Air Pressure

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Air Pressure

Unread postby Stinger4me » Mon Jan 01, 2018 8:32 pm

If anybody can answer this question, Has the air brake pressure for passenger trains and freight trains always been the same? I seem to recall freight trains using 72 lbs. of air to release the brakes. This was back about '67 or '68. Am I hallucinating?
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Re: Air Pressure

Unread postby SD80MAC » Mon Jan 01, 2018 8:37 pm

Passenger trains use 110 lbs and freight trains use 90 lbs. A typical freight train needs at least 75 lbs of air pressure in the brake pipe before conducting a brake test, according to the FRA.
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Re: Air Pressure

Unread postby SousaKerry » Tue Jan 02, 2018 10:21 am

In the past pressures were indeed lower. Don't quote me on dates but at one time passenger was 90 and freight was 75-80, I think sometime before the 50's perhaps back in the 30's. A lot of older switcher locomotives will not go above 90 PSI on the brake pipe without modifications to the brake valves. I know a certain 44 tonner that won't go above 95 PSI screwed all the way in, that is a 14L brake system.
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Re: Air Pressure

Unread postby barnstormer » Mon Jan 08, 2018 6:03 pm

SD80MAC wrote:Passenger trains use 110 lbs and freight trains use 90 lbs. A typical freight train needs at least 75 lbs of air pressure in the brake pipe before conducting a brake test, according to the FRA.


That is really close....To perform a class one/transfer brake test, the rear of the train (EOT or other air gauge) must be pumped up to within 15 lbs of the regulating valve on the head end locomotive, before the test can begin. Then the test may be performed, once a signal to start the test has been received, following other required protocol, such as verifying the amount of leakage, or having a 100% set of the brake on all cars, for compliance with the FRA power-brake law. that is why some of those 2-3 mile long trains don't do so well in such freezing temps.....takes FOREVER to get enough air just to do the test. (I once waited for 1 hr- 45 minutes to get my test completed on 220 cars!

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Re: Air Pressure

Unread postby Schteinkuh » Wed Jan 10, 2018 4:10 pm

SousaKerry wrote:I know a certain 44 tonner that won't go above 95 PSI screwed all the way in, that is a 14L brake system.

I know a certain 50 tonner that..... okay I'm better off not even starting.
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