Bluford hopper screech....

[randgust]

If you've been in N scale long enough, you'll remember Con-Cor and their cars.  In the Rapido coupler days, every once in a while you'd get a car that had a distinct .....SCREECH..... down the track.   It came from the Rapido steel coupler spring coming into contact with the metal axle.  True design flaw.  You'd fix it by distorting the spring right above the axle to clear.   Those were the days....

I haven't heard that sound for years, so imagine my reaction to my right 'out of the box' 3-pack of Bluford PRR 2-bay hoppers, absolutely beautiful cars, going into a 13" radius curve....SCREEEEEEEEE........   Hmm.  Memories going back to when I had hair.

Thought it was the wheels scraping into the bays, did some modifications, finally found it.   It's the axle coming into contact with the steel coupler pocket screw.  Seemed to be related to my superelevated curve, but yeah, the axle was touching the screw.

Ended up adding a Micro-trains nylon washer, that was too much, took some off of the bolster to gain only .010 or so, works fine, dead silent now.   But darn, again, on beautiful equipment, does anybody ever test this stuff on a real layout?

[C855B]

I had the same problem with several Tangent hoppers. Both cases might be a factory problem, substituting a round-head screw when countersunk was spec'ed.

[thomasjmdavis]

I find this surprising. I've never had this issue with any of the couple dozen 2 and 3 bay hoppers I have.  I pulled one out of the box just to check, I couldn't force the axle to touch the screw head, without popping the bolster pin loose. With the axle down as far as I could push it, I could slide in a piece of 0.010 styrene between the axle and screw head.  I wonder if they have either changed screws -mine have black, phillips head, 00-90 (I assume, but tiny, that are almost perfectly level to the coupler box cover...or they have changed something else.

Out of curiosity, which of the several styles (USRA, war emergency, etc) are your hoppers? Now you have me wondering if some of my newer ones, that haven't seen a layout, might exhibit this issue.

I see C855B's response- yes, if you have round head screws, that would be the problem.  Most of my hoppers are early runs of C&EI, and they all have flat-head screws.

[chessie system fan]

Out of curiosity, which of the several styles (USRA, war emergency, etc) are your hoppers? Now you have me wondering if some of my newer ones, that haven't seen a layout, might exhibit this issue.

I thought they all had the same underbody piece?

[thomasjmdavis]

I thought they all had the same underbody piece?

I don't think so. The USRA hopper is about 4 scale feet shorter than the offset-side hopper- so it's underbody is also shorter. (I just checked). I haven't checked every style one against another, but certainly those 2 are different.

[randgust]

Car ID is Bluford Shops 60103 USRA 30'6" 2-bay hopper Pennsylvania.

I love the cars, even more when I raised the trucks about .010.   There is a tiny steel Phillips screw on the coupler pocket that looks like a conventional flathead, but is not flush with the pocket surface at all, it's probably elevated .010-.015.

I was tempted to attempt to just grind the screw down, but doing that to a steel screw would create enough heat to melt something.

[garethashenden]

Would it be possible to remove the screw and countersink the coupler lid a bit more? So that the screw can sit into it more.

[thomasjmdavis]

The coupler box covers on the one I just checked are countersunk. That might be the issue- given it sounds like the screw isn't seated properly.

[C855B]

... There is a tiny steel Phillips screw on the coupler pocket that looks like a conventional flathead, but is not flush with the pocket surface at all, it's probably elevated .010-.015. ...

Yes, I looked tonight and stand corrected on the Tangent hoppers, as well. They are indeed countersunk flathead screws sitting slightly proud from the coupler box. I fixed a couple of bad ones on the first batch I bought by deepening the countersink, but I'm holding off doing the remaining 22    to see if I can retrofit MTL True Scale couplers.

[turbowhiz]

Yes, I looked tonight and stand corrected on the Tangent hoppers, as well. They are indeed countersunk flathead screws sitting slightly proud from the coupler box. I fixed a couple of bad ones on the first batch I bought by deepening the countersink, but I'm holding off doing the remaining 22    to see if I can retrofit MTL True Scale couplers.

If you're a little patient the N-Possible coupler should drop right in to your Bluford hoppers with absolutely no modifications at all, if the box construction matches their 3 bay offset hopper which I've verified. Will be a whole lot easier then adapting TSC's, and will work a whole lot better too!

[southernman]

I have about 20 fox valley silver sides that used to do this exact thing.

[randgust]

The clearances were so subtle on that problem that the only time it would screech was going into a mildly superelevated curve.  On tangent or a flat curve. silent.  So I can see how this would pass 'QC' tests as long as it wasn't test run on anybody's layout.   A washer add alone was really too much as it messed up the coupler height, I carved of the bolster dead flat and then added the MT washer, figure the net gain was .010, and the coupler height was still fine.

It looked to me like a thin flathead screw rather than a countersunk bevel head, I didn't attempt to drill it any deeper as the overall clearances on everything, the wheel flanges into the bays, the wheel flanges into the frame reinforcements - all were all just murderously tight.  At first I thought it was the actually wheel flanges scraping into the bays as there were visible marks on the bays from the flanges rubbing into them.  I took one car and actually carved out the bays to increase clearance (where you really can't see it) and.... it still screeched.  Didn't stop until I raised the trucks a hair.

It's all good now,