What is a "power car"?

[Tadman]

So lately I keep hearing how the Acela locomotives are "power cars", and the same is bandied about with regard to the British 43-class HST.

Help me think this through. The "power car" strictly carries a driver, propulsion equipment, and pantograph. No passengers. Then you have the passenger cars, which carry no driver, only passengers, and have no propulsion gear. In both cases the "power cars" are detachable from the passenger cars.

Huh? Who comes up with this stuff? Why do we waste brainpower on differentiating something that isn't different?

[rcthompson04]

Power car is basically a locomotive that is dedicated for that particular train and becomes an integral part of the trainset. The engines on both ends of an Acela are power cars. Is it even possible to operate the Acela passenger cars without the Acela power cars?

[DutchRailnut]

the power cars are not full locomotives and can not haul other cars , at rear end they have non-conforming coupler at wrong height. and even if both are coupled they have no way to feed HEP to a train, they can only receive power in case of train failure.

The cars have same problem non-conforming couplers at wrong height, a tilt system fed from power cars and no corner post.
it would also be impossible to install trapps for low level access due to load carrying side sill.

[BandA]

I thought a "power car" was generically a car that had engine(s) or motor(s). Not a "trailer". So a locomotive that is "permanently coupled" is also a "power car"? A car that produces HEP but not involved in propulsion would also be a power car.

[Backshophoss]

Power car: 1. standalone car providing HEP/Steam to a consist.
2. Purpose built Loco,set up to move a fixed consist,has cab prime mover,traction motors and provides HEP/Steam to consist.
Can be an electric loco(motor) that gets/uses power from catenary/3rd rail.
3. Purpose built Cab car,part of a Fixed consist,or as a standalone cab car provides only HEP/Steam to consist and controls movement.

Examples: 1. HEP gensets installed in ex US Army kitchen cars to supply HEP to Amfleet I's
2. Acela I,Acela II,purpose built "Loco" on each end of fixed consist,lead used as "Loco",trailing supplies HEP.
Early CB&Q Zephyr sets,Purpose built "Locos"mated to fixed consists
3. Amtrak's NPCU # 403,Has HEP gen=set,can supply HEP to consist,used in "Push/Pull" type operations with Loco on other end.

[andegold]

Don't forget the train that shall not be named. (IINM it had power cars at each end that also had passenger seating.)

[Tadman]

Power car: 1. standalone car providing HEP/Steam to a consist.

Those are indeed power cars. They supply power but are configured as a car, providing no locomotion.

OTOH the British 43 and Acelas have locomotives. Power source and tractive or locomotive effort, no passengers.

The turbo is interesting as it is both provides locomotion and carries passengers.

[David Benton]

I'll go with Backshophoss's breakdown.
I would add some HSR intermediate cars have powered axles as well.
I think the key definitons of power car are,
- has a control cab,
- is designed to be a intergal part of a set consist,( not designed to pull conventional stock )
- provides some or all of the consists power and, and some or all of its propulsion.
The British hst originally had gas turbine propulsion for testing, and was to have an electric option as well( the remains of the APT disaster).This eventually evolved into the Class 91 with a DVT on the other end for the Electrified West Coast main Trunk.

[TomNelligan]

I have always shared Mr. Tadman's unease with the use of the term "power cars" to describe the Acela locomotives, although I acknowledge that it has become the accepted term. Originally the term as applied to a trainset (as opposed to a stand-alone HEP source) referred to things like the end cars of the United Aircraft, Rohr, and ANF Turbos. These end cars combined a cab, propulsion equipment, and passenger seating in a vehicle that was structurally similar to the non-powered cars behind it. The same concept generally applied to many of the early integral diesel streamliner sets. This was different from the the Acela end units, which are structurally locomotives rather than passenger cars. I'm not going to loose any sleep over what people call them, but I do want to make the point that in North American usage the term "power cars" has definitely been expanded since the 1970s to include what we then would have called dedicated locomotives.

[electricron]

Power cars for Acela train set are the locomotives on either end.
Power cars for an EMU unit is every car with motorized bogies or trucks. With Acela trains that's the two locomotives.
Power cars for a DMU unit is every car with motorized bogies or trucks.
Power cars for a GTMU is every car with motorized bogies or trucks.
All the above is simple to understand.

Now comes the difficult to understand train sets.
The Eurostar is an EMU type train set with motorized bogies or trucks on the end cars as well as on many intermediate cars. The Shinkansen copies the Eurostar, or should we say the Eurostar copies it. I guess we could follow the basic EMU scheme above. Not all power cars have to have cabs.

Some train sets can be difficult to classify. Take Stadler's GTW trains for example, whether is is a DMU, EMU, or BMU (B for battery), the power car is in the middle of the train in a very short car. Both power generation or transformers are located in the same short car as the motorized bogies or trucks. But that is not true with Stadler FLIRT trains, EMU versions have the transformers and powered bogies and trucks in the end cars with the cabs, but they can also have motorized bogies or trucks throughout the train depending upon its' length. DMU and BMU versions do not have collection transformers but otherwise have the motorized bogies in the end cars with the cabs, but the diesel generators and/or batteries are located in a very short car in the middle of the train. Both GTWs and FLIRTs can have trailer cars without any power generation or motorized bogies.
It can be very difficult to describe when the power collection is split from the power usage. Should we state the power car is where the motorized boogies or trucks are - or state the power car is where the power is generated or collected - or both?

[Backshophoss]

Given the FRA's stance on High speed trainsets,Purpose build "Locos",supply HEP, carries NO passengers, just train crew members allowed in cab.