SMEE?

[SubwayGuy]

Other notes from this thread:

 

R-44s are not compatible with any other subway equipment due to higher brake pipe pressure (130 lbs) like Joe said

 

R-46s are not compatible pneumatically because of different couplers than all other cars except the R-44. However, the R-46 brake pipe pressure is 110 pounds so it is also incompatible with the R-44 (130 lbs.)

 

SMEE has generally been understood by car MANUFACTURERS and air brake COMPANIES to mean Straight-air Motorcar Electropneumatic and Emergency

 

Transit still distributes materials claiming it stands for Self-lapping Mechanical Electrical Equipment.

 

Engineers will swear by the first one, while train crews are taught the second. In either case, they refer to the same thing - a self lapping brake which is simple to use and electrically controlled simultaneously throughout the train for a smooth application. I've written a longer more detailed explanation of how the SMEE system works almost 18 months ago that you can dig up if you'd like to find but I don't have the time at the moment. Maybe in a week or so when I return from vacation.

[SubwayGuy]

SMEE is a braking system not a propulsion

 

I do need to add a explanation to this sentence as it's not entirely 100% technically true. SMEE braking systems are also tied in somewhat to the propulsion in the sense that the switch group (propulsion control) is involved in dynamic braking. This is explained more thoroughly in the other post which I reference above that I will post at a later date (unless someone has it bookmarked and wants to beat me to the punch for extra credit...and by extra credit I mean for nothing at all).

 

But as a general rule when you are talking about SMEE you are talking about the braking system, not the propulsion control. The propulsion control type is determined by the switch group type, for instance GE switch groups can be of the category SCM, MCM, PCM, PC, and so on. However even that is not accurate because switch groups are very difficult to identify exactly. Many different types fall into each category so that when replacing a group assembly one cannot simply say "this car takes an MCM group" and be assured that the first MCM group they find is a suitable replacement.