"曲柄转动装置" can be translated into English as "crank rotating device" or, more commonly in mechanical engineering contexts, "crank mechanism" (if referring to the system that converts rotary motion into reciprocating motion or vice versa, which is the typical function of a crank-related setup).
"Crank rotating device" directly describes a device involving a rotating crank.
"Crank mechanism" is a more technical and widely used term in mechanical engineering to describe the entire system or arrangement involving a crank.
Choose the one that best fits the context of your usage.