Exhaust Valve Overhauling


  • To overhaul the exhaust valve, place the valve on a wooden platform.
  • Loosen the nuts to remove the safety strap and the oil cylinder.
  • Discard the O ring from the air cylinder.
  • Remove the four screws from the flange on top of the air piston.
  • Take out the flange.
  • Release the safety valve from the air cylinder for the air to escape below the piston.
  • Use a tin hammer to loosen the conical locking ring from the air piston.
  • Remove the air piston.
  • Lift the valve housing clear of the spindle. Take out the air cylinder.
  • Clean it and check the running surface for wear or possible scores.
  • Measure the diameter of the air cylinder at four points diametrically opposite, using an inside micrometer.
  • Remove the screws and dismount the flange of the stuffing box.
  • Remove and discard the O rings.
  • Inspect the bushing in the spindle guide, for wear.
  • Measure the inside diameter of the air cylinder using an inside micrometer.
  • Unscrew and the remove the lock screws which hold the bottom piece.
  • Lift the valve housing approximately ten millimetres.
  • Take out the valve seat using the tin hammer.
  • Lift the valve housing and place it on a couple of wooden planks.
  • Discard the O ring from the groove on to the valve seat.
  • Inspect the seating of the bottom piece for damage with a template for damage.
  • Measure the clearance G3 between the template and the O ring groove, using a feeler gauge.
  • Measure the clearance G2 between the template and the valve seat, using a feeler gauge.
  • Take and record the measurements at four diametrically opposite points on the circumference of the valve spindle.
  • Clean the contact faces on the spindle.
  • Measure the gap between spindle template and seating of the spindle.
  • Check the burn off F1 of the wall spindle at each of the points A, B, C D and E.
  • The notches in the spindle template indicate the points.
  • Check the spindle stem for wear in the area between 460 millimetres and 620 millimetres.
  • Measured from top of the spindle.
  • Take and record the measurements of four diametrically opposite points on the circumference of the valve spindle

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