I have just finished watching a very interesting DVD on the Southern Pacific’s operations over Donner Pass. All of these very looooong heavy freight trains had at least 4 or 5 SDs on the front of the train with usually a couple of pushers at the rear.
I am just wondering how these locos are synchronised so that they all push or pull equally. I guess the ones at the front are connected by hoses/cables etc and controlled from the very front loco so that throttle and brakes all acted together. Were the pushers at the rear also connected by cable or hoses running the full length of the train?
Can’t answer your question. Just noting my interest to get on the reply list.
I think there is no connection to the rear except for radio. I watched a show on TV that indicated that. A review of a major accident where they had grossly overloaded the train and the locos could not hold it on a downhill run. Resulted in a fatal pile up at a curve down the hill at a town in California that I forget the name of. The engineer in the front engines could not control the helpers at the back in that set up. But it was quite a few years back.
Our operation uses the CANAC radio system from Canada. We control the rear loco from the lead cab with a “black box” control console in the loco. We can control the sand, horn, brakes, dynamic brakes, etc. with the box and the throttle is automatically controled by the throttle on the lead loco. We have 4 antennas on each loco mounted on each corner. Response time varies depending on terrain. For example if you are approaching a tunnel and need to adjust speed or dynamics it’s best to do it before entering the tunnel. Most functions on the box are marked with an LED except the brake pressure and amps which have LCD readouts. All in all a very good system.
Maybe I missed something somewhere, but I thought that helper locomotives were usually manned by a crew, in our day and time, an engineer and brakeman/conductor.
Depends on the era you’re talking about. If you’re talking about brand new SD-9’s in 1954, there would be one crew running the front engines and another crew running the rear engines. Radio control of pusher units was around back to maybe the late sixties but didn’t really become common until maybe the eighties. (Seems to me some railroads tried it, then got rid of it because it didn’t work, but later went back to it.) There wasn’t a way to connect the engines thru the cars like the brakeline or anything.
Actually, the Cajon Pass runaway had a crewed helper on the rear. Investigation of the accident turned up a whole bunch of equipment issues, “guesstimation” of the tonnage (the cars hadn’t been weighed,) miscommunication and, ultimately, human error. When the rear end engineer went for emergency air he turned the whole train into a big steel toboggan, with the inevitable result.
The real disaster actually happened days later, during the cleanup. A heavy equipment operator scooping up the spilled cargo dug too deep and punched a high pressure gasoline pipeline. KABLOOIE!!! Human error in that one, too - the pipeline controller sped up the pumps in reaction to the falling pressure!
Murphy had not one, but two field days. Unfortunately, innocent bystanders bought the farm in both.
Also, I hear that the reason why some of the SD40-2’s (and 40T-2 Tunnel Motors) on the UP and SP had an extra-long “snoot” nose was because of the remote control equipment. Can anyone confirm?
I guess that’s one good way to utilize all that extra porch space on the SD40-2! [:D]
The snoot noses were for housing the radio control (“Locotrol”) equipment. Tunnels and hills block radio waves. Some systems have repeaters in tunnels to help out, but losing communication with the remotes was a big problem. The newer systems are called Distributed Power (DP). They have gotten some of the bugs worked out, but until there is a cable running all the way thru the train, there will still be radio issues.
The porches on SD40-2s are nice. It gives you a place to set your grip and lunchbox while getting on/off. Gives the relieving crew somewhere to set their stuff as well.