Abstract:

The retardation and jam occurred in the regulating system of the steam turbine mediumpressure hydraulic servomotor in a thermal power plant.

According to the analysis, it is determined that the gland of the mediumpressure hydraulic servomotor was installed askew by the maintenance staff，the

seal sleeve was squeezed with the shell. When the servomotor piston is moving down quickly, the friction force act as resistance for the seal sleeve, which

disengages the seal sleeve upward and makes the fault of mediumpressure hydraulic servomotor. The servomotor seal sleeve had been taken down and repaired,

and it had been installed again. The hidden danger of the equipment was eliminated, and the equipment accident was avoided.

Key words: medium-pressure hydraulic servomotor, piston seal sleeve, disengagement