The invention discloses a speed regulation and 
control system for a lifting mechanism of a 
tower crane. The lifting mechanism of the 
tower crane is controlled by a PLC through a frequency converter; the switching value of each shift during the ascending and descending of the 
tower crane is input into the PLC; the output of the PLC is connected with the frequency converter; the output of the frequency converter is connected with an ascending motor; and the PLC program design completes the logic operation of a given 
signal and a 
peripheral signal of the ascending frequency converter, the control of a 
brake, the logic judgment and alarm of various fault signals. An electrical towage 
system of the 
tower crane is subjected to technical transformation by using advanced PLC 
frequency conversion and speed regulation technology, so that the lifting mechanism of the crane realizes stable operation, enhances the operating efficiency, improves overload operation, eliminates starting 
impact and braking 
impact, reduces electric maintenance, reduces 
power consumption, and improves power factors. Simultaneously, the lifting mechanism has the advantages of over-current protection, over-
voltage protection, under-
voltage protection and input phase-lacking protection, and over-temperature protection, overload protection and over-speed protection of the frequency converter, overheat protection of a 
brake unit, an I / O fault protection, and motor fault protection and the like.