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The Thunderbolt is a mechanical outdoor warning siren that was manufactured by Federal Signal Corporation from 1951 until its production ended in 1991. [1] It is a unidirectional, rotating siren with a large square-shaped horn, and can come in various colors, usually yellow, by request.
The Thunderbolt siren was developed between 1952 and 1990. It was the first "supercharged" siren, which uses a blower to force air into the rotor, greatly increasing the siren's volume. In the 1980s, when civil defense fell into disuse, thunderbolts across the United States were repurposed for nuclear and storm warning siren systems. During the Gulf War, Federal sent a number of modified Thunderbolt 1003s to Kuwait to warn its citizens of an air raid. These were the system 7000 series and were only found in Kuwait. Later, Kuwait's sirens were all replaced with Federal Signal Modulators. One system 7000 is on display next to a Federal Signal Modulator at the Kuwait General Administration of Civil Defense in Kuwait City, Kuwait. Eventually in 1990, the Thunderbolt was discontinued in favor of the new 2001 Siren Series. Since then many have sat abandoned or have been replaced by newer systems. In the 21st century, many communities lacking siren coverage have purchased Thunderbolts that once sat in various towns, and have been refurbished. Many Thunderbolts are also in private and legal possession. [2]
The Thunderbolt came in several models. The Model 1000 was single tone, while the Model 1000T and Model 1003 were dual tone. [1] The Model 1003 also included two solenoid-operated control valves. They are used to create alternating steady, alternating wail, pulsed steady, and pulsed wail signals, which can be used as a fire warning. Otherwise, it is identical to the 1000T, but used the 5/6 rotor only. Although the 4/5 port rotor is compatible, it was never offered for the 1003. There were also 3 types of gas powered Thunderbolts known as the System series, System 7012 is a model Thunderbolt 1000, System 7022 is a model Thunderbolt 1000T. It is identical to 7012, but has a dual-tone chopper. System 7026 uses a model Thunderbolt 1003. There are other system series thunderbolts, and the only surviving ones have been converted to electric. Only two 4/5 port rotor 1003's exist currently, one in Saint Paul, Nebraska, and the other in University Park, Illinois. The 1003 entered production in 1961 or 1962, and ceased in 1990. The 1003 was the last production model built. The last sirens went to a township in Michigan; all of them have been removed and replaced since 2009. Originally the Thunderbolt used a motor and an Abart gear reducer driven by pulley to drive the large spur gear which makes the projector rotate. The pulleys utilized 3 different belt slots to change the RPM in which the siren rotates, from 2, 4, and 8 RPM. In 1980, Federal wanted to make the Thunderbolt more maintenance free, doing so by turning the motor and gear reducer to face each other and attached to make a direct drive system which rotated at 4 RPM. This rotator was used only on the B-series models. B-series units were only offered in 1980.
A millisecond is a unit of time in the International System of Units equal to one thousandth of a second or 1000 microseconds.
A civil defense siren is a siren used to provide an emergency population warning to the general population of approaching danger. Initially designed to warn city dwellers of air raids during World War II, they were later used to warn of nuclear attack and natural disasters, such as tornadoes. The generalized nature of sirens led to many of them being replaced with more specific warnings, such as the broadcast-based Emergency Alert System and the Cell Broadcast-based Wireless Emergency Alerts and EU-Alert mobile technologies.
The Roots blower is a positive displacement lobe pump which operates by pumping a fluid with a pair of meshing lobes resembling a set of stretched gears. Fluid is trapped in pockets surrounding the lobes and carried from the intake side to the exhaust.
A siren is a loud noise-making device. Civil defense sirens are mounted in fixed locations and used to warn of natural disasters or attacks. Sirens are used on emergency service vehicles such as ambulances, police cars, and fire engines. There are two general types: mechanical and electronic.
The Bell 222 is an American twin-engine light helicopter built by Bell Helicopter. The Bell 230 is an improved development with different engines and other minor changes.
Torsional vibration is the angular vibration of an object - commonly a shaft - along its axis of rotation. Torsional vibration is often a concern in power transmission systems using rotating shafts or couplings, where it can cause failures if not controlled. A second effect of torsional vibrations applies to passenger cars. Torsional vibrations can lead to seat vibrations or noise at certain speeds. Both reduce the comfort.
