I'm not an expert in mechanics, so this is my question.

I will buy the motor of the image below to move my door.

In the motor shaft, there is a gear with 50 mm of diameter which will move the door.

The power you does to move the door is similar to lift 12 kg.

The speed needed is about 0,3 m/s.

So, can this motor move the door?

The text are in Portuguese.

Corrente = Current.

Motor Details

And here is more details of the mechanics, is the idea:

enter image description here

Thanks for any help.

  • $\begingroup$ You need to give us more details of the mechanical system. FOr example, is there a chain on the other end of the gear? Or another gear? And how fast do you want the move the door? $\endgroup$
    – DKNguyen
    Jun 29, 2021 at 18:57
  • $\begingroup$ More details added, thanks $\endgroup$
    – LeandroIP
    Jun 29, 2021 at 19:19
  • $\begingroup$ Please clarify whether the 12 kg is mass or force. $\endgroup$
    – r13
    Jun 30, 2021 at 3:39

2 Answers 2

  • The force required to lift 12 kg against gravity is 12 × 9.81 = 120 N (approx).
  • Your gear radius = 25 mm = 0.025 m.
  • To drive the load you would need a torque of 120 N × 0.025 m = 3 Nm (ignoring all losses).

Your motor specification is 1.16 Nm.


  • $\begingroup$ Thanks for accepting my answer. If you can counter-balance the door you may get away with the 1.16 Nm motor. $\endgroup$
    – Transistor
    Jun 30, 2021 at 11:55

The relation of torque with force is,

$$\tau= F*r \quad 1.16Nm =12*9.8*r \\ r= 1.16/117.6=0.00986m=0.986cm$$

  • $\tau$ = torque

  • f=12kg(g)= 12*9.8=117.6N

  • r= radius of the pully= 0.986cm

So your 5cm=2.5cm radius pulley can not move your door. Either you need to replace it with the small size pulley or you have to use a gear with $r= 2.5/0.986* 2.5=6.33cm \text{ or a diameter of 12.67cm } \ $ engaged with your 50mm pulley.


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