I have a Montgomery MG set installed a rebuilt hoist motor car first would run on inspection. Car no longer will run. I checked armature voltage and I’m only getting 35-45 vdc off generator motor is rated for 200v . When I read resistance on my fields I’m getting 15ohms shop said they should be 87ohms any ideas in which direction I should go from here? This is an old Montgomery where they use a shunt motor in damping circuit. I believe car is late 60 early 70s

Something to check. Does The relay AR energize? It is a relay that is pulled in with amps, not volts. It is in the armature loop circuit. This is all way back memory so like I said, just something to look at.

Another thought just occurred. I believe that the small shunt motor is what pulls AR relay in. The car will not go into high speed without AR. I think as the shunt spins it pulls in AR.

Thank you John jay. Tomorrow I’ll get back to you after having more time trying a few things . I believe your correct its something to do with this shunt motor not feeding circuit correctly .