Abstract: An operation halting circuit comprises a circuit for controlling a system which executes a specified operation and a circuit for shutting off every input to the control circuit so as to prevent the supply voltage from being applied to the control circuit when the supply voltage drops below a specified threshold value.

Abstract: A digital display instrument with an automatic power-off device built-in which comprises a control circuit, a timing circuit and a display detection circuit. The power of the instrument is controlled by a push-button switch so that when the push-button switch is pressed down and released immediately, the power is turned on. If the push-button switch is pressed down and held for about 1.5 seconds, however, the power is turned off. The power can be turned off automatically by detecting if the instrument has not been used for a pre-set period of time. After the power is turned on, the display detection circuit will monitor the reading on the display continuously to determine whether the instrument is in use or not. If the detection shows the instrument is still in use, the timer will be reset to maintain the power on for another period of time. However, if a condition of not being in use is detected within the preset period of time, the power will be turned off automatically.

Abstract: A circuit arrangement in motor vehicles with electrical adjusting members coordinated to equipment components, to which belongs individually a manually actuatable switch and a control unit which upon initiation thereof, energizes the adjusting member for the automatic displacement of the equipment component into an end position; the control units are thereby adapted to be de-energized during the time interval engagement of the adjusting member upon actuation of any switch even prior to reaching the end position. A frequently cumbersome locating of the associated individual switch, respectively, the correct actuation during the automatic movement of the equipment component is dispensed with thereby.

Abstract: A wall box mounted remotely operated voltage module utilizing a low voltage DC control signal which is remotely generated. A power semi conductor device is triggered to deliver a predetermined amount of power from the source of AC electrical power to a load. The AC electrical power is rectified and transformed to produce a low voltage rectified DC signal. A comparator generates a triggering signal to the power semi conductor utilizing the low voltage rectified DC signal and remotely generated low voltage DC control signal as imputs. The comparator also serves as a compensator for changes in the voltage of the AC electrical power from the source.

Abstract: A defrosting circuit switch unit for an electronic range comprises: a frame of said unit, said frame being provided with a shaft; a defrosting circuit switch lever provided in a case in which a time switch is incorporated; a connecting rod having its lower end portion connected with a free end portion of said lever, said connecting rod being slidably moved up and down; a rotary plate rotatably mounted on said frame through said shaft and provided with a stopper extending in a projecting manner, said stopper being received in an elongated hole of an upper portion of said connecting rod, said rotary plate being integrally formed with a projection and a sector cam, said projection abutting on a leaf spring mounted on said frame; and a tension spring mounted between said rotary plate and said frame so as to resiliently biasing said rotary plate, said tension spring being engaged with said rotary plate through an engaging hole provided in said rotary plate.

Abstract: A forced air gas heating furnace system includes a thermostat having a transformer for converting the typical household 115Vac to a 24V thermostat ac control voltage, and a switch, the thermostat elements connected to the junction of an ac to dc converter, a digital control circuit and a TRIAC. The dc output is connected to a dc voltage regulator which outputs Vcc for a digital control circuit. The gate of the TRIAC is connected to the output of the digital control circuit, and operates in response thereto for selectively triggering the TRIAC for passing the 24Vac transformer control power to a solenoid operated gas valve.

Abstract: An electronic switching system, designed to automatically illuminate and delay in extinquishing 115 V 60 Hz outdoor/indoor lights and electrical wall receptacles. The system includes an automatic sensing circuit which detects open and closed circuits, at its input sense terminals wherein sensors are connected. An open detection illuminates lights and energizes wall receptacles connected to the system's input/output screw-type barrier block; and a closed detection thereafter keeps lights and wall receptacles supplied with 115 V 60 Hz for the duration of the delay adjust setting, then exitinguishing power. A regulation pin is incorporated for connecting an electronic clock for regulating the automatic sensing circuit's operation within a predetermined time. A manual power on/off circuit is also included, for operating the system independently of the automatic sensing. When placed in the "OFF" position the manual power on/off circuit initiates a delay in extinquishing 115 V 60 Hz.

Abstract: The invention relates to a feeding or matching circuit for feeding signal circuits, conducted via a multi-pin plug-in connection, of a freely programmable control unit or of a control and instrumentation system comprising at least one electronic module which carries a part of the plug-in connection, or for matching the signal circuits to the inputs or outputs of this module. With respect to a more rational circuit construction, the connection to the supply source or the circuit components necessary for matching is provided in accordance with the invention by means of a multi-pin intermediate connector which can be plugged between the detachable parts of the plug-in connection.

