The phrase "kept shoulder to the wheel" means to continue working hard without giving up. There are several synonyms that can be used to convey the same meaning such as perseverance, persistence, dedication, determination, and tenacity. These words describe the act of continuing to put effort into something despite difficulties or setbacks. Another phrase that could be used as a synonym is "stuck with it" which also implies not giving up. When an individual has kept their shoulder to the wheel, they have shown resilience and the willingness to work hard to achieve their goals. These synonyms highlight the importance of perseverance in achieving success.