Definition of Terms
Bottom Dead Center; refers to the position of the piston or the crank shaft rod journal. The
piston is at its lowest position in the cylinder.
The clearance in an assembly determined by pushing the shaft in an axial direction one
direction, and then pushing the shaft the opposite direction.
Total Indicator Reading; referred to when measuring the concentricity or the run out. The TIR
refers to the total movement of the needle on a dial indicator, from the most negative reading
to the most positive reading.