Roller Bearing Conversions

During the 1960s, Union Pacific rebuilt many of their older, 40-foot boxcars by modernizing them with new plug doors, or a combination of plug and siding doors. In addition, many of the classes were upgraded to roller bearings in place of their original friction or solid bearings. Rather than replace the freight car's truck, UP adapted the side frame to accept roller bearing wheel sets.

These converted roller bearing trucks are one of the more interesting details of Union Pacific's boxcar fleet during the 1960s and 1970s.

Two styles of converted trucks were used by the UP. The first, and perhaps least common, was the Barber S2 stabilized design. Photographs indicate that these trucks were used on all of the B-50-53 and -54 boxcars, rebuilt in 1964 and 1965 from B-50-38/-39s, respectively. The original trucks had a plank under the springs, but, the plank was evidently removed at the time of rebuilding.

The B-50-40 and B-50-42 series were delivered with the same truck, minus the plank.

Although not as common, the Barber roller bearing converted truck occasionally shows up under other classes of rebuilt cars, most notably the extensive series of BF-50 "grain loader" rebuilds.

Examples of the converted trucks still exist under surviving cars.

B-50-53, 108875.

Hooper, Nebraska, August 2010.

The more common style of converted truck was the ASF "Ride Control" design, that is characterized by the "dish" under the springs. Union Pacific used this truck, or one very similar, on the majority of its post-war 40-foot boxcar fleet, including the B-50-41 and B-50-43 series, that combined for total of 4,000 cars. The majority of the -41s were rebuilt into BF-50-2s in 1966-1967, at which time the trucks were converted to roller bearings. These trucks were used under a wide variety rebuilt cars, from several railroads -- they were not unique to the UP -- but thus far I've not been able to locate an extant car with these trucks to take detailed photographs.

A converted ASF truck on a BF-50-2, in maintenance of way service in the 1980s.

Of all the detail parts available for modeling freight cars, for Union Pacific modelers, these roller bearing converted side frames are some of the most needed models.