ELECTRICAL EQUIPMENT—Q.19 6. Thread   the   trigger   (40)   of   the   trip   assembly, through  the  moving  contact  slot.    Place  the  two fixing screws (57) into the trip support, press the plunger   assembly   downwards   maintaining   the pressure, whilst tightening the fixing screws. 7. Fix the contact stop-plate into position by means of   the   two   screws   (50).      Secure   the   flexible resistance    lead    to    the    moving    contact    (52). Ensure  that  the  square-ended  tag  does  not touch   the   back-plate,   and   that   the   solenoid leads are outside this lead to prevent chafing. 8. Check  that  the  plunger  can  he  compressed  at least  0.3125  in  (7,94  mm)  without  the  trip  being released,    and    that    the    first    contact    makes between  0.057  in  —0.081  in  (1,45—2,06  mm) movement. 9. Insert    the    connecting    link    (48)    between    the positive   terminal   (47)   and   the   fixed   contact. Screw  in  the  two  screws  (51)  before  tightening the positive terminal post (47). ASSEMBLING PINION 1. Unscrew  and  remove  the  oil-plug  (7)  and  wick- spring.  Push the wick temporarily out of the way to ensure free entry of the pinion sleeve. 2. Insert the pinion into the drive end-shield. 3. Fit   the   ball-lock   collar   (17)   in   place,   with   its spring,  trip  collar  (19)  and  circlip.    Ensure  that the lock collar slides freely. 4. Using   a   medium   grade   grease,   assemble   the four  steel  balls  (16)  into  the  pinion-sleeve  holes by    inserting    them    through    the    sleeve    bore. Press the balls firmly into the holes to allow free entry of the armature shaft. ASSEMBLING ARMATURE 1. When  assembling  the  armature  to  the  pinion,  it should be noted that the helices are formed by a three  start  thread,  and  the  correct  thread  must be  selected  so  that  the  steel  balls  forming  the lock will locate in the shaft recesses  (39).    To  assist  correct  selection,  both pinion and shaft ends have corresponding "pop" marks. Release  the  ball-lock  by  pulling  the  lock  collar towards  the  commutator  end  and  holding  in  this position push the pinion up to the shaft shoulder. 2. Assemble armature and drive end shield to yoke assembly,    ensuring    that    dowel    is    correctly located. 3. Stand   the   above   assembly   vertical,   with   the flange  resting  on  a  support,  and  the  pinion  face resting  on  another  support,  1  7/8  in     0.002  in lower (47,6   0,051 mm).  Place a straight-edge across the yoke face and build up with shims on shaft  until  a  dimension  of  0.285  in      0.020  in (7,24      0,508   mm)   between   the   commutator sleeve  and  the  yoke  face  is  obtained.    This  will give   1/16   in   (1,6   mm)   end   movement   of   the shaft,     when     the     commutator     endshield     is assembled. 4. Check   that   the   commutator   end-shield   turns freely on the shaft and screw up the two through bolts (37). 5. If necessary, add shims between the commutator end-shield and the shaft circlip (31), to   maintain   a   dimension   of   1.872—1.877   in (47.55—47.68   mm),   between   the   pinion   nose (6A) and flange face (8B). 6. Place the shaft spring (36) in position, and insert the  pad  and  ball.    Replace  the  cover  and  clip into  position.    The  end-shield  should  be  stoned to     remove     any     scoring     etc.,     sustained     in dismantling the end cover clip.  Failure to do so, may   result   in   damage   to   the   sintered   bronze bearing. 7. Complete  the  assembly  by  fitting  brushes,  field screws,   pinion   return-spring,   stop,   and   shaft lock-nut. Screw the two cover-screws (55) into position, in the drive end-shield, and replace the commutator end cover-band accurately to exclude all dirt