Aristo-Craft Heavyweight Passenger Car 3 Axle Truck Types

Aristo-Craft Heavyweight Passenger car 3 axle truck types Vignette
April 14, 2007
Revision GE-B
Ted Doskaris

To date, Aristo-Craft appears to have produced 3 types of 3 axle truck designs for its heavyweight passenger cars with the oldest type dating back to Aristo’s antecedent REA brand name cars.
A couple of example cars are used to illustrate the trucks starting with the newest type and ending with the oldest type.  


Described and shown is a comparison of the newer Heavyweight, ART-31610, 2005 made SP RPO and the older, ART-31609, 1996 made D&RGW RPO cars. These cars primarily differ with respect to their 3 axle truck design.


The below picture shows the Aristo-Craft older D&RGW RPO car of 1996 production date and the new SP RPO car of 2005 production date with the baggage end view comparison. Note the brake wheels are on both cars.


The below picture shows the new SP RPO car and older D&RGW RPO car post office end view comparison with the extra brake wheel on SP car only! I suspect the prototype only had one brake wheel.


Below is the new SP RPO car and older D&RGW RPO car top view that serves to compare the 3 axle truck coupler tang projection differences. Note the new shorter and more realistic SP version.


Below is the Aristo-Craft ART-29103 3 axle truck replacement kit. This particular example is of the older, long coupler tang.
I used these to retrofit my Napa Valley Wine Train cars that originally came with 2 axle trucks. The kit includes one axle as it is meant to transplant the remaining axles from the 2 axle truck that can be seen to the right side of the picture.


Note: When using the Aristo's ART-29103 3 axle truck kit - that comes in truck pairs inclusive of only one wheel assembly per truck - it is intended that the 2 wheel assemblies be removed from the original 2 axle trucks and transplanted into the 3 axle truck assembly. (Since Aristo-Craft has redesigned its heavyweight car trucks and corresponding car bolsters from prior versions, the new design type trucks require corresponding new design type car bolsters.  Thus, attention should be afforded to what type design trucks one has as well as the design type that is in the ART-29103 3 axle truck kits. Aristo typically does not change the “ART…” identification numbers, so close inspection is well advised.)


Shown below is the older design style 3 axle truck without a pivot rib across the top that would be required to accommodate the newer 2005 year production run heavyweight car bolster design.


Below is the new style 3 axle truck removed from the SP RPO car showing it with a pivot rib across the top that is required to accommodate the newer production run heavyweight car bolster design.


The two pictures below show the new design style 3 axle truck installed on the car.
Note the truck's pivot rib as seen against the car's bolster.


The picture brightness was increased to better show the close up view of the car bolster fitment proximity.


The 3 axle truck side frames also differ:

The new design style 3 axle truck side frame now includes a tab that limits the journal box travel when the suspension spring is unloaded. These limiting tabs shown facing upward are located at the bottom of each side frame journal box for the two out board axles.


Below is the old D&RGW design style 3 axle truck side frame that does not have a tab that limits the journal box travel when the suspension spring is unloaded.


Likewise, this older ART-29103 replacement 3 axle truck kit side frame design shown upside down does not have a tab that limits the journal box travel when the suspension spring is unloaded.


The D&RGW RPO old design style 3 axle truck design shown below as unloaded with the end of the car slightly lifted has no tab limited end axle suspension drop. Note no air gap under the end wheel with respect to the rail head.


Below is the SP RPO with new 3 axle truck design as shown unloaded with the limited end axle suspension drop. Note the similar size air gaps under the end and middle wheels.


Observations about wheels and bearings:

The wheel set axle projection tips measure 0.120 inch in diameter as shown below with the new heavyweight 3 axle truck design.


For both new and older design style 3 axle trucks the side frame brass bushings measure 0.150 inch for inside diameter. Thus, there is a great deal of slop allowing notable axle movement!

The new style shown here:


Below is the old style ART-29103 3 axle truck kit side frame brass bushings that measure the same 0.150 inch inside diameter.


The SP RPO car is shown in the below two pictures with the new and larger bolster plate design.  This larger plate includes the surface for the truck pivot rib to work against, and a wear pattern will develop due to rubbing friction. Though a plastic compatible lubricant can be used in this area to reduce pivot friction, I decided to add washers for a total of 0.080 inch thickness for just enough light to show between the truck pivot rib and the car's bolster to minimize the pivot friction and wear.



Below is a picture of the old style, smaller size car bolster of one of my Napa Valley heavyweight cars that the older non pivot rib truck is meant to go with.


