Diesel Electric Passenger Locomotive Top Speed

[Radek]

Hi,

Yes, the voices in this video are definitely Polish.

Now about speed limits for locomotives.  In 2008 I read in one of British railroading journals (sorry, I don't remember which one) about estimated top speed limits for different types of locomotives in regular usage.  Diesels were supposed to go up to 125 mph (200 km/h), electrics powered by 3 kV DC (like the one on video) up to 150-155 mph (240-250 km/h), electrics powered by 25 kV 50 Hz AC up to 210 mph (315 km/h); beyond that only electric multiple units with all axles powered can go.  Of course, for test runs and record settings some extra speed can be squeezed from all types of locomotives.  

The reasons for the limits are as follow: locomotive has to to propel its own weight and weight of any cars attached.  So EMU can top all locomotive speeds because all its axles are powered and it has best ratio of mass to tractive effort and mass to power. Diesel locomotive has the worst ratio of mass to power, because it has to carry prime mover and fuel.  Difference between electrics powered by 3 kV DC and 25 kV AC comes from amount of power which can be delivered through catenary, i.e. with the same value of current running through the catenary 25 kV network can deliver about 8 times as much power as 3 kV network (exact calculation must include passive power for AC network).

[ndbprr]

Of equal importance is the curvature. Real estate limitations on curvature may limit top speed.

[Deggesty]

zardoz

CNW 511 at 90mph by Jim53171, on Flickr

I was actually doing 103 (38 seconds per mile).

Even at this speed, the locomotive was still generating over 500 amps!

Wait--38 seconds/mile = 95 mph; 103 mph = 35 seconds/mile (divide 3600 by seconds to get spped; divide 3600 by speed to get seconds).

Back in 1964, I was riding IC #4 (the Louisiane) up to Jackson, Miss. I timed one mile above Crystal Springs at 35 seconds--we had two E8's or E9's, RPO, baggage, and three coaches (more headend cars were added in Jackson, and more passenger cars were added in Memphis). The IC had ABS and nothing more on this line.