Speed matching on the prototype?

Model Railroader General Discussion (Model Railroader)
1

I have been thinking about this for while. With DCC we can speed match different locos, but how do the prototype solve this with maybe 10 locos?

2

Good question! I have no idea.

3

It’s built into their MU - Multiple Unit equipment. It’s been around since before computers, so I assume it’s done in another way. Standard on most diesels.

Bob Boudreau

4

Actually it is not that complicated. The throttles are coordinated through the MU but locos vary because of age, horsepower, tuning etc. They all work together because of the laws of physics. Think of your company picnic tug-of-war with big guys , little guys, women and kids on the rope. They all pull at different levels but get the job done. Each loco conytributes to the total power required.

5

Use Decoder Pro (it is free) and speed match you engines by adjusting the CV’s to make the engines run at the same speed. No which manufacturer or engine you use, they will all run at the same speed. Works great.

6

That’s great, but the original poster asked “but how do the PROTOTYPE solve this with maybe 10 locos”. This has been answered by following posts.

Bob Boudreau

7

SPEED MATCHING ON THE PROTOTYPE: The real engines have 8 basic throttle positions. Each position is a pre-set engine RPM. This matches up most engines that are ‘geared’ similar. If the lead engine is geared for 65 mph, and the unit behind it is geared for 83 mph; then it is possible that the trailing engine may overwork. This is because the minimum continuous speed for that trailing unit is higher and it may be operating in the ‘red zone’ without the engineer knowing it - A fried electrical system may be the outcome. The engineer may also notice that the trailing unit is ‘pushy’. With the ‘faster’ engine in the lead, you still have an issue if it is pulling the slower unit past it’s maximum speed and it alarms out and/or shuts down. Overspeed on the traction mortors under heavy load can ‘birds nest’ the windings. Most modern engines are geared in the 70-85 mph range, and the AC locomotives do not have windings to fly apart at speed. Most modern DC locomotives have ‘power reduction or limiting’ built in.

Jim Bernier