Jump to content




Photo

Concerning Hawk motors and their brushes


  • Please log in to reply
41 replies to this topic

#1 Brian Cochrane

Brian Cochrane

    Brian Xpro Retro East Member

  • Full Member
  • PipPipPip
  • 195 posts
  • Joined: 05-June 14
  • Gender:Male
  • Location:Long Island, NY

Posted 08 February 2018 - 05:57 AM

I was thinking about the brush orientation in the Hawk motors and why they are turned the wrong direction.

 

Since these motors are not just for slot car use and they fit other applications, is it possible the Hawk motors  are meant for running in both directions in other applications and that is why the brushes are like they are.

 

These motors use a brush that is attached to the spring or brush arm and they are not in a hood-type sleeve like an endbell motor. That means the brush is not supported by a housing to prevent it from rocking back and forth when this type of motor reverses direction. The rocking can cause the brush to possibly catch on the comm if the brushes were oriented correctly when the brushes are new and at their full length with a full radius.

 

Keep in mind that the brushes are on arms that are not fully square to the comm surface because they are not in a square sleeve to hold them in place.The  brush arms are weak which can bend easily.

 

Also may be to reduce arcing when reversing direction.


  • Samiam, Eddie Fleming and Steve Ritter like this




#2 JohnnySlotcar

JohnnySlotcar

    Checkered Flag in Hand

  • Subscriber
  • PipPipPipPipPipPip
  • 1,977 posts
  • Joined: 26-August 06
  • Gender:Male
  • Location:Barrington, IL

Posted 08 February 2018 - 10:09 AM

Why do they have comm timing on them?


John Austin

#3 airhead

airhead

    Race Leader

  • Full Member
  • PipPipPipPipPip
  • 611 posts
  • Joined: 13-January 09
  • Gender:Male
  • Location:Prattville, AL

Posted 08 February 2018 - 10:47 AM

What happens when the brushes wear in to the shape of the comm?


Billy Watson

#4 Samiam

Samiam

    Posting Leader

  • Full Member
  • PipPipPipPipPipPipPip
  • 4,660 posts
  • Joined: 18-January 12
  • Gender:Male
  • Location:Long Island, NY

Posted 08 February 2018 - 10:55 AM

Why do they have comm timing on them?

 

Our race motors are custom spec'd by whomever orders them. 


Sam Levitch
 
"If you have integrity, nothing else matters, and if you do not have integrity, nothing else matters."
     Robert Mueller, special counsel (2013)

#5 Samiam

Samiam

    Posting Leader

  • Full Member
  • PipPipPipPipPipPipPip
  • 4,660 posts
  • Joined: 18-January 12
  • Gender:Male
  • Location:Long Island, NY

Posted 08 February 2018 - 10:59 AM

What happens when the brushes wear in to the shape of the comm?

 

In the case of car mirror motors, this would mean your car is 2000 years old and what happens is moot. :D


  • Tim Neja and Bud Greene like this
Sam Levitch
 
"If you have integrity, nothing else matters, and if you do not have integrity, nothing else matters."
     Robert Mueller, special counsel (2013)

#6 Cheater

Cheater

    Headmaster of the asylum

  • Root Admin
  • PipPipPipPipPipPipPipPip
  • 23,235 posts
  • Joined: 14-February 06
  • Gender:Male
  • Location:Norcross, GA

Posted 08 February 2018 - 11:02 AM

Did you se the post by Haruki Kan in another thread?
 

When I visited a DC motor manufacturer in Tokyo, I asked this brush orientation issue of FK(130) motors to their designer.
He told me the present orientation is right and on purpose.
Those motors are originally designed for moving door mirrors or display monitors of cars.
The less contact between brush and comm makes the less friction.
If brushes were seated perfectly on comms, motors would have more troubles and much shorter life.
Those motors are designed to run less than 8,000 RPM at 12 volt while slot car motors run 40,000 to 50,000 RPM.


