SERVICE MANUAL inlet port. Also connect a manifold with an air gauge and close manual shut-off valve to outlet. With   air   control   valve   in   "out"   position,   open   manual valve to build up 689-861 kPa (100-125 psi) to inlet port. Shut off manual valve.  No air leakage is allowed around piston  or  through  casting  surfaces.  Permissible  leakage at   exhaust   port   is   a   25   mm   (1")   soap   bubble   in   six seconds. Push control valve in and build up 689-861 kPa (100- 125   psi)   pressure   at   both   inlet   and   outlet.      Shut   off manual manual valve and repeat above leakage test. Pull  control  valve  out.  Outlet  port  pressure  should exhaust to zero through valve. Operation Test Begin  with  zero  pressure  at  inlet  and  outlet.    Hold control valve "in" and open manual valve to allow 48-241 kPa  (7-35  psi)  pressure  to  build  up  at  both  inlet  and outlet. Control of valve should remain "in" at 48-241 kPa (7-35 psi) and above. Second   check   is   accomplished   with   689-861   kPa (100-125   psi)   in   both   inlet   and   outlet   ports   and   both manual shut-off valves closed. Slowly open manual valve at   outlet   to   bleed   down   pressure.      The   spring   brake control     should     automatically     move     "out"     when     air pressure at inlet port reaches 48-241 kPa (7-35 psi). If  spring  brake  control  valve  does  not  perform  as described it should be repaired or replaced. DISASSEMBLY (Fig. 2) Before    moving    spring    brake    control    valve    from vehicle, drain all air from all reservoirs. 1. After valve is removed from vehicle, inspect it for damage.  If casting is broken or shows fractures replace valve assembly. 2. Carefully remove end cap snap ring. 3. End   cap,   O-ring   and   spring   can   be   removed now. 4. Remove nut, washer and valve assembly. 5. Pull  piston  with  the  knob  out  end  of  body  and remove O-ring from piston. CLEANING AND INSPECTION Wash   all   metal   parts   in   cleaning   solvent.   Inspect body and end cap seats. Face of seats must be flat and smooth with no cracks or nicks. Use new parts supplied in repair kit. REASSEMBLY (Fig. 2) Lubricate O-rings, O-ring sealing surfaces and piston-to- body surfaces with Item 3 of LUBRICANT SPECIFICATIONS. 1. Install   O-ring   on   piston   and   insert   piston   into body, aligning hex on piston to hex on body. 2. Position valve assembly over end of piston, then position   washer   over   piston   stud   end   against metal face of valve. 3. Install nut and torque as specified on Fig. 2. Piston  should  move  smoothly  back  and  forth  in body. 4. Install spring with small end against valve disc. 5. Position O-ring over end cap. Align end cap over spring and push end cap into body. Hold end cap to prevent spring pushing end cap out. 6. Install snap ring in valve body groove. Plunger should move in and out by applying force to move plunger in and releasing it. Before releasing vehicle for service perform SERVICE CHECKS as outlined. REASSEMBLY Lubricate O-rings, O-ring sealing surfaces and stem with  Item  3  of  LUBRICANT  SPECIFICATIONS  (refer  to Fig. 4 for numbers in parenthesis). 1. Install new O-rings on stem (10) and piston (5). 2. Insert stem in valve body; then position piston (5) in valve body over stem. 3. Install stem nut (3). 4. Install valve end cap (1) and new gasket (2). Before vehicle is  returned  to  service,  perform  SERVICE CHECKS on valve as outlined. TWO  WAY  CONTROL  VALVE  (BENDIX  TYPE  TW-1) DESCRIPTION The  TW-1  two-way  control  valve,  which  is  an  off-on valve,    is    mounted    on    the    instrument    panel    and    is primarily    used    in    conjunction    with    various    other    air devices  in  vehicle  air  systems.    The  systems  in  which these valves may be used are:    transmission  air  control valve,   quick   release   valve,   two-speed   shift   cylinders, manually   operated   tractor   protection   valve   and   power divider lock-out system. CTS-4079 - CHAPTER VII - Page 4