Aristo-Craft Metal Wheels Issues

Aristo-Craft Metal Wheel "train accessory" kits and wheel issues
(Pictures & measurements of selected Aristo wheels and their affect on wheel / axle skew when installed in freight trucks.)
Ted Doskaris
Revision GE-B
April 19, 2007

These wheel sets come in brass, bright metal, or smoke finish (aka blackened).
The basic Aristo number is ART-29111 with a suffix added for its finish ("B" for blackened, "S" for silver) or intended application ("D" for the newer Barber trucks).
 
The ART-29111, B, or S is intended for use with the Aristo Bettendorf trucks of the 40 foot type freight cars. The ART-29111D is intended for use with the newer type Barber trucks that include emulated roller bearing caps. These trucks are used on the 100 ton hopper and EVANS box cars.
(Note: some of the following pictures may  imply metal wheels as being black in appearance when they are actually bright but with a dulled finish. This is due to the camera settings not being optimal.)


As shown below, the Aristo ART-29111B wheels for the Bettendorf truck is at the left and ART-29111D wheels for the Barber truck at the right.


Note: It is to be appreciated that the following hub projection discussion is not to be confused with the overall axle tip to tip dimension of a wheel assembly.

The "D" wheel version must be used in the Barber type trucks as the "B" version has a wider hub to hub dimensional span that will result in binding when installed in the Barber truck fame. (The "B" version, however, can be adapted for use in the Barber trucks by either reversing the side frame brass bushings or countersinking the interior side of the brass bushings.)

Aristo wheel hub comparison as shown below:
The ART-29111B at the left has a projecting hub, whereas the ART-29111D in the middle has a minimal hub projection - as does the plastic wheel at the right.


The Aristo Barber type trucks of current production runs include knurled axle tips on both the plastic wheels and metal wheels to help retain the emulated roller bearing caps. Prior factory production runs did not include this feature.


Axle hub to hub measurements:

As shown below the ART-29111B hub to hub span measures 2.257 inches.


As shown below the ART-29111D hub to hub span measures 2.186 inches.


As shown below the Aristo standard plastic wheel from the Barber type truck has a measured hub to hub span of 2.170 inches.


Shown below is Aristo Bettendorf truck example Plastic wheel with a measured hub to hub span of 2.203 inches. (This example was one of the original wheels removed during a metal wheel retrofit to a Western Pacific 40 foot box car.)


Thus, the Aristo Plastic wheel from the Bettendorf truck of the older Aristo 40 foot type cars appears to have a hub-to-hub span property of a somewhat greater .033 inch amount than the Barber truck plastic wheels, but it still is .054 inch less than its intended replacement metal wheel, ART-29111B.  

Axle tip to tip measurements:

Shown below is the same Aristo Bettendorf truck example Plastic wheel having an axle tip-to-tip span measurement of 2.756 inches:


As shown below the ART-29111B overall axle tip to tip span measures 2.799 inches.


As shown below the ART-29111D overall axle tip to tip span measures 2.796 inches.


As shown below, the Aristo Barber truck plastic wheel overall axle tip to tip span measures 2.754 inches.


Shown below is a top view comparison of Aristo-Craft metal wheels showing the ART-29111B longer hub on the top with the Barber truck wheel on the bottom with its shorter hub.


From left to right are:
Left: ART-29111B (with pointer at axle near projecting hub for some pictures);
Center: ART-29111D with minimal projecting hub;
Right: Aristo standard Barber truck plastic wheel also with minimal axle hub projection beyond its tire face.







Comment:

Some folks may have believed that the "D" version wheels meant for the 100 ton hoppers & EVANS cars would not work on the older 40 foot cars because they are overall too long. This is an incorrect misconception as the measurements show them to be virtually the same as the others.
As to the hub span facet, the "D" version wheels will work in the older 40 foot type car Bettendorf trucks, too, as their hub span is between that of the "B" version meant for the 40 footers and the plastic wheels.  
That said, there is one benefit to the wider hub span of the "B" version wheels in the Bettendorf truck - that being a slight reduction in the amount of excessive lateral (side to side) axle slop in those truck types.

A few more Aristo wheel measurements:
Wheel Diameter measurements:
Aristo ART-29111B metal wheel example "tread" diameter measures 1.154 inches as shown below:


Aristo ART-29111D metal wheel example "tread" diameter measures 1.151 inches as shown below:


Aristo Plastic wheel example from Barber truck "tread" diameter measures 1.172 inches as shown below.

Comment:

Retrofitting metal wheels to the older production run Bettendorf trucks:
Below is a comparison showing Aristo Bettendorf truck brake shoes. The upside down truck shown at the bottom is of the older version truck having projecting shoes that are prone to snag on turnout frogs or track joints if not trimmed. This becomes a problem when ART-29111 metal wheels are installed since they are slightly smaller in diameter than the plastic wheels.


Trimming can be done with a small cutter or using a file by removing a very small amount - parallel to the track rail head.


Overall wheel flange diameter measurements:
Aristo ART-29111B example metal wheel overall flange diameter measures 1.370 inch as shown below:


Aristo ART-29111D example metal wheel shown below also has an overall flange diameter also measurement of 1.370 inch:


And the Aristo Barber truck example Plastic wheel overall flange diameter measures 1.397 inch as shown below:


Thus, all three above wheel examples are virtually the same for overall flange diameter.

