Re: Andy Mark Super Shifter
 

We just installed our SuperShifter this weekend and had trouble with the servo shifting.

Our mentor found out that you have to ease up on acceleration to shift with the servo while the pneumatic you can do under full power.

Re: Andy Mark Super Shifter
 

When you speed shift a motorcycle, some will just bang gears by shifting without letting up on the throttle. But on a motorcycle it will shift faster when you release the torque (on the trans) from the engine and allow it to disengage before the rear wheel starts to drive it.

Drag bikes are one example of this, with a press of a button, their pneumatic shifters kill the engine first, then it shifts.

The bike restarts instantly because it's still rolling. This method works on all motorcycles and cars with manual transmissions.

Some "DOG" style transmissions use an undercut on both dogs (in this case it would be on the slider and the free-wheeler gear). The under cut is approx. 7' to 14' degrees and it helps pull the gears together when shifting. But as you might imagine, a clutch or letting off on the throttle becomes more important.

(Directed at Andy Baker)
I am very curious if you looked in to a Hodaka style transmission before you built the super shifter?

Bill

Re: Andy Mark Super Shifter
 

Bill,

222 has used a 70's hodaka ball shifting type transmission since 2004 and we don't even need to think about backing off one bit to shift using pneumatics. However I will say that Dog shifting has been around FIRST much longer and has many more hours of run time than ball shifting. Both systems have their merits, but I think the dog shifting transmission is probably less costly to produce and doesn't require quite as tight of tolerances. I cannot say this for certain because I have only designed and built ball shifting transmissions.

OK back on topic, I know in the past 222 used servos to shift the drill transmissions and we weren't happy with the results because of the amount of fine tuning they took and also the amount of time they took to shift. To solve this problem we programmed in a 'jog' (cut power, jog motors, then resume operator control) whenever the driver shifted. This method took approximately 1.5 seconds to do, but it ensured as good of shift as we could get.

I have seen and played with the SuperShifters by hand and they feel like they have a very smooth throw. So I have to think it's a servo problem more then anything else. I am of the same belief as Andy Baker that 99% of the time a pneumatic shifter is going to be better on a FIRST robot.

Re: Andy Mark Super Shifter
 

quick question... Did teams that used the Super Shifters this year support the output shaft or did you leave it cantilevered. If cantilevered, did you experience problems?

Re: Andy Mark Super Shifter
 

we use the super shifter's and yes we did support the shaft.

Re: Andy Mark Super Shifter
 

We (973) put the longer output shaft on, and supported it a few inches off the face of the gearbox with cantilevered wheel on the outside of the support.

294 used the normal output shaft cantilevered.

Re: Andy Mark Super Shifter
 

our team use the super shifters w/ servos this yr and it work excellent no problems as far as the actual shift when we were driving the robot the it took bout .5 seconds to see a differenct in speed hints the shift.

Re: Andy Mark Super Shifter
 

We did NOT support the end of the shaft and it turned out okay. We never had any issues with them.

Re: Andy Mark Super Shifter
 

did you use the standard length shaft or the extended? I would guess that the shorter "standard" shaft would be fine but if you got the extended one it would be best to support it.

Re: Andy Mark Super Shifter
 

Short, we ran one sprocket off of it, down to the center wheel, then used the center wheel to run chains to the front and rear wheels. If you use the shaft as a direct drive onto a wheel, you probably do want to somehow anchor the end of the shaft, to avoid bending or misshaping.

Re: Andy Mark Super Shifter
 

Hello All-

Wouldn't supporting the output shaft (presumably with a bearing) mean that this shaft had three support points? I thought this was a no-no.

For those who did support the output shaft, how did you do it?

-Mr. Van
Coach, Robodox

Re: Andy Mark Super Shifter
 

1618 ran the standard shaft cantilevered with two sprockets. No problems whatsoever.

Re: Andy Mark Super Shifter
 

1816 got the longer output shafts and two bearing blocks and supported as shown in these pictures:
http://www.edinarobotics.com/photos/photo_detail.php?recordID=838&GalleryID=100&positi on=8
http://www.edinarobotics.com/photos/photo_detail.php?recordID=837&GalleryID=100&positi on=7
These pictures were from early in the build season, a lot has changed, included parts of the drivetrain, but we kept the shafts supported this way and had no problems so far.

Re: Andy Mark Super Shifter
 

These were my thoughts exactly. I'd presume that teams who supported the shaft built it into their drive train design and also have a tested/proven frame. Power loss due to a misaligned support bearing would be much larger than the standard efficiency loss.

For the record, we did not support the shaft. The 2 sprockets running off the shaft were 1/2" and 7/8" away from the transmission side plate.

Re: Andy Mark Super Shifter
 

I can't speak for other teams who cantilever their wheels, but 254 and 968 avoid this by only having one bearing in the gearbox itself for the output shaft. Our bearing housing for the center wheel extends through the 1x2 frame member and into a slip fit hole on the gearbox side plate.