the elevator car you have to get power and control signals to it, which might also not be very practical for this kind of school project. Even if you have the power source be batteries that are on the car, you still have to get control signals to it. Plus, the motor now has to lift not only the 3 kg payload and weight of a simple car, but now also the weight of the motor and batteries as well as a somewhat heavier car built with suitable mounting points and hardware.

But this is quite a bit of speculation -- it would be nice if the TS provided some info on the constraints they are operating under. As was asked earlier, is the goal simply to lift the weight that distance in that time with someone manually controlling when it starts and stops, or is it supposed to detect when to stop by itself? What safety features, if any, are expected? What is provided in the way of structure beyond the car and payload? Is building/modifying the car to meet their design even allowed?

no the motor won't have to move with the cargo
What I have in my head is that the Motor along with the pulley and the control electronics be mounted firmly on the top floor and have some rope go to the ground so someone attaches what is to be lifted
I haven't though of any safety features for it because I won't lift any living creature
I also had the idea of having a timer in the code of the controller to determine when to stop but then realized that with different weights this won't work as intended

 

Presumably, you are using a newer, improved design motors .

Well all P.M. motors since the 80's.
Torque is different from power (HP) although related.
Voltage = rpm
Current = torque.
Max.

 

Hi,

Just a little note...

The power of the motor has to increase with both load and speed.
To lift more weight at the same speed you need more power, and to lift the same weight with a faster speed requires more power.
Of course to life less weight at the same speed you need less power, and to lift the same weight with a lower speed you can get away with less power too.
There is also a minimum power needed just to move the load platform itself, with zero load weight due to dynamic friction and device tare weight. This may be slightly higher if there is significant sticking friction, which can come from several sources including shaft static friction and individual long term element shape change.

 

no the motor won't have to move with the cargo
What I have in my head is that the Motor along with the pulley and the control electronics be mounted firmly on the top floor and have some rope go to the ground so someone attaches what is to be lifted
I haven't though of any safety features for it because I won't lift any living creature
I also had the idea of having a timer in the code of the controller to determine when to stop but then realized that with different weights this won't work as intended

ok so I need to know a few details to give a good answer.
first of all you say you haven't thought of any safety features as it won't carry anything living..... but its going to be 10meters up in the air holding 3kg's above people at a science fair..... try a brake at least please

what design are we going for with lifting? pulleys, hydraulics, worm drive? each have advantages and can affect motor requirements

what type of motor are you using? stepper, brushless brushed? once again needed to know to give right details

are counterweights being used? this effects distribution of weight. if you push a rock by yourself you struggle if a weight or something is pulling it too then it is easier

if using pulleys are the motors going to act only as a winch and at all times hold the weight of the rope AND casing or do you have something designed for this? if the drive motor is holding the weight of the rope at all times this needs to be accounted for, if however it is acting like a conveyor belt and pushing rope in a direction only then I need to understand the friction created there

what are you using to hold the carriage? rope, steel rope? something else the weight of a 10inch steel rope would be drastically higher then a piece of string. I need to account for weight settings here

what are you using to stabilise the carriage (stop it swinging around as it goes up/down)? if using a sliding carriage are you just lubricating or are there bearings being installed? this will affect friction and as such is needed. if you let it sway in the breeze though then this is also a needed item to know

are you using anything to monitor speed? if its mechanical I need to know this too.

lastly you say it is only lifting 3kg, is that the carriage or the item in the carriage? if its the item in the carriage then what weight is the carriage.

https://www.archtoolbox.com/materials-systems/vertical-circulation/elevatortypes.html this site shows 3 common types of elevators but I always liked a pulley system one as it has benefits of being geared to avoid falling suddenly, has more than 1 point of contact for weight so if one fails it is still safe and when designed with counter weights it can use some relatively small motors ... but that's just my opinion.... heck I am asking how to modify a motor in another thread.

if money is no worries goto an auto shop and buy a winch for a car...... you could lift half the floor with that... if trying to get smallest motor to save costs, more details please

 

ok so I need to know a few details to give a good answer.
first of all you say you haven't thought of any safety features as it won't carry anything living..... but its going to be 10meters up in the air holding 3kg's above people at a science fair..... try a brake at least please
OK will implement that
what design are we going for with lifting? pulleys, hydraulics, worm drive? each have advantages and can affect motor requirements
I am going to use pulleys
what type of motor are you using? stepper, brushless brushed? once again needed to know to give right details
That was the original problem I don't which is the best suitable
are counterweights being used? this effects distribution of weight. if you push a rock by yourself you struggle if a weight or something is pulling it too then it is easier
yeah counter weight are in check I was think of about a half full cargo
if using pulleys are the motors going to act only as a winch and at all times hold the weight of the rope AND casing or do you have something designed for this? if the drive motor is holding the weight of the rope at all times this needs to be accounted for, if however it is acting like a conveyor belt and pushing rope in a direction only then I need to understand the friction created there
yeah the motors have to hold the weight at all times
what are you using to hold the carriage? rope, steel rope? something else the weight of a 10inch steel rope would be drastically higher then a piece of string. I need to account for weight settings here
just normal rope with half of an inch of thickness
what are you using to stabilize the carriage (stop it swinging around as it goes up/down)? if using a sliding carriage are you just lubricating or are there bearings being installed? this will affect friction and as such is needed. if you let it sway in the breeze though then this is also a needed item to know
uhm yeah this in another problem as building a sliding tower sort of thing to direct the movement isn't gonna be possible
are you using anything to monitor speed? if its mechanical I need to know this too.
I am using an arduino
pretty good right?
lastly you say it is only lifting 3kg, is that the carriage or the item in the carriage? if its the item in the carriage then what weight is the carriage.
the carriage is about a kilo and I though of maximum additional weight as 2 kilos
https://www.archtoolbox.com/materials-systems/vertical-circulation/elevatortypes.html this site shows 3 common types of elevators but I always liked a pulley system one as it has benefits of being geared to avoid falling suddenly, has more than 1 point of contact for weight so if one fails it is still safe and when designed with counter weights it can use some relatively small motors ... but that's just my opinion.... heck I am asking how to modify a motor in another thread.

if money is no worries goto an auto shop and buy a winch for a car...... you could lift half the floor with that... if trying to get smallest motor to save costs, more details please


Thank you so much
Sorry for my ignorance but I have never used any kind of motors before for any project

 

First is this project isn't for a lesson its for the science fair and it is supposed to be secret until the event
second I am not constructing towers for the elevator
I will put the lifting assembly just in the top floor and it is gonna stop between the ground and the top floor only
and I thought it is gonna be helpful in pulling large banners to hang for the event
that's why I have a strong feeling that it is gonna get the likes of the judges because we have points for the usefulness of the project

Just how useful is it? Someone has to go up to the top and mount the contraption and lower the rope. Then after someone at the bottom hooks up the banner someone at the top is going to have to run it to lift the banner. Then, from what you've said later, the motor is going to have to be continuously powered (in a stalled condition) to hold it there. And then you are going to need one contraption per banner.

What advantage does this have over someone dropping a rope from the top and, having someone hook it up, and then pulling the banner up by hand and tying it off?

What is the "science" in this science fair project?