M109 Self propelled gun info needed

[jdmcm]

Rob that would be fantastic, I have a nice running powerpack with attached Allison XTG-411 I was lucky enough to obtain from MCB Pendleton in California, but no ancillaries so I am trying to figure out not only how they hook to the final drives but the steering, shifting and breaking...The Israeli's have a company called Nimda that would put these packs in captured T-55 and T-62's, I want to attempt the same...but I am not clear on how they took the pack which drove the front sprockets of the M109 and had it driving the T-55 from the rear...they must have some way to reverse the gearing? From my rudimentary understanding if you simply swapped it to the back you would end up with several reverse gears vs one forward gear would you not? Thoughts?

[David Herbert]

I am not familliar with the final drives of a M109 but it is possible that there is one more stage of gearing and the input shaft turns the other way. If so problem solved. If not it must be possible to reverse the bevel gear drive within the transmission. The older GM two stroke engines could be built up to turn either way quite easily but I doubt the transmission would accept that, particularly the torque converter !

David

[rob love]

The reversal could also be done in the final drives. Not saying that's the way they did it, but just spitballin here.

The M109 transmission was not something we ever worked on the internals. You worried about any external stuff, but rebuilds were done at a central contractor.

[jdmcm]

I'm going to try the local Allison dealer, and if unsuccessful then Tecmotive in Ontario regarding the fwd-reverse issue. Any luck on some info regarding final drive to transmission coupling Rob?

[rob love]

John
Here is a cut and paste from a online manual. Basically it's a pair of ujoints with a small center shaft that fits between the two flanges.

[David Herbert]

A T55 / 62 has a spur geared first stage in the final drives which then drives into an epicyclic seccond stage so the input shaft from the transmission turns the OPPOSITE way to the sprockets.

If a M109 has a purely epicyclic or a two stage spur geared final drive the input shaft will turn the same way as the sprocket and problem solved.

David

[jdmcm]

Thanks Rob, that's a great start...and David you might have just solved the other question! I will get a picture of the output on the Allison and then maybe we could figure out what is missing, I sure do appreciate the help

John