rockshaft
noun
rock·shaft ˈräk-ˌshaft 
: a shaft that oscillates on its journals instead of revolving
Word History
First Known Use
circa 1864, in the meaning defined above
- spar torpedo
- spar tree
- spar varnish
- spar-deck vessel
- spar-decked
- spar-decker
- sparable
- sparable tin
- sparables
- sparagrass
- sparagus
- Sparassis
- sparaxes
- sparaxis
- sparaxises
- sparaxisses
- sparce
- sparcity
- spare
- spare (someone) the details
- spare a thought for
- spare change
- spare hand
- spare no effort
- spare no expense