**
** couplings with cabin bottom 
**
*NSET,NSET=SEAT_TRK_LT_889
  8065,    8066,    8090,  420066,  420069,  420097,  420100
  420273,
*SURFACE,NAME=SEAT_TRK_CAB_BT_LT_889,TYPE=NODE
SEAT_TRK_LT_889,1.0
*COUPLING,REF NODE=8064,SURFACE=SEAT_TRK_CAB_BT_LT_889,CONSTRAINT NAME=SEAT_TRA_CAB_BT_LT1
*DISTRIBUTING
**-----------------------------------------------------
*NSET,NSET=SEAT_TRK_LT_890
  8053,    8054,    8055,    8068,    8093,  420083,  420103
  420104,  420105,  420276,  420277
*SURFACE,NAME=SEAT_TRK_CAB_BT_LT_890,TYPE=NODE
SEAT_TRK_LT_890,1.0
*COUPLING,REF NODE=8052,SURFACE=SEAT_TRK_CAB_BT_LT_890,CONSTRAINT NAME=SEAT_TRA_CAB_BT_LT2
*DISTRIBUTING
**-----------------------------------------------------
*NSET,NSET=SEAT_TRK_RT_891
 8553, 8554, 8555,8568,8593,420208, 420228,
 420229, 420230,420303, 420304,420305,420306
*SURFACE,NAME=SEAT_TRK_CAB_BT_RT_891,TYPE=NODE
SEAT_TRK_RT_891,1.0
*COUPLING,REF NODE=8552,SURFACE=SEAT_TRK_CAB_BT_RT_891,CONSTRAINT NAME=SEAT_TRA_CAB_BT_RT1
*DISTRIBUTING
**-----------------------------------------------------
*NSET,NSET=SEAT_TRK_RT_892
  8565,    8566,    8589,    8591,  420192,  420195,  420222
  420225,  420300,  420301 
*SURFACE,NAME=SEAT_TRK_CAB_BT_RT_892,TYPE=NODE
SEAT_TRK_RT_892,1.0
*COUPLING,REF NODE=8564,SURFACE=SEAT_TRK_CAB_BT_RT_892,CONSTRAINT NAME=SEAT_TRA_CAB_BT_RT2
*DISTRIBUTING
**-----------------------------------------------------
** add dummy mass/rotary inertia to coupling ref nodes
*ELEMENT, TYPE=MASS, ELSET=seat_mass
815001,8064
815002,8052
815003,8552
815004,8564
*MASS, ELSET=seat_mass
<small_mass>,
*ELEMENT, TYPE=ROTARYI, ELSET=seat_rotary
815021,8064
815022,8052
815023,8552
815024,8564
*ROTARY INERTIA, ELSET=seat_rotary
<small_rota>,<small_rota>,<small_rota>
**-----------------------------------------------------
*nset,nset=retained_seat,unsorted
8064,
8052,
8552,
8564,
*nset,nset=retained_all
retained_seat,
**