Go to Post This thread is just as lethal as any design your own game thread. - Schnabel [more]
Home
Go Back   Chief Delphi > Technical > Technical Discussion
CD-Media   CD-Spy  
portal register members calendar search Today's Posts Mark Forums Read FAQ rules

 
Closed Thread
Thread Tools Rating: Thread Rating: 4 votes, 5.00 average. Display Modes
  #31   Spotlight this post!  
Unread 22-12-2003, 12:14
Matt Adams's Avatar
Matt Adams Matt Adams is offline
b(o_o)d
FRC #1525 (Warbots)
Team Role: Engineer
 
Join Date: Dec 2003
Rookie Year: 2000
Location: Arlington Hts. IL
Posts: 375
Matt Adams has a reputation beyond reputeMatt Adams has a reputation beyond reputeMatt Adams has a reputation beyond reputeMatt Adams has a reputation beyond reputeMatt Adams has a reputation beyond reputeMatt Adams has a reputation beyond reputeMatt Adams has a reputation beyond reputeMatt Adams has a reputation beyond reputeMatt Adams has a reputation beyond reputeMatt Adams has a reputation beyond reputeMatt Adams has a reputation beyond repute
Send a message via AIM to Matt Adams
Re: Engaging Gears Perpendicular to Shaft Direction?

Quote:
Originally Posted by Joe Johnson
Have to done a careful sum of the moments calculation about the axis of rotation of the input shaft?

I am suspicious that the drive link can stay engaged with just the aircylinder.
eeek... I gotta say I didn't do that! (Though admittedly, small things like how much those shafts would deflect when they had a pneumatic on them were definitely calculated (.00045 inches))

To do so real quick:

Maybe 250 in-lbs on that center gear, 1 in diameter, moment arm of a half inch off center... the pneumatic is about 3.4 inches away from the pivot point, at around a 15 degree angle, providing a max moment arm in the opposite direction of around 95 lbs * 3.4 inches with a 1.5 inch bore... There's also the force on the gears through the shaft centers, sin(20)*250 is around 85, times it's moment arm of 1.5.... So we've got around 70 in lbs to spare with the half inch. whew! Thanks for the reminder...

Quote:
Originally Posted by Joe Johnson
#1 I alot of careful thought has gone into this. Careful thought is never wasted.
I appreciate you noticing, and while this is true... sometimes outsiders see something obvious that the "careful thought" folks have missed which will make a device infinitely better... which is why it's out here.

Quote:
Originally Posted by Joe Johnson
#2 My brain keeps coming back to, why have the engage/disengage gears at all? You have the chain sprockets. Why not just mount the gears and their shafts on the pivoting link, keep the gears engaged 100% of the time and just pivot the whole mechanism to allow the "high gear" sprocket or the "low gear" sprocket to engage the chain? I think your mechanism gets simpler, your gear loads and forces are more easily managed, and the chain takes all the abuse.
I've reread this about 10 times now.. I just can't visualize what you're saying. Are you suggesting having some loose chaing that is engaged and disengaged with sprockets? If you keep the gears engaged constantly.. how would you shift?

I've already thought of some nice ideas about changing the sizes of the blue connecting sprockets to let them affect the gear ratio, and keep the gears a (larger to reduce load) constant size... but I'm certain this is not what you're proposing. If you could clarify, I'd truly appreciate it!

Thanks,

Matt
__________________
Matt Adams - Engineer at Danaher Motion
Team 1525 - Warbots - Deerfield High School
  #32   Spotlight this post!  
Unread 22-12-2003, 13:46
Wetzel's Avatar
Wetzel Wetzel is offline
DC Robotics
FRC #2914 (Tiger Pride)
Team Role: Mentor
 
Join Date: Sep 2001
Rookie Year: 1999
Location: DC
Posts: 3,522
Wetzel has a reputation beyond reputeWetzel has a reputation beyond reputeWetzel has a reputation beyond reputeWetzel has a reputation beyond reputeWetzel has a reputation beyond reputeWetzel has a reputation beyond reputeWetzel has a reputation beyond reputeWetzel has a reputation beyond reputeWetzel has a reputation beyond reputeWetzel has a reputation beyond reputeWetzel has a reputation beyond repute
Send a message via AIM to Wetzel
Re: Engaging Gears Perpendicular to Shaft Direction?

