The main engine of the ship is diesel engine, reciprocating steam engine, steam turbine, gas turbine, etc.

The low - middle - high - speed engine refers to the rated power speed of diesel engine.

Generally, the speed of < 300RPM is low and

300 -- 1000RPM is medium speed machine

> 1000RPM is a high speed machine

In addition to > 640MM four-stroke cylinder diesel engines, all low-speed engines are currently cross-head two-stroke turbocharged diesel engines.

The cylinder diameter of a two-stroke diesel engine varies from 350MM to 980MM, and the corresponding speed generally ranges from 167RPM to 61RPM.

Due to the use of small cylinder diameter diesel engine on ships, MAN company l16/24 diesel engine 60HZ is a medium-speed engine with a speed of 1200RPM.

> 1000RPM diesel engines are mainly used as emergency generators.Generally, 50HZ is 1500RPM and 60HZ is 1800RPM