Go to Post Ok maybe you cant stop them, but you can utilize that pretty flashing LED pretty darn well! - Andy Grady [more]
Home
Go Back   Chief Delphi > ChiefDelphi.com Website > Extra Discussion
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Reply
Thread Tools Rate Thread Display Modes
  #1   Spotlight this post!  
Unread 25-06-2003, 18:45
CD47-Bot CD47-Bot is offline
Registered User
FRC #0047 (Chief Delphi)
 
Join Date: Dec 2002
Location: Pontiac, MI
Posts: 1,616
CD47-Bot has a reputation beyond reputeCD47-Bot has a reputation beyond reputeCD47-Bot has a reputation beyond reputeCD47-Bot has a reputation beyond reputeCD47-Bot has a reputation beyond reputeCD47-Bot has a reputation beyond reputeCD47-Bot has a reputation beyond reputeCD47-Bot has a reputation beyond reputeCD47-Bot has a reputation beyond reputeCD47-Bot has a reputation beyond reputeCD47-Bot has a reputation beyond repute
pic: Gerrish Gearbox MKII

Reply With Quote
  #2   Spotlight this post!  
Unread 25-06-2003, 18:46
WernerNYK WernerNYK is offline
Registered User
AKA: Chris Werner
FRC #0190 (Gompei & the HERD)
Team Role: Engineer
 
Join Date: Jan 2002
Rookie Year: 2001
Location: Worcester, MA
Posts: 274
WernerNYK is a jewel in the roughWernerNYK is a jewel in the roughWernerNYK is a jewel in the rough
Send a message via AIM to WernerNYK
Hmm, looks interesting. Perhaps some 2D orthographic views though? I can't quite make out exactly what is going on...
__________________
-Chris Werner
"Production Manager"
BattleCry@WPI

Team 190 - WPI & Mass Academy
Est. 1992!

Team 871 - Former team leader
Reply With Quote
  #3   Spotlight this post!  
Unread 25-06-2003, 19:00
Tytus Gerrish's Avatar
Tytus Gerrish Tytus Gerrish is offline
IGAB, ADHD, and Dislexic
AKA: Ty
FRC #0179 (SwampThing)
Team Role: Tactician
 
Join Date: Feb 2003
Rookie Year: 2001
Location: West Palm Beach, Florida
Posts: 2,017
Tytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond repute
Ortho-What now?
Reply With Quote
  #4   Spotlight this post!  
Unread 25-06-2003, 19:15
WernerNYK WernerNYK is offline
Registered User
AKA: Chris Werner
FRC #0190 (Gompei & the HERD)
Team Role: Engineer
 
Join Date: Jan 2002
Rookie Year: 2001
Location: Worcester, MA
Posts: 274
WernerNYK is a jewel in the roughWernerNYK is a jewel in the roughWernerNYK is a jewel in the rough
Send a message via AIM to WernerNYK
The standard in presenting mechanical parts. 2D Top, Front, and Side views....
__________________
-Chris Werner
"Production Manager"
BattleCry@WPI

Team 190 - WPI & Mass Academy
Est. 1992!

Team 871 - Former team leader
Reply With Quote
  #5   Spotlight this post!  
Unread 25-06-2003, 19:38
sanddrag sanddrag is offline
On to my 16th year in FRC
FRC #0696 (Circuit Breakers)
Team Role: Teacher
 
Join Date: Jul 2002
Rookie Year: 2002
Location: Glendale, CA
Posts: 8,519
sanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond repute
A very interesting concept indeed. There is a lego differential that looks exactly like that, just minus the motors on each side and the final drive gear on top. But since that is a differential, it would compensate for the rpm differences in the motors. I'm just not sure how well it would work with a 14,000 rpm difference.
__________________
Teacher/Engineer/Machinist - Team 696 Circuit Breakers, 2011 - Present
Mentor/Engineer/Machinist, Team 968 RAWC, 2007-2010
Technical Mentor, Team 696 Circuit Breakers, 2005-2007
Student Mechanical Leader and Driver, Team 696 Circuit Breakers, 2002-2004
Reply With Quote
  #6   Spotlight this post!  
Unread 25-06-2003, 19:43
Tytus Gerrish's Avatar
Tytus Gerrish Tytus Gerrish is offline
IGAB, ADHD, and Dislexic
AKA: Ty
FRC #0179 (SwampThing)
Team Role: Tactician
 