Shown in the below picture is a comparison of the undersides of the newer ART-31610 2005 made SP RPO and older ART-31609 1996 made D&RGW RPO cars. The trucks are factory wired the same way on the older D&RGW car whereas they are wired different on the newer SP car!
The older way is superior for best electrical pickup from the rails to avoid light flicker. The propensity to have the lights flicker with the trucks wired differently on a car is due to the fact that the electrical wheel to rail pickup is via 4 wheels on one side along with 2 wheels on the other side. This compares to having the trucks wired the same way for a more favorable / equal 3 wheel electrical pickup on each side of the car.
The latest heavyweight ART-31660 2006-07 made SP Baggage car I recently received has its truck pair wired different from one-another, too. It appears the idea of simply making the truck wiring the same for both (all) trucks is an Aristo factory lost art!
As a remedy, If you have 2 of the newer type heavyweight cars, this can be corrected by simply swapping one of the trucks to / from the cars so that they have like kind trucks as to their wiring.
If you only have one heavyweight car - as was my case - this can be corrected by swapping the insulated axles end to end on ONE OF THE TRUCKS ONLY AND swapping the car's interior red / black wire connections to the truck connections. Only one truck should be changed this way otherwise a short circuit to track power via the car's wiring will result. (Doing this avoids having to transplant the truck side frames or electrical wiring with bushing eyelets form side to side on one of the trucks so it will be the same as the other truck. This can be done to fix the problem, too, but would seem to be more work to do.)


The SP RPO car with the new 3 axle truck design style did not come with lubrication and its axles would squeak down the track!  Whilst at it I swapped the end to end insulated direction of the axles to resolve the factory wiring deficiency for the lighting circuit to minimize flicker.
It is to be appreciated that the factory wiring of the truck side frame bushings require that the center axle insulator end be placed opposite in direction to that of the end axles. This is true for both the new and old style 3 axle trucks.


(Caution: use of Aristo-Craft’s Electralube grease has been associated with cracked plastic journal boxes. Aristo-Craft has since changed to a new nylon type plastic material for its truck parts that is not adversely affected by the Electralube. However, it may be difficult to ascertain which material a given car’s trucks are made of. Visually, the new and old material looks the same, but from my experience, the new nylon material is comparatively somewhat less flexible and somewhat harder than the older plastic material.)


As previously stated, for one truck only, I resolved the flickering light problem by swapping the insulated end to end axle directions whilst also switching the red and black truck wire connections for the wires that originate from the car's interior. The end result is 3 wheel power pickup for each rail and no light flicker. The image on the left is the changed truck mounted to the car.


The changed truck by itself on the SP car is shown below.


More detail about the electrical aspects:

To avoid possible short circuits one must pay attention to electrical polarity when attaching wires. Be advised that the body red wires are attached to a truck’s dedicated wire corresponding to the same side of the car (likewise for the black body wire - but on the opposite side of the car).  Moreover, I have found that the color code of the truck wires is not always consistently the same from truck to truck! So matching wire connections based on color code without some checking may cause a short.

If one were to further improve on minimizing light flickering, it appears the pickup harness with their brass bushing electrical eyelets could be transplanted from salvaged 2 axle trucks to the 3 axle truck where there are none. This augmentation would NOT add more wheel area for track power pickup, but it would make use of the axles’ shafts for an electrical conduction path to the opposite side brass bushings having the transplanted eyelets, and thus add twice the axle to bushing pickup area in the side frames.  I did not do this, however.



The oldest Aristo 3 axle truck type:

Below is a picture of an Aristo-Craft antecedent REA brand Heavyweight car 3 axle truck close up.
The picture shows the apparent center mount attachment to the car body. This is unlike both newer and older design styles since about the mid 1990s where the heavyweight car 3 axle trucks are offset mounted to the car bolster.
This offset mounting method is similar to that of the Aristo U25B loco except the loco includes rollers to minimize pivot friction. By offset mounting the trucks, the result would be to minimize coupler projection overhang of the car toward an outside curve rail with the trade-off of more belly overhang when the car is traversing curves. This method appears to be helpful for operation on tighter diameter curve tracks.

Comment:
I have not noticed any car operational difference with the two 3 axle truck design styles on my under house layout. My layout main line is circuitous and includes many 10 foot diameter curves whilst my rail yard access includes 8 foot diameter curves. My layout track work is pretty good, but a layout with irregular track work or grade cresting may bring out some operational differences between the older and newer truck designs.

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