How many locos could a train use?

Question

My 6 years old son wants to know if an electric inter-city train achieves 120miles per hour using 2 locomotives, one front one rear, what speed would be possible if four locos were used?

Many thanks

Steve

Answer 1

About the same,  it is traction motor speed that limits the locomotives speed, some HSTs with brand new tyres were allowed to run at over 130 mph, for a record attempt, and some drivers exceeded 130 down Dauntsey bank until the overspeed was altered to work when coasting.  The GNER class 91 electrics are 140 mph capable but the signalling and power supply is not adequate for this speed.

Answer 2

Top speed has nothing to do with the number of locomotives.

Top speed is determined by the maximum authorized track speed, timetable and Form D restrictions, and equipment restrictions - that in addition to the locomotive's gearing and top (over)speed.

So simply put, putting 4 engines on a train may make it achieve better acceleration, and burn more fuel (on a diesel, or draw more current on an electric), and maintain better uphill pull/downhill dynamic or blended brake (in the case of commuter trains) - thats it. Putting 4 or 30 won't allow it to go any faster than the maximum authorized speed.

Answer 3

bless him he sounds really clever! sorry dont know tho!!

Answer 4

Good question - 6 year olds do know how to ask them, don't they?

It wouldn't be 240 mph though!