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| Re: SMEE (Re: Questions from the eager & curious) (860826) | |||
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Re: SMEE (Re: Questions from the eager & curious) |
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Posted by Jeff H. on Wed Nov 18 21:17:05 2009, in response to Re: SMEE (Re: Questions from the eager & curious), posted by BLE-NIMX on Wed Nov 18 09:10:48 2009. The R9 does not keep up its brake cylinder pressure in emergency while a crew istroubleshooting or layed up and will begin to roll away when the leak is found and corrected as they charge in release where SMEE charges brake pipe in full service. Not 100% true. On AMUE systems using the UE-5 universal valve, the "high pressure cap" on the emergency portion of the UE5 keeps Main Reservoir air applied to the brake cylinders until the valve is recharged and comes out of emergency. This is an improvement over triple valve systems where the emergency cylinder pressure comes only from the auxiliary and supplmentary reservoirs, with no input from MR, and thus will eventually bleed down due to brake cylinder packing cup leakage. But, in terms of starting up a car or train which is "dry" AMUE comes up with no pressure in the cylinders. The quick action portion is initially in the non-emergency position because there is no air pressure in the quick action chamber to force the piston over against the spring stop of the quick action slide valve and piston assembly. The SMEE system has a charging protection valve which ensures that as MR pressure is coming up from 0, the emergency slide valve is moved to the emergency position, and air immediately flows to the cylinders. On AMUE, like any automatic air (brake pipe) system, release and charging are the same position. So in recharging after an emergency application, the brakes want to release immediately. But with the electric brake plug or key inserted, one can put the valve in Electric Holding to recharge the system but hold the air in the cylinders. |
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