They way we define any servo is through a ratings system. This allows us to compare the properties of a servo and help us determine which servo is suitable for the need at hand. There are three main ratings to be aware of on a servo.
The ratings are:
A. Torque
B. Speed
C. Voltage
What Do All The Numbers Mean? Let's break it down and explain each one.

Torque:the unit is KG · CM, Can be understood when the object’s horizontal distance to the center of the rudder shaft in the tiller is 1CM,how heavy weight the servo can drive .
Speed:under no load condition turned over 60 degree's angle in required time ,is to measure the velocity of servo.
Voltage:sometimes it can improve the motor speed and torque. Voltage selection also need to look at our controllors can provide.

oz/in too

Does anyone in the RC servo business understand the correct units for torque? Torque is force times distance (not divided). Especially odd with metric units, which should separate force from gravity. Should be something like N-cm or similar.

/soapbox rant

You already have a thread going about servos.
http://www.rctech.net/forum/radio-el...ose-servo.html

Even though it is (Ounces) (inches) i have always written it Oz/in. so when you say it you say "ounce inches" not really anything to do with the expression it represents. but yes, dave is correct. Not sure where gravity came in though, mass is a property of matter, and doesn't change due to gravity. it is all very messed up scientifically.

Using mass weight for force results in different results, as gravity changes for a variety of reasons. Using a proper force unit like Newton eliminates that, a Newton is always the same force anywhere. Fairly obscure trivia, the proper mass unit for the imperial system is slug. Although lbm and lbf are commonly used (pound mass and pound force).

Oz-in and oz/in are dramatically different units. Oz/in is spoken “ounce per inch”, and could be used for a stiffness value as one example. Although like above it should be noted as ounce force per inch to be unambiguous.

Hardly messed up if applied correctly. But in casual use, well yes, it is that sometimes.

I think for clarities sake I shall be switching over to Oz-In.

Yeah,the same meaning of arm of force.kg/cm or oz/in Just the transfer job.

Yeah ,i agree .It is force but the unit change it to gravity in some way. I wondered before

I just want to study more about servo with all of you ,it also make me think of mechanical design curriculum when i study further.

the torque can be different in different voltage, weight of the force....