Prime Manufacturing is a company that has been in the railroad business for a long time, making all sorts of locomotive accessories and other parts. Some products that they manufacture are pneumatic bell ringers, cab mirrors, air conditioning units, and much more. Also, for a period of close to thirty years, Prime offered locomotive air horns. The first Prime horns were introduced in 1972, and it wasn't until 1999 that Prime finally got out of the horn business. In that time, they sold many horns, mainly consisting of two specific models, the PM920 and PM990. Today, Prime has been purchased by the Dayton-Phoenix Group, Inc. and still manufactures many non-horn related products.

In the end, Prime sold its remaining stock of horns and spare parts to one individual, a private collector. Unfortunately, Prime also purged all records of their horns, including documentation, historical articles, and specifications. Thankfully, there are many collectors who have worked to save what is possible to save of this literature. Also, Union Pacific and Burlington Northern were two large customers, and many of the horns purchased by these railroads are still in service as well.

construction

Prime horns are based on the S-style SuperTyfon series of horns manufactured by Leslie. In fact, all the Prime parts are interchangeable with the corresponding parts on a Leslie S-style horn. If a Prime needs new diaphragms, you can substitute a Leslie S-style diaphragm, for example. Some roads went so far as to upgrade their Prime horns with Leslie RS-style power chambers when they started to fail, extending these horns service lives for many more years. Prime was able to market a line nearly identical to the SuperTyfon, since the 20 year patent on they SuperTyfon design had run out just as Prime's production started.

Even though Prime horns are mechanically almost identical to Leslie's SuperTyfon series, this is where the similarities stop; there are many differences which separate Prime apart from their competitor. Prime's horns are of a much heavier casting, for one. It seems that each part Prime made is cast with much more aluminum than the Leslie counterpart, leading to an overall heavier horn. This extra weight effects the tone of the horn as well; The heavy castings tend to give the Primes a smoother, more rich tone, than a comparable Leslie.

One of the visual differences in the Prime horns are that the bells have a support "rib" on each side, strengthening the bell at the base. The bells have the part number cast in the side, as well as the date on some of the later production bells. In addition, the bells are completely round at the base where they join the manifold, unlike Leslie's "scalloped" bell base. On the power chambers, the backs have a part number cast as well. The front of the power chamber is basically round where it meets the manifold, with six half-circle cutouts (see photos), as opposed to Leslie's narrower, "scalloped" power chamber base. The manifolds are even different. The main difference is that there is no Leslie name present on the manifold, though other subtle differences can be found.

Another difference in the Prime line is the number of accessories that Prime offered for their horns. One common on the Union Pacific was the addition of pressure-triggered valves inside of the horn manifold, introduced in the late 1980s. These valves were made available on the low-profile three-chime manifolds only. They are located in the air passage between the middle bell and each outside bell. The theory is that if the engineer is in an urban setting, he can pull the whistle cord only half way, and the valves would keep the air stream from reaching the outer two bells - a sort of additional modulation, if you will. But when in rural country, the engineer could pull all the way on the whistle cord. When full pressure entered the manifold, the internal valves would open, and the horn would sound all three bells. The manifolds with built-in valves were not in Prime's first offerings, but were introduced not much after the first casting change in 1973 (see below). Another offering, though not as common, was a riser, allowing low profile horns to have extra clearance. These risers basically raised the horn about three inches off the mount, while still providing ample support.

		pm920_2001_1.jpg	my father's PM920 - notice the flat flare on the low bell and support ribs on the sides of each bell
		pm920_030614_1.wav	at Oak Ridge 2003, we blew my dad's standard second generation Prime 920 on the RS1
		pm920_030614_4.wav	later that day, Bill Williamson's PM920 with internal valves was blown - notice how the top bell starts before and stops after the two other bells

designations and chords

Over time, Prime had several different configurations that they offered. Oddly, the chords of some of these changed over time as well. It seems that Prime changed the castings on their bells twice through their history, resulting in a couple different notes for two of their bells. The first change occurred in 1973, only a year after production started, and the second in the early '80s. Also, for clearance reasons, Prime cast the bottoms of their 1 and 4 bells flat instead of completely round after certain points in time. Here is a chart of the Prime bells, along with the notes they played at each production date, whether the bells have a flat bottom flare or not, and their Leslie bell equivalents. To the best of my knowledge, this is accurate.

NOTE: Prime, to my knowledge, never numbered their bells or used Leslie equivalent numbers. I have numbered them here for discussion purposes only, and these numbers should not be taken as Prime's bell numbering scheme.

Prime Bell	1972 - 1973	1973 - mid 80s	mid 80s - 1999	Leslie equivalent
1	C	C*	B*	25
2	D#	D#	D#	31
3	F#	F#	F#	37
4	A	A	G#*	44
5	A#	A#	A#	48
6**	C#**	C#**	C#**	55
* flare on bottom of bell flattened   ** this bell was never produced

Using the table above, we can piece together the horns offered by Prime, and the chords that they sound. First, the most common horn was the PM920. This horn uses bells 1, 2, and 4, and typically came with a low-profile manifold. Up until the mid-80s, this horn played C, D#, A, just like it's Leslie counterpart, the S-3L. However, this then changed with the newest castings, and it then played B, D#, G#. Some transition horns in this time period were found playing Leslie's advertised S-3L chord, B, D#, A. Also, some other horns at this time played an M3-like C, D#, G# - a very pretty G# major triad.

The next most popular horn was the PM990. This horn uses bells 2, 3, and 5, and plays D#, F#, and A#. Just like Leslie's S-3K, it was purchased and used extensively by the Burlington Northern. Strangely, this horn was not in Prime's initial offerings, and didn't appear until a few years after production started.

The last few horns are very rare, as only a few were produced, if any. First, a PM927 is a single-note horn, similar to Leslie's S-25, S-31, etc. I don't know if any of these were ever produced. Next, the PM928 is Prime's copy of the Leslie S-2M, and uses bells 2, and 4. There were very few of these produced, and I know of only one surviving example, thankfully preserved in a collection.

The last offering in the Prime line was the PM929. This horn was meant to mimic a Leslie S-5T, and used bells 1, 2, 3, 4, and 6 on a low-profile 5-chime manifold, nearly identical to the manifold used by Leslie's SL-4TX. Unfortunately, Prime never received an order for a PM929, and so this horn, along with their 5-chime manifold and 6 bell, were never produced.

		pm920_1stgen_1.wav	Ron Chamberlain's 1st generation PM920 - compare this to my dad's horn above, which is a 2nd generation PM920 (Copyright Ron Chamberlain, used with permission)
		pm920_3rdgen_s3l_1.wav	here we have a third generation PM920, followed by a Leslie S-3L for comparison (Copyright Ron Chamberlain, used with permission)
		pm920_mixedbells_1.wav	last, here is a transition horn with a second generation 1 bell and third generation 4 bell, playing G# major triad (Copyright Ron Chamberlain, used with permission)

last updated 03.08.2004