Questions Regarding Choosing the Right Motor

Thread Starter

Lerior

Joined Jan 18, 2018
28
Good Evening,

We are doing a project that resembles an elevator system. We have a task to choose the right DC motor that can lift a max load of 300lb (Up/down movements using pulleys and robes, as well as a counterweight), as well as controlling the distance in which the load will stop. We've suggested to use a 12V stepper motor (or encoder DC motor) in that case. We also plan to use an Arduino to control the switch that turn the motor on/off.

Problem here is none of us have any experience regarding motors, so we are not sure if we are in the right track. We want to know the torque that is most appropriate for that job, as well any resources that can guid as into the right direction (direct the movement of the motor, reverse its direction etc). I would appreciate any help/suggestions. I have sketched a very simple block diagram explaining the initial plan.
 

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MaxHeadRoom

Joined Jul 18, 2013
21,623
I would suggest using some kind of gearing to economize on motor size, an elevator does not typically require a final high rpm.
A DC Treadmill motor could do the trick with reduction used. I don't see a need for encoder, just limit SW's.
A automotive starter also has High torque if limited to 12vdc.
Do you intend building a controller or off-the-shelf?
A 3phase motor is also a possibility with VFD controller.
Max.
 

Thread Starter

Lerior

Joined Jan 18, 2018
28
I would suggest using some kind of gearing to economize on motor size, an elevator does not typically require a final high rpm.
A DC Treadmill motor could do the trick with reduction used. I don't see a need for encoder, just limit SW's.
Do you intend building a controller or off-the-shelf?
A 3phase motor is also a possibility with VFD controller.
Max.
It is more of a small elevator that can only lift, as I mentioned, a max of 250-300lb. The reason why we want to control the motor is because we want the load to reach a certain distance, and then revert back to its original position. This is a project that will be used in homes (Think of a cabinet shelves with max load of 50lbs that moves up and down, the counterweight and the pulleys will add additional load to the motor). A controller sounds like it is the only to do that (of course I could be wrong here).
 
Last edited:

MaxHeadRoom

Joined Jul 18, 2013
21,623
If this is a small distance to lift, it would seem ideal application for a linear actuator.
One advantage is they do not generally back-feed under load.
Max.
 

cork_ie

Joined Oct 8, 2011
428
You mention that there is a counterweight fitted to the system .
Is the max lift 250-300lbs, or is the counterweight doing some of the lifting for you?
If you have a motor raising and lowering 300lbs then you need to consider the speed of the system. There are going to be some hefty forces caused by sudden stops at either end caused by the momentum & Kinetic energy of a 300lbs load unless the speed is quite slow or some sort of braking system is installed.
Can you give us an idea of the nett weight that you need to lift and an approximate speed in cm or m/second?
What kind of friction forces do you expect in the overall system?
Reversing direction is easiest achieved with either a permanent magnet DC motor or 3 phase AC. Other options are more complicated. Braking can also be achieved with the DC motor by shorting across the armature at the limits, to minimise overshoot.
 
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