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Work on C&NW 1385's three sets of 63-inch driving wheels continues. Work is being carried out by the Strasburg Rail Road shop facility in Pennsylvania. Here is a run-down of the status of the drivers as of an October 13, 2014 communication from Strasburg to Mid-Continent's 1385 Task Force:
The estimated completion date for the driving wheels is the end of 2014. The biggest influence of whether the target will be met is uncertainty of the lead time for the delivery of new tires. The order of operations is to press all new crankpins in, then turn the tire seats on the wheel centers. The new tires will then be ordered to fit snugly to the final dimensions of the wheel centers.
See the March 30, 2014 post for a further explanation of wheel centers and tires.
Work on the restoration of Mid-Continent's ex-C&NW R-1 class ALCO locomotive, No. 1385, has quietly progressed through the summer months at SPEC Machine near Middleton, Wisconsin. Project photographer Brian Allen stopped by SPEC Machine's shop on Tuesday, September 16, 2014 to provide some views of the recent efforts.
The photos catalog the extensive weld repairs completed on the locomotive's frame over the summer (see July 1 post for additional details).
On the day of the visit, work and discussion was centered on the spring rigging equalizers. A locomotive's spring rigging distributes the weight of the locomotive over the various wheels. Without equalizers, even small undulations in track elevation could cause substantial variations in how much weight is being supported by a given wheel. Such large variations would cause undue stresses to both locomotive and rail.
In this series of photos, you'll also see some components in fresh, glossy black paint. After months of stripping away layers of old paint and rust from the locomotive's parts to reveal the condition of the underlying metal, seeing fresh paint being reapplied is a welcome sight!
On March 30, 2014, C&NW 1385's three sets of 63-inch driving wheels were shipped from Wisconsin to the Strasburg Rail Road in Pennsylvania in order to be "turned" on a lathe, receive new tires, and have other adjustments and repairs completed (scroll down to the March 30th post for additional detail). On the weekend of June 28, 2014, Mr. Bernard Krebs of Jim Thorpe, PA photographed the drivers for the benefit of this steam status page, allowing us a glimpse of the work in progress.
Strasburg Rail Road makes use of a 90-inch Niles wheel lathe originally sold to the Lehigh Coal and Navigation Company in 1912. Lathes of such sizes were commonplace in the major railroad shops of America when enormous steam engines commonly roamed the rails, but now are rare with a limited number of shops around the country capable of handling tasks of such size.
Modern railroad equipment still undergoes similar maintenance procedures but all feature smaller wheels. The electric traction motors used on modern locomotives make wheel size relatively unimportant compared to steam locomotives where wheel diameter directly impacted piston speeds.
During each full rotation of a driving wheel on a steam locomotive the piston and connecting rods change direction of motion twice (forward then back). This very rapid change of direction puts a large amount of stress on the parts involved. Therefore, increasing the distanced traveled per wheel revolution and thus reducing the number of back-and-forth piston motions per second was an important design feature for high speed operations. It is no coincidence that the Milwaukee Road Class A and Class F7's that were built for 100 MPH-plus running of the Hiawatha trains between Chicago, through nearby Wisconsin Dells, and on to the Twin Cities featured massive 84-inch driving wheels. The British LNWR 2-2-2 3020 Cornwall is an extreme example of this concept, featuring 96-inch driving wheels.
Per Wikipedia, "Freight locomotives generally had driving wheels between 40 and 60 inches in diameter; dual-purpose locomotives generally between 60 and 70 inches, and passenger locomotives between 70 and 100 inches or so." Compare C&NW 1385's drivers with those of Saginaw Timber Company No. 2 as an example. In order to attain a speed of 60 MPH, No. 2's 44-inch drivers would require roughly 7.6 revolutions per second while No. 1385, built for fast freight and secondary passenger service, features 63-inch drivers that would require roughly 5.3 revolutions per second. Worded differently, it means the 1385 can travel 30% farther using the same number of piston motions. The Class A or Class F7's 84-inch drivers meanwhile would only require a comparatively leisurely 4 revolutions per second.
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Company No. 2
|Chicago & North
Western No. 1385
|Western Coal &
Coke No. 1