Maximum radial load to a servo. Rules of thumb? Specs?

Migs

Friends:

Is anyone aware of what the maximum load to a servo is when such load is perpendicular to the shaft axis? Specifically, lets say my robot weighs 4 kg. and I have 6 wheels, and a servo on each wheel. I would like to know if the servo bearings will be worked within a non destructive loading.

Is there a rule of thumb, or better yet a chart of this information for some or most of the common servos?

I ask this for situations where the wheel is connected directly to the servo, and the servo body becomes the mount point to the body. In other words, where using a separate bearing for the wheel shaft is not an option.

Thanks for your comments amigos. -Migs

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"Sometimes we forget that the world itself is paradise." Douglas Coupland, 'Microserfs'
"If the doors of perception were cleansed every thing would appear to man as it is, infinite" - William Blake
"We either make ourselves miserable, or we make ourselves strong. The amount of work is the same." Carlos Castaneda
"One single grateful thought raised to heaven is the most perfect prayer. " G. E. Lessing
“How much of human life is lost in waiting.” Ralph Waldo Emerson
"Men often mistake notoriety for fame, and would rather be remembered for their vices and follies than not be noticed at all.” Harry Truman
My website: www.intoku.net my e-mail:mreznicek@pretensa.com me:Miguel Reznicek

Joe "Bot" Red

Uhmm.... Migs... I have never seen specs for radial loads to the shaft of a servo.. I understand you question, the radial load applied to the shaft and bearing assembly, but I haven't seen radial specs on datasheets, not even on higher end servos like Futaba or Hitec, I guess they are not really meant for that kind of load... :-]

However, your best bet would be to use servos where at least the output shaft is metal and it has double bearings, even then I don't believe you should go above 2 pounds (1 kilo) per servo, so. in your case, 6 wheels can probably accommodate a 6 kilo robot(and I am probably stretching it), in any case I recommend you use plastic horns to attach the wheels to the metal servo shaft, so, in the unfortunate case you step on the robot, the servo horn gives way under the weight, damaging the plastic horn, but the metal shaft will have a good chance to survive, this does not apply to a servo with a plastic output shaft!..

By comparison, the Pittman Gearhead DC Motors series 8xxx are "unofficially" rated at no more than 8 pounds of radial load, and ONLY when the output shaft has double bearings, and these are rugged, all metal motors that weight half a kilo!!... these are tank-like motors compared to el-cheapo servos we usually find in the market, and even then... no more than 8 pounds is recommended..

I hope this helps!.. Happy Roboting Amigo!

Migs

Thanks Joe!

I'm going to think of a better way than radially loading them. Your advice on the plastic horns is a good one, although I think I would die if I stepped on my bot. -NO, I would jump and roll before doing that!

Thanks again,

Migs

▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔▔
"Sometimes we forget that the world itself is paradise." Douglas Coupland, 'Microserfs'
"If the doors of perception were cleansed every thing would appear to man as it is, infinite" - William Blake
"We either make ourselves miserable, or we make ourselves strong. The amount of work is the same." Carlos Castaneda
"One single grateful thought raised to heaven is the most perfect prayer. " G. E. Lessing
“How much of human life is lost in waiting.” Ralph Waldo Emerson
"Men often mistake notoriety for fame, and would rather be remembered for their vices and follies than not be noticed at all.” Harry Truman
My website: www.intoku.net my e-mail:mreznicek@pretensa.com me:Miguel Reznicek

Joe "Bot" Red

Migs said...


·I think I would die if I stepped on my bot. -NO, I would jump and roll before doing that!

Thanks again,

Migs

LOL !!

I would do the same too.... :-)