pic: 1662's test tranny 5

[M4 Sherman]

loading photo ...

[Andy Baker]

(this is the best picture from the bunch)

Kudos to team 1662 for making this style of shifting dog gear. I've always wanted to try out this press-fit-dowel style, and only have depended on hearing how this performs from 1-2 other teams who have done it.

Team 229 did this in 2003, and I believe a few other teams have tried it.

I think I see that there are standard steel dowels pressed into an aluminum disc to make up the dog gear. Is this true?

If you don't mind, I have a few questions:

1. How much of an interference press fit exists between the steel dowels and the aluminum holes? (I am guessing it is 0.001" or 0.0005")

2. What is the size of the dowels? (diameter and length)

3. The shaft that the aluminum disc slides on appears to be square... is it 1/2" wide? If not, what is that thing?

4. How much stroke is needed for a shift?

Like I said above, good job on this. Thanks for sharing the pictures.

Andy B.

[sanddrag]

Looks good. However, I'm wondering why the CIM is driving that gear, as opposed to the next one on the shaft.

Also, how much bigger are the holes in the gears than the pins?

[Manoel]

Good stuff, looks remarkably like our gearbox - only beefier.

Is it me or do you have more holes in the gears than pins in the shifter?

Also, how is the pneumatic cylinder connected to the shifter?

Once again, good job and thanks for sharing the picture!

(I'll see if I can find a close-up of our gearbox to show how similar they look)

[Veselin Kolev]

MY team did this style shifter once. We were running it on an arm, so the torque was a lot higher. We used .375" diameter pins, which were just in a drilled .375" hole with retaining compound. The holes we had them mesh with were on the same size circle pattern, but 1/16" bigger. The shaft it ran on was a .625" keyed shaft. We just ran the power and the sliding through the keyway, it put up fine with it. Meshed very nicely, never had any problems. This was however, a low speed, high torque gearbox. Keep that in mind. Also keep in mind that this was a quick modification made in a day on a drill press and mill. Otherwise, these are a lot easier to make than a real dog-shifter. No cnc. A very ghetto solution when we used it, but it can be made very nicely into a drive train.