Temperature scan

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ptonsparky said:
How hard is it to scan wheel bearings for excessive temperature on moving vehicles?

Next, to help with character minimum, how quickly does a bearing go from Ok to meltdown?
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How about an infared tool hung out the window somehow.

My experience is once the bearings are starting to go then they go quickly
 
230219-0835 EST

ptonsparky:

I think if you drove at 70 MPH for a long enough time, which shouldn't be very long, to heat the bearing, and quickly pulled off the road, and used an IR thermometer that the result would be quite good. This is because the is a fair amount of thermal mass in the structure.

Most wheel bearings are not preloaded, or not much. Thus, I would not expect them to run as hot as differential bearings. Typical preload on differential bearings ( axial force has in the past been about 1500 # producing a drag torque of around 10 to 20 #-in ). These differential bearings produce very good life. There was some effort to try to reduce this preload for fuel economy, but doing so produces a greater gear noise problem.

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The brake disk or drum will conduct heat from braking to the wheel hub to which it's attached. And the wheel bearing is typically behind and/or inside of the wheel hub. So it may be hard at times to distinguish an overheated wheel bearing from normal heating due to braking. Immediately after hard braking the outer part of a rotor or drum will be the hottest. But after a while it will equalize and conduct heat to the hub, albeit at a lower temperature than the initial peak temperature.

To determine whether a wheel bearing is bad on a particular vehicle, I've found that it can usually be detected by jacking up the vehicle and rotating the wheel by hand (after putting the transmission into neutral if it's a driven wheel, releasing parking brake, etc.). Any noise, vibration, or drag can be compared with another wheel to identify a bad one.
 
230219-1726 EST

In the old days, like 1940, the criteria for bearing adjustment on a non-driven front wheel bearing was to tighten the wheel nut until you just eliminated any slop, then back off a fraction of a turn to produce very slight slop. Thus, no preload. If you provided adequate lubrication bearing life would be very good.

In 1977 I had 1/2 ton 4 wheel drive F250 that I put over 200,000 miles on and never replaced the front axle wheel bearings. These bearings were slightly preloaded. Maintaining lubrication is the important factor.

The wheel bearing and associated mass has a moderately long time constant such that you could run at highway speed, and down shift to stop the vehicle with very little braking. Then make your measurement.

The other possibility is to build a bracket to hold an IR sensor in a viewing position. Another approach is place a thermistor in contact with the wheel bearing.

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Some of the farmers I know use an infrared thermometer gun to check the bearings on their quadtrack tractors a of times a day.

I was thinking that Burlington Northern has devices spaced along their tracks to detect hot bearings on their railroad cars.
 
A railroad spur ends at my shop from what was the Milwaukee Rail road. There are about 25 miles of track that are now owned by our local port district. I think that is the only trackage still left in Washington from the Milwaukee line. There is a stranded locomotive a couple buildings from my shop. It has plain or journal bearings. Burlington Northern will not allow plain bearing equipment on their tracks. Has to have roller bearings on the axles to be allowed on BN track age.

And yes BN does remotely monitor all trains on their tracks for hot bearings. They can even compare temperatures for a train between monitoring stations and alert the train if they see increasing wheel bearing trmperatures on an individual axle.
 
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