Quote:
Originally Posted by Matt Adams

Quote:
Originally Posted by Joe Johnson
#2 My brain keeps coming back to, why have the engage/disengage gears at all? You have the chain sprockets. Why not just mount the gears and their shafts on the pivoting link, keep the gears engaged 100% of the time and just pivot the whole mechanism to allow the "high gear" sprocket or the "low gear" sprocket to engage the chain? I think your mechanism gets simpler, your gear loads and forces are more easily managed, and the chain takes all the abuse.
I've reread this about 10 times now.. I just can't visualize what you're saying. Are you suggesting having some loose chaing that is engaged and disengaged with sprockets? If you keep the gears engaged constantly.. how would you shift?

Thanks,

Matt

I think he means to move gear to chain, rather then gear to gear.
Have both final gears spinning, but rotate them to move the proper one into contact with the output chain. Puts all the meshing forces onto the chain.

At least, that is what I understood him to be saying.


Wetzel
~~~~~~~~~~~~~~~
Making and breaking chain with needlenose pliers is fun.
I swear.
  #33   Spotlight this post!  
Unread 22-12-2003, 14:31
Joe Johnson's Avatar Unsung FIRST Hero
Joe Johnson Joe Johnson is offline
Engineer at Medrobotics
AKA: Dr. Joe
FRC #0088 (TJ2)
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 1996
Location: Raynham, MA
Posts: 2,648
Joe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond repute
How's this kluggie cut up?

The idea is to move the gears closer together so that they are always turning with the input gear.

Then put an idler sprocket on the same shaft as the input shaft (now the shaft marked with the green cross).

Then pivot the both output shafts on a lever that also pivots about the input shaft (it is outlined roughly in a T shape in the image attached).

Then when you drive this link, you engage one sprocket or the other with the chain. (The sprockets are those round black circle things)

You can have the air cylinder either be strong enough to take the load you are pulling on the chain -- in which case you sort of get a chain tensioner built in for free. Or you can add a drive link between the aircylinder and the sprocket pivoting gig - in this case, you can make the whole thing non-backdriveable and then tension in the chain cannot push the mechanism out of engagement (I like this solution better... ...but time is limited so I will have to discuss it another time if there is interest).

The chain routing is shown for the mechanism in high gear (the thickish blue line).

I hope this helps.

Joe J.
Attached Thumbnails
Click image for larger version

Name:	Cutup Chain Shifter.jpg
Views:	82
Size:	20.3 KB
ID:	1633  

Last edited by Joe Johnson : 22-12-2003 at 14:35.
  #34   Spotlight this post!  
Unread 22-12-2003, 14:43
Stu Bloom's Avatar
Stu Bloom Stu Bloom is offline
I REALLY want to be Andy Baker
FRC #1018 (RoboDevils)
Team Role: Mentor
 
Join Date: Dec 2002
Rookie Year: 2002
Location: Indianapolis, IN
Posts: 662
Stu Bloom has a reputation beyond reputeStu Bloom has a reputation beyond reputeStu Bloom has a reputation beyond reputeStu Bloom has a reputation beyond reputeStu Bloom has a reputation beyond reputeStu Bloom has a reputation beyond reputeStu Bloom has a reputation beyond reputeStu Bloom has a reputation beyond reputeStu Bloom has a reputation beyond reputeStu Bloom has a reputation beyond reputeStu Bloom has a reputation beyond repute
Send a message via AIM to Stu Bloom Send a message via Yahoo to Stu Bloom
Re: How's this kluggie cut up?

That's BRILLIANT Dr. J !!
__________________
Stuart Bloom
Mechanical Engineer
Rolls-Royce Corporation
FIRST Team 1018 - Pike HS RoboDevils
My activity for 2012:
  • Boilermaker planning committee
  • Israel Head Ref - DONE (and it was FANTASTIC!)
  • Boilermaker Regional (with 1018) - DONE
  • Midwest Head Ref - DONE
  • WORLD Championships (with 1018) - DONE
  • IRI Head Ref - DONE
  • CAGE Match Head Ref
  #35   Spotlight this post!  
Unread 22-12-2003, 14:46
Stu Bloom's Avatar
Stu Bloom Stu Bloom is offline
I REALLY want to be Andy Baker
FRC #1018 (RoboDevils)
Team Role: Mentor
 
Join Date: Dec 2002
Rookie Year: 2002
Location: Indianapolis, IN
Posts: 662
Stu Bloom has a reputation beyond reputeStu Bloom has a reputation beyond reputeStu Bloom has a reputation beyond reputeStu Bloom has a reputation beyond reputeStu Bloom has a reputation beyond reputeStu Bloom has a reputation beyond reputeStu Bloom has a reputation beyond reputeStu Bloom has a reputation beyond reputeStu Bloom has a reputation beyond reputeStu Bloom has a reputation beyond reputeStu Bloom has a reputation beyond repute
