YES THE SECURITY THING CAME UP ON ME.I’M NOT YELLING I JUST CAN’T TYPE !
TRY TO CONVINCE SOMEONE WHO LIVES ALONG THE TRACKS THAT THAT BLUE SMOKE ISN’T HAZARDUS.
To amplify just a little bit – it is possible for the brake travel to be sufficiently long to affect the braking effort, but only if the brake rigging is WAY out of whack.
And the pop up is someone on this thread has a server which does not provide the proper certificate for a picture… usually not a problem.
And under the proper conditions a brake shoe can heat up enough, and thereby transfer enough heat to the wheel, for the wheel to come off the axle! Big problems then. Luckily it doesn’t happen often.
zardoz - this does not sound right.
Trains are braked by controlling the pressure in the brake line.
You are confusing train air brake operation with automotive hydraulic brake operation.
With hydraulic brakes, the shoe or pad rest against lightly the drum or disc, so the travel distance for the brake shoe is far less than the distance the piston can travel, which gives you infinite variable pressure, the harder you pu***he pedal, (apply pressure) the more pressure you apply to the shoe, the faster you stop.
With train brakes, you have a fixed distance the piston can travel, and a fixed number of reductions (pressure) you can apply.
The reason for this is because with hydraulic brakes, you are only stopping one vehicle, with train brakes, you are stopping several, and each one acts different…its not the single application of one set of brakes that stops the train, its the cumulative total of all the brakes on all of the cars.
If the pressure on one car was far in excess of the others, you can have a mess real quick…
Next time you get the chance, look hard at the brake rigging diagram plate on a rail car…note it involves brake beams, levers and rods, which translates the piston travel into braking force.
The piston has a limited distance it can travel; I believe it is 6” max.
Because each wheel does not have its own piston, but uses the mechanical rigging to allow one piston per car to apply all the brakes on that car, you have to allow some play in them, because each axel has a brake beam across the car, wheel to wheel, and it has to be able to pivot and self adjust to “seat” against the wheel tread.
If it didn’t, it would not only lock the wheel set and make it slide, but it would lock it in a straight line with the car body, and if you’re in a curve, your wheels and trucks have to be able to pivot on the king pins.
To make up for some of this play, brake arms have a adjuster, which allows you to set the distance from the brake shoe face to the wheel tread on each brake shoe, so all the sho
In modern railroading, with 40 years actual experience in it, I have yet to hear of this be a cause of an incident; that being said in Steam Locomotive days, the tire (containing the flange and the surface that contacts the rail) was shrunk fit on the wheel center of the drivers. Extended use of the locomotive brakes could cause the tire to heat and expand and come off the wheel center and become the cause of a major delay, if not a catastrophic derailment…
It has been known for imporperly mounted wheels to come disengaged from the axle, however.
I don’t think so…
Virlon
save your ticket… the P.E. will rise again.
I
Back in olden times when I worked the BN train from Pullman Wa***o E Lewiston Idaho we had a REALLY stiff grade getting from the high Palouse country down to the Clearwater River. W/ a fairly heavy train we would sometimes have to stop and let the wheels cool. Now those things were so hot they not only smoked but changed color. They were about the color of a new, brightly blued gun. We never had any wheels fall off though.