Blomberg B
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Bogie Trucks
The EMD#Blomberg is a 2Axle bogie truck, introduced in 1939 under the EMD#FT locomotive series; the original design and later improved versions became and remain standard equipment as of this 2019 writing under 4Axle B-B locomotives in North America. Officially EMD refered to this design as the 2Axle Outside Swing Hanger bogie truck; unofficially it is named after EMD designer Martin Blomberg; it evolved from a prior 3axle A1A design also by Blomberg; see U.S. patent 2,189,125 filed 1938Jan29 then granted 1940Feb06.
Blomberg B version
The original "B"lomberg version can be identified by their prominent outside swing hangers, which afford a better ride during side-to-side movement. The outside placement has the advantage of widening its spring base from 56 to 96 inches (1,422 to 2,438 mm).
Due to the swinging hanger suspension system these trucks are commonly referred to in the railroad business as "swing hanger trucks". The term "Blomberg" truck isn't used even in some railroad training literature that specifically describes truck types.
A popular modification by railroads in later years was reducing the number of brake shoes from 8 to 4 by reconfiguring the double-clasp brake rigging, removing one brake shoe per wheel. This can give the Blomberg B a similar appearance of later Blomberg M trucks.
Although possibly a few exceptions exist, where a customer specifically requested plain bearings, almost all Blomberg B and M trucks (freight), and all Blomberg A1A trucks (passenger) which preceded these, were fitted with roller bearings.
Blomberg B trucks are occasionally seen on competitors' locomotives, the General Electric Universal Series in particular, where the railroad has requested re-use of traded-in EMD trucks and possibly also EMD traction motors on new GE locomotives.
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Blomberg M version
bogie trucks
This "M"odified version was introduced in 1972 with the EMD Dash2 locomotive series. This version typically has 2 brake cylinders with threaded adjusters and 4 composite brake shoes, instead of 4 brake cyclinders and 8 cast iron shoes on the older "B" version. Hydraulic snubbers (shocks) are mounted diagonally opposite (front right and rear left) journals. Older Hyatt roller bearings have been replaced by newer APcGG conical bearings. This version is typical on GP60 and F59PH locomotives, and on 2003 or later MotivePowerIndustries#MPX MP32 and MP36 series locomotives.
Blomberg X version
The "X"press versions official model is the MPI#2237; it directly evolved from the BlombergM, but is a new larger casting, not a rebuilt BlombergB or BlombergM; it is typical on 2007 or later MotivePowerIndustries#MP40+MP54 Xpress series locomotives. These have a longer 9ft 4in wheel base, steel leaf springs replaced by hybrid rubber steel laminate damper springs, and sway damper shocks between the truck and carbody; each a new feature required for more powerful trac motors, higher speeds and heavier locomotives.
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