pantograph pressure

how many pounds of pressure does a pantograph apply to the overhead to guarantee a constant electrical connection, given roadbed variances, variances in the wire surface, wind, overhead sag (not as much with constant tension catenary), and not overly stress the carbon tube on the arm?

based on handling pull down pole , I would say about 20 lbs of spring pressure.

Maybe years ago I could give a better answer but 20 pounds pressure with the spring does not seem to me to be enough to account for pantograph bounce, wind pressures and speed. I read somewhere that trolley cars often had around 20 pounds pressure but in this case wind was nowhere near the factor that it would be for MU and electric locomotives. On the New Haven the trolley wire had more ups and downs than on some other railroads notably the Pennsylvania where the electrification was somewhat newer and had better overall clearances. As for the pantograph working slower than one might expect these pantographs were/are spring raised and air lowered. The pan down cylinder is normally under pressure anytime the pantograph is not raised and the equipment in question has air in the system. Most generally the proper way to raise a pantograph would be to release the air in the down cylinder at the same time or right after you unlock the lock down cylinder so the pantograph unlocks while air is still releasing from the pan down cylinder this preventing the pantograph from flying up to the wire which results in a sizable arc and is hard on both the wires and the pantographs. Years ago electric operating instructions were even issued to this effect. In other words the railroads wanted the pantograph to touch the wire gently and not with a bang. I hope I have expressed myself OK on this one. I suspect for the pantograph to have a better ride and contact with the wire 20 pounds might not be quite enough.
Noel Weaver

the M-2 faiveley have a small airfoil to keep pressure even at higher speeds, the air cylinder lowers the pantograph into a pantograph catch.
the catch releases the pantograph when up button is pushed.

Almost certain it's 45 lbs. as to whether that's the spring or the air to bring it down I'm not certain.

45 Lbs seems like hell of lot of pressure on a contact area of 2 inch by 0.06 inch, as contact area to wire is not much larger 2 inch carbon strips and a like about pencil stripe wide.