Federal Signal AX series

Federal Signal AF

The **Federal Signal AX** timers are a series of signal timer produced by Federal Signal Corporation from 1952 to 2007. It is capable of (depending on the model) 3 3-minute signals, these being the attack signal, alert signal, and fire signal. The AX-5 increases the signal duration to five minutes. In addition to the standard buttons on the unit itself, the timer provides terminals for either external push buttons or remote activation equipment. In remote installations, the AX timers are generally installed inside of an ARCH cabinet, which contains the timer unit as well as remote activation equipment, such as a radio with tone decoder.

There were 2 models of AX timers, the AR and AF. The AR timer has 4 signals; "Test", "Alert", "Attack", and "Cancel". The AF timer introduces a 5th button, "Fire". The AX timers underwent several changes throughout the years, which resulted in 4 different revisions. These revisions affected the circuitry and appearance of the unit, however the functionality remained the same.

The Federal Signal AX timer was succeeded by the FC controller.

## 1st generation

The first revision of the AX timers were used on early A-series Thunderbolts and differ from the later revisions in a few ways. The most notable difference is the physical appearance, with a single red light, a wider design, exposed buttons, and the lack of a cancel button. Internally, the components are a bit more simplified, consisting of the motor and cams, the switches, and two relays. In addition, the components are spaced out more and are a bit more exposed. The timer uses mechanical switch levers which are activated by a series of cams moved by the timer motor.

The top button on the front panel is the "Manual" button which operates the siren for only as long as the button is depressed. This is the same function as the "test" button used on later model Federal timers. The second button from the top is the "Take Cover" signal which operates the siren in a on-off or wavering mode for 3 minutes. On later timers this function button is labeled "Attack." The bottom button is the "Alert" signal which operates the siren in a steady "on" mode for 3 minutes. On later timers this function has the same name. The early AF timers also adds the fire signal button between the "manual" button and the "alert" button.

## 2nd generation

Compared to its predecessor and successor, there is very little information regarding 2nd generation AX timers. From what we currently know, the 2nd generation AX timers are essentially the same as the 1st generation timers, with the addition of a "cancel" button on the front panel. They were produced for an extremely short time, being superseded by the 3rd generation AX timers early on into their production run. 2nd generation AX timers are extremely hard to come by, and no images are known to exist. At least one 2nd generation AR timer is in private possession, owned by a user on the Siren Board.

## 3rd generation

WIP

The 3rd generation AX timers have the same functions as the early timers, but the front panel, dimensions, and internals are quite different.

The inside of the later AX timers are, though different, follow the same principals as the older AX timers, but with newer more compact components. 3rd generation timers use smaller rotary cams and microswitches instead of the much larger lever switches. A transformer was also added so the timer could be connected to 120 or 240 volts. These timers could also have transformers in them for connection to high voltage supply.

## 4th generation

    Similar to the 2nd generation AX timers, less is known about the 4th generation AX timers compared to the 1st and 3rd generations.

The 4th generation AX timers are similar in appearance to the 3rd generation, with a few minor differences. The most notable difference is the tag at the bottom of the front panel, which is now black instead of red. The "Test" button is now named "Manual Test", and the "Attack" button is now "Attack Warning". Additionally, the screw on the front panel used to open it is larger and moved slightly to the right. Finally, there is only 1 light on 4th generation AX timers. Due to their rarity, the internals of the 4th generation AX timer are unknown. It is likely they are similar to those of the 3rd generation.

Only one 4th generation AX timer is known to exist, in Lehigh County, Pennsylvania. It is an AF timer and is hooked up to an STH-10.