TM 5-3895-382-24 Swashplate Neutral Adjustment Procedure (9XL1-228,    3WZ1-157,    2JM1-578,    4JZ1-121,    3TM1-705, 5BZ1-118, 6EN1-126, 1ZN1-120, 2TN1-117) Tools Needed 6V-7830 Tetra Gauges 1 Make reference to WARNING on first page of Troubleshooting. NOTE: Tests should be performed on tires or loose dirt. Tires    are    recommended.        Never    operate    the vibratory     system     when     the     machine     is     on concrete. NOTE: Make  sure  the  parking  brake  is  applied,  and  the propel control lever is in neutral. Flushing Manifold. (1) Test port for vibratory (low amplitude) pressure.  (2) Test port for vibratory (high amplitude) pressure.  (3) Servo Port. 1. Connect two 60 000 kPa (8700 psi) pressure gauges to test ports (1) and (2). 2. Install  a  3445  kPa  (500  psi)  minimum  pressure  hose and   needle   valve   between   servo   port   (3)   and   the opposite servo port, on other side.  This will cross port the    servo    and    remove    the    effects    of    any    control pressure on the servo piston. 3. Start  and  slowly  accelerate  the  engine  to  full  throttle. Operate   the   vibratory   system   in   both   high   and   low amplitudes  several  times  and  then  stop  the  vibratory system. 4. With the servo  cross-port  line  installed  and  the  needle valve  open,  note  the  system  pressure  gauge  readings with  engine  running  at  low  idle.    The  difference  in  the system pressure gauge readings is the offset pressure. NOTE: To achieve finer gauge resolution, lower pressure gauges  will  be  required.    60  000  kPa  (8700  psi) pressure   gauges   are   used   at   the   beginning   to prevent gauge damage. 5. If   the   offset   pressure   is   not   zero,   loosen   the   servo locknut with an 11/16 hex wrench.  Turn the adjustment screw with a 3/16 internal hex wrench to decrease the highest system pressure to half of the offset pressure. 6. Close the needle valve (disconnect the servo cross port line/plug the servo ports).  Operate the vibratory system in both high and low amplitudes several times.  Return the pump to neutral (non-vibratory) and open the needle valve  (reinstall  the  cross-port  line)  this  will  allow  the servo  spring  to  locate  the  swashplate  in  the  neutral position. 7. Install  the  low  pressure  gauges  and  note  the  system pressure gauge readings.  If the offset pressure is not zero, repeat Steps 5 through 8. 8. Once the swashplate neutral has been found, hold the servo  adjustment  screw  from  turning  and  torque  the servo locknut to 18 to 24 Nm (13 to 18 lb-ft). 9. Stop the engine.  Remove the pressure gauges. 13-33