# Motor that can lift 20 pounds/~10kg?

Hello everyone!

I want to build a sort of robot arm that has the capacity to lift at least 20 pounds. I know that this is a very heavy load, and most likely exceeds the limitations of the typical hobby servo. I'm curious as to whether anyone knows of a way to lift such a load (efficiently as well). I'm not sure if a gearbox by itself will be enough; there may be some potential in DC motors but I honestly haven't done too much in-depth research on them, nor do I know exactly what I would need to program them to act like a servo.

Does anyone have any information I could perhaps work from? Thanks so much! :)

You have to work out the physics a little bit more before attempting such a project. Any motor can lift 10kg providing it is geared low enough, In order to lift a given weight with a given speed you will need a given amount of power. The force needed to lift a weight with mass m(kg) : F=mg where g is the gravitational constant 9,81N/kg The energy needed to lift a weight to a given hight: W=Fh where W is work/energy in joules and h is lifting hight in meters The power needed to perform the lifting in a given time P=W/t where P is power in watts and t is time in seconds. All these are linear movements. When working with rotational movements you have to convert between force and torque. M=F*d or F=M/d where M is torque in Nm and d is the length of the torque arm perpendicula to the force in m. In robotic applications you will need a surplus of power since there is a need for rapid acceleration and deceleration in order to keep precision. There are servos from Volz and seiko that are quit powerful but expensive. http://www.rcmodelcentre.co.uk/Industrial-Servo-0-7S/120Kg/prod_7180.html http://www.volz-servos.com/en/products/0102-class_24-30V.php?m=m

Perhaps something like this? - Scotty

Knowing the force alone isn't enough to spec the hardware. You also need to know how fast you need it to move, and it would help to know how far you want it to move and whether it will be pushing, pulling, whether it needs to provide any sort of support to the thing being removed and so on. For example, a tiny hobby motor can lift several tons if you gear it down far enough (and find a strong enough gearbox) but you will grow old waiting for it.