Abstract: An automatic controller for a master gas switch includes a timer for keeping the switch opened for a selectable time. The controller includes an electrical motor for rapidly closing the switch. The motor is responsive to two conditions: When the timer reaches the end of a selectable time, it energizes the motor to cause the gas switch to close. Secondly, a flame induction rod monitors a gas burner flame, and when the flame stops, such rod causes a relay to close and energize the motor for gas switch closure.

Abstract: A cycling circuit for cycling a power source alternately between two loads provides switching circuitry having two switches interconnected between the power source and each of the loads. When each switch is in an active state, its respective load receives power, and when each switch is in an inactive state, its respective load does not receive power. A timing circuit controls the activation and deactivation of the switches so that the activation of one switch deactivates the other with the timing circuit establishing directions for each switch's active/deactive state. These durations may be set or selectively variable. A condition sensing element may also be included as part of the timing circuit so that the relative time durations vary automatically in response to environmental conditions such as temperature.

Abstract: A two mode timing device is described for insertion between an energizing control switch and a load. The device enables the load to be controlled in either a timing mode or a continuous mode. Selection of the mode that the device operates in depends upon a novel use of the energizing control switch and, in particular, depends upon usage of the control switch to de-energize the device for either a long duration or a short duration. Upon re-energizing the device, the load is then controlled in either the selected timing mode or the selected continuous mode. The timed mode has two variations. One timed mode embodiment energizes the load immediately and upon expiry of an internal selectable timer will de-energize the load. The other timed mode embodiment initially leaves the load de-energized, and upon expiry of the internal timer then energizes the load. The selection of continuous mode operation simply energizes the load for as long as the device itself is energized.

Abstract: A self contained electronic timer device for controlling the length of time that a peripheral device connected to the timer will operate. The timer has a novel way of use a capacitor bank with charge ladling so that a precision time can be selected with a minimal of cheap components.

Abstract: The invention relates to a method and a device for setting a timer circuit, especially in a fuse (1b), there being used a setting unit (1a) for the transfer of setting signal to the timer circuit which is housed in the fuse (1b). For the purpose of simplifying the communication between the fuse (1b) and the fuse setting unit (1a), both as regards to avoiding previous calibration of the timer reference of the system, and as regards a reduction of the electro-mechanical contact connection between the fuse (1b) and the setting unit (1a) to a minimum, it has according to the invention been suggested that there are provided setting signals such that the time to which the timer circuit is to be set, is transferred from the setting unit (1a) to the fuse (1b) by pulse width modulation of the power supply voltage. The setting signal can then be transferred via only two contacts (K1, K2) on the surface of the fuse.

Abstract: Multi-time delay power controller apparatus for providing time delayed power-up and power-down for associated electrical equipment, such as computer systems, comprises a power stage configured for connecting to a conventional power outlet, a D.C. power supply connected to an internal D.C. voltage bus, an output stage having a plurality of time delayed outputs and a plurality of time delay turn-on timing stages connected in electrical series with one another between the D.C. bus and ground. Each such stage comprises an R-C circuit and a type 555 integrated circuit which together function as a timer. Included in each stage is a control relay. The energizing coils of the relays in odd numbered stages are connected to ground and of even numbered stages to the D.C. bus. The timing stages are connected so that the timing out of one stage starts the timing of the next-in-sequence stage, the timing of the first-in-sequence stage being started when the apparatus is turned on.

Abstract: A time switch for controlling the supply of electricity from an electricity source to an electrical load is provided with an auxiliary actuator means for controlling the supply of electricity to the electrical load independent of the time switch. The time switch includes one or more switch contacts and cam which control the position of the switch contacts in response to a timing mechanism. The auxiliary actuator mechanism includes a solenoid mounted directly to the time switch, with a linkage interposed between the solenoid and one or more cams operable independent of the time switch cams to control the position of the switch contacts independent of the time switch. In one embodiment, a photoelectric control is provided between the solenoid and the electricity source, to regulate the supply of electricity to the solenoid in response to the presence or absence of a predetermined level of ambient light.

