Westinghouse 1BYC air pump--info needed

[amuller]

There is some good discussion of these here. Mine looks just like the one pictured in this thread: https://www.garagejournal.com/forum/threads/westinghouse-1byc-compressor-retro.485826/

The only manual I've been able to find online is this one, https://npeinc.com/manuals/General Electric/GEBK-IBvendor/WABCO.PDF covering somewhat similar "VC-WC models." Can anyone point me to a manual covering this model specifically?

I think I now *mostly* understand how the oil pressure operated unloader works (but what is the ball check valve in the upper fitting?), EXCEPT:

The air discharge is plumbed directly into the tank without a check valve, and this is also what the manual mentioned above shows. But this doesn't make sense to me. What prevents the entire contents of the tank from discharging into the crankcase? Surely there needs to be a check valve??

And is there a way to measure the oil pressure and what should that pressure be?

Thanks for any guidance!

 

[MrKona]

See attached... Hope this helps.

 

[MacMcMacmac]

Your 1BYC does not work the same as the later models with the oil pressure operated head unloaders. Yours has a simple oil pressure operated relief valve to dump air from the HP head at cut out.

If you look at the Group 10 Lubrication sheet in the .pdf MrKona supplied above, you will see that your pump has a plunger style oil pump running on an eccentric that actuates a lever inside the end cover (Group 5, End Cover sheet) to operate an unloader valve inside the end cover to bleed off air at cut out.

When oil pressure is established, a piston is forced out at the back of the crankshaft that presses against the lever to allow it to move and let the spring loaded dump valve seat and seal off the bleed port. At shut down, oil pressure falls, the piston retracts, allowing the spring loaded lever to move and lift the unloader valve to dump trapped air from the HP head to allow a loadless start.

There are no provisions to unload the intake valves, however, if there is no oil pressure to activate the lever to close the bleed valve at startup, the air being produced by the compressor will simply bleed into the crankcase and no air will be produced. Now you know why the crankcase vent line is so big. This is an elegant and very over-built system that works very well, although I am generally not a fan of dumping potentially moist air inside the crankcase. Many companies have done it however, IR being the obvious example.

Some companies (Quincy, Curtis and it seems, Westinghouse) use the HP discharge valve as the check valve. It works ok although I am generally not a fan. The compressor must bleed air off before the HP discharge valve, which means there is full tank pressure right at the valve, instead of an empty discharge line between the compressor and tank, which would give the motor a bit of extra time to spool up before getting under way. Obviously it works, and the engineers have done the math.

I do not know of any way to measure the oil pressure since it is all contained exclusively inside the crankshaft. There are no ports or passage you can drill into. If the pump is producing air, you have sufficient oil pressure.