Looking for a Gearmotor; How Much Torque to Close this door?

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In summary, the conversation discusses the search for a gearmotor that can provide enough torque to close a door with a mass of 136lbs and dimensions of 40in width x 85in height. The desired closing time is 60 seconds and the rotation of the door is 180 degrees. More information is needed, such as the direction of the gravity vector and the location of the hinge or axis of rotation, to accurately determine the required torque. The equation for torque is mentioned, along with the need for fudge factors and sizing the gearmotor accordingly. The conversation ends with the mention of the helpfulness of using the mass moment of inertia in the calculations, and the confirmation that the axis of rotation is on the right side of
  • #1
Hes
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I'm trying to find a gearmotor that applies enough torque to close this door.

Door Mass = 136lbs
Door Dims = 40in width x 85in height
Time to close = 60sec
Door's rotation = 180 degrees

upload_2017-12-21_17-37-37.png


Any tips and advice would truly be appreciated.
 

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  • #2
Do you have an actual door in mind?

Where is the door hinge axis?

If this is a real door you might simply measure the force needed to close it at the point where you plan to connect the lever arm.
 
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  • #3
I can't see from the drawing how this could operate as a door closer. Is the gearmotor supposed to have a rotary output?
Is closure speed fixed? 180° open to closed in 60 seconds (2°/second) is rather slow over much of the closure range.
Take care to rescue the angel; crushing one in a door mechanism is considered poor engineering practice.
 
  • #4
Much more info needed for any kind of intelligent answer:
  • This figure is plan (top) view, correct? If not, specify it so the community can determine the direction of the gravity vector. Gravity may add force requirements.
  • Is the door hinged? If hinged, where is the hinge? Specify it.
  • If no hinged, about what axis does the door pivot? Specify it.
  • door mass ≠ lbs. You better figure that out first.
  • Torque = (mass moment of inertia) x (angular acceleration)
  • (mass moment of inertia) will likely be estimated from inertia primitive formulas and modified with parallel axis theorem. Look 'em both up.
  • (angular accel) is estimated α ≅ Δ(angular velocity)/Δ(time to accelerate)
  • Add a bunch of fudge factors for safety, friction, gravity effects, windage effects, robustness, etc., and that will give your peak torque. Size the gearmotor for that.
 
  • #5
tygerdawg said:
Much more info needed for any kind of intelligent answer:
  • This figure is plan (top) view, correct? If not, specify it so the community can determine the direction of the gravity vector. Gravity may add force requirements. Yes this is top view
  • Is the door hinged? If hinged, where is the hinge? Specify it. Yes on the right side.
  • If no hinged, about what axis does the door pivot? Specify it.
  • door mass ≠ lbs. You better figure that out first.
  • Torque = (mass moment of inertia) x (angular acceleration)
  • (mass moment of inertia) will likely be estimated from inertia primitive formulas and modified with parallel axis theorem. Look 'em both up.
  • (angular accel) is estimated α ≅ Δ(angular velocity)/Δ(time to accelerate)
  • Add a bunch of fudge factors for safety, friction, gravity effects, windage effects, robustness, etc., and that will give your peak torque. Size the gearmotor for that.
Thank you very much for your help. I kept struggling with finding the torque, using a different equation. That mass moment of inertia is going to help me a lot
 
  • #6
The moment of inertia won't anyone here wanting to help if we don’t know the axis of rotation for the door.
 
  • #7
jedishrfu said:
The moment of inertia won't anyone here wanting to help if we don’t know the axis of rotation for the door.
the axis of rotation is the end of the door on the right side
 

Related to Looking for a Gearmotor; How Much Torque to Close this door?

1. What is a gearmotor?

A gearmotor is a type of motor that combines a gear reducer and an electric motor, typically used to produce high torque output at low speeds.

2. How much torque does a gearmotor produce?

The amount of torque produced by a gearmotor depends on various factors such as the size and type of motor, gear reduction ratio, and load being driven. Generally, gearmotors can produce torque ranging from a few ounce-inches to several hundred pound-feet.

3. How do I determine the torque needed to close a door?

To determine the torque needed to close a door, you will need to know the weight of the door and the distance from the hinge to the point where the gearmotor will be mounted. You can then use the formula: Torque = Force x Distance. Keep in mind that the force required to close a door may vary depending on factors such as friction and air resistance.

4. What is the recommended torque for closing a standard door?

The recommended torque for closing a standard door is typically between 10-20 pound-feet. However, this may vary depending on the weight and size of the door, as well as other factors mentioned earlier.

5. Can a gearmotor be used to open and close a door?

Yes, a gearmotor can be used to open and close a door. However, you will need to make sure that the gearmotor has a reversible function and that the torque is sufficient for both opening and closing the door. You may also need to consider adding a limit switch or other safety mechanisms to ensure proper operation.

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