Holding power torque vs. regular (?) torque
01-04-2004, 08:04 PM
#1
Holding power torque vs. regular (?) torque
I am trying to compare JR servos to Multiplex servos. It seems the Multiplex are big on the "holding power", but the JR site doesn't list it. What's the difference and how can I compare the two different makes?
TIA
TIA
01-04-2004, 11:20 PM
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RE: Holding power torque vs. regular (?) torque
ORIGINAL: sideshow
I am trying to compare JR servos to Multiplex servos. It seems the Multiplex are big on the "holding power", but the JR site doesn't list it. What's the difference and how can I compare the two different makes?
TIA
I am trying to compare JR servos to Multiplex servos. It seems the Multiplex are big on the "holding power", but the JR site doesn't list it. What's the difference and how can I compare the two different makes?
TIA
To compare the servos I would use the torque rating and the dead band along with weight and size and other obvious things. It would be helpful if they were to give the current draw at the maximum torque.
01-05-2004, 02:26 PM
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RE: Holding power torque vs. regular (?) torque
Holding torque will be 3-5 times higher than the standing toque on digital servos only.
What servos are you comparing?
Mike.
What servos are you comparing?
Mike.
01-05-2004, 08:32 PM
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RE: Holding power torque vs. regular (?) torque
Since no one has really answered your question, I'll give it a shot.
You can't compare a holding torque number to a running torque number. Holding torque is typically much higher than running torque for servos we would use in RC. However, the differance between running and haloding torque can vary greatly based on servo design. Again, you can not convert one torque type to another.
Holding torque is the ability of a servo to hold a commanded position. In other words, this is how much external torque must be applied to move the servo arm from a static position.
Running torque, the number typically listed for servos, is the maximum torque the servo can apply while moving.
Both numbers are important, but for typicaly RC applications, running torque is more significant... if you can't move the surface in the first place, who cares what holding torque you have. The only way to honestly compare the brands is to compare apples to apples, i.e. holding torque @ 6V vs holding torque @ 6V, etc.
You can't compare a holding torque number to a running torque number. Holding torque is typically much higher than running torque for servos we would use in RC. However, the differance between running and haloding torque can vary greatly based on servo design. Again, you can not convert one torque type to another.
Holding torque is the ability of a servo to hold a commanded position. In other words, this is how much external torque must be applied to move the servo arm from a static position.
Running torque, the number typically listed for servos, is the maximum torque the servo can apply while moving.
Both numbers are important, but for typicaly RC applications, running torque is more significant... if you can't move the surface in the first place, who cares what holding torque you have. The only way to honestly compare the brands is to compare apples to apples, i.e. holding torque @ 6V vs holding torque @ 6V, etc.
01-06-2004, 12:10 AM
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RE: Holding power torque vs. regular (?) torque
ORIGINAL: JohnWillman
Since no one has really answered your question, I'll give it a shot.
You can't compare a holding torque number to a running torque number. Holding torque is typically much higher than running torque for servos we would use in RC. However, the differance between running and haloding torque can vary greatly based on servo design. Again, you can not convert one torque type to another.
Holding torque is the ability of a servo to hold a commanded position. In other words, this is how much external torque must be applied to move the servo arm from a static position.
Running torque, the number typically listed for servos, is the maximum torque the servo can apply while moving.
Both numbers are important, but for typicaly RC applications, running torque is more significant... if you can't move the surface in the first place, who cares what holding torque you have. The only way to honestly compare the brands is to compare apples to apples, i.e. holding torque @ 6V vs holding torque @ 6V, etc.
Since no one has really answered your question, I'll give it a shot.
You can't compare a holding torque number to a running torque number. Holding torque is typically much higher than running torque for servos we would use in RC. However, the differance between running and haloding torque can vary greatly based on servo design. Again, you can not convert one torque type to another.
Holding torque is the ability of a servo to hold a commanded position. In other words, this is how much external torque must be applied to move the servo arm from a static position.
