35. Q. How would you locate broken exhaust ring in piston valve?

A. Watch the cross-head when engine is working steam. As there will be
three normal and one light exhausts, you can determine on which side of
the engine the light exhaust takes place.

36. Q. What is meant by lead? What by line and line?

A. Lead is the amount of port opening for live steam to cylinder ahead
or back of piston when the piston is on the dead center. If the steam
edge of the valve is in line with the edge of the steam port when the
piston is on the center, it is said to be line and line.

37. Q. What is meant by steam lap?

A. The distance that the valve overlaps the live steam edges of the
steam ports when it is in the center of its travel over the seat. This
distance is measured at one end only, although the valve laps equally at
both ends.

38. Q. What is meant by exhaust lap? What by exhaust clearance?

A. Exhaust lap is the distance that the exhaust edge of the valve
overlaps the exhaust edge of the steam port when the valve is in
central position. Exhaust clearance is the opening between the exhaust
edge of the valve and the exhaust edge of the steam port with valve in
central position. If the valve has neither exhaust lap or clearance it
is said to be line and line.

39. Q. What is meant by release? What by compression?