Nathan M3


The picture illustrates a common arrangement of the bells with the #1 bell reversed (turned backward). In this configuration, the horn is designated an M3R1.

Side view of the M3R1.

The M3 was first produced in 1950 as a derivative of the M5. As with the early M5's, the first year of M3 production featured bells that were round where they joined the manifold (or base), such as the horn at left. In 1951, the design was modified to the so-called "scallop base" shape illustrated by the horn shown above. M3's were the common horn on the Denver Rio Grande Western and were quite common on locomotives operated by SP, SP&S, Pennsy, D&H and many other eastern railroads. Round base M3 and photo courtesy Brent Lee.

The M3RT1 is a variation of the M3 in which the #1 bell has an elliptical flare and is angled upward 10 degrees from horizontal. It is believed that this modification was made for the Delaware & Hudson so the horn could be mounted on the "shelf" in front of the cab of their Alco RS-3 locomotives and have the rear-facing #1 bell clear the cab roof. The sound is the same as a standard M3. Photo courtesy Ed Kaspriske, Horns Inc.


Factory tuning for the M3 was: A major triad (C#,E,A).

Over time as a result of use, C#,D#,A, C#,E,A#, and C#,D#,A# dischords were common.

The horn used the M-series #1, 2, and 4 bells.


The M3 suffered the maintenance problems common to all M-series horns. Once very popular, few new M3's have been made since the early 1980's, and the horns are rare to find in use today. Willamette & Pacific applied old M3's to most of their locomotives in the 1990's, and a few shortlines still have locomotives with M3's. A scattered handful of M3's survive on Union Pacific, mostly on former Rio Grande power.


M3 sound samples:

Modesto & Empire Traction GE 70-ton:
Sample 1...306kB...14 seconds
Sample 2...402kB...18 seconds
Sample 3...221kB...10 seconds

Niles Canyon Railway GE 80-ton (horn courtesy 5CC):
Sample 1...92kB...4 seconds
Sample 2...108kB...5 seconds
Sample 3...229kB...10 seconds
Sample 4...212kB...9 seconds
Sample 5...286kB...13 seconds

Pandrol Jackson railgrinder:
Sample 1...237kB...11 seconds

Willamette & Pacific GP39-2:
Sample 1...304kB...14 seconds


When bad things happen to good horns:

The M-series horns were supposed to be tuned and voiced every six months or so to keep them sounding properly. Otherwise, the horns soon went out of tune. Sometimes M3's managed to sound good, if different, despite deferred maintenance. Other times they did not:

Modesto & Empire Traction GE 70-ton:
Sample 1...194kB...9 seconds

Willamette & Pacific GP39-2:
Sample 2...361kB...16 seconds
Sample 3...471kB...21 seconds



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