Send a message via AIM to Stu Bloom Send a message via Yahoo to Stu Bloom
Re: How's this kluggie cut up?

Can the chain &/or sprocket(s) take this type of abuse (shift on-the-fly ...) ?
__________________
Stuart Bloom
Mechanical Engineer
Rolls-Royce Corporation
FIRST Team 1018 - Pike HS RoboDevils
My activity for 2012:
  • Boilermaker planning committee
  • Israel Head Ref - DONE (and it was FANTASTIC!)
  • Boilermaker Regional (with 1018) - DONE
  • Midwest Head Ref - DONE
  • WORLD Championships (with 1018) - DONE
  • IRI Head Ref - DONE
  • CAGE Match Head Ref
  #36   Spotlight this post!  
Unread 22-12-2003, 14:58
Joe Johnson's Avatar Unsung FIRST Hero
Joe Johnson Joe Johnson is offline
Engineer at Medrobotics
AKA: Dr. Joe
FRC #0088 (TJ2)
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 1996
Location: Raynham, MA
Posts: 2,648
Joe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond repute
Re: How's this kluggie cut up?

Quote:
Originally Posted by Stu Bloom
Can the chain &/or sprocket(s) take this type of abuse (shift on-the-fly ...) ?
If I had my choice of chain or gear teeth that had to take the abuse I know which one I would pick.

Shift on the fly may be a bit of a stretch, but I suppose that it wouldn't be too bad if you could figure a way to use #35 chain.

Joe J.
  #37   Spotlight this post!  
Unread 22-12-2003, 15:01
Joe Johnson's Avatar Unsung FIRST Hero
Joe Johnson Joe Johnson is offline
Engineer at Medrobotics
AKA: Dr. Joe
FRC #0088 (TJ2)
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 1996
Location: Raynham, MA
Posts: 2,648
Joe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond reputeJoe Johnson has a reputation beyond repute
Careful is an adjective not to be glossed over...

Quote:
Originally Posted by Matt Adams
eeek... I gotta say I didn't do that! ...
...
Maybe 250 in-lbs on that center gear, 1 in diameter, moment arm of a half inch off center... the pneumatic is about 3.4 inches away from the pivot point, at around a 15 degree angle, providing a max moment arm in the opposite direction of around 95 lbs * 3.4 inches with a 1.5 inch bore... There's also the force on the gears through the shaft centers, sin(20)*250 is around 85, times it's moment arm of 1.5.... So we've got around 70 in lbs to spare with the half inch. whew! Thanks for the reminder...

You forgot the input torque of 250 in-lbs (or else you have to include the torque from the internal short chain -- which magically will work out to be the same 250 in-lbs).

I see 4 torques to deal with
In high gear with driving the input CCW,
Tinput = 250 in-lbs
Taircylinder = 95 lbs*3.4 in = 320 in-lbs
TtoothNormal= -(250 in-lbs/.5 in)*.5 in = -250 in-lbs
TtoothSep= ((250 in-lbs /.5) * sin(20deg) ) *1.5 in = 250 in-lbs
This is okay because they sum to 470 in-lbs (and CCW is toward engagement).

If you do the same thing only have the input torque switch to CW you will get
Tinput = -250
Taircyliner= 320
TtoothNormal = +250 (the normal tooth load is trying to ENGAGE the mechanism in this case)
TtoothSep = -250
Sum = 70 in-lbs

Having done the summing carefully, I get the same answer as your "quick calculation", so what do I know?

I suppose I will shut up now ;-)

Joe J.
  #38   Spotlight this post!  
Unread 22-12-2003, 16:24
Unsung FIRST Hero
JVN JVN is offline
@JohnVNeun
AKA: John Vielkind-Neun
FRC #0148 (Robowranglers)
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 2000
Location: Greenville, Tx
Posts: 3,159
JVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond repute
Re: Engaging Gears Perpendicular to Shaft Direction?

Quote:
Originally Posted by Rob Colatutto

...teams who were planning on doing a 2 motor, or even possibly a 3 motor gearbox per side can still use that gearbox, run chain from it into the shifter, and then from the shifter to the wheels. [/edit]
Jeez!
Doing that would put waaaay more torque through this box than I would think is healthy. (I haven't run numbers on this). In order to function correctly, this thing would have to be as "early" in the gearbox as possible, to minimize torque on the shifter.

Matt--
I'm very impressed with this design.
This may be a step closer to the "rookie solution" to shifting the FIRST community could use so badly. (Sorry Andy )

I'm very curious to see how it will work out for you guys.

John
__________________
In the interest of full disclosure: I work for VEX Robotics a subsidiary of Innovation First International (IFI) Crown Supplier & Proud Supporter of FIRST
