''This article is about the railroad Fail-safe device, for the more general use, see dead man's switch'' ---- A '''dead-man's control (Also: controller, switch, peddle, or handle''') is a mechanical, electro-mechanical or electronic device designed to stop a railroad train in the event the train operator acts (or fails to act) in such a way as to indicate that he or she may be incapacitated and therefore incapable of operating the train safely. The name derives from the concept that if the operator were to death, the train would stop automatically. ==Background== Interest in dead-man's controls increased with the introduction of trolley and especially of electrified rapid transit trains. In conventional steam railroad trains, there was always a second in the cab with the engineer, the ''fireman'', charged with shoveling coal to heat the engine's boiler, and/or otherwise look after the tasks required for a running engine other its actual operation. For many decades, this was also the practice on electric or diesel engines, which could theoretically be operated by a single person. In the event something should happen to the engineer, the fireman was always available to assist and bring the train to a stop. With urban and suburban railway systems, the operator, called the motorman, was typically in an enclosed cab or otherwise remote from other personnel in the event an emergency occurred. Though automatic devices were already beginning to be deployed on newer installations of the New York City Subway system in the early 20th century, the disastrous Malbone Street Wreck on the Brooklyn Rapid Transit system in 1918 pointed up the need for universal deployment of devices to halt trains in the event of an operator's disability. == Types == Pneumatically or electrically-linked dead-man's controls, still used today, involve relatively simple modifications of the ''controller handle'', the device that regulates the flow of electricity to the train's motors. The main requirement is that the train's brakes be placed in brakes in emergency condition if live pressure is not maintained on the controller. Typically, the controller handle was a horizontal bar that is rotated to apply the required power for the train. Attached to the bottom of the handle is a rod which, when pushed down, contacts a solenoid or switch inside the control housing. In the event pressure is removed from the handle it springs up, releasing the rod's contact with the internal switch and instantly cutting power and applying brakes. Though there are ways that this type of dead-man's control could conceivably fail, they have proven highly reliable. On some earlier equipment, pressure was not maintained on the entire controller, but on a large button protruding from the part of the handle the motorman grasped. This button also had to be pressed continuously, typically with the palm of the hand so that the button's top was flush with the top of the handle. Another method used, particularly with some lever-type controllers, which are pushed or pulled rather than rotated, requires that the handle on the lever be turned 90 degrees and held in that position while the train is in operation. Some dead-man's controls require the motorman to hold it in the mid-position rather than apply full pressure (see pilot valve) Sometimes, a more elaborate design of a dead man's switch requires the operator not only to keep the switch pressed but also to release it periodically, say, at least once every 30 seconds. Such a system is in mandatory use in the locomotives in some countries' railway networks (for example the "SiFa" (Sicherheitsfahrschaltung) of Germany railway locomotives). In many modern New York Subway trains, for example, the dead man's switch is incorporated into the train's speed control (on the R142A, the lever must be continually held in place by the train operator; because the lever is also used to both accelerate and stop the train, it must remain in constant use). == Accidents related to dead man's controls == Dead man's controls are not perfect, as the following accidents illustrate: * Moorgate tube crash * Waterfall train disaster ==See Also== *vigilance control electric railways
Should penalty switch, vigilance control, dead-man's switch and dead-man's control be merged? They are very similar. User:Andrew pmk 03:16, 23 May 2005 (UTC)
See other meanings of words starting from letter:
Words begining with Dead-man\'s_control:
Dead-man's_control
Dead-man's_control
Dead-man's control
''This article is about the railroad Fail-safe device, for the more general use, see dead man's switch'' ---- A '''dead-man's control (Also: controller, switch, peddle, or handle''') is a mechanical, electro-mechanical or electronic device designed to stop a railroad train in the event the train operator acts (or fails to act) in such a way as to indicate that he or she may be incapacitated and therefore incapable of operating the train safely. The name derives from the concept that if the operator were to death, the train would stop automatically. ==Background== Interest in dead-man's controls increased with the introduction of trolley and especially of electrified rapid transit trains. In conventional steam railroad trains, there was always a second in the cab with the engineer, the ''fireman'', charged with shoveling coal to heat the engine's boiler, and/or otherwise look after the tasks required for a running engine other its actual operation. For many decades, this was also the practice on electric or diesel engines, which could theoretically be operated by a single person. In the event something should happen to the engineer, the fireman was always available to assist and bring the train to a stop. With urban and suburban railway systems, the operator, called the motorman, was typically in an enclosed cab or otherwise remote from other personnel in the event an emergency occurred. Though automatic devices were already beginning to be deployed on newer installations of the New York City Subway system in the early 20th century, the disastrous Malbone Street Wreck on the Brooklyn Rapid Transit system in 1918 pointed up the need for universal deployment of devices to halt trains in the event of an operator's disability. == Types == Pneumatically or electrically-linked dead-man's controls, still used today, involve relatively simple modifications of the ''controller handle'', the device that regulates the flow of electricity to the train's motors. The main requirement is that the train's brakes be placed in brakes in emergency condition if live pressure is not maintained on the controller. Typically, the controller handle was a horizontal bar that is rotated to apply the required power for the train. Attached to the bottom of the handle is a rod which, when pushed down, contacts a solenoid or switch inside the control housing. In the event pressure is removed from the handle it springs up, releasing the rod's contact with the internal switch and instantly cutting power and applying brakes. Though there are ways that this type of dead-man's control could conceivably fail, they have proven highly reliable. On some earlier equipment, pressure was not maintained on the entire controller, but on a large button protruding from the part of the handle the motorman grasped. This button also had to be pressed continuously, typically with the palm of the hand so that the button's top was flush with the top of the handle. Another method used, particularly with some lever-type controllers, which are pushed or pulled rather than rotated, requires that the handle on the lever be turned 90 degrees and held in that position while the train is in operation. Some dead-man's controls require the motorman to hold it in the mid-position rather than apply full pressure (see pilot valve) Sometimes, a more elaborate design of a dead man's switch requires the operator not only to keep the switch pressed but also to release it periodically, say, at least once every 30 seconds. Such a system is in mandatory use in the locomotives in some countries' railway networks (for example the "SiFa" (Sicherheitsfahrschaltung) of Germany railway locomotives). In many modern New York Subway trains, for example, the dead man's switch is incorporated into the train's speed control (on the R142A, the lever must be continually held in place by the train operator; because the lever is also used to both accelerate and stop the train, it must remain in constant use). == Accidents related to dead man's controls == Dead man's controls are not perfect, as the following accidents illustrate: * Moorgate tube crash * Waterfall train disaster ==See Also== *vigilance control electric railways
Dead-man's control
Should penalty switch, vigilance control, dead-man's switch and dead-man's control be merged? They are very similar. User:Andrew pmk 03:16, 23 May 2005 (UTC)
See other meanings of words starting from letter:
D
DA | DB | DC | DE | DF | DG | DH | DI | DJ | DK | DL | DM | DN | DO | DP | DR | DS | DT | DU | DW | DX | DY | DZ |Words begining with Dead-man\'s_control:
Dead-man's_control
Dead-man's_control
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