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Posted by BLE-NIMX on Sun Apr 23 11:35:48 2006, in response to Re: SMEE, posted by tracksionmotor on Sat Apr 22 22:57:11 2006.

Peter thats the second post you said the SAP goes as high as 150. That sounds like main reservoir, not straight air. The spotting wire in emergency will flow feed valve air into the SAP when the CCO is on and the reversor key is in direction. Once the emergency contactors and car valves are in agreement, the regulating pneumatic and pendulum finger portions of the ME42/43 serves to regulate the SAP to about 70 and giving variable control over it as well to brake and release. R44 and R46s (I ran those too with stripes) had common main reseroir pipes. Their equipment read BC with inshot, BP (which indicated the car's own MR since there was no feed valve) a jewelled idiot light for snow and handbrake and the never to be forgotten P-Wire Ammeter, half an amp for release and zero amps for emergency. The R46 had a second SCM group box for dynamic braking.
Jeff can correct me here as far as freight goes, each railroad car has a 3 port reservoir system known as ABDX storing two ports of maximum pressure (one for emergency air and one for controlling brake air, both at 90 PSI, all charged from the brake pipe, and one port which samples and references the air in the brake pipe as it rises or lowers dependging on the engineer actions in the cab. If the BP falls slowly (LE applying brakes) the valves inside will unport and flow stored control air to the brake cylinders until control air and BP are equal, thus the valve will seal the BC port and thus self lap. When the air rises (engineer releases) the BP rises, forcing the port valves to recharge the air in the tanks and vents the BC piping. All the while, the emergency air does not fall below 90 during BP reduction until a rapid reduction in brake pipe is detected which will initiate an emergency brake application. I don't know of any springs on freight cars. The work trains in TA had some older 100 numbered flat cars which had one big brake cylinder with push rods mechanically applying the brake shoes with some heavy springs on them to assist in releasing the brakes and most clasp type cylinders need about 5 PSI to overcome "release springs". THats my 101, now back to the show.

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