Smaller shifting cylinder

[asid61]

I'm working on a shifting gearbox design with two gears on the CIM that go directly to the shifting gears. I'm running into an issue where the CIM is too close to the shifter shaft, so I can't easily fit a regular Vex pancake cylinder there. I was going to swap it out for a 3/4" bore round body cylinder, but the mounting nut on that one is too large and hits the CIM. Is it feasible to use a 9/16" bore cylinder in place of the 3/4" bore? According to my calculation its force output is 16lbs compared to the 3/4" bore's 27lbs, but this is also on the first stage of the gearbox so the force required to shift should be less (there's a 2:1 reduction happening after the shifter).

[R.C.]

Originally Posted by asid61

I'm working on a shifting gearbox design with two gears on the CIM that go directly to the shifting gears. I'm running into an issue where the CIM is too close to the shifter shaft, so I can't easily fit a regular Vex pancake cylinder there. I was going to swap it out for a 3/4" bore round body cylinder, but the mounting nut on that one is too large and hits the CIM. Is it feasible to use a 9/16" bore cylinder in place of the 3/4" bore? According to my calculation its force output is 16lbs compared to the 3/4" bore's 27lbs, but this is also on the first stage of the gearbox so the force required to shift should be less (there's a 2:1 reduction happening after the shifter).

We used a smaller shifter cylinder (round), 9/16 in both 2011 and 2012. Going to a smaller cylinder worked great, I think 973 did the same thing (Adam)? Also I recommend just tapping the mount so you can get a better OD/ID ratio.

[asid61]

Originally Posted by R.C.

We used a smaller shifter cylinder (round), 9/16 in both 2011 and 2012. Going to a smaller cylinder worked great, I think 973 did the same thing (Adam)? Also I recommend just tapping the mount so you can get a better OD/ID ratio.

Thank you! That sounds really good.

[GeeTwo]

It should work; you're still getting a better shifting force than with a servo. You may have difficulty shifting while driving hard. Without more specific details on how the shifting is done (e.g. ball, dog, and the anticipated torque and speed of the shaft during the shift) others' experience may correspond to comparing apples to cantaloupes. This is something you will probably just have to try out in driver practice. When you do this test, don't just set up a bare drive chassis; add an amount of weight similar to what your competition robot will have.

If you really like your design otherwise but can't get a large enough cylinder into position, you may be able to move the cylinder farther back along the axis, or move it to the side and use a lever to push/pull the shifter.

[IndySam]

Back in the earlier AM Shifter days we would put a separate regulator to turn the shifter air down to 40PSI to prevent the roll pins on the shifters from breaking. We never had any problems with the reduced amount of force.

[asid61]

It's a ball shifter, so already there's an advantage force-wise.
I considered using a lever but I wanted to use the Vex shifting attachment.

[AdamHeard]

Used 9/16 bore on traditional wcd 2 speed a few times.

Used 7/16 on swerve, but that was a stage earlier in reduction.

Both were dog shifters.