WABCo A Series Train Horns
Among the earliest air horns manufactured by WABCo are the A-1 train horns. A typical A-1 horn has a bell that is generally made of brass material. It is also straight; although some A-1 horns appear to have bells that are curved outwards. The bell very much looks like that of the A-2 horn, only that there are no spiny lines at the side of it. The bell, too, comes with a built-in nozzle that bolts onto a back cap. This acts as its mount and air orifice. If the buyer so desires, WABCo can manufacture the back cap with a lower mounting foot to enable the train horn to be secured horizontally. Another option, although this is rarely seen, is to mount it vertically. The back has a couple of holes in wherein the horn could be securely fastened.
The bells of the A-1 train horns come in two different sizes. The larger sized bell is tuned to a D#, while the smaller bell is tuned to a G. Naturally, heavier diaphragms are used on train horns having the larger sized bells. Bells on the earlier models of the A series horns were slightly different, however. An important consideration during that time had something to do with the bolts --- whether or not they should be fastened from the side of the bell or from the side of the base. As time went on, the A-1 horn evolved with a base that looked a lot like that of the A-2 horn.
The A-1 horn, as well as all WABCo train horns of the A-series, has a single weighted diaphragm that is of a thick disk, with its weight concentrated on the middle of the disk.
The first railroad chime horn produced is thought to be the AA-1 train horn. The AA-1 horn has both bells of the A-1 horn fastened to a single back cap or mount, and this may either be horizontally or vertically. This train horn can play a D#, a G, and a third interval. Its bells may be tilted to 90 degrees, or they may not; however, tilted bells were commonly seen on MU cars early on.
The most common of the WABCo train horns may have well been the A-2 horns. A-2 horns typically look like A-1 horns, except for a few refinements here and there. For one, a particular difference between the A-1 and the A-2 horns is that the A-2 horn has four support ribs on the side of its bell. This gives the bell a rigid or unbending quality to it. There are also two bells in the A-2 horn; one is longer, about 15 inches, perhaps, and the other is shorter, just around 11 5/32 inches. The longer bell is tuned to a D, while the shorter bell sounds a G.
Much like the A-1 train horn, the A-2 has two different diaphragms --- one is heavier, while the other is lighter. How these diaphragms are used depend much on the kind of bell it will be used with. For instance, if larger bells are used, the diaphragm with a heavier weight will be used. In the same way, if smaller bells are used, then the diaphragm which is lighter in weight will be used. Unlike the A-1 horn, however, the A-2 horn does not have a flexible back cap, to allow a vertical mount. A-2 horns are generally mounted horizontally. Small that they are, the A-2 horns are, in general, very heavy, as they were manufactured using cast iron. Many A-2 horns can be found in switch engines.
Another model from the A series train horns is the AA-2 horn. The AA-2 horns combine two available A-2 bells to produce a fourth interval sound --- a D and a G. The AA-2 horns were commonly found in certain MU cars as well as in quite a lot of interurban cars and small industrial engines. A lot of the AA-2 horns are still being used by the New Jersey Transit electric MU cars. At present, it is even the only kind of train horn being offered by WABCo.
The last type of train horns belonging to the A-series is the A-6 horn. The A-6 horn looks like a larger version of the A-2 horn. Like the A-2 horn, the A-6 horn also has support ribs on the side and has more or less the same mount as the A-2’s mount. It is not certain what sounds the A-6 horns produced, although, accordingly, its long bell can sound off an A while its short bell is tuned to a C.