Abstract: A timer controlled multipole circuit breaker has a pair of breaker contacts in each pole which are connected to load and line terminals respectively provided in the current path of each pole. Incorporated in the breaker is electric timer for controlling to open and close the breaker contacts according to a predetermined timing schedule. The electric timer has its input end connected across the line terminals of the adjacent poles so as to be energized by the common power on the line terminals of the breaker without requiring any additional external wiring. The circuit breaker incorporating the electric timer of the present invention further provides a safeguard which inhibits the automatic reclosing of the contacts by the timer operation until the fault current condition is cleared.

Abstract: An automatic lighting device having a circuit for operating an electric light, a switch for manually actuating the circuit, a detector circuit for determining whether movement above a prescribed threshold level has occurred within the area covered by the electric light within a first preselected period, a circuit responsive to the detector circuit for disabling the circuit for providing electricity if movement has not occurred in the area during the first preselected period, and a circuit for reactivating the circuit for providing electricity in response to the detection of movement in the area within a second preselected period.

Abstract: An electric appliance control system is disclosed in which a logic controlled, solid-state, electronic system is used in conjunction with a mechanical switching device in the form of a cam disc operating a plurality of cam-operated switches. The control system combines the capabilities of performing complicated and numerous operational programs with the reliability of the cam-operated mechanical switching device.

Abstract: An on/off circuit is provided to automatically turn "on" or "off" a radar warning receiver upon lapse of a preset period of time after an automobile engine is turned "on" or "off". The receiver is powered by a D.C. input signal from the battery of the automobile via its cigarette lighter plug. The circuit includes an on/off switch connected to the cigarette lighter plug and the receiver and being switchable between "on" and "off" states to correspondingly transmit and not transmit the D.C. input signal to the receiver for turning it "on" and "off". A noise sensor is also connected to the cigarette lighter plug for sensing the presence or absence of a varying noise signal superimposed on the D.C. input signal which depends on whether or not the automobile engine is running.

Abstract: A power adapter for timed control of auxiliary electrical loads is provided for connection between a streetlight fixture or the like and a control module of the fixture. The adapter has a weather-resistant housing and an electrical jumper in the housing extending a power source connection to an input of the module, another jumper returning a control output from the module to a main load of the fixture. An auxiliary socket at the side of the housing powers the auxiliary load, which can be a holiday lighting display. In one version, the adapter has a clock timer for controlling the auxiliary load independently of the main load. In another version, a programmable delay timer, synchronized with commencement of main load operation, terminates operation of the auxiliary load following a predetermined interval of main load operation.

Abstract: Multi-time delay power controller apparatus for providing time-delayed power or control signals to associated electrical equipment, such as computers and disc drives, comprises a power stage configured for connecting to a conventional power outlet, a D.C. power supply connected to an interval D.C. voltage bus, an output stage having a plurality of time delayed outputs and a plurality of time delay timing stages connected in electrical series to one another between the D.C. voltage bus and ground. Each such timing stage includes a timing means, and a normally open control relay. Coils of odd numbered timing stages are connected to ground and of even numbered stages to the D.C. voltage bus. The timing stages are connected so that the timing out of one stage starts the timing of the next-in-sequence stage, timing of the first-in-sequence timing stage being started when the apparatus is turned on.

Abstract: A plug-in timer has a set of input terminals and a set of output terminals as well as a contactor operable to make and/or break electrical connection between these sets of terminals in accordance with a pre-setable 24 hour program. The timer is powered from a small built-in battery, and comprises its own quartz clock and programming-and-control means. The contactor is actuated by a miniature DC motor through a gear and cam arrangement. The operation of the DC motor is controlled by the programming-and-control means, which provides power from the battery to the motor in accordance with a pre-set program; which pre-set program may be modified at any time by way of a keyboard and a numeric display means.The contactor operates by way of hard metal contacts and very little power dissipation occurs within the timer. The timer can be plugged into an ordinary household electrical receptacle, and a load may be plugged into the timer.

Abstract: A timer apparatus which can simultaneously process a plurality of timer service requests of a plurality of control units by a single timer. This timer apparatus includes a timer for counting a clock pulse, a circuit for setting different times having a constant period from different termials and an output circuit for outputting a signal to the terminal at which the time was set from the corresponding terminal when the time coincides with a time signal output from the timer.