  #39   Spotlight this post!  
Unread 22-12-2003, 16:50
SarahB's Avatar
SarahB SarahB is offline
Registered User
no team
Team Role: Engineer
 
Join Date: Feb 2003
Rookie Year: 2002
Location: Syracuse, NY
Posts: 231
SarahB has a spectacular aura aboutSarahB has a spectacular aura aboutSarahB has a spectacular aura about
Send a message via AIM to SarahB
Re: Engaging Gears Perpendicular to Shaft Direction?

Quote:
Originally Posted by JVN
Jeez!
Doing that would put waaaay more torque through this box than I would think is healthy. (I haven't run numbers on this). In order to function correctly, this thing would have to be as "early" in the gearbox as possible, to minimize torque on the shifter.
Not necessarily, if you’re doing a multiple motor gearbox you could just combine in the gearbox, go straight to the shifter, then adjust in the chain. Doing it this way could actually be really helpful as only the smallest sprockets come in nice sized bores and you need a very large sprocket if you only want to drive the wheel(instead of the whole shaft) in your chain.

National champion team 469 used the exact same(or at least very similar) shifting design in 2003 with two motors per side without any trouble, even though the shifter was very late in the transmission.
__________________
FRC:
Team 30 - FURY (Student, 2002-2004)
Team 229 - Division by Zero (Mentor, 2005-2007)
FLL:
Robo-Monkeys (Founder/Mentor, 2003-2006)

Currently working as a Radar Systems Engineer at Lockheed Martin in Liverpool, NY and pursuing my MSEE from Clarkson, while easing my way back into FIRST
  #40   Spotlight this post!  
Unread 22-12-2003, 18:32
Rob Colatutto's Avatar
Rob Colatutto Rob Colatutto is offline
Roboticsrob
FTC #10092 (Green.Griffins;)
Team Role: Mentor
 
Join Date: Feb 2002
Rookie Year: 2001
Location: San Diego, CA
Posts: 849
Rob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to behold
Re: Engaging Gears Perpendicular to Shaft Direction?

One change that can be easily made to the shifter to increase the speed change without using different gears could be making the output shaft always be the shaft that currently has the 1:1 ratio, and changing the blue sprocket to a 20 tooth if the other one is a 10 tooth, or something similar. This would give you a 3:1 reduction and then a 2:1 reduction giving you 6:1 and a 1:1. you could do less or more teeth to make the increase more or less dramatic. That way newer can be very competitive with just an atwood drive having maybe 6ft/s and then 1ft/s or whatever they would like.
__________________
Follow me on twitter @roboticsrob and my FTC team @griffins10092
  #41   Spotlight this post!  
Unread 22-12-2003, 18:34
Unsung FIRST Hero
JVN JVN is offline
@JohnVNeun
AKA: John Vielkind-Neun
FRC #0148 (Robowranglers)
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 2000
Location: Greenville, Tx
Posts: 3,159
JVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond repute
Re: Engaging Gears Perpendicular to Shaft Direction?

Quote:
Originally Posted by SarahB
Not necessarily, if you’re doing a multiple motor gearbox you could just combine in the gearbox, go straight to the shifter, then adjust in the chain. Doing it this way could actually be really helpful as only the smallest sprockets come in nice sized bores and you need a very large sprocket if you only want to drive the wheel(instead of the whole shaft) in your chain.

National champion team 469 used the exact same(or at least very similar) shifting design in 2003 with two motors per side without any trouble, even though the shifter was very late in the transmission.
The torque applied depends greatly on your motor combining, and what speed they are matched at. Especially if this combiner gearbox is designed to go straight to the wheel after (as Rob mentioned). The final sprocket reduction is limited by several factors. (Such as Chain size... note: I believe "national champion team 469" blew 1/4" chain like nobodies business towards the end)

Also... I'm almost 100% positive, "national champion team 469" used a shifter NOT like Matt's, but similar to 60-2002, or 116-2002 -- where the gears slide laterally. This system is able to handle much more torque than Matt's (in which applied torque would actually try to push the shifter out of gear).


John
__________________
In the interest of full disclosure: I work for VEX Robotics a subsidiary of Innovation First International (IFI) Crown Supplier & Proud Supporter of FIRST
  #42   Spotlight this post!  
Unread 23-12-2003, 06:54
SarahB's Avatar
SarahB SarahB is offline
