workhorse
n. countable B2 Upper Intermediate US //ˈwɝkˌhɔɹs// UK //wˈɜːkhɔːs// work·horse
n. a person or machine that is very reliable and does a lot of hard work. You use this to describe someone who is not flashy but gets the job done.
n. a person or machine that is exceptionally reliable and capable of performing a large amount of work. Often used metaphorically to describe a dependable employee or a robust piece of equipment.
He is a real workhorse who never complains about long hours.
The company relies on her as a workhorse, knowing she can handle the most difficult tasks with ease.
While the newer models are more stylish, the older truck remains a workhorse, enduring the harsh conditions of the construction site without any mechanical failures.
From Middle English werkehorse, equivalent to work + horse.