EUD-2016026-00 Rev.2, SmartScanIS User’s Guide for Union Pacific, 14 January 2021
183
10.7 Hot Bearing Alarms
The SmartScanIS checks for hot bearings during the scanning process. The four types of hot
bearing alarms (aka Hotbox alarms) are:
Absolute
. To trigger an Absolute alarm, a bearing temperature must exceed the limit
that was established using the
Absolute option
on the Alarm Limits submenu. This
alarm limit is an offset, in degrees Fahrenheit, above the ambient temperature.
Differential
. To trigger a Differential alarm, a bearing temperature must exceed the
opposite side bearing temperature of the same axle by a differential amount
established using the
Differential option
on the Alarm Limits submenu. A Differential
alarm doesn't appear on an axle that already contains an Absolute alarm.
Pyrometer Saturation
. To trigger a Pyrometer Saturation alarm, an interaxle bearing
temperature must exceed the limit that was established using the
Absolute option
on
the Alarm Limits submenu. If an Absolute alarm or a Differential alarm has already
been triggered for the axle, a Pyrometer Saturation alarm isn't generated. For more
details on the Pyrometer Saturation alarm, see
Appendix G - Predictive Gate
Scanning
.
Carside Slope
. To trigger a Carside Slope alarm, a bearing temperature must meet or
exceed a calculated alarm level and a minimum heat value. The bearing temperature
must also be at least twice the opposite bearing's temperature. If an Absolute alarm or
a Differential alarm has already been triggered for the axle, a Carside Slope alarm isn't
generated. The minimum heat value is established using the
Carside Minimum
option
.
Absolute alarms, Differential alarms, and Pyrometer Saturation alarms are always checked for
by the system. In order for Carside Slope alarms to be processed, they must be enabled
using the
Carside Slope option
on the Equipment submenu.
The SmartScanIS detects and records every Hotbox alarm that occurs. However, it is
physically impossible to have more than one Hotbox alarm per axle per rail.
10.7.1 Bearing Scan Process
Bearing scanners are mounted in the center of the crib of two ties spaced at least 14 inches
(35.6 centimeters) apart. Both bearing scanners are mounted in the crib immediately ahead of
the gating transducers (that is, in the crib immediately to the south or west of the gating
transducers). They are mounted directly opposite each other, one on each rail of the track.
The hole on the top of the scanner covers faces north or east.
Summary of Contents for SmartScanIS
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