Registered User
no team
Team Role: Engineer
 
Join Date: Feb 2003
Rookie Year: 2002
Location: Syracuse, NY
Posts: 231
SarahB has a spectacular aura aboutSarahB has a spectacular aura aboutSarahB has a spectacular aura about
Send a message via AIM to SarahB
Re: Engaging Gears Perpendicular to Shaft Direction?

Quote:
Originally Posted by JVN
The torque applied depends greatly on your motor combining, and what speed they are matched at. Especially if this combiner gearbox is designed to go straight to the wheel after (as Rob mentioned). The final sprocket reduction is limited by several factors. (Such as Chain size... note: I believe "national champion team 469" blew 1/4" chain like nobodies business towards the end)
Yes it does, however that torque is the same if you use a dog shifter or a shifter such as this. Plus he said he was possibly using 16 pitch gears, and steel 16 pitch gears are a lot stronger than your average shifter.

Keep in mind, his design doesn't even use #25 chain. While the reductions possible using sprockets is somewhat limited, its still pretty wide. Using #35 chain, you can get as much as a 3:20 reduction, which is pretty good. If you needed any more than that you could just change the ratios inside the shifter or add another box with another reduction after.
__________________
FRC:
Team 30 - FURY (Student, 2002-2004)
Team 229 - Division by Zero (Mentor, 2005-2007)
FLL:
Robo-Monkeys (Founder/Mentor, 2003-2006)

Currently working as a Radar Systems Engineer at Lockheed Martin in Liverpool, NY and pursuing my MSEE from Clarkson, while easing my way back into FIRST
  #43   Spotlight this post!  
Unread 23-12-2003, 12:27
Matt Adams's Avatar
Matt Adams Matt Adams is offline
b(o_o)d
FRC #1525 (Warbots)
Team Role: Engineer
 
Join Date: Dec 2003
Rookie Year: 2000
Location: Arlington Hts. IL
Posts: 375
Matt Adams has a reputation beyond reputeMatt Adams has a reputation beyond reputeMatt Adams has a reputation beyond reputeMatt Adams has a reputation beyond reputeMatt Adams has a reputation beyond reputeMatt Adams has a reputation beyond reputeMatt Adams has a reputation beyond reputeMatt Adams has a reputation beyond reputeMatt Adams has a reputation beyond reputeMatt Adams has a reputation beyond reputeMatt Adams has a reputation beyond repute
Send a message via AIM to Matt Adams
Post Some Info

Quote:
Originally Posted by SarahB
Plus he said he was possibly using 16 pitch gears, and steel 16 pitch gears are a lot stronger than your average shifter.
Actually, this really depends on what you mean by "average shifter" I would wholeheartedly rather bet me life savings (which is admittedly negative since I'm a college student) on a dog style shifter than gears engaging face to face, if you're speaking about going on the fly. WHICH THIS DESIGN IS NOT INTENDED TO HANDLE.

I've plugged some numbers into a Lewis bending equation spreadsheet I've made, and let me tell you, with the 1" gears, failure is VERY possible, depending on where you place it in the drive train. Using the initial configuration I had, the factor of safety was around 0.7...

Quote:
Keep in mind, his design doesn't even use #25 chain.
I most definitely do use #25 chain in this design, since it's loads are planned to be somewhat light. If I were placing this on a drive train, I'd probably slow the Chips down by maybe by 3 or 4, throw that shaft into this magic box, and probably use sprockets on the wheels to slim it down by another 4. By this, I don't expect the gear box to see torques exceeding around 50 or 75 in-lbs. I think that #25 is safe in these situations, even with the small diameter of the sprockets being used. #35 chain might add another half pound per box, for no real good reason.

Just some thoughts,

Matt
__________________
Matt Adams - Engineer at Danaher Motion
Team 1525 - Warbots - Deerfield High School

Last edited by Matt Adams : 23-12-2003 at 15:12.
  #44   Spotlight this post!  
Unread 23-12-2003, 14:47
Unsung FIRST Hero
JVN JVN is offline
@JohnVNeun
AKA: John Vielkind-Neun
FRC #0148 (Robowranglers)
Team Role: Engineer
 
Join Date: May 2001
Rookie Year: 2000
Location: Greenville, Tx
Posts: 3,159
JVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond reputeJVN has a reputation beyond repute
Re: Engaging Gears Perpendicular to Shaft Direction?

Quote:
Originally Posted by SarahB
Yes it does, however that torque is the same if you use a dog shifter or a shifter such as this. Plus he said he was possibly using 16 pitch gears, and steel 16 pitch gears are a lot stronger than your average shifter.
