machinery 是指machines in general, or machines that are used in a factory or on a farm，就是机器，机械的总称。它和machine还有区别，machine是指一部机器，machinery是指一套机械系统。如The machinery in the factory consists of several different kinds of machines.
但是生物学文献中经常能碰到machinery，翻译成“机器”总感觉不是太好。它有“机制、系统、组织、结构、体制”（the organization or structure of sth; the system for doing sth）的意思，所以就译为“机制或系统”。

如：

1. The observed different responses to powdery mildew are due to an altered auxin signaling pathway mediated by miRNA machinery.

2. The authors further hypothesized that hijacking the host RNA interference machinery requires AGO1, as these Bc-sRNAs are enriched in RISC consisting of AGO1.