The Learjet 25 is an American ten-seat, twin-engine, high-speed business jet aircraft manufactured by Learjet. It is a stretched version of the Learjet 24.
Federal Signal Corporation is an American manufacturer headquartered in Downers Grove, Illinois. Federal Signal manufactures street sweeper vehicles, public address systems, emergency vehicle equipment, and emergency vehicle lighting.
Federal Signal Modulators are electronic warning devices produced by Federal Signal Corporation that are used to alert the public about tornadoes, severe weather, earthquakes, fires, lahars, tsunamis, or any other disaster. They are identified mostly by their distinctive stacked "flying saucer" design. The Modulator II is sold based on the more compact chassis of the siren compared to the original Modulators.
The Whelen Engineering Company is an American corporation that designs and manufactures audio and visual warning equipment for automotive, aviation, and mass notification industries worldwide. Founded in a Deep River, Connecticut garage in 1952, Whelen has become a provider of warning lights, white illumination lighting, sirens, and controllers. Whelen products are designed, manufactured, and assembled in two facilities in Chester, Connecticut and Charlestown, New Hampshire.
SiraTone was a brand of electronic outdoor warning sirens produced by Federal Signal Corporation which began production in the early 1980s. These sirens were designed to broadcast high-intensity warning signals over a large area. SiraTone products are/were used for natural disaster notification, HAZMAT incident notification, fire call systems, and more. The SiraTone product line is no longer in production. The product line was succeeded by the Modulator and DSA electronic outdoor warning sirens.
The Mount Rainier Volcano Lahar Warning System consists of two separate components, operating in tandem: Acoustic Flow Monitors (AFM) and the All Hazard Alert Broadcast (AHAB) sirens. The AFM system was developed by the United States Geological Survey (USGS) in 1998 and is now maintained by Pierce County Emergency Management. The purpose of the warning system is to assist in the evacuation of residents in the river valleys around Mount Rainier, a volcano in Washington, in the event of a lahar. Pierce County works in partnership with the USGS, the Pacific Northwest Seismic Network (PNSN), Washington Military Department's Emergency Management Division, and South Sound 9-1-1 to monitor and operate the system.
American Signal Corporation (ASC) is an outdoor warning siren and mass notification company in the United States. ASC was founded in 1873 as Biersach and Niedermeyer (B&N). After performing poorly, the company reformed as Alerting Communicators of America (ACA) in 1968, and expanded the line of warning systems they produced. In 1992, ACA went bankrupt and was bought and reformed as the American Signal Corporation.
The ACA Hurricane is an electro-mechanical and rotating-directional, 130dB civil defense siren, created and produced by Alerting Communicators of America (ACA). ACA began manufacturing the Hurricane 130 in 1968, and ended production in 1981. The Hurricane 130 is very similar to the Federal Signal Thunderbolt series, being a supercharged siren.
In civil defense sirens, the ATI High-Power Speaker Station (HPSS) is an electronic outdoor warning siren manufactured by Acoustic Technology, Inc (ATI) that is used to alert citizens of air raids, and natural disasters.
The Federal Signal Model 2 is an omnidirectional outdoor warning siren produced by Federal Signal Corporation.
The ACA Cyclone was an electro-mechanical, omnidirectional, dual-tone outdoor warning siren produced from 1968 to 2007 by Alerting Communicators of America (ACA). Originally intended for civil defense purposes, early versions of the Cyclone were rated at 120dB from 100ft, and later models were rated at 125dB.
The Federal Signal 3T22 / 2T22 is a dual tone, mechanical outdoor warning siren once made by Federal Signal Corporation from 1952 through the early 1990s. It has a very recognizable design, having a ten-port rotor (chopper) on the bottom with ten cones (horns) and a 12-port one on top with twelve cones.
Canadian Line Materials LTD. (CLM) was a Canadian siren manufacturing company which built civil defense sirens. These sirens were built and installed all over Canada to warn residents and military about incoming nuclear attacks from the USSR during the Cold War.