I think you fail to understand what I'm saying, and the main principle behind my comment.

Any torque applied through THIS design, will cause the gears to try to disengage from each other. The only thing preventing this is the force of the pneumatic, holding the shafts together.

In a Dog-style, Pin-Style, Mesh-Style... Shifter, the kind of shifters we see every day in this competition: The shafts are held rigidly. Therefore the applied torque CANNOT seperate the gears from meshing (unless it deflects the shaft, which is a discussion for another time).

See the major differences?
See why Matt's design would have MAJOR torque limitations that wouldn't apply to a "normal" shifter?

I can guaruntee you haven't seen any design like this one in the FRC, so it is unfair of you to draw parallels between this box and another and make broad statements concerning it's capabilities.

I love 469, they are a great team, their last 2 bots have been works of art, and their 2002 bot kicked my butt pretty hard. Great designs, in every part of their bots, including the shifter.
But... that doesn't really apply here, now does it?

Unless you understand all the principles involved, and the design itself... which you've shown some confusion about... perhaps you should limit the broad statements you make about it?


John
__________________
In the interest of full disclosure: I work for VEX Robotics a subsidiary of Innovation First International (IFI) Crown Supplier & Proud Supporter of FIRST
  #45   Spotlight this post!  
Unread 23-12-2003, 17:40
Rob Colatutto's Avatar
Rob Colatutto Rob Colatutto is offline
Roboticsrob
FTC #10092 (Green.Griffins;)
Team Role: Mentor
 
Join Date: Feb 2002
Rookie Year: 2001
Location: San Diego, CA
Posts: 849
Rob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to beholdRob Colatutto is a splendid one to behold
Re: Engaging Gears Perpendicular to Shaft Direction?

Quote:
Originally Posted by JVN
Any torque applied through THIS design, will cause the gears to try to disengage from each other. The only thing preventing this is the force of the pneumatic, holding the shafts together.
John
Joe Johnson had said earlier that the design should be able to hold in gear just with the piston. If that was ever a problem you could always increase the bore size. With over 120 pounds pushing against it you can put some considerable torque into the shifter and under normal circumstances not have to worry about it disengaging. Matt had even said that he has a spring system in the workings to hold it in tighter, so if you were afraid of it comming out in low gear you could always reinforce it with springs.


Quote:
Originally Posted by Matt Adams
I most definitely do use #25 chain in this design, since it's loads are planned to be somewhat light.
I believe the statement about the chain sizings was reffering to the final chain coming from the output shaft and powering the wheels.


Quote:
Originally Posted by JVN
I think you fail to understand what I'm saying, and the main principle behind my comment.
Unless you understand all the principles involved, and the design itself... which you've shown some confusion about... perhaps you should limit the broad statements you make about it?
John
John, lets try to keep negative comments out of general discussion. The point of the thread is to express ideas and possible improvements to Matt's design and to TEACH people if they don't understand a concept. You could possibly explain something you feel is being misunderstood instead of suggesting the person not post ideas they may have. Undeserved comments should be kept in private, not on the forum discussions.

With the possibility of using multiple motors, you can still put this shifter as early in the transmission as you would with any other shifter. From my understandings Matt was trying to make a shifter for newer teams who do not have the machining capability that some of us have. No where has anyone said that the design was perfect, but you can always work in some additional support to the shifter to accomodate a more torquey drive to an extent.
__________________
Follow me on twitter @roboticsrob and my FTC team @griffins10092
Closed Thread


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
Hint #1 for Ken Leung Shawn60 General Forum 35 11-02-2003 08:04
Need Help on Shaft Mounting... archiver 2001 3 23-06-2002 23:29
"Motors and Drive train edition" of Fresh From the Forum Ken Leung CD Forum Support 6 29-01-2002 12:32


All times are GMT -5. The time now is 18:11.

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