# Calculation of roll coefficient on tangent track

Program QUASI in the GENSYS package can be used when calculating the roll coefficient of the carbody. In order to make the calculation the input data file has to be prepared in the following way.

• Set constraints to the wheelsets, in order to put the vehicle in a tilted position. Example:
```
constr fix_rigid_1 axl_111  x 0.000
constr fix_rigid_1 axl_112  x 0.000
constr fix_rigid_1 axl_121  x 0.000
constr fix_rigid_1 axl_122  x 0.000
constr fix_rigid_1 axl_111  y 0.000
constr fix_rigid_1 axl_112  y 0.000
constr fix_rigid_1 axl_121  y 0.000
constr fix_rigid_1 axl_122  y 0.000
constr fix_rigid_1 axl_111  z 0.000
constr fix_rigid_1 axl_112  z 0.000
constr fix_rigid_1 axl_121  z 0.000
constr fix_rigid_1 axl_122  z 0.000
constr fix_rigid_1 axl_111  f 0.001
constr fix_rigid_1 axl_112  f 0.001
constr fix_rigid_1 axl_121  f 0.001
constr fix_rigid_1 axl_122  f 0.001
constr fix_rigid_1 axl_111  p 0.000
constr fix_rigid_1 axl_112  p 0.000
constr fix_rigid_1 axl_121  p 0.000
constr fix_rigid_1 axl_122  p 0.000

```

• Perform a quasistatic analysis in program QUASI.

• The results can be obtained by checking the *.gp-file by the program CATA_GP.
Example: A printout from the CATA_GP program (The information has been selected in order to reduce the amount of data in this paper).
```
Start  of  program  CATA_GP rel.9703
====================================

ident   =  qroll

head    =  Example of a Bobo-vehicle running at a speed of = 160. (km/h)
Wheel/rail geometry function cylindrical  friction= .000
Ideal track geom=Tangent_Track; Track irregularities=ideal
Calculation of roll-coefficient

date    =  1997-09-24

freedom                     value
car_1.x                    0.00000E+00
car_1.y                    1.51493E-03
car_1.z                   -7.37960E-07
car_1.f                    1.10006E-03
car_1.k                    0.00000E+00
car_1.p                    0.00000E+00
bog_11.x                   0.00000E+00
bog_11.y                   5.00033E-05
bog_11.z                   0.00000E+00
bog_11.f                   1.04707E-03
bog_11.k                   2.38676E-08
bog_11.p                   0.00000E+00
bog_12.x                   0.00000E+00
bog_12.y                   5.00033E-05
bog_12.z                   0.00000E+00
bog_12.f                   1.04707E-03
bog_12.k                  -2.38625E-08
bog_12.p                   0.00000E+00

End    of  program  CATA_GP
===========================

```

• The roll coefficient for a tilted vehicle on tangent track can be calculated according to the following formula:
```
C_phi = phi_ks / phi_s - 1.

```

Where:
 C_phi = The roll coefficient phi_ks = The roll angle of the carbody (car_1.f in the above example) phi_s = The roll angle of the axles (0.001 in the above example)