Axle bearings are among the components of rail vehicles subjected to highest loads.
Defective roller bearings or insufficient lubrication lead to dramatically increasing operating temperatures and as a consequence inevitably to axle-journal fractures with derailing of wagons. Slide bearings heat more slowly in case of insufficient lubrication compared to roller bearings, however the damage caused in the end is the same.
Blocked brakes over a long distance lead to inadmissible heating of the running surfaces of the wheels and consequently to changes in the structure and high wear. Quite frequently red-hot running surfaces of wheels of rail vehicles can be seen caused by blocked brakes.

HOA and FOA automatically check the condition of axle bearings and blocked brakes of running trains.

This system is installed on rails or in a steel hollow sleeper and is designed in such a way that it collects temperatures of different types of axle bearings, like roller bearings, slide bearings and wheel sets.
The hot-box and blocked brake detection system, VAE HOA/FOA 400, is a contactless, stationary thermometer for axle bearings and wheel sets of rail vehicles which can pass the measuring spot at up to 400 kph. A specifically designed scanning procedure, permitting the scanning of axle bearings in the direction the train is running, particularly for the HOA, which in turn guarantees that the hottest spot of the axle bearing for all different types of bearings and for the highest train speeds is securely recorded and the absolute temperature of the axle bearing is measured. This is one of the most significant improvements in comparison with conventional systems.

In addition to the HOA or as a stand-alone system an FOA can be installed, which measures the temperature of wheel sets of up to 650°C and therefore locates blocked shoe brakes (optionally, also over-heated disk brakes).

VAE HOA/FOA 400, fastened to rail

System layout

• Scanning procedure allows scanning of complete axle bearing
• Double Scan – 2 scanning areas possible, one inside and one outside at the axle bearing
• Minimum 120 temperature measuring points
• Exact measurement of absolute axle bearing temperature
• Patented measuring gate element – accurately switching rail contacts to exclude external heat sources
• Single and double track variants
• Single and dual direction operation
• HOA and FOA scanner can be installed in a sleeper
• Modular design (scanners can be supplied separately)
• Self-diagnosis, maintenance once a year
• Patented axle-counting system
• Wagon and train identification through measurement of distance between axles for adaptive alarm level assessment
• HOA system with wagon identification system (metros)

VAE HOA/FOA 400, fastened to rail

VAE HOA 400 DS for HOA Measurement Double Scan, arrangement in the sleeper

Oscillating tilted mirror

VAE HOA 400 DS for HOA Measurement Double Scan, arrangement in the sleeper

VAE HOA 400 DS for HOA Measurement Double Scan, arrangement in the sleeper

VAE HOA 400 DS for Double Scan, arrangement in the sleeper during winter operation

System cabinet in detail

Screenshot of evaluation software at the central station

HOA/FOA Scanner:

Usable train speed 2 to 400 kph
Measuring principle Scanning system with 2.4 kHz
Measuring range of HOA scanner 20°C to 150°C*
Measuring range of FOA scanner 80°C to 600°C*
Temperature range of operation -30°C to +60°C
Approvals EMC: EN 50121-4

Environment: IEC 68-2-1, 2, 14, 30

Mechanical:

shock: vertical, 100g, 60 sec.
Oscillation: sinus, 50g, 60 sec
Housing Double-walled, cast aluminium housing, the innermost chamber is hermetically sealed.
Locking system Electro-magnetically operated shutter, monitored in both end positions.
Signal transmission Digital
Connection Cable with special external sheath, MIL plug IP66
Automatic calibration Adjustable temperature probe, mounted below scanner shutter, 30°C to 150°C
* other measuring ranges on request 

Wheel Sensors:

Usable train speed 2 to 400 kph
Minimum wheel diameter to be acquired 230 / up to 600 mm
Operating temperature range -30°C to +80°C
System of protection IP67
Insulation voltage relative to rail 3.5 kV max. value
Distribution supply 12 VDC
Fixation On the rail web or the rail foot by means of a dog, adjustable to the type of rail
Connection A neoprene sheathed cable, cast-in connection with bolting PG11
EMC:EN 50121-4