Running torque, the number typically listed for servos, is the maximum torque the servo can apply while moving.
Both numbers are important, but for typicaly RC applications, running torque is more significant... if you can't move the surface in the first place, who cares what holding torque you have. The only way to honestly compare the brands is to compare apples to apples, i.e. holding torque @ 6V vs holding torque @ 6V, etc.
I don't think the torque listed in the specifications is what you refer to as running torque. I think the torque listed in the specifications is the torque produced when the motor is stalled.
Your definition of holding torque must specify how much the servo is permitted to move from its static position. There is a band called the dead band that it takes only the torque to overcome the friction of the gears to move the servo arm. This is why the dead band is important. However its not that simple. What we need is a specification of the band width in degrees of the servo at say 10% of the stalled torque. That way we could make a comparison between servos that would mean something. You would see clearly how superior the digital servo is.
01-06-2004, 12:45 AM
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RE: Holding power torque vs. regular (?) torque
DirtyBird, for the most part I agree with your reply to my post... but the measurement method your suggest will probably never happen becasue then we really could compare brand X to brand Y, and neither brand X or Y wants that. Your preaching to the choir on this one, I've been on the "give me a useful measurement" bandwagon for years. Knowing % deflection = X delivered torque really would show which servos were better.
OK, fine line here... torque at point of stalled motor could be the same as the maximum torque the motor can apply while moving. If the servo just reached the point where it can no longer move, then the motor stalled... its the same thing, see my point?
Anyway... I'm really confused myself now. Holding torque, standing torque, running torque... sheesh. Somebody PLEASE do a independent review of popular servos and publish the result.
OK, fine line here... torque at point of stalled motor could be the same as the maximum torque the motor can apply while moving. If the servo just reached the point where it can no longer move, then the motor stalled... its the same thing, see my point?
Anyway... I'm really confused myself now. Holding torque, standing torque, running torque... sheesh. Somebody PLEASE do a independent review of popular servos and publish the result.
01-06-2004, 02:02 AM
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RE: Holding power torque vs. regular (?) torque
...if you can do so and retain your sanity 
Just always buy coreless digitals and you'll be good to go [8D]
Just always buy coreless digitals and you'll be good to go [8D]
01-06-2004, 01:42 PM
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RE: Holding power torque vs. regular (?) torque
ORIGINAL: MikeMayberry
Holding torque will be 3-5 times higher than the standing toque on digital servos only.
What servos are you comparing?
Mike.
Holding torque will be 3-5 times higher than the standing toque on digital servos only.
What servos are you comparing?
Mike.
01-06-2004, 06:11 PM
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RE: Holding power torque vs. regular (?) torque
John I think you must be mistaken, torque rateing's for motors (servo's included) are ALWAYS given as a measure of the amount of force required to stall the motor. Holding power is just a glitz word companies use on digital servo's because they can provide higher torque than an analog servo if the deviation from center is low. A torque listing for a servo is always 'stall torque' and speed rateing are always no-load. If you want more information than that you have to plug the thing into a dyno and figure out the torque vs speed curve.
01-07-2004, 02:24 AM
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RE: Holding power torque vs. regular (?) torque
Lynx, it wouldn't be beyond me to be wrong. I'm willing to accept that what I understand as holding torque may not be what I think. I made some assumptions (naughty me) that the servos may be rated similar to certain elect motors that do have both a running and static torque, such as a stepper motor. I know, not the same as servos. However, I'm still really confused. Multiplex does list a separate "torque" and "Holding Power." I've seen two figures listed elsewhere for other servos, but I can't remember exactly where. There must be a diff. If one is holding, i.e. static torque, the other has to be dynamic, i.e. moving torque. It makes sens to me that a servo can hold static a lot more than it can move because of the dynamics of how motors work. I just assumed that the two measurements reflect this. Just check out multiplex's web site and you'll see what I mean, they list seperate static and dynamic torques. What they really mean, I can't say for sure.
