Federal Electric Type Mach. B

The **Type Mach. B** is a horizontal electric siren originally produced by Federal Sign System (Electric), later known as the Federal Electric Company and Federal Signal Corporation. The Type Mach. B was introduced in 1917 and intended to compete directly with the widely successful Sterling Model M.

The Type Mach. B would be advertised primarily as an outdoor fire alarm for use by volunteer fire departments but would also be advertised for use in mines and industrial plants as an electrically powered alternative to steam whistles.

## History and Design

The Type Mach. B was first introduced in 1917, alongside the smaller Type A siren. At this time, it was commonplace for Fire Departments to use bells and steam or air whistles to call volunteer firemen to action. While these signals were effective in terms of volume, they were rather indistinct. This, alongside the rising popularity of electricity and especially electric motors, lead to the development of a new type of signal, these being electric sirens.

The first companies to produce electric sirens were the Interstate Machine Company, The Dillon-Box Iron Works Company and Heath Engineering Laboratories. The sirens produced by these companies would see rapid and widespread success, with the Sterling Model M being the most successful model at the time. This success would coax Federal Sign Systems into entering the market with their own design, in hopes of capitalizing on the new trend.

While all three generations of the Type Mach. B have several wildly distinct differences, all three variants also share several key design features. Most notably, all three variants of the sirens share the same overall unit construction, with the stators of the siren being mounted to the base on which the electric motor sits. In theory, this would make the siren much more prone to stator chaffing issues caused by misalignments, though in practice this would hardly prove to be an issue.

The overall rotor design of all three versions of the siren would also remain mostly, with the rotor commonly being of an all short-vane design, with a wide ring over the end of the impeller. This would prove to be the main shortcoming of the siren, as the loose intake would result in a low operating pressure, while the small vanes would pull very little air, resulting in a rather quiet siren. This would prove especially detrimental at lower speeds. Many Type Mach. Bs take over a second to become audible upon winding up.

### 1st generation (1917-1922)

The first generation of the Type Mach. B was introduced in 1917, and takes very heavy inspiration from the Sterling Model M. The original Type Mach. B was unique from other sirens at the time in its overall construction, due to it having its horns cast as one piece with the rest of the stator. The ports on this siren are distinctly split down the middle, and much like a Sterling M, the Type Mach. B features a set of sounders to guide sound that would usually travel skyward back down to the ground. The sirens were advertised as being sold in 4 distinct styles, which are believed to be a single or a double head siren, with either straight or curved horns. Regardless of what style was chosen, the siren was exclusively sold in a 15-port high tone configuration, which at the time was believed to be the best for long range.

From the factory, the sirens would be painted in a bright "fire alarm red", with black pinstriping along the sounders, horns and motor hood, with a decal reading "FEDERAL SYSTEM" placed on the side of the hood. The sirens could be ordered with either single phase, two phase or three phase motors, with the center portion of a single phase Type Mach. B being nearly as twice long as a two or three phase equivalent. Regardless of phase, the sirens would typically be outfitted with two horsepower electric motors.
Early production Type Mach. Bs had slightly different stator castings than the more common variants, and featured a unique set of rotors with three long vanes, as opposed to the typical set of 15 short vanes.

### 2nd generation (1922-1926)

The second generation of the Type Mach. B was introduced in 1922, featuring several key design changes. The most notable change on the new generation of the Type Mach. B would be a change in design for the stators. The new models featured a shortened set of horns and a semi-circular, flat section cast into the rear of the stator. Rather than featuring a set of metal sounders similar to those seen on a Sterling Model M, the new version of the Type Mach. B instead covered the stator port openings with a pair of flat metal sheets, which would heavily simplify the production of the siren.

With the second generation of sirens game the introduction of a 10 port, low toned option. The low tone models are distinct from the high tone sirens due to their lack of splits down the middle of the ports. Several other smaller improvements were added to the second generation sirens over time, such as the inclusion of Intake and stator screens, as well as motor hoods with hinged, latching tops being seen on some models.

A quad-rotor version of the Type Mach. B was also introduced alongside the standard generation two models. It was most likely intended to directly compete with Sterling's Super Quad Siren. Quad-Rotor models were exclusively made in a 10/15 port dual tone configuration, with distinctly longer stators to accommodate the two extra fans it carried. The inner set of rotors have intakes facing towards the siren's motor, with the motor hood having a set of screened cutouts in the side to allow air to reach them. Two dual tone units are currently known to exist.

### 3rd generation (1926-~1953)

    In 1926, the Type Mach. B would see its final design change. The 3rd generation of the siren would take a big step away from the previous two models, featuring an all new set of castings and a brand new housing design, allowing the siren to have a much more customizable and efficient sound projection pattern while also giving it a much stockier silhouette. The silhouette of the new siren was not the only aspect about it that was larger, however, as the 3rd generation Type Mach Bs would now be powered by a five horsepower electric motor, driving two 14.5" rotors, opposed to the comparatively tiny 11" fans of the first two models.

Unlike the second generation model, the new Type Mach. B was produced exclusively in a 15 port, high toned configuration. The 3rd generation model would share the same general unit construction as the first two generations, as well as sharing a similar rotor design. Earlier versions of the Type Mach. B would feature a set of horns that were designed to be removed and mounted around the stator in different orientations, though this would be eliminated on later models in favor of having a singular horn mounted next to the stators to help project sound outwards.

Despite being rendered largely obsolete by 1929 with the introduction of the Fedelcode lineup of vertical sirens, the Type Mach. B would enjoy another good 20+ years of production before finally being discontinued sometime around 1953. As such, the 3rd generation models tend to be found more commonly than the earlier two versions of the siren, and while not being notably loud, the Type Mach. B would prove to be a rather reliable siren for its age.

## Further Reading

* https://patents.google.com/patent/US1585219A
* https://www.federalsignal.com/our-story
* Low Tone Type Mach. B in operation
* High Tone Type Mach. B in operation