  • Tim Neja likes this

Gregory Wells

Never forget that first place goes to the racer with the MOST laps, not the racer with the FASTEST lap


#7 Cheater

Cheater

    Headmaster of the asylum

  • Root Admin
  • PipPipPipPipPipPipPipPip
  • 23,235 posts
  • Joined: 14-February 06
  • Gender:Male
  • Location:Norcross, GA

Posted 08 February 2018 - 11:17 AM

Why do they have comm timing on them?


In a three-pole permenent magnet DC motor, comm timing is not necessary for starting, which would be the case with a two-pole PMDC motor.

As I see it, comm timing is basically a mechanical speed control.

In a PMDC motor, the motor acts as both a motor and a generator at the same time. That is, while power is applied to rotate the motor, the motor is also generating a voltage termed 'back EMF', (EMF meaning electromotive force, i.e. voltage). It is termed 'back EMF' because it opposes the direction of the applied voltage. When the back EMF grows to equal the applied voltage, the motor has reached its maximum RPM.

Increasing the timing of a motor has the effect of making the motor a less efficient generator, which allows the motor to reach a higher RPM before the back EMF equals the applied voltage.

There are other effects that result from comm timing as well, but this is the basic effect.

Here's a very basic web seminar on brushed DC motors that actually mentions slot cars. It will be too basic for many here, but for some it will be a good grounding.

 

Brushed DC Motor Basics


  • gotboostedvr6, Samiam and Brian Cochrane like this

Gregory Wells

Never forget that first place goes to the racer with the MOST laps, not the racer with the FASTEST lap


#8 Brian Cochrane

Brian Cochrane

    Brian Xpro Retro East Member

  • Full Member
  • PipPipPip
  • 195 posts
  • Joined: 05-June 14
  • Gender:Male
  • Location:Long Island, NY

Posted 08 February 2018 - 11:21 AM

All good questions that I knew would be asked.

 

I'm sure the manufacturer of the motors has a standard of each type. You pick the type and then make small changes such as the timing you would like, the spacers you want, the magnets you want, etc. Without literally making an all new motor from scratch, just subtle changes within the guidelines of the basic motor you chose to do it to.

 

The other question asked was what happens when the brushes wear in. By that time there will be less spring tension and the brushes will be more square to the comm and when the motor is run in reverse the brushes will hold to the comm better because of the matched surfaces.



#9 MSwiss

MSwiss

    Grand Champion Poster

  • Advertiser
  • PipPipPipPipPipPipPipPip
  • 20,350 posts
  • Joined: 16-April 06
  • Gender:Male

Posted 08 February 2018 - 11:47 AM

(1) The rocking can cause the brush to possibly catch on the comm.

(2) The brush arms are weak which can bend easily.

 

1 - I don't think so. Not where it would lock up the motor.

2 - I disagree that they can bend easily. Not in racing.

Who has ever heard of a brush arm bending in a bad wreck, and the motor performance being effected?


  • Matt Sheldon likes this

Mike Swiss
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990), eight G7 main appearances
Eight-time G7 King track single lap world record holder

17B West Ogden Ave Westmont, IL 60559, (708) 203-8003, mikeswiss86@hotmail.com (also my PayPal address)

Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516


#10 slotcarone

slotcarone

    Posting Leader

  • Full Member
  • PipPipPipPipPipPipPip
  • 3,398 posts
  • Joined: 23-January 07
  • Gender:Male
  • Location:Dutchess County, NY

Posted 08 February 2018 - 12:12 PM

I had it happen once in a wreck. Really fast motor lost a lot of speed and was definitely in the motor. Could not see anything amiss in it.

Mike Katz

Scratchbuilts forever!!


#11 MSwiss

MSwiss

    Grand Champion Poster

  • Advertiser
  • PipPipPipPipPipPipPipPip
  • 20,350 posts
  • Joined: 16-April 06
  • Gender:Male

Posted 08 February 2018 - 12:17 PM

So the "weak" brush arms weren't a twisted mass of copper? Lol

I just don't see how they could bend, unless the bushings disintegrated.

