SERVICE MANUAL ber of the governor.  The more common cut-out pressure is 862 ± 35 kPa (125 ± 5 psi). With  the  engine  still  running  make  a  series  of  brake applications  to  reduce  the  air  pressure  and  observe  at which pressure the governor cuts in the compressor.  As in  the  case  of  the  cut-out  pressure,  the  cut-in  pressure should    be    in    accordance    with    the    governor    piece number.    Common  cut-in  pressure  is  690  to  717  kPa (100 to 105 psi).  Never condemn or adjust the governor pressure   settings   unless   they   are   checked   with   an accurate test gauge or a  dash  gauge  that  is  registering accurately.  If the pressure settings of the governor are inaccurate   or   it   is   necessary   that   they   be   changed, procedure is as follows. First,   unscrew   the   cover   at   the   top   of   the governor.    Next,  loosen  the  adjusting  screw  lock  nut, With    a    screwdriver    the    adjusting    screw    is    turned counterclockwise  to  raise  the  pressure  setting  and  the screw is turned clockwise to lower the pressure setting. After  the  adjustment  is  completed,  the  adjusting  screw lock nut should be tightened to lock this adjustment. NOTE: 1/4 turn will change the setting approximately 28 kPa  (4  psi).    Any  governor  requiring  more  than  a  360° adjustment should be cleaned and inspected. LEAKAGE TESTS Leakage checks on the D-2 governor are made at its exhaust port in both cut-in and cut-out positions.  In the  cut-in  position  check  exhaust  port   for   inlet   valve leakage by applying a soap solution at the port.  Leakage could  also  be  past  the  bottom  piston  grommet.    In  the cut-out  position  check  the   exhaust   port   to   determine leakage at the exhaust valve seat or stem grommet.  In this position leakage could also be past the upper piston grommet. Leakage in excess of 25 mm (1 in.) soap bubble in 3 seconds is not permissible in either of the foregoing tests.  If excess leakage is found, the governor must be repaired or replaced. REMOVE Apply parking brakes or block wheels to prevent vehicle from moving. Drain air brake system. If governor is compressor-mounted type, disconnect    reservoir    air    line.        If    remote-mounted governor, disconnect both the unloader and reservoir air lines. Remove governor mounting bolts, then governor. INSTALL If  compressor-mounted  type  governor,  clean  mounting pad  on  both  compressor  and  governor  block.    Clean connecting   line   or   lines.      Also   be   sure   compressor unloading port is clear and clean. If  the  governor  is  being  mounted  remotely,  it should   be   positioned   so   that   its   exhaust   port   points down.  It should be mounted higher than the compressor so  that  its  connecting  lines  will  drain  away  from  the governor. Install governor. If     compressor-mounted     type,     use     a     new governor mounting gasket. Connect air lines to governor.  Test governor as outlined under SERVICE CHECKS. DISASSEMBLY Clean governor  exterior  of  road  dirt  and  grease using a good cleaning solvent and brush. Unscrew the top cover. With  a  pair  of  retaining  ring  pliers  remove  the spring assembly retaining ring. Remove     the     adjusting     screw     and     spring assembly. Remove the lock nut, then the hex-shaped upper spring seat from the adjusting screw. Remove    the    pressure    setting    spring,    lower spring seat, spring guide and the other lower spring seat from the adjusting screw. Remove  the  exhaust  stem  and  its  spring  from the top of the piston. With the body in the inverted position tap it lightly and the piston should fall out. Remove  the  inlet  and  exhaust  valve  spring  and the valve from the piston. Remove  the  two  piston  grommets  and  with  a hooked wire remove the exhaust stem grommet. Clean or remove the unloader and reservoir port filters. CLEANING AND INSPECTION Clean all metal parts in a good cleaning solvent. Wipe rubber parts dry. Inspect  body  for  cracks  or  other  damage.    Be particularly careful that the body air passages, the filters, exhaust stem and piston are not obstructed. Check springs for cracks, distortion or corrosion. Replace   all   parts   not   considered   serviceable during these inspections. PRINTED IN UNITED STATES OF AMERICA CTS-4097A - CHAPTER I Page 3