TM 5-3895-374-24-2 GENERAL The   maintenance   section   of   this   book   covers   only those   operations   with   which   maintenance   personnel   may not    be    too    familiar.        It    is    expected    that    the    average mechanic’s    training    and    experience    will    permit    him    to perform  the  more  common  maintenance  functions  without the need for detailed instructions. AIR VALVE INSPECTION (See Valve/Gasket Kit on Pages 21 & 23) The    valve    assemblies    should    be    removed    from    your compressor and new valves installed to the valve plate after every 2000 hours of operation. 1. Refer to the instructions furnished with the valve/gasket kit to replace the valves. 2. Refer  to  Figure  6-1.    Disconnect  and  remove  the tubing  to  the  inlet  unloader(s).    Remove  the  inlet filter/silencer from the inlet unloader cover. 3. Loosen  and  remove  the  inlet  unloader  capscrews, then pull the inlet unloader cover away from the air head,  using  care  not  to  damage  the  inlet  cover o-ring. 4. Loosen   and   remove   the   capscrews   securing   the intercooler manifold to the air head. 5. Loosen  and  remove  the  air  head  capscrews  from the   air   head,   and   remove   the   air   head   from   the valve  assembly.    If  the  valve  assembly  and  the  air head    are    removed    from    the    cylinder    together, observe  the  assembly  direction  of  the  valve  plate before  removing  from  air  head.    Make  note  of  this direction  in  order  to  re-assemble  the  air  head  and valve assembly to the cylinder. 6. Reverse the disassembly procedures to re- assemble   the   compressor.      (See   Torque   Valve Table below.) Figure 6-1.  Valve and air head assembly. TORQUE VALUE TABLE NATIONAL COARSE GRADE 2 GRADE 5 GRADE 8 Dia.   Pitch Ft.   Lbs. Kg - Meters Ft.   Lbs. Kg - Meters Ft.  Lbs. Kg-Meters 1/4"-20 4 .55 6 .82 9 1.24 5/16"-18 8 1.10 12 1.66 18 2.49 3/8"-16 15 2.10 23 3.18 31 4.29 7/16"-14 24 3.32 36 4.98 51 7.05 1/2"-13 37 5.12 56 7.74 80 11.06 9/16"-12 53 7.33 81 11.20 116 16.04 5/8"-11 68 9.40 113 15.63 160 22.12 3/4"-10 131 18.12 203 28.07 286 39.55 We recommend the use of a torque wrench on all bolts, capscrews, and nuts using the values in the following table.  The values given are for threads lubricated with oil or grease. To determine the grade of the bolt or capscrew being tightened, use the following information. Grade 2: No markings or vendor identification on the head. Grade 5: Letter "S" or 3 lines and/or vendor identification on the head. Grade 8: Letter "V" or 6 lines and/or vendor identification on the head. page 3 - 841