Falcon 5's use to change speed in bad wrecks, from the comm twisting, either advancing or retarding the timing.

Mike Swiss
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990), eight G7 main appearances
Eight-time G7 King track single lap world record holder

17B West Ogden Ave Westmont, IL 60559, (708) 203-8003, mikeswiss86@hotmail.com (also my PayPal address)

Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516


#12 slotcarone

slotcarone

    Posting Leader

  • Full Member
  • PipPipPipPipPipPipPip
  • 3,398 posts
  • Joined: 23-January 07
  • Gender:Male
  • Location:Dutchess County, NY

Posted 08 February 2018 - 12:26 PM

Brushes looked fine. I am thinking maybe the magnets moved?

Mike Katz

Scratchbuilts forever!!


#13 Brian Cochrane

Brian Cochrane

    Brian Xpro Retro East Member

  • Full Member
  • PipPipPip
  • 195 posts
  • Joined: 05-June 14
  • Gender:Male
  • Location:Long Island, NY

Posted 08 February 2018 - 12:43 PM

I'm saying if the motor has many other uses and it had the brushes oriented in the correct direction, the use of it when in reverse when the motor is new and not broken-in may cause it to either not seat in properly and cause damage and that is why they may put the brushes in the way they do. I don't think it will twist up the brush arms; it could cause the brush to tooth out like a buck tooth.

 

I'm just saying this might be the reason for the brushes installed the way they are. The brushes are pushed in to the arm with a slot connection and going forward and reverse with the brushes when new may loosen or cause the brush to not break-in properly. The brush seats in faster with only two sides of it touching the comm, plus there is less friction on the comm because there is less surface coverage.

 

In order to retool and make the brushes for a one direction spinning motor would probably double the cost of the motor.

 

PS: These motors when in a crash and maybe hitting a stopped object while your finger is pressing the trigger will give 13 volts to a motor that is not spinning which will heat up the brush arms and kill their tension. It will also pit the comm and/or heat up the wire on the pole of the arm that is in the power mode. It will also blister the comm if it gets hot enough. Take a crap motor and hold the shaft while putting power to it and see what happens...

 

Even if you stick a pin inside the motor to clean out the comm slots it kills these motors. That's how sensitive the brushes and brush arms are.

 

I am not directing this comment at anyone; it's just a general comment. Thanks



#14 MSwiss

MSwiss

    Grand Champion Poster

  • Advertiser
  • PipPipPipPipPipPipPipPip
  • 20,350 posts
  • Joined: 16-April 06
  • Gender:Male

Posted 08 February 2018 - 01:09 PM

I agree with all the above, but I'll add, if you lock up a traditional motor, it will kill those brush springs, also, and probably worse.

I can probably count on two hands how many times I've seen a traditional spring pop like a fuse when something was preventing the motor from turning.


  • Brian Cochrane likes this

Mike Swiss
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990), eight G7 main appearances
Eight-time G7 King track single lap world record holder

17B West Ogden Ave Westmont, IL 60559, (708) 203-8003, mikeswiss86@hotmail.com (also my PayPal address)

Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516


#15 Matt Sheldon

Matt Sheldon

    Duffy's HMI Executive

  • Full Member
  • PipPipPipPipPipPip
  • 1,711 posts
  • Joined: 19-January 10
  • Gender:Male
  • Location:Platteville, CO

Posted 08 February 2018 - 01:38 PM

Brush orientation was designed by Hyundai to allow ice buildup and debri to pass while allowing brush contact to remain constant. This was done specifically for their car mirrors that are used in extreme climates. The glue on the arms was done to limit the arm from lifting while ice was passing.

They also found that a vented can works better as a can with no hole retained/created too much condensation.

 

I agree with Mike's responses.


