Hey,
Can someone explain to me the idea behind putting a harder / stronger spring on the positive side of a motor?

Thanks

The reason for putting the stiffer spring on the positive side is because that side always seems to arc more. whell instead of changing boath springs to a stiffer rate why not just fix the side that is arcing right? So its a best of boath worlds thing. first you take care of the arcing, secondly you dont rob alot of rpm due to brush friction by adding 2 stiffer springs. I hope you can understand what I wrote. Sometimes the way I wright is very hard to understand. :tongue:

HOPE THIS HELPS
Sean Scott

Thanks for the reply, I understand thats the general idea behind it. But i'd like someone to tell me why theres more arching on the postive side.

whell Electricity is a very mysterious force. Even I dont understand all of it. So one of the best ways I can think to explain is it is like water. Ok think of the negative terminal as the watter flowing into the motor. (electricity actualy flows from the negative side, many people dont know this) now the electricity "water" flows into the motor, does its thing makes the motor turn part of a rotation. now it is leaving the motor thrugh the positive brush. the electricity exerts a force similar to watter pushing the brush away from the comm. What do you do when you have a leak in your garden hose? Tighten it right? whell the same rool applys if you dont want the watter to leak you use greater force. If you dont want electricity to be bled off in the form of light, sound, and the extra force it takes to push thrugh the air. so you use a greater force to keep it from leaking. GOT IT. GOOD! I think realy if you want the true answer you are going to have to talk to a phisics profesor. but That is what I learned from reading some of mike reedy's motor tuning books.

HOPE THIS HELPS
Sean Scott

so pretty much it like a light bulb, goes in one side comes out the other!!!

lol kind of instead of light energy its mechanical and noise energy. and some is waisted on producing light thrugh arcs. arcs realy waste power. thats why incondesent light bulbs pull so much power. all they are is large controled energy wasters.

whell Electricity is a very mysterious force. Even I dont understand all of it. So one of the best ways I can think to explain is it is like water. Ok think of the negative terminal as the watter flowing into the motor. (electricity actualy flows from the negative side, many people dont know this) now the electricity "water" flows into the motor, does its thing makes the motor turn part of a rotation. now it is leaving the motor thrugh the positive brush. the electricity exerts a force similar to watter pushing the brush away from the comm. What do you do when you have a leak in your garden hose? Tighten it right? whell the same rool applys if you dont want the watter to leak you use greater force. If you dont want electricity to be bled off in the form of light, sound, and the extra force it takes to push thrugh the air. so you use a greater force to keep it from leaking. GOT IT. GOOD! I think realy if you want the true answer you are going to have to talk to a phisics profesor. but That is what I learned from reading some of mike reedy's motor tuning books.

HOPE THIS HELPS
Sean Scott

This post isnt getting much info, its a shame when there seems to be a bunch of motor tuners here.

I find it interesting that you said the above that i have highlighted in bold. When BJ said:

Question: Why is it necessary to have a stiffer spring on the pos side? Doesn't the stiffer spring cause unbalanced com wear?

BJ's Answer: The purpose of the springs is to keep the brush in contact with the comm when the arcing wants to blow it away. The more the brush arcs, the more spring tension is needed. The theory is that since the current enters the motor from the pos side, that brush is going to arc more than the neg side. Therefore more spring tension is need on the pos side.

We have a bit of a conflict here... maybe now people might want to discuss this some more?

electrons flow from negative to positive IN THEORY... it has never been proven to this day.

basically, the lighter the brush sits against the com (light springs), the less current that can pass through..... the heavier the spring(s), the more current that will pass through BUT at the cost of efficientcy.... more rpm/ less torque... more torque/less rpm. YAY 4200s!

it's hard to teach someone about motors in one day. look up fundamentals of DC motors and start reading..... and reading........ and oh yeah, reading.

electrons flow from negative to positive IN THEORY... it has never been proven to this day.

You need to read a few lines (don't have them handy) from Stephen Hawking's "A Brief History of Time". In it he points out that when scientits speak of a "theory", they don't just mean "some idea that someone has." They mean a mathematical and physical description of the way the universe works.

