What percent of the false alarms for each of them?
Where can I read about systems installed on American railways?
I have read brief articles about GE’s HBD, and WILD system.
HBD:
What criteria are given: levels, or degrees?
WILD:
What criteria are given: dynamic overload, or flat length?
Does the WILD distinguish flats and out-of-round defects?
Regards,
Alex
HBD : The detectors can be set to alarm above a certain threshold, or a differential between ends of the same axle. I have see reports that are given in millimeters, which is the amount of deflection of the of the recorder arm, rather than in degrees. It can be set by the railroad on individual detectors.
WILD : It doesn’t measure length of flat spots, it measures wheel impacts, I think it uses an acceleration measure, it doesn’t measure out of round as far as I know.
Dave H.
In my experience as both a conductor and dispatcher I have found that both kinds of detectors give false alarms. I regularly rode on long freights over our one impact detector on the Indy line and I would get a wheel impact about 130 cars deep only to find that particular wheel and the wheels of surrounding cars are just fine. There are two levels of impacts, a level 1 or level 2. Level 2’s are taken seriously and the car is usually set out reguardless of what the conductor finds.
As far as hot box detectors, trains have been stopped for what is thought to be no problem. But, if a train is stopped two times for the same axle the car or engine is set out without question.
When it comes to detectors it’s better to be safe than sorry. If something is indicated and it seems border line; as in the wheel is warm, but doesn’t melt the temple stick, OR there is a small flatspot on the wheel but below the prescribed size to set the car out I’m usually going to have to the crew set the car off because you never what could happen down the road. It would also look really bad if a derailment were to occur and then it’s documented that no action was taken to correct the situation.
I don’t have exact figures on false alarm rates for either one, but they are relatively low. As n_stephenson said, it’s much better to safe than sorry.
Wheel impacts are problematic, in that it is sometimes difficult to see a flat spot which sets the alarm off. However, a wheel which is giving a high impact is a definite danger – rails do break under impact, and that’s a short cut to immediate trouble.
Hot box detectors are by no means perfect. When they first came out, the most frequent problem which they were looking for was a hot box – a friction journal which, for some reason, had run out of oil and was heating up. They heated relatively slowly, and failed even more slowly (although they did it fairly frequently). Now pretty much everything is roller bearings. While roller bearings fail much less often, they fail – when they do – much more quickly, which is why if you get two alarms on an axle, set it out. They also don’t smell, don’t produce visible flame – and may not even get the cover that hot on the way to la la land (which means a failing bearing can be very hard for the trainmen to find). It’s worth remembering, too, that they won’t pick up sticking brakes (particularly inside disc brakes!) or failing traction motor bearings and the like…
UP must not have any flat wheel detectors, there is rarley a train that goes by that doesnt have atleast 1 flat wheel on it
Thank you for your explanations.
In the SmartScanNG (HBD) documentation I have read that the Alarm Limits must be set. Who is authorised to set the limits?
Does every railroad produce its own “defect detection policy” or it is regulated by FRA?
n_stephenson,
About setting car out of a train. It’s not easy, since the journey time will being increased.
In Russian Railroads there are penalties for ungrounded delays.
Does railroad send claim to HBD producer in case of false alarm (no melting of templestik)?
It seems in this forum I have read about caboose elimination. Who is now inspecting bearings and wheels?
Amusin…
Generally the railroad sets the alarm limits for its detectors. Further, the procedures to be followed once a detector sounds off vary by railroad (believe it or not, on my old show the HBDs and WILDs are monitored in central Canada. Also believe it or not, the system works…).
Quite right about setting a car out of a train. It’s a nuisance and will delay you. On the other hand, the same could be said for a derailment…
As far as I know no railroad would send a claim to the HBD manufacturer. Too many other variables. They’d probably have to sue, and who needs that?
Who is now inspecting bearings and wheels? Other than roll-bys, which is everybody’s responsibility? You get an alarm, the conductor gets to take a hike…
Jamie,
Generally the railroad sets the alarm limits for its detectors. Further, the
procedures to be followed once a detector sounds off vary by railroad (believe
it or not, on my old show the HBDs and WILDs are monitored in central
Canada. Also believe it or not, the system works…).
We have the same technology. A database replication allows it.
Quite right about setting a car out of a train. It’s a nuisance and will delay you.
On the other hand, the same could be said for a derailment…
Exactly! But our officers do not keep in mind that!
As far as I know no railroad would send a claim to the HBD manufacturer. Too many other variables.
I only know the math term “variable” :). What is meaning in this case?
They’d probably have to sue, and who needs that?
For example, to return the losses because of delay.
Who is now inspecting bearings and wheels? Other than roll-bys, which is everybody’s responsibility? You get an alarm, the conductor gets to take a hike…
It’s now clear. Thank you for the answer.
Alex.
Let me just add a couple things here in regaurds to my job as a Carman on CSX up here in Ohio. We call it a Wheel Impact Detector. It measures in what they call Kips. They have a Level one & level 2 readings. Level 2 means the car has to be set out & that wheel or wheels have got to be changed, which is what I do. But our Mechanical Dept. has what we call a rocker gauge to check these Out-of- Round conditions . We used to come out & check them in the train, but they changed that to where they just set it out now, or can continue on to destination at only 30 MPH, or the nearest siding. Lately we have been changing an average of 10 to 12 wheels a week. Thanks, John
John,
We call it a Wheel Impact Detector. It measures in what they call Kips.
kips is an abbreviation of “kilo pounds * g” (g - acceleration of free fall).
In Europe the kN (kilo Newton) unit is used.
Lately we have been changing an average of 10 to 12 wheels a week.
In that case when do you ride? 
Thank you.
Alex
Hi Alex, I really don’t ride the trains anymore. I used to back when I first hired out & worked on a steam wrecker. I’m in the Mechanical Dept. My job title is Carman, better known as the old term, Carknocker. I work on a repair truck, & change wheels & make repairs in a shop & on the road. We carry 2 wheels & jacks, & other tools along with air for working on the breaks, & a welder. Thanks for that abrv. of Kips. John