travel application_number US 5258979 A description referring now to fig1 and 2 there is shown an embodiment of an emergency stop apparatus for electric elevators employing a static leonard system in the figure reference numeral 1 designates a three phase ac power source numeral 2 a power rectifier connected to the power source 1 numeral 3 an armature of a dc motor for driving an elevator its associated field winding is not shown numeral 4 a driving sheave of a traction machine driven by the armature 3 and numeral 5 a main rope wound around the driving sheave 4 and connecting a cage 6 with a counter weight 7 reference numeral 8 designates a tachometer generator driven by the armature 3 to produce a speed signal numeral 9 a discharge resistor numeral 10 a power stoppage detecting relay with normally open contacts designated by numerals 10a and 10b numerals 11 a control circuit for the static leonard system numeral 12 a voltage detecting circuit related to the tachometer generator 8 numeral 13 a voltage detecting relay which is deenergized when the voltage produced by the tachometer generator 8 becomes 0 and having a normally closed contact 13a numeral 14 a dc power source such as a battery which is operable independently of power stoppage numeral 16 a start command relay contact which is closed in response to a start command issued and numeral 17 a contactor for a main circuit with a normally open contact 17a and a normally closed contact 17b in operation assume now that the ac power source 1 is active and the cage 6 stops under this condition the tachometer generator 8 produces no output voltage and thus the voltage detecting relay 13 is.