TM 5-3805-260-24 AIR SYSTEM AND BRAKES WARNING Sudden  movement  of  the  machine  or  release of    air    under    pressure    can    cause    injury    to persons  on  or  near  the  machine.    To  prevent possible  injury,  do  the  procedure  that  follows before testing and adjusting the air system and brakes: 1. Move  the  machine  to  a  smooth  horizontal  location. Move  away  from  working  machines  and  personnel. Stop the engine. 2.   Permit  only  one  operator  on  the  machine.    Keep  all other  personnel  either  away  from  the  machine  or  in view of the operator. 3.   Activate  the  parking  and  emergency  brakes.  Lower the bowl to the ground. Put blocks in front of and 4. Push on the brake pedal many times until there is no more brake air pressure. 5.   Make   sure   all   air   pressure   is   released   before   any fitting,   hose   or   component   is   loosened,   tightened, removed or adjusted. NOTE: Before any operation checks are made, open the drain  valves  to  release  any  water  in  the  air  reservoirs. Water   lowers   the   capacity   in   the   reservoirs   and   can cause  the  air  compressor  to  run  constantly.    Close  the drain  valve.    Start  the  engine  and  operate  the  machine until it is at the normal temperature for operation. VISUAL CHECKS Before   any   operation   checks   are   made   to   the   air system and brakes, visually inspect the complete system as follows: 1.   Check for cracks or wear in hoses and lines. 2.   Check for restriction to flow; like sharp bends, clamps that are not installed correctly, and damage to hoses and lines. 3.   Check for loose connections. 4.   Check for damage to components. OPERATION CHECKS WARNING Make reference to WARNING at the beginning of AIR SYSTEM AND BRAKES TESTING AND ADJUSTING section. Operation  checks  of  the  air  system  and  brakes  can be used to find the source of leakage in the system or to make a diagnosis of bad performance. Leakage Checks Tools Needed: 8M2885 Pressure Gauge, 0 to 200 psi (O to 1380 kPa). 5S5123 or 6V4161 Hydraulic Testing Group. NOTE:  It is possible to hear the sound of air leakage. Air leakage   can   be   seen   when   water   with   soap   (soapy water) is put on the connections, valves and hoses. 1. Start  the  engine  and  let  the  air  pressure  go  up  to the cutout pressure. Stop the engine. NOTE:    The  governor  cutout  pressure  is  to  be  125  +  5 psi (860 + 35 kPa). If cutout pressure is not correct, see the subject, AIR COMPRESSOR GOVERNOR. 2. Check   for   leakage   in   the   hoses,   lines   and   con- nections  from  the  air  compressor  and  governor  to the tractor reservoirs. 3. Check   for   leakage   in   the   hoses,   lines   and   con- nections   from   the   tractor   reservoirs   to   the   brake control valve, emergency pilot valve and accessory circuit. 4. Check for leakage in the brake control valve. NOTE:  If the air pressure gets below 100 psi (690 kPa) (cut-in  pressure),  start  and  run  the  engine  until  the  air pressure goes up to the cutout pressure. 5. Check     for     leakage     in     the     hoses,     lines     and connections from the brake control valve to the seat suspension,  differential  lock  salve  and  emergency and parking brake control valves. 6. Check for leakage in the valves and switches. 7.    Check for leakage in the hoses, lines and connections   from   the   brake   control   valve   to   the parking and emergency brake control valves. 8.    Move the knob on the parking and emergency brake control valves to the OFF position (pushed in). 2-145