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Old 02-25-2008, 07:07 AM
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Howard
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Default RE: Hi Torque servo has very little torque

Torque = (distance from center of rotation) x (perpendicular component of the force to the radius) This means that if you have a 160 in oz servo it will apply a force of 160 oz at eactly one inch from the center of the servo arm exactly perpendicular to the that arm. From the pictures your load is not perpendicular to the servo arm which means actual force would be the weight of the bed multiplied by either 1/sine or 1/cosine (which is greater than the actual bed weight) plus it appears greater than one inch from the center of the servo arm all of which is why it does not work. Remember that 160 in oz servo will only provide a force of 80 oz if the load is applied two inches from the center of the servo.

You can figure out what is going on by using a first semester physics book (pick one that uses algebra instead of calculus) and using the principal of (1) sum of the torque = 0 and (2) sum of the forces = 0. You must understand torque to resolve this so spend some time reading and re-reading on that subject. Most folks don't fully completely understand torque and usually lump it into the mysterious area of mechanical advantage - which it is, just not mysterious.

If all else fails you can send me a schematic/picutre and the numbers and I can let you know how much torque you will need.

Hope that helps.