Join Date: Feb 2003
Rookie Year: 2001
Location: West Palm Beach, Florida
Posts: 2,017
Tytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond repute
Thanks

But, Where Am I going to find a 14,000 rpm diffrence?
Reply With Quote
  #7   Spotlight this post!  
Unread 25-06-2003, 19:51
FotoPlasma FotoPlasma is offline
\: |
no team
 
Join Date: Jul 2001
Rookie Year: 2001
Location: San Jose
Posts: 1,900
FotoPlasma has a reputation beyond reputeFotoPlasma has a reputation beyond reputeFotoPlasma has a reputation beyond reputeFotoPlasma has a reputation beyond reputeFotoPlasma has a reputation beyond reputeFotoPlasma has a reputation beyond reputeFotoPlasma has a reputation beyond reputeFotoPlasma has a reputation beyond reputeFotoPlasma has a reputation beyond reputeFotoPlasma has a reputation beyond reputeFotoPlasma has a reputation beyond repute
Send a message via AIM to FotoPlasma
Quote:
Originally posted by Tytus Gerrish
Thanks

But, Where Am I going to find a 14,000 rpm diffrence?
He's referring to the difference between the Atwood's speed and the drill's. The Atwood is supposed to be ~5000 rpm, and the drill is supposed to be ~19000 rpm, hence the 14000 rpm difference.
__________________
I played hacky sack with Andy Baker.

2001-2004: Team 258, The Sea Dawgs
2005: Team 1693, The Robo Lobos
Reply With Quote
  #8   Spotlight this post!  
Unread 25-06-2003, 19:59
Madison's Avatar
Madison Madison is offline
Dancing through life...
FRC #0488 (Xbot)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 1999
Location: Seattle, WA
Posts: 5,246
Madison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond repute
...I'm not sure I understand how this would work.

Shouldn't a differential have two outputs? I'll admit, though, I'm really not clear on how they work.

But, again, since the motors would each have varying RPMs. . . well, how does it work? The Drill output is 19,470 RPM or something. The Chiaphua is 5,500 RPM. They're each connected to a unique shaft and miter gear? Then those two shafts input into a single miter gear there at the bottom? That does nothing to compensate for the difference. Then, I guess, one of those original two miter gears is attached to the larger miter gear, with then gears *up* to the output?

I don't know that I follow what this is meant to do at all.

Perhaps an explanation coupled with a few less fancy drawings is in order?
__________________
--Madison--

...down at the Ozdust!

Like a grand and miraculous spaceship, our planet has sailed through the universe of time. And for a brief moment, we have been among its many passengers.
Reply With Quote
  #9   Spotlight this post!  
Unread 25-06-2003, 20:04
rlowerr_1's Avatar
rlowerr_1 rlowerr_1 is offline
Registered User
#0930 (M³)
 
Join Date: Jan 2002
Location: Wisconsin
Posts: 61
rlowerr_1 is an unknown quantity at this point
Send a message via AIM to rlowerr_1
I did some tests with this theory out of legos.

On one side of the differential I geared a Lego motor up (40 tooth on motor shaft meshed with 8 tooth gear going to differential). On the other side I geared a Lego motor down (8 tooth gear meshed with 40 tooth gear going to differential).

The differential spun at the speed and torque of the geared up motor. The geared down motor did not have any effect on until I held the differential until the geared up motor stalled. That is when the geared down motor kicked in and spun the differential with the speed and torque of the geared down motor.

