after top center

after top center

after top centerclick for a larger image
The crankshaft, crankpin, and cylinder are all in line at top dead center and thereafter direction of motion of piston changes from upward to downward at “after top center.”
The position of a piston in the cylinder of a reciprocating engine after the crankshaft, turning in its normal direction of rotation, has caused a piston to pass the top of its stroke and start back down.