TM5-3805-260-24 c.    Wear  or  damage  to  the  scraper  quick  release valve prevents or slows the release of pressure air from the air chamber and brake cylinder. d.   Wear  or  damage  to  the   components   between the   brake   control   valve   and   the   tractor   and scraper air chamber and brake cylinder. e.   Wear  or  damage  to  the  tractor  and  scraper  air chamber and brake cylinder. f. Wear or damage to the emergency brake control valve  releases  the  pressure  air  to  the  tractor and scraper air chamber and brake cylinder. g.   Wear or damage to the double check valve. 3. EMERGENCY BRAKES DO NOT ENGAGE CORRECTLY Causes: a.  Wear  or  damage  to  the  emergency  brake  control valve prevents or slows the release of pressure air. b.  Wear or damage to the emergency pilot valve, and double check valve. c.    Brakes have wear or damage. d.  Wear   or   damage   to   the   tractor   and   scraper   air chamber and brake cylinder. 4.    EMERGENCY BRAKES DO NOT RELEASE CORRECTLY Causes: a.  Wear  or  damage  to  the  emergency  brake  control valve  releases  the  pressure  air  to  the  tractor  and scraper air chamber and brake cylinder. b.  Wear   or   damage   to   the   tractor   and   scraper   air chamber and brake cylinder. 5. PARKING BRAKES DO NOT ENGAGE CORRECTLY Causes: a.  Wear or damage to the parking brake control valve prevents or slows the release of pressure air. b.  Adjustment of rod travel of parking brake chamber not correct. c.    Brake has wear or damage. d.   Wear or damage to the parking brake chamber. 6. PARKING BRAKES DO NOT RELEASE CORRECTLY Causes: a.   Wear   or   damage   to   the   parking   brake   control valve   releases   the   pressure   air   to   the   parking   brake chamber. b.   Wear or damage to the parking brake chamber. 7. DIFFERENTIAL LOCK DOES NOT ENGAGE CORRECTLY Causes: a.  No   pressure   air   at   the   supply   passage   of   the differential lock valve. b.  Wear   or   damage   to   the   differential   lock   valve permits  little  or  no  air  pressure  at  the  differential lock. c.    Pedal adjustment not correct. 8. DIFFERENTIAL LOCK DOES NOT RELEASE CORRECTLY Causes: a.  Wear   or   damage   to   the   differential   lock   valve prevents or slows the release of pressure air from the line to the differential lock. b.   Pedal adjustment not correct. TEST PROCEDURES WARNING Make  reference  to  WARNING  on  first  page  of AIR  SYSTEM  AND  BRAKES  TESTING  AND ADJUSTING section. Air Pressure Gauge Tools Needed: 8M2885 Pressure Gauge, 0 to 1400 kPa (O to 200 psi). 5S5123 or 6V4161 Hydraulic Testing Group. 1.   Release  the  pressure  air  from  the  tractor  reservoirs by opening front drain valve (1) and center drain valve (2). 2.   Remove rear drain valve (3). 3.   Install    4M5317    Reducing    Bushing    and    the    hose assembly in the opening for the drain valve. 4.   Connect the hose assembly to the IS8937 Valve from the test group. Connect the 1400 kPa (200 psi) gauge to the valve. 5.   Start  the  engine  and  let  the  pressure  go  up  to  the cutout pressure. 6.   Make  a  comparison  of  the  pressure  gauge  on  the machine with the test gauge. 2-147