Leslie SL-4T

Horn and photo courtesy Harvey Henkelmann.

The SL-4T was developed in 1973 for Amtrak and was used exclusively on their first new locomotives, the SDP40F's. The horn used the same three bells as the S-3K plus the #55 bell. The chord was suggested by Deane Ellsworth, who was working for Chessie System at the time but would soon move to Amtrak and spearhead the development of other airhorns for the passenger carrier. Photos courtesy Brent Lee

The first 40 SDP40F's (#500-539) received the horn shown in the pictures, with all four bells on a low-profile version of the standard 5-chime Leslie manifold. This is the SL-4T. It was originally dubbed an SL-4TX, with the X denoting "experimental," but the X was later dropped. The remaining 110 SDP40F's had the same bells spread over two 2-chime manifolds (essentially an S-2G and an S-2H). The resulting horn is called an S-4T, and has an even lower profile than the SL-4T. Photo courtesy Ed Kaspriske, Horns Inc.

The position of the "blank" in the SL-4T was variable. Dave Decker provides this photo of his SL-4T with the middle position occupied by the #37 bell.

Factory tuning: 311, 370, 480, and 554 Hz (approximately D#,F#,A#,C#)

The horn uses the Leslie #31, 37, 48, and 55 bells.

The SL-4T/S-4T was one of the shortest-lived horns ever produced in quantity. Within two years of its introduction, it had been supplanted by the Nathan P5a as Amtrak's standard horn (the P5a in turn would be replaced by the K5LA a few years later). Even then, some SL-4T's might have persisted on Amtrak for a decade or more had it not been for the poor fortune of the locomotives on which they were mounted. A series of derailments blamed on the SDP40F's led Amtrak to phase the big units out of service by the early 1980's. A few horns were swapped around onto other Amtrak units, but in general the SL-4T's were retired along with the SDP40F's. As a result, the horn is essentially extinct in railroad use today.

SL-4T sound samples:

Amtrak SDP40F (courtesy Dave Decker):
Sample 1...372kB...17 seconds
Sample 2...219kB...10 seconds
Sample 3...201kB...9 seconds
Sample 4...260kB...12 seconds
Sample 5...153kB...7 seconds

Dave Decker's SL-4T:
Sample 1...152kB...7 seconds
Sample 2...229kB...10 seconds
Sample 3...404kB...18 seconds
Sample 4...277kB...12 seconds
Sample 5...366kB...16 seconds
Sample 6...354kB...16 seconds

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