What are the functions of a turning gear device?

[DeReed]

Turning gear refers to manually rotating the motor a few turns before starting it, to determine whether the load driven by the motor (i.e., the mechanical or transmission part) is stuck and experiencing increased resistance, thereby preventing the motor from being damaged due to an excessive starting load. The turning gear device serves the function of manually rotating the motor a few turns. Its specific functions are as follows: 1. Lubrication: It helps establish an oil film lubrication on all bearings of the steam turbine to reduce dry or semi-dry friction between the journal and the bearing, protecting the journal from damage. 2. Heat dissipation: While ensuring uniform heating or cooling of the rotor, it enhances the rotor's stirring effect on the steam inside the cylinder, reducing the temperature difference between the upper and lower cylinders and the resulting thermal deformation and stress. However, a disadvantage of high-speed turning gear is the large starting torque. To reduce the torque, a jacking oil system is usually employed. 3. Reducing impact: When the steam turbine is started, it can reduce the rotor's inertia and the impact force on the blades. During major overhauls, the turning gear can also be used for machining operations such as turning the exciter's brush slip rings.