SHUTOFF AND ALARM SYSTEMS SYSTEMS OPERATION The  engine  speed  is  felt  by  magnetic  pickup  (  ).  As  the teeth  of  the  flywheel  go  through  the  magnetic  lines  of force  around  the  pickup.  an  AC  voltage  is  made.  Dual speed   switch   (2)   measures    engine    speed    from    the frequency of the voltage. Time  delay  relay  (7)  controls  the  operation  of  shutdown relay  (9),  which  in  turn,  controls  the  operation  of  fuel shutoff solenoid ( 12). Time delay relay (7) will keep the fuel  shutoff  solenoid  energized  for  70  seconds  after  a fault   condition.   This   prevents   the   engine   from   being started again before the flywheel has stopped rotation. When  the  engine  starts  and  gets  to  a  speed  just above  cranking  speed,   the   normally   open   contacts   of crank  terminate  switch  (4)  [which  is  part  of  dual  speed switch (2)] will close. This will complete the circuit to time delay relay (7) through terminal TD-2. In approximately 9 seconds N.O. switch (8) in time delay relay (7) will close and complete the circuit between shutdown relay (9) and terminal  TD-7  of  the  time  delay  relay.  If  the  engine  oil pressure  has  not  activated  oil  pressure  switch  (6)  by  9 seconds, current will flow through the N.C.  switch in the oil   pressure   switch   and   through   the   now   closed   N.O. switch  (8)  to  activate  shutdown  relay  (9)  which  in  turn activates fuel shutoff solenoid (12). If engine oil pressure activates   oil   pressure   switch   (6),   the   N.O.   switch   will close  and  the  N.C.  switch  will  open.  This  will  let  current flow    to    terminal    TDI    of    the    time    delay    relay    and immediately close N.O. switch (8). At the same time the N.C.   switch   in   the   oil   pressure   switch   will   open   and prevent current flow to switch (8). If  the  engine  speed  increases  above  the  overspeed setting ( 118% of rated speed) of the dual speed switch, the overspeed switch (part of the dual speed switch) will close across terminals DSS-7 and DSS-8. This completes  the  circuit  to  shutdown  relay  (6)  through  the now  closed  switch  (8)  at  terminal  TD-7.  Shutdown  relay (9) is activated and in turn activates fuel shutoff solenoid (12) to cause the engine to shutdown. When the engine speed gets less than the cranking speed  setting,  switch  (4)  opens.  This  stops  the  flow  of current  to  terminal  TD-2  of  the  time  delay  relay.  When the  engine  stops,  engine  oil  pressure  will  become  less than   the   setting   of   the   oil   pressure   switch.   The   N.O. switch  will  open  and  stop  the  flow  of  current  to  terminal TD-I of the time delay relay. This will start the time delay relay  timer.  After  70  seconds,  switch  (8)  will  open  and stop  current  flow  to  shutdown  relay  (9)  and  fuel  shutoff solenoid (12) will no longer be activated. NOTICE To help prevent damage to the engine, find and  correct  the  problem  that  caused  the  engine  to overspeed before the engine is started again. After  an  overspeed  shutdown.  a  button  on  the  dual speed  switch  must  be  pushed  to  open  the  overspeed switch before the engine will run. When  the  engine  has  been  started  and  is  running. the  time  delay  relay  will  close  switch  (8).  If  the  engine coolant   temperature   goes   above   the   setting   of   water temperature switch (5). the N.O. contacts will close.  This lets  current  flow  through  the  water  temperature  switch and through switch (8) to activate shutdown relay (9) and in turn activates fuel shutoff solenoid ( 12). When the engine speed gets less than the cranking speed  setting,  switch  (4)  opens.  This  stops  the  flow  of current  to  terminal  TD-2  of  the  time  delay  relay.  When the  engine  stops,  engine  oil  pressure  will  become  less than   the   setting   of   the   oil   pressure   switch.   The   N.O. switch   will   open   and   stop   the   the   flow   of   current   to terminal  TDI  of  the  time  delay  relav.  This  will  start  the time  delav  relav  timer.  After  70  seconds.  switch  (8)  \  ill open and stop current flow to shutdown relay (9) and fuel shutoff solenoid (12) will no longer be activated. NOTICE To help prevent damage to the engine, find and  correct  the  problem  that  caused  the  engine  to get too hot before the engine is started again. When  the  engine  has  been  started  and  is  running, the time delay relay will close switch (8). If the engine oil pressure gets less than the setting of oil pressure switch (6).  the  N.C.  switch  will  close.  This  will  let  current  flow through  switch  (8)  to  activate  shutdown  relay  (9)  and  in turn activates fuel shutoff solenoid (12). The N.O.  switch will  also  open  and  stop  current  flow  to  terminal  TD-I  of the  time  delay  relay.  When  the  engine  speed  gets  less than  the  cranking  speed  setting.  switch  (4)  opens.  This stops  the  flow  of  current  to  terminal  TD-2  of  the  time delay relay and starts the time delay relay timer. After 70 seconds.  switch  (8)  will  open  and  stop  current  flow  to shutdown relay (9) and fuel shutoff  solenoid  (12)  will  no longer be activated. NOTICE To help prevent damage to the engine, find and  correct  the  cause  for  low  engine  oil  pressure before the engine is started again. 25