# Thread: trains and ka band?

1. ## trains and ka band?

i know that trains use k band to monitor wheel slip but i was sitting waiting for a train the other day and got a ka band at about 33.6ish...might they be using ka band on some of them?

2. ## Re: false

It might have been a false. Mk

3. I get that too with Southern Pacific trains.

4. ## Re: trains and ka band?

Originally Posted by Mackid343
i know that trains use k band to monitor wheel slip but i was sitting waiting for a train the other day and got a ka band at about 33.6ish...might they be using ka band on some of them?
weird i only have gotten k band but i guess ill keep my eyes open now :shock:

5. ## Re: trains and ka band?

Wheel slip? what's that? I get multiple bogies from trains and above ground subways all the time around NYC Metro area.. I assumed they used it to check distances and for things ahead of the train..

Originally Posted by Mackid343
i know that trains use k band to monitor wheel slip
but i was sitting waiting for a train the other day and got a ka band at about 33.6ish...might they be using ka band on some of them?

6. Since trains use smooth metallic wheels, the friction coefficient is relatively low. The force of gravity on the track is very high of course which negates this somewhat. So it would be nice to know the wheels are turning more or less as fast as the train is...

7. Originally Posted by SmaartAasSaabr
Since trains use smooth metallic wheels, the friction coefficient is relatively low. The force of gravity on the track is very high of course which negates this somewhat. So it would be nice to know the wheels are turning more or less as fast as the train is...
i learn something new every day on the internet......i should have skipped college :P

8. So they use K-band to keep track of how fast the wheels are spinnintg? I don't quite get why or how that would work? Why not measure their RPMs or something? Wouldn't RADAR only work if the wheel's distance from the antenna was changing? Since the wheel is stationary and just moving in a circle... I'm confused still :P

Originally Posted by SmaartAasSaabr
Since trains use smooth metallic wheels, the friction coefficient is relatively low. The force of gravity on the track is very high of course which negates this somewhat. So it would be nice to know the wheels are turning more or less as fast as the train is...

9. Originally Posted by guardian
So they use K-band to keep track of how fast the wheels are spinnintg? I don't quite get why or how that would work? Why not measure their RPMs or something? Wouldn't RADAR only work if the wheel's distance from the antenna was changing? Since the wheel is stationary and just moving in a circle... I'm confused still :P
I really don't know anything about trains, but what I am guessing is that they know the RPMs of the train (which can be calucated into speed) and they measure that to the actually speed of the train. In other words, their speedometer (if they have them) would say 10MPH, but if the wheels were slipping, then the radar would say 5MPH, cause they aren't getting the full power transfer to the track.

For instance, have you ever gotten stuck in snow or ice and you gas it and the speedometer will say 20 MPH, but you aren't going anywhere? That is cause the speedometer is attached to your transmission and measure the RPMs. If you had a radar attached to your car, you could see that you weren't going anywhere.
Again, I am not expert, just makes sense.

10. Bingo! At least that's how I understand it... I may an engineer-type but not in the way of pulling the thing to make the "choo choo"

#### Posting Permissions

• You may not post new threads
• You may not post replies
• You may not post attachments
• You may not edit your posts
•