What's the purpose of B units? Other than filling the need for additional motive power without adding unnecessary cab controls, is there anything else unique about them? Can't two or more A units be lashed together?
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Originally booster units were created based on the concern that union rules would require a crew for every cab like a steam locomotive. The original FTs were delivered to the Santa Fe as permanently connected AB units. An ABBA set of FTs was classified originally as a single locomotive.
Booster units also came at a bit of a cost savings and in many cases the extra space afforded by the lack of a cab allowed for a steam generator with a larger water storage capacity for passenger train heat.
As an aside, boosters also often had a hostlers control stand for maneuvering units around the yards and the engine houses.
For the most parts, booster units fell out of favor in the late 40's and early 50's with the exception being the ATSF GP60bs. I don't know the history behind why the ATSF ordered them with that configuration.
Also, the Burlington Northern ordered 120 B30-7A(B) cabless locomotives from GE in 1982. Various railroads have rebuilt wreck damaged locomotives without a cab or a blanked out cab, so they are essentially booster units.
Maybe unintentional, but the B units do make for a "cleaner/smoother" looking consist!
Wabash bought seven Alco C-424's at a bargain price that were cancelled by NdeM. As all the controls and gauges were labeled in Spanish, they were relegated to B-unit status, numbered B900-B906. N&W corrected the issue when they acquired the Wabash.
Rusty
@NW posted:What's the purpose of B units?
Add additional power to the consist.
Other than filling the need for additional motive power without adding unnecessary cab controls, is there anything else unique about them?
Nope.
Can't two or more A units be lashed together?
1) Real railroad locomotives are NOT "lashed together"!!!! Diesel and electric locomotives may be coupled, and electrically MU'ed together.
2) In many cases another A Unit may not be available. Then again, there were/are many, MANY cases where more than two or more units may be required to power the train (freight or passenger), thus B Units were very desirable.
@Rusty Traque posted:Wabash bought seven Alco C-424's at a bargain price that were cancelled by NdeM. As all the controls and gauges were labeled in Spanish, they were relegated to B-unit status, numbered B900-B906. N&W corrected the issue when they acquired the Wabash.
Rusty
¿Cuál fue el problema?
The Chicago Great Western was famous for having 3,4,5 B-units in their locomotive consists.
Rusty
@Rusty Traque posted:The Chicago Great Western was famous for having 3,4,5 B-units in their locomotive consists.
Rusty
Rusty,
As you would know, so did the combined El Capitan / Super Chief. That was one long train!
always thought the GP-9 b-units looked crazy, but cool. apart from the PRR, I don't seem to run across many pics of them. not that I've looked for them.
@Times Square posted:always thought the GP-9 b-units looked crazy, but cool. apart from the PRR, I don't seem to run across many pics of them. not that I've looked for them.
Union Pacific also had GP9B's, along with GP30B's.
Rusty
When Union Pacific's first GP9 cab and booster units were brand new in 1954, they were sent to the Southern California line to replace the F3's and Alco FA-1's. At the very beginning, they ran in 4-unit consists with two GP9B's in the middle position. It did not last long, and the units were soon scrambled and used as available, but GP9B's were very common.
During the brand-new period, my uncle, a UPRR Engineer at Los Angeles, took my brother and I to East Yard on payday to pick up his paycheck, and we got a ride in the yard aboard this GP9 consist: 131-131B-132B-132.
The FTs only had 1350 horsepower each. Powerful enough for a switcher, but not for a road engine. As designed, each A-B set was connected with a drawbar to create in effect one two-section locomotive (kinda like an articulated steam engine with two sets of drivers) of 2700 HP - roughly equivalent to a Mikado. Running two A-B sets back to back created 5400 HP - similar to a 2-8-8-2.
In the forties, railroads tended to buy diesels for specific purposes, an A-B set to replace medium sized steam engines, A-B-A sets to replace larger engines, and A-B+B-A sets to replace the Mallets and articulateds. In time, railroads started to see the benefit of doing "building blocks" where you added enough engines needed for that particular train. B-units had to be run with some other engine, but non-cab engines could be used by themselves, or in a pair, or in a larger group, so B-units came to be seen as less desireable.
@wjstix posted:The FTs only had 1350 horsepower each. Powerful enough for a switcher, but not for a road engine. As designed, each A-B set was connected with a drawbar to create in effect one two-section locomotive (kinda like an articulated steam engine with two sets of drivers) of 2700 HP - roughly equivalent to a Mikado. Running two A-B sets back to back created 5400 HP - similar to a 2-8-8-2.
The EMC Sales and Engineering staff designed the FT (F = Freight, T = Twenty-seven hundred HP) to compete against the main line freight steam locomotive of the 1930s, that being the approximately 5000HP 4-8-4 "Super Power" locomotives of the late 1930s. NOT "2-8-8-2" compound locomotives.
Also, another main reason that the "A" was drawbar connected to the "B" was, the batteries (for starting the prime movers) were located in only one unit. Thus, an "A" HAD to have a "B" mu'ed to it.
In the forties, railroads tended to buy diesels for specific purposes, an A-B set to replace medium sized steam engines, A-B-A sets to replace larger engines, and A-B+B-A sets to replace the Mallets and articulateds.
Only after the end of WWII.
In time, railroads started to see the benefit of doing "building blocks" where you added enough engines needed for that particular train. B-units had to be run with some other engine, but non-cab engines could be used by themselves, or in a pair, or in a larger group, so B-units came to be seen as less desireable.
1. Several books talking about FTs compare the power of an A-B-B-A set as equivalent to a Mallet or other large articulated locomotive, of which a 2-8-8-2 was an example. I wasn't saying they designed the FTs to be 10 MPH drag freight engines, just talking horsepower.
2. Obviously, the FTs couldn't be mated with any other F-units until after World War Two, because there weren't any other F-units until the F2 came out in 1946.
when I was on Santa Fe, we had a few cabless SD45-s that were rebilt from standard units that started out with cabs., and earlier we had I think five cabless GP7's, and some EMD yard switchers "Cow & calf" which were end cab switchers with cabless B units, I saw those quite a bit in Kansas City. Maybe hundreds of F7 & Ff9 cabless B units, and then later were the GP60-B cabless units.
On some railroads, in the first generation F models, there had to be a B unit, or a steam generator car, because the A units lacked steam genetators.
Santa Fe comes to mind. GN and/or NP perhaps?
