workhorse
/ˈwɜːkhɔːs/noun
1- a horse used for work on a farm役马; 耕马。
1.1
- a person or machine that dependably performs hard work over a long period of time工作吃重的人, 吃苦耐劳的人; 重负荷的机器：
the aircraft was the standard workhorse of Soviet medium-haul routes.
该型飞机是苏联中程运输线上的标准主力运输工具。