So from my findings it seems that this does not work, unless anyone can prove it correct.
Reply With Quote
  #10   Spotlight this post!  
Unread 25-06-2003, 20:08
Gadget470's Avatar
Gadget470 Gadget470 is offline
A Fire Outside
AKA: Brandon Joerges
no team (Alpha Omega)
Team Role: Alumni
 
Join Date: Jan 2002
Rookie Year: 2000
Location: Madison Heights, MI
Posts: 1,000
Gadget470 is a jewel in the roughGadget470 is a jewel in the roughGadget470 is a jewel in the roughGadget470 is a jewel in the rough
Send a message via ICQ to Gadget470 Send a message via AIM to Gadget470
I studied it for a few minutes.. and I think it's more for a pretty picture with 3DMax than anything else.
Reply With Quote
  #11   Spotlight this post!  
Unread 25-06-2003, 20:31
sanddrag sanddrag is offline
On to my 16th year in FRC
FRC #0696 (Circuit Breakers)
Team Role: Teacher
 
Join Date: Jul 2002
Rookie Year: 2002
Location: Glendale, CA
Posts: 8,519
sanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond reputesanddrag has a reputation beyond repute
Well, I guess differentials don't work in reverse then where there are two motors and one output instead of one motor and two outputs. It was an interesting concept to toy with though. I wonder if there would be better results if the speed difference was not so much.
__________________
Teacher/Engineer/Machinist - Team 696 Circuit Breakers, 2011 - Present
Mentor/Engineer/Machinist, Team 968 RAWC, 2007-2010
Technical Mentor, Team 696 Circuit Breakers, 2005-2007
Student Mechanical Leader and Driver, Team 696 Circuit Breakers, 2002-2004
Reply With Quote
  #12   Spotlight this post!  
Unread 25-06-2003, 22:16
Adam Y.'s Avatar
Adam Y. Adam Y. is offline
Adam Y.
no team (?????)
 
Join Date: Mar 2002
Location: Long Island
Posts: 1,979
Adam Y. is a splendid one to beholdAdam Y. is a splendid one to beholdAdam Y. is a splendid one to beholdAdam Y. is a splendid one to beholdAdam Y. is a splendid one to beholdAdam Y. is a splendid one to beholdAdam Y. is a splendid one to behold
Send a message via AIM to Adam Y.
Quote:
The differential spun at the speed and torque of the geared up motor. The geared down motor did not have any effect on until I held the differential until the geared up motor stalled. That is when the geared down motor kicked in and spun the differential with the speed and torque of the geared down motor.
Yeah it really doesn't work that way. It is just the way that a differntial is designed. That same problem can be rather quite problemsome backwards also if you loose all traction in one tire. Btw After watching a few episodes of junkyard wars can someone tell me what it means to lock a differntial??? From the way it sounds it might just fix the above problem though it would probably defeat the purpose of it.
__________________
If either a public officer or any one else saw a person attempting to cross a bridge which had been ascertained to be unsafe, and there were no time to warn him of his danger, they might seize him and turn him back without any real infringement of his liberty; for liberty consists in doing what one desires, and he does not desire to fall into the river. -Mill

Last edited by Adam Y. : 25-06-2003 at 22:19.
Reply With Quote
  #13   Spotlight this post!  
Unread 25-06-2003, 22:22
Madison's Avatar
Madison Madison is offline
Dancing through life...
FRC #0488 (Xbot)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 1999
Location: Seattle, WA
Posts: 5,246
Madison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond repute
Quote:
Originally posted by Adam Y.
Yeah it really doesn't work that way. It is just the way that a differntial is designed. That same problem can be rather quite problemsome backwards also if you loose all traction in one tire. Btw After watching a few episodes of junkyard wars can someone tell me what it means to lock a differntial??? From the way it sounds it might just fix the above problem though it would probably defeat the purpose of it.
Locking a differential is accomplished by physically connecting the two, otherwise separate output shafts so they act as one. In situations where an open-differential would result in getting stuck. . .where one wheel is sleep and the other is getting no torque, locking the differential would make the rear axle act as a solid piece, giving torque to the wheel that's not stuck.
__________________
--Madison--

...down at the Ozdust!

