TM 55-4920-328-13 four   flush-mounted   retaining   screws.      Cutouts   in   the front  panel  mount  the  following  back-lighted  switches, depicted in figure 1-26: INST PWR S1 (7), S2 (31) Brake Pump S3 (8), S4 (30) Cooling Pump S5 (9), S6 (29) Tower Fan No.  1 S7 (10), S8 (28) Tower Fan No.  2 S9 (11), S10 (27) Air Comp S11 (12), S12 (26) Lube Pump S13 (13), S14 (25) Oil Pre-Heat S15 (14), S16 (24) Oil Pump S17 (15), S18 (23) Fuel Pump S19 (16), S20 (22) Flood Lights S21 (17), S22 (21) Beacon S23 (19), S24 (20) Left Console Fan S25 (6) Right Console Fan S26 (18) The  upper  row  of  12  switches  across  the  lower  front panel  of  the  No.    1  power  control  panel  assembly  are placarded ON or START as appropriate.  These guarded switches   are   identical   in   design   and   function.      Each switch  is  a  spdt,  red  lens,  pushbutton  type  unit  with  a continuous  service  rating  of  five  amperes  and  having 0.25  inch  of  travel.    The  lower  row  of  12  switches  are placarded    OFF    or    STOP,    as    appropriate.        These guarded switches are similar to the top row of switches except  that  each  lens  is  green.    The  chassis  assembly also  mounts  six  relays:  K1,  K2,  K3,  K4,  K5,  and  K6. The  under  frequency  relay  (76,  figure  719)  will  actuate causing the system to shut down should the input power frequency    fall    below    55    Hertz.        An    over    voltage protection system consisting of a voltage sensitive relay (27C, figure 7-19) is incorporated.  This relay, adjustable from  92V  to  140V,  is  deenergized  while  the  voltage  is maintained  within  normal  limits  and  energized  at  the over  voltage  condition.    All  power  to  the  motors  and consoles   except   the   water   pump   motor   and   lube   oil pump  motor  will  be  cutoff  when  the  relay  is  energized. Power can be manually restored to the system when the voltage  drops  below  the  maximum  set  point.    Terminal board assembly TB1 is installed in the lower panel of the chassis assembly.  The rear panel provides a mounting for five connectors J1 through J5. (j)    Left  hand  castle  assembly  (Unit  8). The  left  hand  castle  assembly  8A1  (14,  figure  1-21), installed in the control cab assembly, consists essentially  of  a  blower  8A1  mounted  in  a  rectangular castle  assembly.    Five  Blank  filler  panels  are  mounted on  the  front  of  the  castle  assembly,  immediately  below the   blower,   by   the   use   of   20   sets   of   receptacles, retainers,  and  screws.    The  castle  assembly  is  a  sheet metal   structure   22.00   inches,         TM   55-4920-328-13 wide, 27.56 inches high, and 16.38 inches deep. The  blower  (8A1)  (1,  figure  7-20)  is  a  standard  19inch rack-mounted  chassis  provided  in  the  left  hand  castle assembly to provide forced air or exhaust ventilation for the   control   cab   module,   depending   on   the   mode   of installation.    The  blower  will  selectively  deliver  100  or 200  cfm  of  air  in  either  mode.    The  unit  utilizes  an  8- inch, dynamically balance, squirrel cage wheel driven by a 1/20horsepower motor powered by 117v ac, threewire, single-phase,   60   Hz   power.      Two   motor   speeds   are available by use of a speed selector switch.  The unit is equipped    with    an    oil-impregnated    fiberglass    filter. Intake  or  exhaust  air,  as  determined  by  the  mode  of installation, passes through a chrome-plated grill. (k)    Right   hand   castle   assembly   (unit 9).The  right  hand  castle  assembly  9A1  (figure  1-27)  is installed in the control cab assembly opposite to the left hand  castle  assembly.    The  castle  assembly  utilized  in this  unit  is  essentially  identical  to  that  used  in  Unit  8, except  for  the  panel-mounted  components.    The  right hand castle assembly is equipped with a blower 9A1 (1), identical   to   the   Unit   8   blower,   a   filler   panel   (2),   a pneumatic  control  assembly  9A2  (10),  and  an  ancillary panel  assembly  9A3  (3).    These  panel  assemblies  are secured to the front cutout portion of the enclosure with 12   sets   of   receptacles,   retainers,   and   flushmounted screws. 1.    Pneumatic   control   assembly   9A2.      The pneumatic control assembly (10, figure 1-27) is chassis- mounted   assembly   consisting   essentially   of   an   AIR SUPPLY   switch   (9),   air   pressure   gage   (8),   solenoid valve  (34,  figure  7-21),  pressure  regulator  (6,  figure  1- 27),     electrical     wiring,     plumbing     runs,     and     hose assembly.  A connector J1 and a chassis ground stud El are installed on the rear panel of the chassis assembly. a. Air  pressure  gage.    The  air  pressure  gage  (8, figure  1-27)  is  a  conventional  Bourdon  tube  pneumatic gage having a full scale range of 0 to 160 psig, with the dial   graduated   in   10-psi   increments.      Three   screws secure  the  flange  of  the  gage  to  the  front  panel  of  the pneumatic    control    assembly    (10).        The    pressure connection   located   on   the   rear   face   of   the   housing accommodates   a   1/8-27   NPT   adapter   for   connection into the pneumatic circuit. b. Solenoid valve.  The solenoid valve (34, figure Z-21)   is   a   normally-closed,   solenoid-operated   valve used   in   the   air   system.      Operation   of   the   valve   is controlled  by  the  AIR  SUPPLY  switch  (9,  figure  1-27). When  the  switch  is  positioned  to  ON,  28v  dc  electrical power is made 1-53