User's Manual

SECTION III OPERATION
SM 7063 07/97 3-14
3.8.5 Calibrating the Odometer Using a Measured Mile
Calibration of the Odometer is used to compensate for locomotive wheel wear and differences in wheel
diameter from one locomotive to another.
The allowable range of locomotive wheel diameters is 34.00 inches through 46.00 inches. The CDU’s
default value is 40.00 inches.
Calibration of the wheel diameter can be done in one of two ways:
Direct Entry though the use of the Diagnostic PC (see Section IV).
Through the use of the odometer while traveling past measured mile markers along the track.
This section describes odometer calibration using a measured mile.
1. To calibrate using a measured mile, press the
MENU UP
or
MENU DOWN
key until the
Function
Menu Display
reads:
" Measured Mile: press SET "
When the "Zero Mile" marker is passed, press the
SET
key to begin the measurement. The pulses
from the axle alternator are converted into a distance based on the current calibration value. The
Function Menu Display
reads:
" Press SET at End of Mile #### ft "
where #### is the incremental 4-digit count of the distance traveled in the currently configured units
(mile or kilometer) as the train moves through the measured mile (or measured kilometer).
2. When the "One Mile" marker is reached, press the
SET
key a second time to mark the end of the
mile and to calculate the new wheel size.
3. If the measurement is such that the calculated wheel size falls within the permitted range, the
calibration passes and the sonalert will beep once to indicate that the measurement is complete.
For example, the
Function Menu Display
reads:
" 4954 ft, corrected to 5280 ft "
The newly calculated wheel size is stored in the CDU’s parameter storage EEPROM.
4. However, if the measurement is such that the calculated wheel size falls outside of the permitted
range, the calibration fails, the sonalert will beep once, and the
Function Menu Display
reads:
" Measured Mile FAILED "
In this case, the currently stored wheel diameter is retained.