Like a grand and miraculous spaceship, our planet has sailed through the universe of time. And for a brief moment, we have been among its many passengers.
Reply With Quote
  #14   Spotlight this post!  
Unread 25-06-2003, 22:29
Tytus Gerrish's Avatar
Tytus Gerrish Tytus Gerrish is offline
IGAB, ADHD, and Dislexic
AKA: Ty
FRC #0179 (SwampThing)
Team Role: Tactician
 
Join Date: Feb 2003
Rookie Year: 2001
Location: West Palm Beach, Florida
Posts: 2,017
Tytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond reputeTytus Gerrish has a reputation beyond repute
Sorry

If it is not clear how this device works i will make a more clear and understandable render with labels for now i tell you it has two inputs (the motors) and one output (the shaft on top)
Reply With Quote
  #15   Spotlight this post!  
Unread 25-06-2003, 23:21
Madison's Avatar
Madison Madison is offline
Dancing through life...
FRC #0488 (Xbot)
Team Role: Engineer
 
Join Date: Jun 2001
Rookie Year: 1999
Location: Seattle, WA
Posts: 5,246
Madison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond reputeMadison has a reputation beyond repute
Re: Sorry

Quote:
Originally posted by Tytus Gerrish
If it is not clear how this device works i will make a more clear and understandable render with labels for now i tell you it has two inputs (the motors) and one output (the shaft on top)
After spending the last few hours reading a lot about differentials and their hellspawn, I'm pretty sure that what you're attempting here will not work.

The entire point of a differential is to vary the speed and torque of two output shafts . By reducing it to a single output with two inputs, you're not creating a differential anymore. After all, what's "different" about the output(s)? Nothing. It's a single output operating at single speed at any given time.

Now, though, I think I understand what you're trying to accomplish. You're using the concept of a differential in reverse to mate two motors, and then you need two of these modules on a robot to operate both sides independently.

Based on this the mathematical relationship at work in a differential with 1:1 gearing is input = (outputA + outputB) /2.

So, for example, let's say input is 10. Therefore, it's 2(10) = outputA + outputB. While driving in a straight line, outputA and outputB would be equal at 10 each -- or the same as the input. If there is resistance against one output, more power/speed/torque will go to the output with lesser resistance. This might end up being a 12 + 8 or a 3 + 17 or even a 20 + 0 scenario.

Your idea here reverses this concept. So, therefore, out equation would read more like this:

output = (inputA + inputB) / 2

So, again for example, let's look at the motor RPMs for the chiaphua and drill under no load.

output = (5500 + 19000) / 2
2(output) = 24500
output = 12,250

Simple enough, right?

Well, now let's look at this in terms of torque.

inputA = 2.2 Nm
inputB = 1.2 Nm

2(output) = 2.2 + 1.2 = 3.4
3.4/2 = output = 1.7 Nm.

So, as you can see, the output of your differential is actually less than what you'd get from a single motor.

I'm unsure if there any circumstances where this wouldn't be the case, but it doesn't appear that there are.

I'm also unsure how things would be affected if the gearing were something other than 1:1.

If I've made some grossly wrong assumption here, please correct me. Thanks.
__________________
--Madison--

...down at the Ozdust!

Like a grand and miraculous spaceship, our planet has sailed through the universe of time. And for a brief moment, we have been among its many passengers.
Reply With Quote
Reply


Thread Tools
Display Modes Rate This Thread
Rate This Thread:

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
pic: LEGO Vernier Gearbox CD47-Bot Extra Discussion 9 10-10-2003 09:43
pic: dual speed gearbox CD47-Bot Extra Discussion 9 07-10-2003 15:04
pic: Gerrish Gearbox MK-III #2 CD47-Bot Extra Discussion 26 12-09-2003 11:35
pic: Gerrish Gearbox MK-III CD47-Bot Extra Discussion 22 04-09-2003 16:32


All times are GMT -5. The time now is 17:52.

The Chief Delphi Forums are sponsored by Innovation First International, Inc.


Powered by vBulletin® Version 3.6.4
Copyright ©2000 - 2017, Jelsoft Enterprises Ltd.
Copyright © Chief Delphi