Heisler Universals & Shafts Design
Nelson Riedel, Nelson@NelsonsLocomotive.com
2/27
/2005, last updated 04/09/2006

 

This page describes the design of the model universals and drive shafts.  The Cass foreman had told me end caps with grease fitting had been added to the Cass 6 universals to improve lubrication.  The following couple photos show the end caps and pin retention bolts.   

This shows the end cap on one side of a  female slip joint that mates with the square end of the driveshaft.   The end caps (one on each side) are held to the U by six screws.  That is a grease nipple in the center of the end cap
This is one of the pins which joins the two halves of the U joint pictured above.   The bolts hold the pin in the center cross. (The other pin has a notch cut in the side  This pin holds the second pin in place via the notch.) 

The groves in the side of the pin are lubrication (grease) channels.  

     

This close-up photo of a center cross shows the holes for the bolts that retain the pin.
This is the end or one of the Us on MRSR91.  Note that there is no end cover.  The  pin is held in place by a retaining clip.  There is a second clip on the other end of the pin.  The other pin is held in place by this pin via the notch half way through the side of the other pin to let this pin pass by but prevent the other pin from slipping out.. 

I didn't notice any way to lubricate the pins on this universal.  Maybe they are lubricated only when assembled.  That is maybe why the folks at Cass modified their Us.

I plan to use the retaining ring scheme to  avoid making all the caps and drilling screw holes, etc. 

Lubrication will be provided via a channel drilled in each end of each pin that mates with a small cross drilled hole that comes out the side of the pin near the center of the bearing.       

The plan is to pretty much scale the shafts and universals.  As a starting point the following decisions were made about the shafts and Us:  

  • Shaft Diameter will be 5/8""

  • Shaft slip joint will have a 11/16" square cross-section.

  • Round U will accept a 1" length of shaft.

  • Square U slip joint length will accept a 1.5" length of shaft

  • Cross pins will be 3/8" diameter.

 

Bearing:  A standard flanged sleeve bearing will be used in the ends of the Universal Us.  

Universal Cross: The Universal Cross will be cast in iron.  The main machining required will be reaming the holes to the correct size to accept the Universal Pins and possibly filing the ends so that fit between the bearing flanges of the Us.

The 6-32 hole will also need to be drilled and tapped.  This hole will hold a set screw which will keep the pin without the notch from rotating in the cross.  

The photo on right shows the universal cross pattern.  The pattern was fabricated from brass rod.  The two pieces were soft soldered together.  The white grains in the photo are sand from  the blasting process.   3
Universal Round Shaft U: The U castings  will require reaming of the holes. The 5/8" diameter shaft hole will be broached for the  key and also have the  hole drilled and tapped for the set screw. 

The sleeve bearings will be pressed into the holes in the end of the U  with the flanges on the inside.

The round shaft U pattern is shown on the right.   The pattern was machined from a single aluminum block.   Bronze sleeve bearings were installed for the photo.
Universal Square Shaft U: The bearing of the square U casting will require reaming.  The square hole for the slip joint should require no machining except possibly for smoothing with a file. 

The sleeve bearings will be pressed into the holes with the flanges on the inside in the ends of the U.     

 
This is the square shaft U pattern.  The U part was machined from an aluminum block.  The square part was assembled from a U channel and a cover plate.  The end of the square pare was tuned round and inserted into a mating hole in the U part.  The two pieces were held together with Loctite.   The pink stuff barely visible is body filler used to fill holes.
Universal Pins: The pins will be made from 3/8" diameter mild steel rods.  The shorter pin is retained by the other pin via the notch.  The longer pin is held in place by .029" wide external retaining rings (standard hardware for 3/8" diameter shaft) 

The 3/16" holes in the ends and 1/16" cross holes are for lubrication.  The 3/16" holes will be fitted with the oil hole covers described below.

 

Oil Hole Cover:  These oil hole covers will be used in the ends of the universal pins.  They are available from McMaster-Carr.  Part #1214K1 has  A=3/16", B=1/4" and C=9/32".  The catalog says: These low-profile covers have a self-closing ball valve. When you're ready to fill, the pressure of your oil container easily depresses the ball.   Friend Dave Johnson uses this type cover on his Ten Wheeler for grease nipples.  He uses a grease gun with a tapered nose fitting --- works great.   The drive-in covers are zinc-plated steel.
 

Drive Shafts: The drive shafts are made from 11/16" mild steel square stock. The entire length except for the slip joint square end is turned to 5/8" diameter.  There will be a key slot milled in the round end to mate with the slot broached in the Universal U.   The lengths vary from about 7" for the shaft to in the front truck to about 15" for the shaft to the middle truck.   The exact length of the shafts will be determined after all other variables have been  fixed.
Assembled Universal:  The universal can be assembled with one square U and one round U as shown on the right or with two round Us.  Each three truck Heisler has three Square-Round Universals and three Round-Round Universals.   

Photo above shows the patterns assembled into a complete U joint. 

Drawings and a Parts List for the Gears & Shafts may be downloaded from the Drawings and Parts List pages.  

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