  • Bernie likes this
Matt Sheldon

#16 MSwiss

MSwiss

    Grand Champion Poster

  • Advertiser
  • PipPipPipPipPipPipPipPip
  • 20,350 posts
  • Joined: 16-April 06
  • Gender:Male

Posted 08 February 2018 - 01:54 PM

Very interesting, Matt.

Regardless, the brush orientation on these motors, while always a perceived issue, was never a real life issue until the latest batch of hard brushes.

With the pre-7R motors, with RTRs I had in my case, if a customer was planning to use one for my Wednesday night competition, it was easy to find one that was OK.

I could run it on the King, on 12.2V, and within 15-20 laps, it would pick up .2-.4, and I could determine if it was suitable for the customer, to be competitive, or if it was better for the five-year old girl who is just looking for a car with a pink or purple body.

PS: Matt, when you converse with Mill on FB, how do you keep track of what side of an issue he is on at any particular moment?

Do you use a spreadsheet? LOL.


  • kvanpelt, Bernie and NSwanberg like this

Mike Swiss
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990), eight G7 main appearances
Eight-time G7 King track single lap world record holder

17B West Ogden Ave Westmont, IL 60559, (708) 203-8003, mikeswiss86@hotmail.com (also my PayPal address)

Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516


#17 Matt Sheldon

Matt Sheldon

    Duffy's HMI Executive

  • Full Member
  • PipPipPipPipPipPip
  • 1,711 posts
  • Joined: 19-January 10
  • Gender:Male
  • Location:Platteville, CO

Posted 08 February 2018 - 02:03 PM

PS: Matt, when you converse with Mill on FB, how do you keep track of what side of an issue he is on at any particular moment?

Do you use a spreadsheet? LOL.

 

I don't think it is possible.


  • Cheater, MSwiss, kvanpelt and 2 others like this
Matt Sheldon

#18 Racer36

Racer36

    Race Leader

  • Subscriber
  • PipPipPipPipPip
  • 811 posts
  • Joined: 09-October 11
  • Gender:Male
  • Location:St. Catharines, Ontario, Canada

Posted 08 February 2018 - 02:33 PM

Hyundai? That's scary. I was a mechanic in a Hyundai dealership for 18 months. Longest five years of my life...


  • MSwiss and DOCinCocoa like this

Dennis Dominey

Lifelong half-assed slot racer


#19 MSwiss

MSwiss

    Grand Champion Poster

  • Advertiser
  • PipPipPipPipPipPipPipPip
  • 20,350 posts
  • Joined: 16-April 06
  • Gender:Male

Posted 08 February 2018 - 03:06 PM

MSwiss said; PS: Matt, when you converse with Mill on FB, how do you keep track of what side of an issue he is on at any particular moment?

 

Matt Sheldon replied: I don't think it is possible.

 

Mybil.


Mike Swiss
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990), eight G7 main appearances
Eight-time G7 King track single lap world record holder

17B West Ogden Ave Westmont, IL 60559, (708) 203-8003, mikeswiss86@hotmail.com (also my PayPal address)

Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516


#20 Brian Cochrane

Brian Cochrane

    Brian Xpro Retro East Member

  • Full Member
  • PipPipPip
  • 195 posts
  • Joined: 05-June 14
  • Gender:Male
  • Location:Long Island, NY

Posted 08 February 2018 - 04:24 PM

Here's another thought about these motors. Did you ever take one of these motors or any motor for that matter and race it around the track and see what times it runs, and then put it on a break in box and run it backwards for a while? Then put it on the track and try it and it is slow as chit?

 

Well, in my opinion, that's how touchy brushes can be to the speed of a motor. When you run the motor backwards it knocks off the nice edge that the brush had on it from rotating in the correct direction and by running it backwards you just changed the brush enough to make your motor slow. Sometimes it takes the motor a while to get back to it's happy spot and sometimes it never will be happy ever again.