It is true that it is a "theory" that electrons flow from negative to positive, but it is also true that all the actually existing and working electronic devices (like the computer you typed your message on and your cell phone) operate based on this "theory". If the "theory" that electrons travel from negative to positive was not true, your computer would not be working and you could not have responded to the previous post.

And actually, it has been proven in the sense that it is the definition of what electricity is. The definition of electricity is the flow of electrons. Since electrons are negtively charged particles (the positive ones are in the nucleus and don't move around) they must be flowing from the negative terminal to the positive terminal.

Websters Dictionary "Theory : a hypothesis assumed for the sake of argument or investigation b : an unproved assumption"

Fact, Alot of motor/brush combos run better with a heavier spring on the positive brush.

It really doesn't matter which directions the electrons flow, what matters is that the motor runs better with the stiffer spring on the positive side.

And yes it can be proven which way electricity flows by the use of a battery. A battery is two different materials in an electrolyte. One of these materials has an available electron and it gives it up to the other material which can use an electron. This is something taught in high school chemistry. But it really doesn't matter in the world of RC racing.

Here is a good link I found about electricity flow. I agree with 90-95% of it.


http://www.amasci.com/amateur/elecdir.html

Websters Dictionary "Theory : a hypothesis assumed for the sake of argument or investigation b : an unproved assumption"

Fact, Alot of motor/brush combos run better with a heavier spring on the positive brush.

Read the Stephen Hawking description.

The nature of electricity is not simply a "theory" as described above but a "Scientific Theory". They are two different things. Hawking explains that.

The fact that a lot of motor/brush combos run better with a heavier spring on the positive brush does not negate (no pun intended) the Scientific Theory of electricity (actually of matter and energy and lots of other things, which the description of electricity and elctrons is a small part.)

Here is a good link I found about electricity flow. I agree with 90-95% of it.

http://www.amasci.com/amateur/elecdir.html

Good article. It makes the point that in METALS (all of the flow path in an RC motor except the brushes which have some other material), it is the electrons that are flowing.

it is what it is... i did'nt make it up.

btw, i myself agree with the theory. i just know that it has never been proven.

evolution is a different story, LOL! thats just ghey :tongue:

The way we do things in RC may not conform to Scientific Methods but for rc use it works.
For rc motors the power a motor makes is relative to the how well you can get the current to flow to it. Most motor builders and tuners feel it's the positive side of motor where you gain the most current. So along with using a heavier spring to keep brush in contact with comm at operating rpm levels, the content of brush is changed so it can carry more current-usually higher silver content. The negative side uses a lighter spring to reduce drag, lower silver content brush is used to reduce comm wear. In serious racing less concern is placed on wear and more towards making power. A few motor builders used the other method, heavier on negative. In some forms of racing the norm was to use a Purple/Red spring combination as the made motors produce higher amp draw or was related to rpms. But it was also found to affect the motor low end power when raced on small tight tracks. The heavier brush affected how motor accelerated off the turns so norm is to use a Red/Green or two Red spring for layout of track.

Wrong, you aren't gaining any current on the positive side of the motor; you are reducing it's restriction, which is the whole basis of efficiency. Electricity does flow from NEG to POS, simple as that. If you don't truly believe that, then you must have missed something in school (we learned this in 5th grade here). I've gone on to learn more through high school and engineering. You can try and argue with the scientific method (the ways in which things are proven or disproven) all you want, but you are going to lose if you believe electricity flows POS to NEG.

The best explaination (IMHO) of arcing, which USUALLY, but not ALWAYS occurs on the positive side of the motor is due to differences in electronic efficiency of the materials. Copper accepts electrons from the NEG brush because it is so much more efficient. However, as the electrons jump to the POS brush, which is so much LESS efficient than copper, they have a difficult time finding room on the 'walkways' (a theoretical path) to get off the copper fast enough. As more and more gather on the POS brush, they build up and literally push the brush due their utter repulsiveness of each other. Therefore, you get arcing ad use a stiffer spring to reduce that effect. If you could develop a material for a POS brush that was more efficient than copper (or whatever the armature material was) you would gain many percent on the power, efficiency, and torque curves of a motor. Most of this would be for not though, as the longevity of the comm. would severely decrease.

This is my theory anyway, you don't have to believe it. What isn't my theory is electricity flowing NEG to POS, it's just the truth. All of my motor talk is in understanding and assumption that we are discussing a well trued motor, meaning the comm. is within limits and perfectly round.

