rated revolution meaning in English

额定转数
额定转速

The propeller may be overloaded which caused by some reasons when ship has been serviced for a period of time . as a result , the rated revolution of the engine cannot be achieved , or the engine may be on overloaded operation condition . it will not be in the optimum matching between the propeller and the engine
船舶在使用过程中，常因各种因素使螺旋桨出现负荷过“重”的现象，主机达不到额定转速或超负荷运转，桨机不能处于最佳匹配；另外当船舶人为地降速航行时，主机处在半负荷情况下工作，如果转速下降太多，使得主机的工作条件变坏，容易引起主机部件的损坏。