Abstract: For protecting service personnel during maintenance work on a metal-encapsulated, compressed-gas-insulated high-voltage switching installation, a protective device is provided which is used if gas spaces with voltage-carrying conductor parts are bounded by unilaterally exposed bulkhead bushing insulators. Sensors of the protective device are arranged at the gas spaces and their signals are fed via an evaluating unit to a tripping unit for opening feed switches to cut off the voltage to the conductor elements in the gas spaces as well as for blocking the reclosing of these feed switches.

Abstract: A multi-function circuit controller provides auxiliary control functions for an existing single-pole, single-throw toggle switch by counting the number of changes of state of the switch that occur within predesignated delay periods from one state change to the next. An encoder responsive to a sequencer counter develops control functions such as dimming and timing functions which attenuate the power delivered to the load and regulate the on-off time of the load. The invention may be used in conjunction with a household lighting circuit to provide these functions for an existing wall-mounted switch, thereby providing dimmer and programmable timing for the lighting normally controlled by the switch.

Abstract: A programmer timer for an appliance, such as microwave cooking oven, having a magnetron power switch positioned by a control selectively moved to one of three power level settings by user rotation of the single rotary knob to a selected position on one of three separate cooking program interval range scales on the dial. Selection of a knob position on the first scale provides a 100% magnetron duty cycle, or full "ON", cooking mode for the desired cooking interval, selection of a knob position on the second scale provides a first predetermined fractional duty cycle for "MEDIUM" power level magnetron operation for the desired cooking interval; and, selection of a knob position on the third scale provides a second predetermined fractional duty cycle for "LOW" or "DEFROST" power level magnetron operation for the desired cooking program interval. A single timing motor drives a cam advance mechanism for effecting time-out of the selected program interval for the three power levels of operation.

Abstract: A power supply control device for a copier of the type having a timer therein is disclosed. The device allows a power supply of the copier to be turned on and off at any desired time which is set through ten keys. Data entered through the ten keys are loaded in a store. The data read out of the store and present time data output from the timer are compared and, as they compare equal, a power supply driver turns on the power supply. Guidance displays are referenced in the event of entering data.

Abstract: A machine controller having start and time delay functions activated and set by a single switch. There is a cycler for activating and deactivating machine functions in a timed sequence. There is a manually operable start/delay-set switch and an electronic circuit responsive to the switch which produces a start signal upon initial closing of the switch, and which produces a delay signal after the switch is held closed for a predetermined time. An electronic control circuit responds to the start and delay signals to store a delay time and activate the cycler after the stored delay time has expired.

Abstract: The timing controller includes a triac, a receptacle, and an AC wall outlet coupled in series. A sensor is coupled across the receptacle to sense when a lamp plugged therein is turned on or off. A microprocessor is coupled to the sensor circuit and stores each time the lamp is turned on and each time it is turned off. After twenty-four hours have lapsed, the microprocessor operates the electronic switch in accordance with the stored temporary program to turn the lamp on and off at the same times on each succeeding day. In the event of a power failure, the subsequent reapplication of power will cause the microprocessor to turn the lamp on and off for four-hour periods.

Abstract: Electric power switch housed in a housing B, operated manually by a toggle or button I and connected to ends V and W of an electric power cord supplying power to an electrical appliance or apparatus. In the housing B there is a built-in cyclical electronic control timer which when the commutator S is in the "stand-by" position continously stores during a gliding period of time (cycle) the schedule of sequences of on/off power switchings, as commanded by the user by operation of I, into an electronic memory. When the commutator S is in the "simulation" position, operation of the electric power switch is taken over by the electronic control timer, which implements power switchings cyclically and indefinitely according to the schedule of sequences of on/off power switchings stored in said memory during the cycle immediately preceding the transition from the "stand-by" to the "simulation" mode of operation and as long as the commutator S stays in the "simulation" position.

Abstract: A circuit device which is connected to an existing clocked memory circuit to provide additional clocked memory circuitry for a plurality of substantially independent switches within the parameters and constraints established at the main control station for an existing switch.

Abstract: A touch operated switch for control of electrical lighting, appliances, machinery and equipment which requires non sparking fail-safe operation. The switch utilizes digital complementary metal oxide semi-conductor technology which requires nearly insignificant standby power and incorporates a unique count down reset circuit which prevents extraneous operation from static discharge, radio frequency (RF) signals or power line transients. The switch will only respond to the electromagnetic flux generated by the power source that the controlled load is connected to. All other signals or pulses of differing frequencies are ignored by the switch thereby preventing inadvertent operation. Due to the limited number of discreet components utilized the total cost of manufacture will be extremely low and is expected to be less than the present manufacturing cost of the standard wall-type light switches that this invention will replace.

