basic questions on how servos work.

[rampbrian]

im wondering how they exactly work. and how diffrent types of servo motors act and react in situations, like coreless servo motors, are they some kind of brushless motors in the servo? and a 3 pole servo motor? does it tend to burn out with prolonged use , ex - if you were running in a circle, holding full right steering, would the servo motor be stalled out trying to keep torquing to the right to steer the car, wouldnt this cause the servo motor to eventually burn out , or become less effective over time?

im just wondering why my steering servo finaly decided it was tired of doing its job. it was a box stock ae servo on my mgt, and it had one heck of a time trying to turn those big wheels, but it lasted a fiew gallons of fuel, im curious as to wich parts of the servo wore out.
and what the signs are of a servo that is getting to that point - and if there is any maintnence I can do to help prolong the life of the servos on my rc stuff. it would be real bad if a rudder servo decided to konk out in flight.

[viper7016]

A coreless servo has a basket weave winding instead of the conventional method. It is lighter and provides faster transit and more torque for a given amount of energy.

Yes, servos can easily burn out if they are constantly trying to push past the stopping point of the steering linkages. Radios with end point settings are your friend and pretty much mandatory for high torque servos.

Quoted from: http://www.misbehavin-rc.com/pit-lane/servo/nrevo-differences.asp

"I often hear people in the hobby complain about a brand of servos that they see as having centering issues. They proceed to complain about that brand and often consider it a "cheap brand" of servo. However that's not truly the case. The problem lies in the components of the servo itself, and this issue can be reproduced among any brand of servo. It lies in the way that the servo itself converts an instruction into a motion.

Most servos, especially the more affordable ones, are 3 or 5 pole servos. The internal components of these servos, aside from the gears, are very similar to an electric RC motor. You have an armature, which is the part with the wire windings, that spins inside a set of magnets. Most servos have 3 or 5 of these magnets which are called "poles". Just like with any electric motor when you are between the magnets the motor is noticeably weaker. When this happens in a servo application, this can often cause the centering to drift slightly in one direction or another. Factor in the fact that the magnets lose their strength over time, and you'll find that the problem can intensify as the servo gets older.

Coreless motors do not suffer from this problem. They use a wire mesh that spins around the outside of a magnet, and this provides a more consistent and smoother pattern of travel. Another side benefit of this is that holding strength is also increased. This is because you eliminate the heavy armature that would be spinning in a standard pole-type servo and the weak areas that would be between the magnets. So a coreless servo will be much more accurate when returning itself to center under load.

Whether bashing or racing a servo that is more accurate, and that can hit center perfectly time after time, can make a big difference to the way your RC performs. So if you can shell out the extra cash, a coreless servo can be a very good investment."