Freight truck wheel / axle skew  and drag issues:
The prior discussed axle measurements affect how the wheels operate when the axles are installed in a truck (aka bogie).

Operation of a train on curves results in a noticeable increase in drag.
This is particularly significant on tight curves like many of us may employ on our model RR layouts. I decided to do a test to get an idea of what the effects of truck axle side play have on the drag. The test I did was to look for the amount of wheel skew with respect to the track rail when I coasted various example Aristo freight trucks on an 8 foot curve track whilst also getting a “feel” for their rolling drag. It is to be appreciated that actual truck operation may be different when mounted on a rail car, and whether or not truck mount or body mount couplers are used.

Below are 6 example Aristo freight trucks with different type wheels of various hub to hub dimensional spacing with a couple examples fitted with Aristo's ART-29411 miniature ball bearings (with and without added washer spacers) as tested for wheel skew on an 8 foot diameter curve track. Five of the trucks are Bettendorf types and the sixth is a Barber truck as shown on the far right end.


Shown below is an overhead view of the 6 Aristo freight trucks:


Shown below is overall vertical view of the 6 Aristo freight car trucks. Again, five of the trucks are Bettendorf types and the sixth is a Barber truck as shown on the top.


Shown below is an example Bettendorf truck fitted with ART-29111D metal wheels normally intended for the EVANS or 100 ton hopper cars. This example has the worst wheel skew with respect to the track rail when coasted on the curve track. The two axles tend to walk to opposite extremes of each other within the truck whilst the truck traverses the track curve. This is the worst example truck with the most wheel to track skew angle and rolling drag since the axle hub to hub dimension is the narrowest.


Shown below is an example Bettendorf truck with standard plastic wheels. It has the 2nd worst wheel skew when coasted on the curve track. Again, the two axles tend to walk to opposite extremes of each other within the truck whilst the truck traverses the track curve.


Shown below is an example Bettendorf truck fitted with its intended ART-29111B version metal wheels. It has the 3rd worst wheel skew - being better than the first or second examples - when coasted on the curve track. The two axles tend to walk to opposite extremes of each other within the truck whilst the truck traverses the track curve.


Shown below is an example Bettendorf truck fitted with the ART-29111B metal wheels but also with Aristo’s ball bearings installed into the side frames.
The ball bearings include a flange that serves to eliminate some of the axle side play much like what a washer would do. This example truck is better than the prior first, second, and third examples when coasted on the curve track. Still, the two axles tend to walk to opposite extremes of each other within the truck whilst the truck traverses the track curve.


Below is an example Bettendorf truck fitted with the ART-29111B metal wheels and the ball bearings but now with .015 inch thick washers - 2 per axle with one at each wheel end. It is the best example of all the trucks tested - when coasted on the curve track. The two axles walk minimally to opposite extremes of each other within the truck whilst the truck traverses the track curve. I have found that adding thicker washers or additional washers would cause rolling drag even on straight track, so care must be afforded so as not to eliminate all axle side play.  


Finally, an example Barber truck with its standard brass bushings fitted with its intended ART-29111D metal wheels has some wheel skew when coasted on the curve track. Like all the other truck examples, the two axles tend to walk to opposite extremes of each other within the truck whilst the truck traverses the track curve. For this truck type, the amount of walking is also dependent on how far the plastic bearing caps are pressed onto the axle tips. This is not a controlled amount and subject to whatever the factory may do on a given day with a given worker – or for that matter, whatever we users may do. (On some Barber trucks, I have noticed that if I press the caps on as far as they will go, drag can result.) If Aristo were to make the bearing caps a bit shorter or axle tips a bit longer or design them with some kind of ridge to serve as a stop for the bearing caps, consistent control would be afforded.



Comment:

The above “coast test” example trucks show that adding spacer washers will indeed help, but be sure to leave some small amount of axle side play.
Of all the tested trucks, the Bettendorf truck fitted with ART29111B metal wheels, ball bearings, and .015 inch thick spacer washers was the best example truck. This example truck having minimal side play is still free to roll. (It measures a coincidental .015 inch axle side play clearance. The slop in the bolster / side frame recess makes it somewhat difficult to measure, so I evened out the "slop" when I made this measurement with an automotive feeler gauge.)


Wheel / axle skew and prototype railroads:

An example prototype 2 axle railroad truck with steerable axles is discussed in:
United States Patent 5,000,097  
“Self-steering railway truck”

As to what I referred to as “wheel skew”, this patent describes in terms of “angle of attack”. See excerpt below:
“...Another undesirable result of restraining the axles to be parallel is having the lead axle run with a substantial angle of attack against the outer rail in curves, causing objectionable noise and excessive wear of both flanges and rails. This operation also presents a derailment hazard. The hazard is due in part to high flange climbing forces associated with the wheel/rail angle of attack and in part to the cumulative damage done to the track by the high forces...”

The below patent Figures 5A through 5D are helpful in illustrating what prototype railroads may be doing with trucks and their wheel relationship to the rails on a curve track.




This patent can be seen at the below link.
(For viewing USPTO “images”, the “AlternaTIFF” plug-in must be installed on your browser.)
http://patft1.uspto.gov/netacgi/nph-Parser?patentnumber=5,000,097

The patent may be used as a tutorial. If so doing, ignore the claims and study the embodiment.

Another patent that may be of interest is:
United States Patent 4,676,172
“Frameless radial truck”
http://patft1.uspto.gov/netacgi/nph-Parser?patentnumber=4,676,172


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