Pennsy’s most venerable steamer

Perhaps Pennsy’s most venerable steamer. (Photo courtesy Joe Suo collection©.)

—The February 2018 entry of my Audio-Visual Designs black-and-white All-Pennsy Calendar is an M-1a Mountain (4-8-2).
The Mountain was probably Pennsy’s most successful steam-locomotive, or at least the one they most venerated. It was developed in 1923, and there are two versions:

M-1 (uncast). (Photo by Gene Foster.)

M-1a (cast). (Photo courtesy the Pennsylvania Railroad.)

The one pictured is an M-1a. Its steam-chest between the smokebox and the two drive-cylinders is cast. The M-1 has piping to the cylinders, much like most Pennsy locomotives.
The “M” is essentially the giant Decapod (2-10-0) boiler and firebox (70 square feet) with a long combustion-chamber penciled in.
The combustion-chamber allowed coal to better burn, and increased heating-surface.
The Mountains weren’t passenger power, nor were they drag freighters. They were more all-purpose = 30-60 mph. With driver-diameters of only 72 inches (6 feet) they weren’t runners like the E-6s Atlantic (4-4-2) or the K-4s Pacific (4-6-2), both of which had 80-inch drivers.
The M’s were used to haul freight all over Pennsy, but especially on Pennsy’s vaunted Middle Division, Harrisburg to Altoona, right until the end of steam in late 1957. Diesels mighta done better, but no sense dumping the M’s when they were excellent for the service.
The one pictured, #6775, was built by Lima Locomotive Works, one of 24. There were 100 M-1a’s, some built by Baldwin, others in Juniata.
The M-1a’s also had giant “coast-to-coast” tenders, 22,090 gallons, 31&1/2 tons of coal. The only problem running them on Pennsy’s Middle Division is they needed to be re-coaled, etc.
That was done at Pennsy’s giant Denholm coaling facility, long ago removed. Foundations of the old facility remain, and the right-of-way still widens. In 1906 Denholm had twelve tracks. Three remain. Never did any railroad have a 12-track coaling facility.


Re-watering at Denholm. (Photo by Don Wood©.)

Trains pulled in and stopped for re-coaling from hopper-cars above on a cross/right-of-way bridge. The engines also got serviced and re-watered from trackside standpipes supplied by a Pennsy-owned reservoir. I have many pictures of M’s stopped at Denholm.
Sadly, that’s all gone. What remains are memories of one of Pennsy’s favorite steamers. And it’s not a 4-8-4, with which many railroads ended steam. It’s only a 4-8-2, but Pennsy used it like a 4-8-4; they were fabulous locomotives.


Heading out onto Rockville Bridge. (Photo by Don Wood©.)

• Two things: “Rockville Bridge” is a link to a blog I wrote a few years ago. Since then I’ve received updates regarding two possible mistakes. -A) Rockville may indeed be all masonry, no concrete core, and -B) Norfolk Southern trains toward New York City use Rockville, since that’s more direct to the old Reading line. Via Enola probably could be done, but would involve a lotta time-consuming backing and switching.