Chrysler Air Raid Siren Maintenance Manual Supplement

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CIRCUIT OPERATION OF RELAYS REMOTE CONTROL

The following is the sequence of events occuring in the operation of the Relay controls to start and operate a Siren from a Remote Headquarters. The Circuits from the Remote Headquarters Station Control Box are fed into the Local Station Control Box, installed near, but not on the Siren. The Circuits from the Local Station Control Box are fed into the rotating Siren assembly through four of the Slip Rings mounted on the Siren Turntable. Follow the step by step procedure outlined in the following paragraphs on the Schematic Wiring Diagram (Figure 1).


[ Enlarge Figure 1 ]

When the Operator presses the Remote Signal Switch for the first Four second period, the closing of its contacts completes a circuit to energize the "CONTROL RELAY" at the Local Station Control Box. When the "CONTROL RELAY" closes its contacts, A Ground Circuit from the Remote side of the Selector Switch is fed through the "CONTROL RELAY" contacts to and through the Turn-table IGNITION Slip Ring, to the "IGNITION RELAY" BAT terminal and to the "THERMAL TIME DELAY RE LAY" #3 terminal, Thermal Coil. The 'IGNITION RELAY" becomes energized and a Battery feed is provided through its INT-PRI terminals, to the "SAFETY RELAY" #3 terminal, through the "SAFETY RELAY" normally closed contacts to its #5 terminal, to the Engine IGNITION COIL, to and through the "CRANKING TIME LIMITOR" to and through the "AUTOMATIC CIRCUIT CONTROLLER" to the "STARTIX" which immediately causes the Starter to turn the Engine over until it starts and the Siren Engine will begin to Idle. As soon as the Engine starts, the "STARTIX" automatically prevents further cranking.

When the Operator pressed the Remote Signal Switch, the initials Four seconds, causing the "IGNITION RELAY" to become energized, the "IGNITION RELAY" then received a "hold-in" Ground circuit through its own SOL terminal, to the "THERMAL CONTACT RELAY" #5 terminal, through the "THERMAL CONTACT RELAYS" normally closed contacts to its # 3 terminal, to and through the Turntable IGNITION LOCK-IN Slip Ring, to and through the Remote side of the Selector Switch, to Ground. The "THERMAL CONTACT RELAY" will continue to keep the "IGNITION RELAY" energized until the "THERMAL TIME DELAY RELAY" heats sufficiently (Ten to Twelve seconds) to close its contacts.

When the "THERMAL TIME DELAY RELAY" closes its contacts, it will energize the "THERMAL CONTACT RELAY", which will open its normally closed contacts, and close its normally open contacts. This will open the circuit to the "IGNITION RELAY" and close the circuit to energize the "LOCK-IN RELAY".

The "LOCK-IN RELAY" will now supply the Battery feed, through its INT terminal, to and through the normally closed contacts of the "SAFETY RELAY" #3 to #5 terminals, to the Engine Ignition and Starting circuit. This results in continuous Engine Ignition and Starting circuit operation after the initial Four second contact of the Remote Signal Switch.

When the Engine is cranking and starts, the Oil pressure builds up sufficiently to trip the "PENN SWITCH" movable arm contactor "S" against its normal pressure and temperature contact "D". Then when the "LOCK-IN RELAY" is energized, a Battery feed from "LOCKIN RELAY" PRI terminal is supplied to "PENN SWITCH" "S" terminal, through its "D" terminal, to and through Turntable SIGNAL Slip Ring, to Remote "SIGNAL RELAY" in Local Station Control Box, energizing the Remote "SIGNAL RELAY" which closes a circuit to cause a Signal Light to GLOW, at Central Headquarters, indicating to the Operator that Siren is running and Engine has normal oil pressure and water temperature.

