Diabllo Posted May 7, 2010 Share #1 Posted May 7, 2010 About the wheels that are on all NYC subway trains why is there a white crescent on the wheel? It's been bothering me since I was a kid. Link to comment Share on other sites More sharing options...
m7zanr160s Posted May 7, 2010 Share #2 Posted May 7, 2010 I figure it's for alignment reasons. Maybe it's used to determine wheel slippage. Like how screws have a white mark through them when they are tight. If the screw loosens you can visually tell it has. Link to comment Share on other sites More sharing options...
DOB2RTO Posted May 7, 2010 Share #3 Posted May 7, 2010 I figure it's for alignment reasons. Maybe it's used to determine wheel slippage. Like how screws have a white mark through them when they are tight. If the screw loosens you can visually tell it has. They use yellow now, for the screws......... Link to comment Share on other sites More sharing options...
SubwayGuy Posted May 7, 2010 Share #4 Posted May 7, 2010 About the wheels that are on all NYC subway trains why is there a white crescent on the wheel? It's been bothering me since I was a kid. Are you referring to the painted white "strips" on the wheels (sometimes on the rollers in the center) that visibly spin around as the wheel spins? If so, those are markings so that car inspectors can make sure the wheels are spinning when the car is moving (ie the bearing is not bound up and the wheel turns freely - if it binds up it will drag on the rail and flatten out). Link to comment Share on other sites More sharing options...
Joe Posted May 7, 2010 Share #5 Posted May 7, 2010 Wheels are attached to the axles with a hydraulic press. Only pressure keeps that wheel on that axle...the markings are used to ensure that the wheel hasn't come loose. Link to comment Share on other sites More sharing options...
Eric B Posted May 7, 2010 Share #6 Posted May 7, 2010 I thought they were to mark flat spots. Link to comment Share on other sites More sharing options...
Arby Posted May 7, 2010 Share #7 Posted May 7, 2010 Are you referring to the painted white "strips" on the wheels (sometimes on the rollers in the center) that visibly spin around as the wheel spins? If so, those are markings so that car inspectors can make sure the wheels are spinning when the car is moving (ie the bearing is not bound up and the wheel turns freely - if it binds up it will drag on the rail and flatten out). Exactly. Link to comment Share on other sites More sharing options...
Jah Posted May 7, 2010 Share #8 Posted May 7, 2010 Are you referring to the painted white "strips" on the wheels (sometimes on the rollers in the center) that visibly spin around as the wheel spins? If so, those are markings so that car inspectors can make sure the wheels are spinning when the car is moving (ie the bearing is not bound up and the wheel turns freely - if it binds up it will drag on the rail and flatten out). You're correct! Painted on to make it easy to see if the wheels are spinning free. Link to comment Share on other sites More sharing options...
KTrainExp Posted May 8, 2010 Share #9 Posted May 8, 2010 I have a question. Back in 2003 or 4, there were these protective coverings over the spot where the white crescents were on the R68s. There were also some on the R142s. Why did they have these and what was the purpose of these. Link to comment Share on other sites More sharing options...
Diabllo Posted May 8, 2010 Author Share #10 Posted May 8, 2010 Ahh yes I remember that too. That was going to be another question for me too. Link to comment Share on other sites More sharing options...
R44 5278 Posted May 9, 2010 Share #11 Posted May 9, 2010 The crescents on the wheels serves the same purpose as the swirl marks in jet engines; indicating movement. Link to comment Share on other sites More sharing options...
m7zanr160s Posted May 9, 2010 Share #12 Posted May 9, 2010 They use yellow now, for the screws......... Yeah, you're right, yellow. Link to comment Share on other sites More sharing options...
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