Abstract: A molded case circuit breaker includes a solenoid control circuit for controllably energizing a solenoid to actuate a motor operator to automatically move a handle of the circuit breaker to change the operative condition of the circuit breaker. The control circuit includes a monostable multivibrator that supplies an electrical pulse to the solenoid upon the receipt of a switching initiation signal. The time duration of the electrical pulse is controlled to be sufficiently long to assure proper operation of the solenoid and is determined by a timing circuit coupled to the source of operating voltage for the solenoid. If the operating voltage decreases, the time required to charge the timing circuit increases, increasing the duration of the electrical pulse of the solenoid to assure proper operation under low voltage conditions.

Abstract: A power distribution device having a first input that can be operably connected to a power source, a second input that can be operably connected to an operator controlled switch, and an output for connection to peripheral devices to be powered. The device further includes a first comparator unit for sensing when the operator controlled switch has been closed and for providing an output signal in response thereto, and a second comparator unit that can respond to the output signal created by the first comparator unit to provide a control signal. A power switch unit responds to the control signal and can connect and disconnect the output of the device to the power source input. A delay unit serves to delay the response of the second comparator unit to a change in the output signal state of the first comparator unit.

Abstract: An ignition control device that utilizes a very sensitive flame rectification signal responsive circuit is disclosed. A printed wiring board arrangement is utilized with a careful arrangement of the conductive areas on the printed wiring board to substantially eliminate leakage paths that can provide a false indication of the presence of flame when none in fact is present.

Abstract: An electronic control device enables a load to be separated from a power supply network for a time corresponding to the period which the load would cause a major disturbance in the network due to the state of the load at the time of a temporary main outage. The electric circuit control device comprises a first, normally open controlled switch (2) connected in the electric circuit, a second, normally closed, controlled switch (4) shunted with the first controlled switch (2), a power supply network (6) for supplying power to the control device, first time delay control network (17) connected to the first controlled switch (2), second time delay control network (30) connected to the second controlled switch (4) and memory network (41) connected to the second controlled switch (4), the time delay of the first control network (17) being at most equal to the time delay of the second control network (30).

Abstract: The mechanism has a drive roller which engages the cord that opens and closes a closure member such as a drapery. An electric motor that rotates the driver roller is supplied with power through first and second timed switches. An adjustment associated with the first timed switch may be set to control the times at which power to the electric motor is initiated, while an adjustment associated with the second timed switch may be set to determine the interval after which power to the electric motor is terminated.

Abstract: An automatic electric switch assembly with associated timers re-synchronizes a time clock with real time after a power interruption.

Abstract: A circuit for varying the current to a load and, simultaneously, limiting the output of the load to a predetermined time interval. A timer chip having an RC network receives rectified current from an AC voltage source and responds thereto with a high output, which is used to bias an NPN transistor. The transistor permits the flow of rectified current to a logic triac, thereby triggering the logic triac and enabling current from the AC voltage source to flow to a variable resistor in series connection with a gating/AC timing capacitor, thereby triggering a diac. The diac responds to the controlled current flow from the variable resistor by operating the gate of a power control triac and permitting the desired current flow between the load and the AC voltage source through the power control triac.

Abstract: A device for regulating the maximum time a television or the like can be operated, comprising a first counter (19) that can be manually set by use of a key (24A) to set a switch (24) with a predetermined time period. A second counter (20) deducts the actual operating time of the television from the first counter. The device interrupts the power circuit to the television when the predetermined time period expires. The switch can be set to allow operation of the television without deducting time from the first counter.

Abstract: An automatic slow down setting device for a signature prior to folding thereof in chopper forders for web fed printing presses comprises a single detector of abutment of the signature, relay timing means connected to said detector and having an opening contact means and closing contact means, and two different phase setting motor control circuits, i.e. a "more advance" circuit with relay means and said closing contact, and a "less advance" circuit with relay means and said opening contact, and by means of which the signature can be precisely adjusted to abutment.

Abstract: A plurality of electrical devices are controlled by a single operation switch. A transfer switch selectively connects the operation switch with one of the electrical devices. When a push button switch is actuated, the connection of the transfer switch is controlled so as to connect the operation switch with another of the electrical devices for a predetermined period of time.

