TM 5-4210-230-14&P-1 VEHICLE OPERATION SHIFTING (Two-speed rear axle) SHIFTING INTO THE LOW SPEED RATIO 1. On level grades or at high truck speeds: a. Keep  the  accelerator pedal  depressed  and  push  the control down. b. To  complete  the  shift,  release  the  accelerator  pedal and then depress the accelerator again as quickly as possible.  Do not operate the clutch. 2. On upgrades or at slow truck speeds: a. Keep the accelerator depressed and push the switch control down. b. To complete the shift, keep the accelerator depressed  and  disengage  and  re-engage  the  clutch as quickly as possible. 3. On downgrades against the engine: a. Release  the  accelerator  pedal  and  push  the  switch control down. b. To complete the shift, press down on the accelerator pedal     enough     to     synchronize     the     gears,     then immediately release the accelerator.  Do not operate the clutch. SHIFTING INTO THE HIGH SPEED RATIO 1. On downgrades against the engine: a. Release   the   accelerator   pedal   and   pull   the   switch control up. b. To  complete  the  shift,  disengage  and  reengage  the clutch with the accelerator pedal released. 2. At any time except on downgrades against the engine: a. Keep  the  accelerator  pedal  depressed  and  pull  the switch control up. b. Gradually   release   the   accelerator   to   complete   the shift.  Do not depress the accelerator until the shift is completed. SPLIT SHIFTING To shift to the next higher gear in the transmission and at the same time from the high to the low speed axle, shift the transmission  in  the  usual  way  and  push  the  switch  control down just before engaging the clutch. To shift to the next lower gear in the transmission and at the same time from the low to the high speed axle, pull the switch  control  up  and  release  the  accelerator,  then  complete the transmission shift in the usual way. Always park and start in low range. STARTING A TURBOCHARGED TRUCK ON A GRADE Under normal circumstances, when a driver is starting a   load   on   a   grade   with   either   a   naturally   aspirated   diesel engine or a gasoline engine, he begins to engage the clutch at which   time   the   rpm   starts   to   fall   slightly   and   very   quickly recovers as the vehicle begins moving. The   turbocharged   diesel   engines   have   a   somewhat different  feeling  -once  the  clutch  is  engaged  the  rpm  falls  off significantly.  This is due to the emission control device on the turbocharged engine which controls the fuel input during first gear  acceleration.    After  the  initial  drop  in  speed,  the  engine will recover and accelerate in a normal manner.  However, it is  a  different  feeling  and  when  the  rpm  falls  off,  the  natural reaction is to disengage the clutch rapidly and try to bring up the  rpm.    Do  not  do  this,  for  if  you  do,  the  cab  will  begin  to buck    and,    in    extreme    cases,    damage    to    the    driveline components can result. THE PROPER PROCEDURE SHOULD BE: 1. Set  the  trailer  brakes,  bring  the  rpm  up  slightly  and begin  to  engage  the  clutch  while,  at  the  same  time, releasing the trailer brakes. 2. As  the  rpm  begins  to  fall  off,  DO  NOT  disengage  the clutch.  The rpm will quickly come back and the vehicle will rapidly accelerate up the grade. TOWING INSTRUCTIONS Before  moving  the  towed  vehicle,  check  for  adequate road clearance of vehicle components. Also  before  towing  a  disabled  vehicle,  be  sure  to  fully release the parking brake.  See Parking Brakes. TOWING VEHICLE WITH FRONT WHEELS SUSPENDED When  it  is  necessary  to  tow  a  vehicle  with  the  front wheels  suspended,  if  at  all  possible,  use  a  towing  dolly  to position   rear   wheels   on,   thus   avoiding   any   unnecessary transmission  or  differential  damage.    If  a  towing  dolly  is  not available, proceed as follows. 9