Page 14 - NMRA Roundhouse September October 2020

N Scale Great Northern
Gas-Electric Catenary Tower Car
Part 1 Jonathan Small
Photos by Jonathan Small
MODELLING ARTICLE
F rom the completion of the first which is consistent with service as a rev- cables and stanchions, an interesting
electrified Cascade Tunnel in 1900, the Great Northern (GN) employed a small “Tower” car
for catenary maintenance on the short electrified section. However with the 1928 opening of the new CascadeTunnel, and the extension of the electrified sec- tion to 71 miles, a modern self-propelled vehicle was required. Like many west- ern roads the GN operated a fleet of motor cars of widely varying makes and histories in local and branch line service. Experience with these vehicles led to the decision to order a suitable motor from the Mack Co. to be fitted out for cate- nary service at GN’s Jackson Street, St. Paul shops.Assigned number 2337 as a motorcar in the GN’s classifications the basic car was built in 1928 by Mack as a heavyweight model AR car to a St.Louis carbody with cargo-only space. It was 76 ft. 7 1⁄2 in. in length, weighed 70 tons and was powered by three separate Mack AP six-cylinder 135 h.p. gasoline engines, and driven by three traction motors, two in the lead truck and the third in the rear.
One of only six Mack model AR cars ever built, GN’s #2337 was never intend- ed for revenue service.According to the railway’s assignment list for Gas-Mechan- ical and Gas-Electric Motorcars dated October 4, 1929 it was listed as a “New car at Jackson Street Shops awaiting ma- terial.This car for service Cascade Divn. Electric Crews.” This proves conclusively that the oft-repeated description of the car as having been converted from a branchline “doodlebug” is quite erro- neous. Perhaps this misunderstanding derives from the original number 2337,
enue motor. On 9 December 1930 the car was renumbered to X2804 at the Wenatchee Electrical Division shops, and received its final work number X-838 on 21 December 1945. The Mack engines were replaced in January 1946 by three Cummins diesels of similar horsepower. With the removal of electrification in 1956 the car was rendered redundant and was sold for scrap in spring 1958, after a 28-year career.
I suspect that X838 and its like would certainly fail modern health and safety regulations: due to the proximity of
the engine compartment and exhaust manifold, noise in the cab was so severe that conversation was impossible – and hearing damage would be inevitable. The pilot and conductor of X838 was for many years a Mr. Shirley Alger, for whom special closely-spaced steps were appar- ently installed below the end doors.
exhaust manifold and stack, and a single pantograph: not to pick up current but to ground (earth) the vehicle safely while work was in progress.There were also side-lifting booms, and air vents for the engines which gave it an asymmet- ric appearance. It was painted in the GN’s Empire Builder orange and green scheme, to match the railway’s other electric locomotives.
Plans and Sources
Photos of X838, in color and b/w are available in several publications, which I’ve listed at the end.The most useful when designing was the GNRHS refer- ence sheet.This includes the GN’s AFE plan with many dimensions, although the roof equipment is shown only barely, and some carbody details differ from photographic evidence. I drew my own technical drawings from these sources.
Construction
I started with the mechanism of an N scale Atlas RS3, which I selected for
the similarity of the side frames of the drive trucks. I removed the rear truck from the chassis, and then took the drive gears from this truck so that it would freewheel. X838 had a 52 ft 10 in. wheelbase, so I built a new chassis and installed the rear truck some distance away from the motor.Although this meant that the car would have only one drive truck I decided this would not be a problem, as X838 would never have to haul more than a couple of work cars.
For the new chassis I started with a strip of 2mm thick styrene cut to the car’s
ROUNDHOUSE - September/October 2020 - 75th Anniversary Issue
Modelling considerations
Much of the fun and challenge involved in modelling this machine is the varie- ty of work equipment installed on its roof. X838 exhibited a glazed cupola
to the fireman’s side, a collapsible work platform, lifting booms, walkways, safety
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