I'm trying to choose a 12vdc geared motor for a TV lift system for an RV. It's mounted in an overhead drawer.
I'm an ME but I've never had to deal with motors or the physics involved. I've done a little research and reviewed the principles but I'm not sure about my results or the method I've used to get there.
Am I missing any dynamics on the profile of the lift? I'm seeing it as a pivoting diagonal lift? Are motors rated by a straight vertical lift? Because it's a hinged lift, will the lift angle make any considerable difference in my torque requirements?
Can anyone tell me if I've gone wrong or missed anything?
Formula used: τ[Nm]=(mass[kg]× g) × pulley radius[m]
TV mass = 4.5kg
g = 9.81
Pulley radius = (12mm dia / 2) = 6mm / 1000 = .006m
τ[Nm]= (4.5 x 9.81) x .006
τ[Nm]= .26487Nm (264.87mNm or 2.7kgf cm)
Motor I've chosen based on 2.7 kgf cm:
RPM = 40
Rated Torque = 5.6 kg.cm
Max Torque = 24 kg.cm
Ratio reduction = 150
No-Load Current (ma) = ≤60
Rated Current (A) = ≤0.6
Stall Current (A) = 1.3
Here's the drawing. Note: the pin point is attached to the drawer.
What you are dealing with is called overhung load. This pdf should explain it much better than I can.
Gearmotor Sizing Guide.pdf
Great drawing but I am not certain how the raising/lowering is taking place (winding a cable?). You may have to change the driver or driven pulley to get the speed right. If you want to have easy speed change look into DC drives. Cheap and easy.