no more passenger B-units

I'm sure it probably because of newer technology, and more powerful engines, but I've been wondering why there are no Cab-less engine car "B-units" for the F-40's and P-42's, like the FPA-4's, FP9's and FP7's? When a longer train needed more power to pull the consist they had an A-B-B type of set up, but now they all have 3 "A-units" in a row...

VIA moderator's note: topic moved to Locomotives, Rolling Stock, and Equipment since it isn't specific to VIA Rail.

It's a question of flexibility. B-units are not flexible, because they can only be run behind an A-unit and cannot power a train independently. Their main purpose in previous decades was to blend in to the rest of the train and to eliminate the cost of an additional set of controls. They were also partly a holdover from the FT era--many EMD FT's consisted of an A-unit and a B-unit that were drawbar-connected and that shared various systems, making it impossible to run one without the other.

Today, operations trump appearance, and having a bunch of locomotives that are restricted to trailing-unit-only status would be a big handicap. BNSF has discovered that with their GP60B's, which were initially purchased in order to save on the cost of an additional set of controls. These units are now being retrofitted with standard cabs, turning them into GP60's.

The other issue is that a P42DC has almost three times the horsepower of an F-unit, which means that a much larger proportion of the trains can be powered by a single unit.

A Winton (EMC) 201 series Diesel engine was rated around 900HP for a 12 cylinder unit (IRM has one)

An EMD 567 series Diesel engine was rated around up to 1750 HP (depending on cylinder and time manufactured)

An EMD 645 series in a GP-38-2 ran around 2000HP.

An EMD 710 running 16 cyliners is 4000HP.

I see, on the BNSF (ex CB&Q) mainline KC-Lincoln coal trains running only 1 lead and 1 pusher unit (granted, that's in the Missouri River flatland.

Does this help?

Agreed. There are too many variables to having an A-B scenario. If the A unit has a safety defect/mechanical issue en-route between Chicago and Oakland you are pretty much hosed. While it does not happen very often, you will find that the leader needs to be swapped out with the second motor. There are not enough Amtrak motors to have "spares" throughout the system and the cost of adding foreign power to the head end to get the train to the final destination is quite costly.

Better to have to primary movers instead of being "stuck" somewhere waiting for help.

warwgn3 wrote:I'm sure it probably because of newer technology, and more powerful engines, but I've been wondering why there are no Cab-less engine car "B-units" for the F-40's and P-42's, like the FPA-4's, FP9's and FP7's? When a longer train needed more power to pull the consist they had an A-B-B type of set up, but now they all have 3 "A-units" in a row...

VIA moderator's note: topic moved to Locomotives, Rolling Stock, and Equipment since it isn't specific to VIA Rail.

Originally, there was some concern that the unions would demand that every diesel locomotive cab be staffed with an engineer and fireman, hence the origin of B-units. Today, there's no need for a B-unit, as it would sacrifice so much operational flexibility, while saving very little money by deleting the cab and associated controls. Truth be know, B-units should never have been produced to begin with, although again, there was some fear of unions and since early diesels were much less powerful, there was need for more booster units.

That is a good point. In the steam era, every steamer had an engineer and a fireman. Don't know about early paired electrics, though.

I can see the railroads' concern, in the Depression era, about multiple crews...

In the days of steam-heated passenger trains, a steam-generator-equipped B unit could be added behind a lead unit that was not equipped to produce steam, thus taking care of that problem. For example, when the F40PH-2 was first introduced on VIA Rail, it was common to see a steam-generator equipped F9B behind the lead F40, to supply heat for the steam-heated cars.

This problem could also be solved by the use of Steam-generator cars, a much less-costly alternative. The only added benefit to using a B unit for steam was the extra power, but in the case of the F40PH, most of the trains in question could easily be handled by a single unit, making the addition of a B-unit as opposed to an SGU just to provide steam an unnecessary addition.

Well, since steam is long dead as a heating source for most US passenger operations, that reason for having B units is off the table.

John_Perkowski wrote:Well, since steam is long dead as a heating source for most US passenger operations, that reason for having B units is off the table.

Well, except for HEP (Head End Power). The Ontario Northland uses some B-units exclusively for HEP, with the PMs and traction motors removed, since they're using standard GP-38s. Of course, an old A-unit would be even more useful, since you could use it for HEP as well as push-pull, with the LIRR being a past example.

Then its no longer a B-unit but a HEP power car.

Very rarely does a passenger train run with more than one unit. Today, Amtrak wants a single unified fleet that can be used anywhere for anything.

P&W has a few freight B units, not sure if they were designed that way, or if they are wrecks that had their cabs removed. In that case, they use 4-axle power so 4+ locos is not uncommon, and a few B units floating around starts to make sense.

GP40 6694 wrote:P&W has a few freight B units, not sure if they were designed that way, or if they are wrecks that had their cabs removed.

They were designed that way, and one of the reasons they were retired by their original owner (Burlington Northern) was their inherent lack of flexibility.

GP40 6694 wrote:Very rarely does a passenger train run with more than one unit.

Define "rarely." On Amtrak's long distance trains, multiple locomotives are pretty much standard operating procedure.

MEC407 wrote: They were designed that way, and one of the reasons they were retired by their original owner (Burlington Northern) was their inherent lack of flexibility.

Define "rarely." On Amtrak's long distance trains, multiple locomotives are pretty much standard operating procedure.

Ok, makes sense. P&W and other carriers on the NEC also end up with a bunch of locos that can't lead since they have cabs, but no cab signals, so I guess they're just used to stuff like that. I think they have A-B-B-A sets for coal trains, since you need more 4-axle units. P&W is like a haven for 4-axle power, since that's all they run, AFAIK.

Yeah, ok, that was bad phrasing. I should say, often they don't, sometimes they do.