As I recall, when WABCO ceased to make the compressors that had been originally designed for PCC use, the agencies still using air electric cars found that Quincy made a suitable replacement.

Thanks Jennie.

I recently performed a Locomotive inspection for another owner. It had been repowered at some point and had two Quincy’s similar to these. The ones in the other Loco had unloaders on both cylinders of both compressors. Mine only has them on the High Pressure cylinders. I might have to add some to my compressors to go along with an Unloader controller, so I can dial in the pressures that I want. Still have a lot to learn.

Not the biggest update… but still pushing forward.

Here are the drawings I made today to build the front engine mount. Need to get the factory Cummins mount to adapt to the Plymouth chassis. Pretty crude, but it’ll get the job done.

Will get the crankshaft centerline in the right place.

Have the front engine mount ready to test fit.

Still needs all of the holes drilled, but the final build is done. When I drew it up, I planned for 1/2” steel. Way off!

Ended up making it out of 1” plate. Should be plenty strong to support the front of the new engine.

Also, making progress on the instrument panel. As always, there’s more to do.

Next step will be to mount the new ignition switch and get the air pressure gauges pretty and calibrated.

Edit…

My pics seem to show up in the wrong order. Oh well, you understand where the project is heading.

Working on the air gauges. They are calibrating very well. Gave the deadweight tester a good workout today!

Did a test-fit of the front engine mount. Looks good, will drill the mounting holes tomorrow. I’m ready to hear this ‘new’ engine run!

Have the engine cradle 95% done. Have it notched out for the front mount.

Maybe get the new engine installed within a week or two.

Little Sunday update. Happy Easter!

The engine mounts are installed and ready to go. Just need my heavy equipment guy to come over and lift the new engine into place.

I removed the transmission input shaft housing today. Have the nut removed but my makeshift removal tool isn’t getting the gear off. I’ll press it apart tomorrow and see what’s worn. Hopefully it’s just a failed bearing. Will find out tomorrow.

Looks like some pretty good progress so far. The worrywart in me wonders if the flat plate cradle for the front of the engine is stiff enough to resist the engine torque without flexing over time. IIRC, maybe not, the engine bolts to the bottom horizontal of the cradle leaving the bends and diagonals to resist the torque. Just wondering….

Excellent observation Eric!

I worry about these things also. When I drew up that front mount I made it 1/2” thick. That’s strong enough for everything else I’ve ever built!

Thinking about the forces involved changed my mind. Made it from 1” plate.

I’m only counting on the front mount to handle the weight of the engine and vibrations.

The torsional load should be handled by the rear mounts on the bellhousing. They are better equipped to twisting forces of the engine.

I copied this idea from an engine I installed in #12 at the RR. Also an 855 Cummins. It mounts directly to the traction generator. That handles all the torsional stuff. The front mount still needs to be there, but doesn’t have as much stress on it.

Isn't there some elastic or resilient motor mounting? Even with the back of the engine bolted to the final drive, wouldn't a little compliance between engine and frame be a good idea?

Similarly: if the engine has a harmonic balancer in its crankshaft pulley, take care to retain it without damage if you can.

I’d have definitely raised an eyebrow at 1/2”. You’re right that the rear mount and tranny will help stabilize it. I’ll cross my fingers for ya.


Hard bolting to the frame helps ensure everything stays in critical alignment and doesn’t over stress connections between components. Elastomeric mounts, like in an automobile, are there only to take up vibration for a more comfortable driving experience. The engine and transmission, for all intents and purposes, are essentially one unit bolted together driving a sliding shaft with u-joints to so there aren’t any alignment problems. However, their mass is much less than the drive train in even a small locomotive thus more prone to transmit vibration. In a Plymouth or similar critter, there’s no drive shaft to deal with the variable alignment with the output shaft of the transmission. So hard bolting to the frame, crude as it seems, was the best way to go. IIRC, most heavy equipment is done that way.

Thanks for the discussion guys.

The original engine was hard mounted as well as the giant transmission. They were also bolted to each other with housings that surrounded the original clutch.

My new setup will be slightly different. Both components will still be hard mounted, but will have a straight coupling between the PTO output shaft and the transmission input shaft. This will allow me to use the new PTO clutch assembly.

I was thinking more of isolation, as in the EMD 'sleds', and perhaps some avoidance of resonant critical-speed shock. I agree that automotive-style motor mounts, even those in pusher motor homes or whatever uses that size engine would be unnecessary (unless you were planning much higher-speed operation than the Plymouth suspension would accommodate!)

On big trucks and equipment the mounts on the bellhousing take the torque. The front mount is just to hold the engine up.

Got the transmission input housing apart today.

The input bearing was spinning its outer race and wore into the housing pretty far. The bearing doesn’t seem too bad, but I’ll replace it anyway. The worn housing was the source of the excessive side to side play of the input shaft.

Interesting design in this transmission.

Most of the bearings rely on splash lubrication from the gear oil bath. Certain bearings that may not get enough lubrication from the gear lube also have external grease fittings to supplement the lubricating. This was all pretty well thought out by the Plymouth designers. Guess which bearing is in a bad spot for splash lubrication and does Not have an external grease fitting?? The input shaft bearing.

Not the best design, but I’ll fix the issue before it gets reassembled. When it goes back together I’ll either add a grease passage and fitting or I’ll use a 2RS sealed bearing for the input bearing.

The first picture shows the worst of the wear. It has worn away about 1/8” and is into the threads of the cover hole.