Abstract: A static inverter has a chopper transistor between a unidirectional source and the inverter load current carrying semiconductor switches, time ratio controlling means including a constant frequency oscillator for modulating the chopper at the constant oscillator frequency and for regulating the width of pulses conducted by the chopper as a function of the magnitude of an analog command signal, means for modulating the inverter semiconductor switches at a frequency which is a function of the analog command signal to establish the inverter output frequency, and means for synchronizing the switching of the chopper to the inverter output frequency so that the chopper is reset at the beginning of each half cycle of inverter output frequency.

Abstract: A static polyphase inverter for supplying variable frequency, variable magnitude voltage to a load such as a polyphase motor has a transistor chopper between a unidirectional power source and an inverter bridge having n phase legs each of which includes a load current carrying controlled rectifier in series with the emitter-collector path of a transistor switch and the junction therebetween connected a phase winding of the motor; time ratio controlling means including a constant frequency oscillator for modulating the chopper at the constant oscillator frequency and for regulating the width of pulses conducted by the chopper as a function of the magnitude of an analog command signal; means for selectively controlling the switching frequency of the load current carrying controlled rectifiers as a function of the magnitude of the analog command signal to establish the inverter fundamental output frequency; means for intermittently applying a bias source in opposite polarity to the anode-cathode path of the cont

Abstract: A pressure compensated, variable volume, rotary piston device has a housing with an elongated cavity and inlet and exhaust ports; a reaction ring movable within the cavity and defining a cylindrical bore; a lenticular rotary piston rotatable and reciprocable radially within the bore and dividing it into first and second variable volume chambers; a shaft rotatably journalled in the housing and carrying a crankarm which constitutes the sole force transmitting means between shaft and piston and is operatively coupled to the piston so that shaft and piston rotate in a one-to-one ratio while the piston rocks relative to the crankarm and, without the use of phasing gears, the apices of the rotary piston remain in continuous contact with the bore in all positions of the rotary piston and in all positions of the reaction ring within the cavity and so cam the piston that it reciprocates within the bore as it rotates and varies the volume of the first and second chambers inversely from minimum to maximum and back to mi

Abstract: A pulse width modulation chopper controller for a D.C. traction motor has plug sensing means which monitors the voltage across the motor armature on a pulse-by-pulse basis and is responsive, only when the power switch is turned on, to the motor acting as a generator to limit the "on-time" of the power switch before current of high magnitude can flow in the motor.

Abstract: A rotary piston expansible chamber device without phasing gears has a crankshaft whose axis is offset from the center of the closed curve defining the working chamber cross section and a rotary piston operatively connected to the crankshaft through a crankarm so that crankshaft and piston rotate together in a one-to-one ratio and the rotary piston is displaced as it revolves to maintain arcuately spaced apices thereon in continuous sliding and sealing engagement with the working chamber walls and vary first and second expansible chambers formed on opposite sides of the rotary piston from minimum to maximum and back to minimum during each revolution of the crankshaft.

Abstract: An auxiliary interlock switch for a DC contactor has a reciprocable one-piece insulating contact carrier and plural bridging contacts interchangeably mounted thereon in alternative positions to provide different desired arrangements of normally open and normally closed contact sets with the stationary contact posts. The contact carrier has a return spring compressed within a spring-receiving cavity and elongated abutment-receiving apertures registering with opposite ends of said cavity through which an abutment member, that is releasably assembled to the contact carrier, may interchangeably freely extend to permit relative movement therebetween and against which one end of the return spring reacts to resiliently bias the contact carrier against reciprocation in one direction.

Abstract: An overload protective system continuousy monitors the forward overturning moment on a counterbalanced lift truck and prevents further raising of the carriage or further forward tilting of the mast when the tilting moment is excessive.

Abstract: A forced commutation chopper control for regulating speed of a DC series tractive motor limits peak motor current by sensing the voltage across the commutation capacitor during the on-time of the current pulses and gating the commutation SCR on in response to a predetermined magnitude of sensed voltage to thereby terminate current pulses to the motor.

Abstract: A vehicle is driven by a traction motor energized by pulses of current from a battery conducted by a power switch and has forward and reverse contactors to control motor direction and a variable time-ratio control for regulating motor speed including an RC timing circuit in series with a bidirectional speed potentiometer whose resistance element is provided with a midtap for selectively varying time duration of the pulses. The speed potentiometer wiper is coupled to a manual speed and direction selecting lever having a neutral position wherein the speed potentiometer wiper engages the midtap so that duty cycle of the pulses is minimum and neither contactor is energized, and actuation of the lever in either direction from neutral increases the time duration of the pulses and also energizes the forward or the reverse contactors to thereby control direction of vehicle travel.

Abstract: A transistor inverter drive provides variable frequency and variable voltage power to an electric motor and pulse width modulates a predetermined number of harmonic-reduced constant volt/hertz pulses per cycle of motor frequency to selectively vary the motor stator voltage so that constant torque over a wide speed range can be accomplished and increases the number of constant volt/hertz PWM pulses per motor frequency cycle at low motor speeds to boost the stator voltage and thereby compensate for decrease in magnetizing current and in torque which would otherwise occur at low frequencies.

Abstract: A harmonic reduced pulse width modulation, variable speed transistor bridge inverter drive controls frequency and magnitude of stator voltage applied to an induction motor so as to maintain constant flux in the motor and permit maximum driving torque to be realized from the motor over a wide speed range. An oscillator generates a train of clock pulses whose frequency is proportional to an analog speed signal, and a three phase generator derives three phase reference waves having periods which include a predetermined number of clock pulses. A resettable volt/hertz integrator derives a train of ramp pulses which are synchronized to the clock pulses and vary in magnitude as a function of the integral of the output voltage from the bridge inverter with respect to time. The constant volt/hertz ramp signals are compared to first and second reference voltages to derive phase-displaced first and second control pulses.

Abstract: A digital automatic control for a change-speed transmission receives digitally coded electrical signals from a gear selector and automatically shifts transmission gears, up to the maximum speed selected, to maintain transmission speed within a range which will assure the most efficient use of available engine power.

Abstract: A lift truck energized from a battery to supply pressurized fluid to elevate a load-supporting carriage has an energy recovery system for converting kinetic energy of the elevated carriage into battery charging current including a fluid motor through which fluid from the lift ram is exhausted when the carriage is descending, an alternator driven by the fluid motor, a rectifier between alternator and battery, a transistor having its emitter-collector circuit in series with the field winding of the alternator, and a rate-of-descent adjusting potentiometer for selectively varying base drive to the transistor to thereby regulate field excitation of the alternator and the regenerative braking of the fluid motor.

Abstract: A grain loss monitor for a combine harvester derives a grain loss rate signal in accordance with the number of grains impinging on a transducer and a ground speed signal proportional to the ground speed of the combine and divides the former by the latter to derive an analog of grain loss per unit area which is independent of time.

Abstract: An n-phase electronically commutated motor has a stator with n angularly displaced phase windings, each of which comprises a pair of power windings, and each power winding is connected in series with a transistor power switch across an electric power source so that the power windings of each phase generate magnetic fluxes in opposite directions and operate in push-pull. A capacitive rotor sensor coupled to the motor rotor derives n-phase square wave rotor position signals displaced 360/n degrees apart at a frequency proportional to rotor speed and n sets of logic gates receive the rotor position signals and control the conduction interval of the power transistors. The logic gates are opened during rotor position signals which energize the power switches in a sequence that generates a rotating magnetic field within the stator.