Valve seats.
The Valve is the piece that actually moves in and out, or "opens and closes" - the part of the block that the valve rests on is called the valve seat.
plinth
A block of wood that a hammer rests on is typically called a hammer block or a hammer rest. It is used to support the hammer in a stable position when not in use.
The hammer rests on a wooden block called a "buck." It is typically made of hard wood like oak or hickory to provide a solid surface for hammering.
the capstone or pyramidion
The point on which a lever rests is called the fulcrum. It acts as a pivot point around which the lever rotates to exert a force.
When all power and authority rests with one person, it is called a dictatorship or autocracy.
Oligarchy
Open the cylinder and look inside on the frame where the crane assembly rests.
The Cradle
The symbol that represents silence in music is called a "rest." Rests come in different durations, such as whole rests, half rests, quarter rests, etc., and indicate a period of silence where no sound is played.
The resting position where the bar rests in weightlifting is called the "rack position."