Abstract: A fully automatic programmable wall switch timer for controlling lighting circuits is described. The device provides user selected lighting circuit operation at predetermined event times, for predetermined event duration at said times, and at a selected light brightness or intensity level. The device is microprocessor controlled and is intended for installation in a standard wall switch box using existing wall switch plates. Included are a time of day and programming display and a three-way switch option. Separate switches are provided for isolating the unit from the power line, selecting lighting circuit operation, and advancing the display time. Additionally, various user programming modes are provided by operation of said switches singly and in conjunction with each other.

Abstract: The provision in a range having an electrically energizable heating unit and a control for selectively causing energization of the heating unit from a power supply of an improved circuit for causing time-delayed initiation of energization of the heating unit for a period of time which is a function of the period of inrush current which occurs when the heating unit is energized. The circuit causes such a delay in the event the circuit senses a preselected power delivery from the power supply at the time of attempted initiation of energization of the heating unit. The novel circuit is advantageously utilized in a range having a plurality of electrically energizable heating units and assures that the heating units will be sequentially energized with a time delay between initiation of energization of each so that the total inrush current is substantially less than the sum of all of the inrush currents of the heating units concurrently attempted to be energized.

Abstract: A diaphragm pump wherein the diaphragm is deformable by the reciprocable armature of an electromagnet which is energizable at a selected frequency by a timer circuit and at random frequency by a pulse generator. The pulse generator is connectable with the electromagnet by a cable having separable male and female coupling elements which automatically deactivate the timer circuit when the male coupling element is inserted into the female coupling element. A selector switch is provided to deactivate the timer circuit independently of the coupling elements. A knob serves to adjust a potentiometer of the timer circuit simultaneously with closing of the selector switch so that the frequency at which the timer circuit can energize the electromagnet is reduced to a minimum value.

Abstract: Apparatus for switching alternating current from a power source to a load for substantially all of one selected half-cycle, but not before at least one full cycle after the apparatus receives an operator command to switch the current, includes a mechanical switch for commanding the apparatus at an arbitrary time to switch the current. Electrical control devices produce a control output during a portion of the selected half-cycle. A second switch device, such as an SCR, responsive to the control output switches the current to the load during the selected half-cycle. The control output is turned off before the end of the half-cycle and is not produced again until the mechanical switch is released and provides another command to switch the current.

Abstract: An energy saving light switch is disclosed. The light switch includes a human actuable switch and a control circuit responsive thereto. The control circuit operates a light in a first timed mode in which the light is turned on for a predetermined period of time responsive to an initial actuation of the switch and operates the light in a second untimed mode in which the light is turned on for an indefinite period of time responsive to the actuation of the switch during a predetermined time window forming part of the predetermined time period.

Abstract: An improved power switch circuit for turning on manually and for turning off either manually or automatically a battery operated electronic instrument. The circuit includes one manual momentary contact on/off switch, a bilateral switch or transmission gate, a microprocessor, and a capacitor that charges to a threshold level when the on/off switch is momentarily closed (on) and that discharges when either the on/off switch is momentarily closed again (off) or after a fixed amount of time has elapsed as determined by the microprocessor. The bilateral switch is switched on when the threshold potential is reached thereby preconditioning the on/off switch for turning the instrument off. The on/off switch can now be closed to discharge the capacitor or the microprocessor can discharge the capacitor thereby switching off the bilateral switch and preconditioning the on/off switch for again turning on the power to the electronic instrument.

Abstract: Disclosed is a muting circuit, in which the generation of click noise is prevented in that the muting operation is caused to occur at an instant when the instantaneous level (i.e., waveform level) of the input audio signal becomes zero for the first time since the appearance of a muting signal. .Iadd.A muting-off circuit is also disclosed for turning off the muting circuit. .Iaddend.

Abstract: A circuit for providing an adjustable period of delay in a vehicle which is started by engaging the engine of the vehicle and a brake means, then disengaging the brake means after the period of delay, has a relay for selectively engaging and disengaging the brake. A variable time delay provides the period of delay. A switch selectively causes the relay to engage the brake and then to disengage the brake after the period of delay. A safety activation means prevents the relay from engaging the brake means in the absence of the switch selected to cause the relay to engage the brake means.