At the same time, this Battery feed from the "PENN SWITCH" terminal "D" is also supplied to the "THROTTLE RELAY" IGN terminal, through the Relay Coil to its TH terminal, to the now open "IGNITION RELAY" SOL terminal. The next time the Operator pushes the Remote Signal Switch causing the energizing of the "IGNITION RELAY", a Ground circuit is supplied to the "IGNITION RELAY" SOL terminal to complete the circuit and energize the "THROTTLE RELAY". The "THROTTLE RELAY" supplies a Battery feed to energize the "THROTTLE SOLENOID". The "THROTTLE SOLENOID" snaps its plunger out to move the Engine Carburetor Throttle to wide open position. Immediately Siren Engine speed increases to 4600 R.P.M. Release of pressure on the Remote Signal Switch and the Siren Engine speed returns to Idle speed 650 R.P.M. The action of the "THROTTLE SOLENOID" is instantaneous and allows for the exact timing of the Eight Second "ON" and Four second "OFF" "Warning" Cycle operation.

Upon completion of any "Signal" operation and if no further pressure is applied to the Remote Signal Switch, the "THERMAL TIME DELAY RELAY" will allow the Siren Engine to Idle for a short time delay period, at the end of this time, the Thermal Coil will cool sufficiently to open its contacts, this will open the circuit to the "THERMAL CONTACT RELAY" which will open the circuit to the "LOCK-IN RELAY" which in turn will interrupt the Battery feed to the Engine IGNITION COIL and stop the Engine. It will also interrupt the Battery feed to the "PENN SWITCH" and in turn the Remote "SIGNAL RELAY" at the Local Control Station will open, interrupting Signal Light Circuit. The Signal Light at the Central Headquarters will go out, indicating to the Operator the Siren Engine is Secured until further operation is desired.

The following is the sequence of events as they would occur in case of failure due to excessive Engine Speed (4700 R.P.M.) Low Oil pressure (15 psi) High Water Temperature (200 degrees F.)

SHOULD THE ENGINE OVERSPEED:

The Overspeed Governor's normally open contacts will close and a Battery feed will be supplied from its "L" to "M" terminal, to the "SAFETY RELAY" #2 terminal, energizing the "SAFETY RELAY", which will open its normally closed contacts #3 to #5, interrupting Battery feed to the Engine IGNITION COIL and stop the Engine. The Remote Control Operator will know some Safety Control has stopped the Siren as the Signal Light has gone out. The "SAFETY RELAY" will remain energized until the "THERMAL TIME DELAY RELAY'? cools and opens the circuit to the "THERMAL CONTACT RELAY" and in turn to the "LOCK-IN RELAY" which requires a short time delay period. After this elapse of time, the Engine may be restarted by pressure on the Remote Signal Switch. If the trouble still persists, the Engine will stop again and Signal Light will go out. Failure must be located and corrected.

SHOULD THE OIL PRESSURE DROP BELOW FIFTEEN (15) PSI:

The' PENNSWITCH" movable arm contactor "S" will trip from "ON" contact "D" to "OFF" contact "M", and a Battery feed will be supplied to "SAFETY RELAY" #2 terminal, energizing "SAFETY RELAY", which will open its normally closed contacts #3 to #5, interrupting the Battery feed to the Engine IGNITION COIL and stop the Engine. The Remote Control Operator will know some Safety Control has stopped the Siren Engine as the Signal Light has gone out. The "SAFETY RELAY" will remain energized until the "THERMAL TIME DELAY RELAY" cools and opens the circuit to the "THERMAL CONTACT RELAY" and in turn to the "LOCK-IN RELAY" which requires a short time delay period. After this elapse of time, the Engine maybe restarted by pressure on the Remote Signal Switch. If the trouble still persists, the Engine will stop again and Signal Light will remain out.

SHOULD THE ENGINE WATER TEMPERATURE EXCEED TWO HUNDRED (200) DEGREES F.:

The actions of the "PENN SWITCH", "SAFETY RELAY" and Remote Signal Light are the same as described in the Low Oil Pressure failure, with this exception: The "PENN SWITCH" will not allow its movable arm contactor "S" to trip back to "ON" position "D", until the Engine water temperature cools down below the critical value.

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