Battery lift magnet control
First Claim
1. Electrical controlling and signalling apparatus comprising,an electrical circuit,a battery in the circuit,an electromagnet in the circuit in series with the battery and adapted to be charged by the battery and when charged operable for magnetically holding a load,signal means in the circuit and including a SAFE indicator and an UNSAFE indicator, those indicators being in mutual parallel relationship but together in series with the battery and electromagnet, andcontrol means in the circuit, in series with the battery, electromagnet and signal means, operable in response to current in the circuit, for energizing the UNSAFE indicator when the electromagnet is not charged and energizing the SAFE indicator when the electromagnet is charged.
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Accused Products
Abstract
A lift magnet for a lift truck, crane, etc., energized by a battery, and a transformer and rectifier are provided for charging the battery from an AC source; a transistorized circuit is included; a SAFE signal light is provided and controlled by a first transistor in services therewith; the transistor is normally conducting and when a failure occurs the transistor becomes non-conducting and the SAFE signal light de-energized; the failure may be from low voltage condition of the battery, or such defects as a break in the circuit or switch means, such as would prevent proper operation despite full voltage; also, before the electromagnet is fully energized, and the current therefore is low, an UNSAFE signal light indicates such low current condition; a second transistor is provided in series with the UNSAFE signal light, this second transistor being normally held in non-conducting condition by the first transistor; when an UNSAFE condition results the first transistor de-energizes the SAFE signal light and in the same operational step renders the second transistor conducting which thereby energizes the UNSAFE light; a zener diode is incorporated in conjunction with the transistorized circuit for providing a stabilized voltage therefor.
10 Citations
9 Claims
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1. Electrical controlling and signalling apparatus comprising,
an electrical circuit, a battery in the circuit, an electromagnet in the circuit in series with the battery and adapted to be charged by the battery and when charged operable for magnetically holding a load, signal means in the circuit and including a SAFE indicator and an UNSAFE indicator, those indicators being in mutual parallel relationship but together in series with the battery and electromagnet, and control means in the circuit, in series with the battery, electromagnet and signal means, operable in response to current in the circuit, for energizing the UNSAFE indicator when the electromagnet is not charged and energizing the SAFE indicator when the electromagnet is charged.
Specification