#21 MSwiss

MSwiss

    Grand Champion Poster

  • Advertiser
  • PipPipPipPipPipPipPipPip
  • 20,350 posts
  • Joined: 16-April 06
  • Gender:Male

Posted 08 February 2018 - 05:15 PM

Brian,

 

I'll try that tonight if I get a chance.

 

How long do I have to run the car/motor, backwards?

 

Making it perfectly clear, I'm not just trying to give a hard time. I really admire you. You collect all the cool stuff, I wish I had as a kid.

 

And I really like your "march to my own beat with Retro chassis construction."

 

But so much of your theory and scenarios are based on purposely abusing the equipment.

 

"You ever notice how your car doesn't handle the same, after you drop a cement block on it?" :laugh2:


  • Brian Cochrane likes this

Mike Swiss
IRRA® Components Committee Chairman
Five-time USRA National Champion (two G7, one G27, two G7 Senior)
Two-time G7 World Champion (1988, 1990), eight G7 main appearances
Eight-time G7 King track single lap world record holder

17B West Ogden Ave Westmont, IL 60559, (708) 203-8003, mikeswiss86@hotmail.com (also my PayPal address)

Note: Send all USPS packages and mail to: 5858 Chase Ave., Downers Grove, IL 60516


#22 Eddie Fleming

Eddie Fleming

    Checkered Flag in Hand

  • Full Member
  • PipPipPipPipPipPip
  • 1,147 posts
  • Joined: 27-April 14
  • Gender:Male
  • Location:Fayetteville, GA

Posted 08 February 2018 - 05:21 PM

I have tried breaking-in a motor and then break-in in the reverse direction to try to even out the seating between the two brushes. Then I did more break-in in the normal direction. I would not recommend trying it. Of the two I tried one runs pretty well and one not so much. 


Eddie Fleming

#23 Samiam

Samiam

    Posting Leader

  • Full Member
  • PipPipPipPipPipPipPip
  • 4,660 posts
  • Joined: 18-January 12
  • Gender:Male
  • Location:Long Island, NY

Posted 08 February 2018 - 06:35 PM

.Sometimes it takes the motor a while to get back to it's happy spot and sometimes it never will be happy ever again.

 

This is true with people, too. 
 


Sam Levitch
 
"If you have integrity, nothing else matters, and if you do not have integrity, nothing else matters."
     Robert Mueller, special counsel (2013)

#24 Matt Sheldon

Matt Sheldon

    Duffy's HMI Executive

  • Full Member
  • PipPipPipPipPipPip
  • 1,711 posts
  • Joined: 19-January 10
  • Gender:Male
  • Location:Platteville, CO

Posted 08 February 2018 - 06:40 PM

Here's another tidbit about the brushes say in the newer Retro Hawks...

 

They are hard and hard bounces more than soft. That's where the two-speed issue comes from in my opinion. When the motor reaches a certain vibration the brushes bounce on the comm. And if you turn the power up a little more it gets past that vibration bounce and kicks into overdrive. If I have a motor with this problem I bring the power up just before the shifting point and let it run in there. It will vibrate until the bushings free up and usually be a fast motor.

 

Before you put it in the car, rinse the bushings out good with lighter fluid to remove all of the particles that may be in the bushings. Reoil with clean oil and go racing.

 

You are getting warmer. The brush bounce however is not from the brush hardness.


Matt Sheldon

#25 Samiam

Samiam

    Posting Leader

  • Full Member
  • PipPipPipPipPipPipPip
  • 4,660 posts
  • Joined: 18-January 12
  • Gender:Male
  • Location:Long Island, NY

Posted 08 February 2018 - 07:28 PM

PS: Matt, when you converse with Mill on FB, how do you keep track of what side of an issue he is on at any particular moment?

Do you use a spreadsheet? LOL.

 

There's an app for that. :D


Sam Levitch
 
"If you have integrity, nothing else matters, and if you do not have integrity, nothing else matters."
     Robert Mueller, special counsel (2013)





Electric Dreams Online Shop