PROCOR Rock Limestone Covered Hopper Cars

Canadian Rail No. 278 March 1975 Image taken from Canadian Rail Publication March 1975.

By Keith MacCauley

Among the more unfamiliar designs of covered hopper cars (AAR designated ‘LO’) were a series built by Procor beginning in 1969. Most likely inspired by the so called ‘Barrel’ Ore cars constructed by NSC in 1967, the small 2,100 cu. ft. capacity cars, would spend their entire lives in relative obscurity moving limestone minerals two hundred miles from a mine in Cadomin (SE of Hinton, AB) to a cement processing plant located in NW Edmonton (CN Bissell Yard). Similar to the NSC built ore cars, they operated in unit train fashion. Constructed by Procor at their Oakville Ontario plant between 1969 and 1980, the cars were lifetime leased to Inland Cement.

While comparable in appearance to the NSC built cars, the Inland LO’s featured in motion loading and unloading. Copying the NSC roof geometry the Inland cars were equipped with full length rectangular hatches fitted with rubber-tired masts. Scroll assemblies located pre-loading and post loading opened and closed the hatches as the cars moved through the filling operation. Track beneath the loading tipple was on a 2.5% grade. Disconnected from the motive power, the cars moved through the tipple by gravity. Connected to plant air, the cars were advanced manually and positioned using their onboard air brakes. At the destination cement plant, unloading was accomplished by indexing each car over a pit. Horizontal sprockets equipped with cams and levers connected by a chain loop operated full length bottom doors. Placed beneath the center sill the sprocket cams were engaged by angle iron fixtures placed between the rails to open and close the doors. The bottom doors were positioned such that the limestone payload, known as ‘rock limestone’, was dumped outside the rails through grating into a pit.

Initial estimates of the available limestone reserve were that the mine would play out in just over half a century. While this would indicate a ceasing of operations in the early 2020’s, Google earth images show current ongoing activity. Between 1969 and 1980 Procor constructed some 181 so called ‘rock limestone’ cars. Owing to revised bridge loading requirements (known as Cooper E60), cars built post 1976 were made artificially longer while maintaining the same overall capacity. Related to mayhem during unit train operation, a handful of the later built cars were constructed as wreck replacements. The line from Cadomin to Edmonton has portions with severe grades. As a result, Canadian National stipulated that the cars be equipped with a higher braking ratio, i.e. higher braking forces. Nevertheless, on one occasion the unit train ran away uncontrolled and derailed with a handful of cars careening deep into a canyon. In the aftermath some of the derailed cars were repaired and returned to service, while others are, in theory, still in the canyon. At its peak, operation of the unit trains (CN U894/895) involved sixty-car consists, scheduled twice per week. Some four hundred thousand tons of limestone were transported annually.

Initially constructed with UTCX reporting marks, early on the Procor rock limestone cars were remarked UNPX. In the mid to late 1990’s, acknowledging a revised lease structure with Lehigh Hanson, the cars were remarked with PWCX reporting marks. Through mergers and acquisitions, Inland Cement became Lehigh Hanson and today is known as Heidelberg Materials; see https://www.heidelbergmaterials.us/about/history. Simultaneously, in the mid 1990’s the AAR Gross Rail Load (GRL) limit increased from 263,000 lbs to 286,000 lbs. Owing to the forty-year eligible life limit of the initial build of cars (built pre-July 1, 1974) and with no opportunity to increase the capacity of a closed car body, the diminutive covered hopper cars were removed from service 2008/2009. As mentioned, the limestone mineral to cement processing operation continues. The highly specialized LO’s were supplanted by 2,300 cu. ft. Trinity built open top hoppers cars (AAR Class HTS), equipped with rapid discharge outlet gates. Apparently, the need to keep the minerals out of the elements and dry was overcome. For a relatively brief period the two groups of cars were intermixed. Current Google earth images of the Heidelberg Materials installation show several dozen of the HTS’s cued up for off-loading. Photos of both the Procor built (UNPX/PWCX) and Trinity built (PWCX) can be found online at https://canadianfreightcargallery.ca/  and https://www.rrpicturearchives.net/

UTCX 44670a1

Built 10/1969 (first car built); renumbered UNPX 121600

Bottom UTCX 44670b1

gate opened

UTCX 44670c1

Bottom gate closed

UTCX 44670c1

Bottom gate closed

UTCX 44670e1

Bottom gate opening fixture

UTCX 44670f1

Bottom gate closed

UTCX 44670g1

Unloading pit. Note the fixture shown in the top of the photo, I believe employed as a car shaker to dislodge any frozen minerals

Among the more unfamiliar designs of covered hopper cars (AAR designated ‘LO’) were a series built

by Procor beginning in 1969. Most likely inspired by the so called ‘Barrel’ Ore cars constructed by

NSC in 1967, the small 2,100 cu. ft. capacity cars, would spend their entire lives in relative obscurity

moving limestone minerals two hundred miles from a mine in Cadomin (SE of Hinton, AB) to a

cement processing plant located in NW Edmonton (CN Bissell Yard). Similar to the NSC built ore

cars, they operated in unit train fashion. Constructed by Procor at their Oakville Ontario plant between

1969 and 1980, the cars were lifetime leased to Inland Cement.

While comparable in