Getting the 783 Hudson running as it should

This was a 783 and tender, in the box and never run. Sitting for 20+ years. With the high stack, higher torque, engine along with the engines weight it should pull well. First you have to get it to where it can pull itself.

First the Tender

DO NOT RUN the tender until you have checked the board inside.  The circuit board was held on with 2 layers of double back tape.  Tender base, double back tape layer 1,  aluminum sheet, double back tape layer 2 and then the circuit board. The original double back tape had rotted. It wasn't holding anything.  If I had run the tender as it was the sound board could have shorted.  The double back tape layers were replaced with new, high grade double back tape.  It was work to clean off the old tape to save the aluminum sheet. 

There is a wire against a layer of aluminum foil that goes to the speaker.  Some kind of capacitor action.  It was assembled as before with new double back tape. When done the sound worked. 

There is a black wire from the speaker to the aluminum sheet.  Just bare wire held against the sheet with the double back tape.  I calculate it is for some capacitor type action.


The chug is "noise generator" type chug.  The whistle is first gen.   It works.  The grand kids like the funny whistle sound.  Upgrading the tender sound system may be the next project.  

Fixing the engine

First out of the box, the engine wiring was poorly soldered,  2 wires hanging by a thread.  That was fixed first.

When the engine ran, the motor made a lot of noise.  The worm shaft would push the motor shaft back into the brush plate. It was a high stack from the factory, but only a single thrust bearing inside the motor.   The tolerance around the motor shaft and the bearing seemed very loose.  With the motor out of the engine and running by itself, the motor shaft rattled.  Anew 773-200x high stack motor as it was labeled was installed.  They come with single thrust bearing or dual thrust bearing.  The dual thrust bearing was used, with thrust bearings inside and outside.  This shows the thrust bearing on the outside with the C clip holding the bearing and shaft in place.

How much axial play should there have been in the worms shaft assembly, .010"/0.25mm.  How much was there?  .05"/1.5mm or so, it was obvious. Thin spacer washers (671M-23) were added until there was .010"/.25mm axial play. About 1 spacer washer thickness.  The vertical distance was good, no binding in that direction when the 2 brass blocks were level with the top of the casting.  

The worm shaft clearance where it connects to the motor with the rubber block was too tight.  Combinations of 2 motors and 2 worm shaft assemblies did not correct it.  It was the same no matter the combination.  There was a problem in the main casting with the  distance from the motor mount to the gear box.   This caused the shaft to push into the brush plate on the original motor.  With the new motor,  and the 2nd bearing preventing the motor shaft moving axially, it bound up.  20% was cut off the length of the rubber block and the pins were pushed into the blocks a little to get the right adjustment. 

Once the clearance was adjusted, it ran well and much quieter.  It has all new modern grease and correctly oiled.  

The gears and wheels were good.  The linkage needed adjustment. The eccentric rod would catch/rub on the eccentric bolt head.   The bolt head looks like it has the same clearance as the original 773.  The eccentric standoff connection for the eccentric rod was a little shallow.  Adjustments were made to make the eccentric rod clear the eccentric bolt head.   With small enough washers or spacers used on the end of the eccentric, the rod could clear without bending anything.

The smoke rod needed a little adjustment so it wouldn't bind the linkage.  A small bend in the linkage contact was all that was needed to make sure the linkage ran smooth.

The smoke unit was weak or non-functioning. There was no packing in the smoke unit.  I have another engine similar era, same smoke unit.  No packing in it either.   Same problem with that engine also.   It would take a lot of fluid to fill it enough without packing.  Then the smoke unit would have a hard time heating up in a pool of fluid. Packing was added.  It has been run and shows burn spots in this picture where it contacts the heat element.

A postwar smoke resister was used for the unit element.  It can be made to fit like original and within the packing correctly.  Now good, long smoke production.  Steam chest and Smoke stack. 


The 783 now runs almost as quiet as an original 1950 773.  It smokes well out of the stack and the steam chest.  It does what it should have done out of the box. It doesn't run as fast as many engines, it has low gearing.  Fast enough to derail on  36" circle track at full speed from time to time, while pulling 5 cars.   

The original 1950 773 has a standard Pullmor motor and runs and pulls just as well.  No tune up was needed for the 1950 version.  Precision, tolerance and fit makes a big difference.

Last Update Nov 24, 2021