Gantry crane cable truck equipment - uses linear motors with pole pitches and grooves to suit garland positions

摘要

The gantry crane has trucks supporting a cable garland and driven by linear motors supplied by a travel direction switch on the crab or at the driving position via a single thyristor-controlled inverter with a common adjustable voltage and frequency. Speed and acceleration of all trucks is stepped to suit their positions in the garland and they are kept at regular intervals. Frequency and voltage are raised proportional to speed for all motors, to give sufficient thrust. Using an inverter which can be set down to very low frequencies, the pole pitches and the number of grooves per pole of the motors of the individual trucks are arranged in accordance with their sequence in the garland. The same section of sheet metal is used with differing numbers of turns. The rated frequency at the inverter output ensures the desired maximum speed of the fastest truck with a minimum groove pitch of 1cm. approximately.