Environment: IEC 68-2-1, 2, 14, 30

Mechanical:

shock: IEC 68-2-27
oscillation: IEC 68-2-6

System Electronics/ Software:

Power consumption
for single track variant Stand-by without heating: 300 VA
Passing train with heating: 1830 VA
Power consumption for double track variant Stand-by without heating: 450 VA
Passing train with heating: 3300 VA
Distribution voltage 230 V, 50 Hz ? 10%
Master fuse 16 A
Connection system circular connector
Ambient temperature 0° - 50°C
Ventilation internal: rack ventilator in continuous operation
external: filter ventilator if required
UPS minimum 10 minutes of autonomous time
System of protection IP 43
Approvals EMC: EN 50121-4
Environment: IEC 68-2-1, 2, 14, 30
Central station Software for data analysis and alarm handling for client/server or stand-alone system
Wagon and train identification Via measuring of distance between axles for adaptive alarm level assessment

Mounting of the Scanner on the Rail:

HOA Scanner FOA Scanner Axle Counter Axle Counter for Measuring Gate System Cabinet Supply Cabinet
Module G1 One direction, one track 2 1 1 1 1
Module G2 One direction, one track, with FOA 2 1 1 2 1 1
Module G3 One direction, two tracks 4 2 2 1 1
Module G4 One direction, two tracks, with FOA 4 2 2 4 1 1
Module G5 FOA addition second track side 1 Extension Extension
Module G6 Addition for two-directional operation on one track 1
The following components are available as an option:
Hardware:
3 Phase isolation transformer
Modem cabinet for outdoor installations
Operating elements for outdoor installations consisting of 15" TFT screen and 19" keyboard
15" TFT screen for central station
Non-switched line modems for data transmission to central station
Switched line modems, for fixed net or GSM, for remote maintenance of outdoor installations and central station
Software:
MS-DOS central station for up to 2 outdoor installations
WINDOWS-NT central station with Multiport interface card for up to 64 outdoor installations (server option)
Waggon identification system (Transponder-Tags, Reader)
Waggon and/or train identification via axle distances

Mounting of Scanner in Hollow Steel Sleeper:

HOA Scanner HOA Scanner DS FOA Scanner Axle Counter Axle Counter for Measuring Gate System Cabinet Supply Cabinet
Module S1 One direction, one track 2 1 1 1 1
Module S2 One direction, two tracks 4 2 2 1 1
Module S3 One direction, one track with double scan 2 1 1 1 1
Module S4 One direction, two tracks with double scan 4 2 2 1 1
Module S5 One direction, one track, FOA mounted in sleeper 2 1 1 2 1 1
Module S6 One direction, two tracks, FOA mounted in sleeper 4 2 2 4 1 1
Module S7 One direction, one track, FOA mounted on rail 2 1 1 2 1 1
Module S8 One direction, two tracks, FOA mounted on rail 4 2 2 4 1 1
Module S9 One direction, one track, double scan, FOA mounted in sleeper 2 1 1 2 1 1
Module S10 One direction, two tracks, double scan, FOA mounted in sleeper 4 2 2 4 1 1
Module S11 One direction, one track, double scan, FOA mounted on rail 2 1 1 2 1 1
Module S12 One direction, two tracks, double scan, FOA mounted on rail 4 2 2 4 1 1
Module S13 Addition for Module 7S, 8S, 11S, 11S, 12S, FOA addition second track side, for mounting on rail only 1 Extension Extension
Module S14 Addition for two-directional operation on one track 1
The following components are available as an option:
Hardware:
3 Phase isolation transformer
Modem cabinet for outdoor installations
Operating elements for outdoor installations consisting of 15" TFT screen and 19" keyboard
15" TFT screen for central station
Non-switched line modems for data transmission to central station
Switched line modems, for fixed net or GSM, for remote maintenance of outdoor installations and central station
Software:
MS-DOS central station for up to 2 outdoor installations
WINDOWS-NT central station with Multiport interface card for up to 64 outdoor installations (server option)
Waggon identification system (Transponder-Tags, Reader)
Waggon and/or train identification via axle distances