That is the best theory I have heard for why the POS tends to arc mor than the negative side. So that leads me to wonder if it would be worth using one of the XXX brushes on the POS side and a regular brush on the NEG side and still get the benfits of both. Thanks!

The best thing you could do is try it in the Real World and forget about theorys! LOL

The best thing you could do is try it in the Real World and forget about theorys! LOL

You mean we're not supposed to calculate the aerodynamic efficiency of having an antenna tube routed outside the shell vs. inside?! ;)

That is the best theory I have heard for why the POS tends to arc mor than the negative side. So that leads me to wonder if it would be worth using one of the XXX brushes on the POS side and a regular brush on the NEG side and still get the benfits of both. Thanks!

I'd like to hear someone else's in put on this comment lol. would that work alright? or is it a ...give out 20 bucks and try it your self type deal? lol

You mean we're not supposed to calculate the aerodynamic efficiency of having an antenna tube routed outside the shell vs. inside?! ;)


LMFAO!!! Thats the funniest thing i've herd all year :lol: :lol:

The arc is actually plasma, you use the heaver spring to make a better ground for the current, you will never make all the arc go away if you did the motor would not run. The speed controls always break the negative side as the electrons are trying to get to ground to complete the circuit.

My belief is that if the motor is brushed and sprung correctly the brush at max RPM isn't even touching the com but is riding on a very thin layer of plasma..

When I developed my comm drops i was trying to fool the motor into think there was more plasma than there really was. Thus when the drops are applied to the com on a dyno ther arcing actually increases but so does the watts, amp draw and torque.

Bulitbill
www.bulitmotorsports.com

The arc is actually plasma, you use the heaver spring to make a better ground for the current, you will never make all the arc go away if you did the motor would not run. The speed controls always break the negative side as the electrons are trying to get to ground to complete the circuit.

My belief is that if the motor is brushed and sprung correctly the brush at max RPM isn't even touching the com but is riding on a very thin layer of plasma..

When I developed my comm drops i was trying to fool the motor into think there was more plasma than there really was. Thus when the drops are applied to the com on a dyno ther arcing actually increases but so does the watts, amp draw and torque.

Bulitbill
www.bulitmotorsports.com (http://www.bulitmotorsports.com) not only did the comdrops work well on motors you could also turn a white tshirt purple i n afew minutes lol

The confusion in this thread could have all been avoided by Ben Franklin not 'assuming' that electrons hold a positive charge!

These threads never really end well. Everyone has a theory about why the pos brush has more arcing and what to do about it. I've yet to see a real study to show the process that makes this side different than the other. There are some pretty good theories but no real proof. At least some are kind enough to interject that the answer is only their opinion.

In the end the physics behind why the brush has more arcing doesn't really matter. It is what it is and nothing more. We can change a bunch of things to help with brush arcing and we know that they help. It doesn't matter if it's a heavier spring, cut brush, different brush compounds, or any number of other changes. As long as it makes more useable power it's a good thing. Knowing why is less important than knowing what to do to help the problem.

Wise man once said:



In the end the physics behind why the brush has more arcing doesn't really matter. It is what it is and nothing more. We can change a bunch of things to help with brush arcing and we know that they help. It doesn't matter if it's a heavier spring, cut brush, different brush compounds, or any number of other changes. As long as it makes more useable power it's a good thing. Knowing why is less important than knowing what to do to help the problem.

After reading all this I agree with most of the thread comments and there's some very educated people commenting .

What I've personnally experienced is a fairly stiff spring on both sides or a stiffer spring on the neg.

The speed controller always controlls the neg side which does prove electrons flow out the neg side of a DC battery.

With the positive wire connected dirrectly to the motor , the only variable is the neg , and with its voltage / amperage constantly going up and down with the throttle action you need a slightly stiffer spring on the neg for better power and longer com life.

Any snowmobilers out there ? What happens to a trail when your constantly on and off the throttle ?

But again just my opinion-----------

The first cars were all pos. grnd with all the switching being done from the neg side "technically correct " - BUT the average person couldn't understand that type of thinking so the car manufacturers had to go to neg ground and switch the pos.