Truck Journal Boxes
Nelson Riedel,
11/1/2012, last updated 11/09/2012


Cast Boxes for Sleeve Bearings:

The drawing above is of Ken McCauley's cast aluminum journal box with lid.   The lid is a separate casting.   

The first thing I did to the casting was to grind and file the hinge on the lid and box castings such that the two pieces fit together.   I drilled the hinge pin holes through the lid first and then used  those holes to spot the holes for the pin in the box casting.   I drilled the hinge pin hole in the box from both sides, starting with a ~ .040" drill and the increasing the hole size to ~ .050".   I used a length of ~ .040" diameter brass wire with the ends bent over for the hinge pin.

The 1/8"  holes for the rods were drilled next.   I made a drilling template that fit over the tabs but found that the variance in the tabs made it almost useless.   Locating the holes in the middle of the tabs front-to-back and equal distance from the ends worked much better.   The castings have a short round stub on the inside of each tab ---- probably to match the prototype.    The rod holes should be inside this stub.   If one wants to use a rod threaded on each end then the stubs work fine.   I was too lazy to thread rod ends and used treaded rod instead.   I didn't like the looks of the rod threads between the tabs so I cut off those stubs and cut of a length of 5/32" OD - 1/8" ID brass tube to cover the rod threads between the tabs.  

The three  5/16-18 threaded holes are for set screws to keep the sleeve bearing centered in the journal; the casting comes with a ~ 0.7" hole so the 5/8" OD bearing will have plenty of slop. (The bearing is described in the Axel & Wheels section)  .  The top set screw should be 5/16" long.  I bought 3/8" long cup point  set  screws and ground 1/16" off the cup end.  The side setscrews need to be 3/8" long; I used 3/8" long set screws here too, but ground the ends slightly to flatten the ridge on the cup points.  The top of the upper set screw should be flush with the top of the casting.  The two side setscrews should be adjusted against the flat sides of the bearing but not tight so that the axel can rotate up and down with respect to the side frame.   The bearing is not secured on the bottom side to enable this rotation.   The setscrews were secured with Loctite.   

The photos show the finished journal box.  These were taken just after the sides were painted.   The top nuts on the rods are loose and the top bar is not in place.

New Cast Journal: After making a couple trucks I order some more castings from Ken McCauley.  I told Ken that it would be nice if he extended a half round down each side of the journal similar to the to arch bar support.  The holes for the 4-40 threaded rods can be drilled in the half round thus hiding the threaded rod and negating the need for the 5/32" OD brass tubes.   Photo of a couple of the new journals is on the right.        

Cast Boxes for Ball Bearings:

 Ken McCauley intended the journal boxes to be used with 7/8" OD-3/8" ID- 9/32" wide (R6) ball bearings.   I used those bearings on the little log car I built  with Ken's castings and they work great.    The drawing above shows how the casings are machined for the ball bearings.  Quite simply, the set screws are not used and instead  a 7/8" OD end mill is used to drill a hole 3/4" deep.  The end mill is then moved 0.01" toward the top of the box  and.0.01" toward the bottom of the box to elongate the hole by 0.020" to give the bearing room to move slightly with respect to the journal box.   This is very easy to do since it is easy to grasp the box sides in the milling vise.   There should be a lip at the bottom of the 3/4" deep bearing hole that will control the side-to-side movement of the axel.   That lip on some of the boxes I had was very small and  I was concerned that the bearing could lift over the lip.   I put a 4-40 FH screw up from the bottom of the casting such that the end of the screw supplemented the lip in retaining the bearing.  

Fabricated Journal Box for Sleeve Bearings:

Photo above shows the some of the journals I fabricated from aluminum bar stock.   The half round slots on the sides are 1/4" wide for 1/4" diameter rods.   The rods are center drilled 1/8" for 4-40 threaded rods.   The truck bars hold the 1/4" rods in place  and the rods in turn secure the journals.   I made three pair of trucks using these journals and they all have performed great.   Two pair are now in use on disconnected log trucks.   After working with the cast journals I decided if I fabricate any more of the journals I'll modify the design slightly to be a closer match to the cast boxes.    That is the design presented below.   I haven't made any of these boxes and as long as I can get the castings from Ken McCauley I probably won't.       


The box is fabricated from 1 1/4" X 1 1/4" aluminum bar stock.  The  machining sequence is the 3/16" hole first.  The half inch wide bearing hole is next by drilling 3/8" holes at the centers for the two rounded ends and then using a 1/2" end mill to open the hole to the final shape.    Next, the 1/2" wide slots should be milled in the top and bottom.   The 3/16" pin should be inserted and secured with Loctite and then the 4-40 holes drilled and tapped.  The radius and slope should then machined (milled) on the front surface.   The  Tab Bars (use same steel as the truck bars)  should be drilled as indicated and then attached to the the aluminum block with 4-40 FH screws.     

A lid as shown above can be added to improve the appearance of the boxes.   The lid is made from a 3/16" X 1"  aluminum bar stock.   A 15/16" length of the end of the long bar is milled to 1/8" thickness and then the end is sawed off the bar 1" back.  This leaves a 1/8" thick lid with a 1/16" lip an the top representing a hinge of sorts.   The lip hooks over the top edge of the sloped front of the box.   The lid is attached to the box with a 4-40 FH screw.    The screw is slightly recessed and the hole filled with composite and sanded flat.   


Fabricated Journal Box for Ball Bearings:

The fabricated box can also be used with 7/8" OD ball bearings.   The 3/16" hole and rod is eliminated and then an elongated 7/8" diameter hole 3/4" deep is drilled into the box using the procedure described for the cast box above. 


Trucks Home

NLW Home