Nostalgia & History > SOU GP40X #7000 Under Test at McCook

My notes say this unit is new and being tested at EMD (McCook, IL). Note all the wires on the left side and also for another purpose, the overhead wire. July 10, 1978.



Enjoy,
Marty Bernard

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Definitely at the EMD McCook plant. The overhead wire was for the GM10B and GM6C electric development program.

I can't recall what these trucks were called under the Southern GP40Xs--can anybody help? They were unique in that they were unlike the rest of the EMD GP40Xs, and further, the EMD Amtrak F40PHs/F40PHRs built after this date sported this truck--a modification of the standard Blomberg M--selling point of which I recall was a "lower center of gravity" (for both better pulling power and higher speed ops). And certainly smoother-riding than the standard GP40X truck (and I can't recall the nomenclature of that unique-looking truck found on the rest of the GP40X units such as the UP and SP's which was a very rough-rider even though used in 90 MPH service on the head end of the AMTK SFZ with the UPRR GP40Xs which supplanted the UP E-Units that were added ahead of SDP40Fs and then the F40PHs on that train).

Perhaps a few truck photos of the F40s with this particular truck (with nomenclature?) and also, the more typical GP40X truck as found under UP and SP units (with nomenclature?...that one is just on the tip of my tongue but I just can't spit it out!!!)...

Interesting photo, BTW...

I remember that some GP40X units had the experimental "High Traction" B type truck, named "HT-B" as compared to the "HT-C" truck used on SD units from 1972 onward.

If I recall correctly, the Southern GP40X did not have the HT-B but other GP40X's did. The HT-B died quickly. Tests showed that the then-new wheel slip control system made the HT-B unnecessary.

The Blomberg B is a "B" diesel locomotive truck. These trucks were the standard EMD four wheel truck from the FT up until the GP60. EMD introduced the truck in 1939. Unofficially it is named after Martin Blomberg, who joined the company the year before. The truck was derived from an earlier three axle truck (A1A) designed by Blomberg (described in U.S. Patent 2,189,125, filed January 29, 1938, and approved February 6, 1940), and was used starting with the FT.

A modified (M) version of the truck called the Blomberg - M was used starting with the four-axle Dash 2 series locomotives in 1972. Hydraulic snubbers (shocks) were used on diagonally opposite (front right and rear left) journals, and the leaf spring suspension was replaced with rubber pads. This version had only one brake actuating cylinder per side and revised brake rigging using threaded adjusters, reducing the number of brake shoes to 4 versus 8 on the earlier B model.

There is also a later variation of the Blomberg 4 Axle Truck called Blomberg - P delivered on Southern Railway GP40-X Models #7000 to #7002 in 1978, and on Amtrak F40PHR models #325 to #328 in September 1979 geared for a 103 MPH as Test Beds. Then Amtrak received production Blomberg –P’s on Amtrak F40PH’s #329 to #360 from August 1980 to December 1980 geared for a 110 MPH and on all remaining new F40PHs delivered starting in 1981 to include Amtrak #361 to #409 from April 1981 to January 1988 geared for a 103 MPH. The Blomberg - P trucks came with a different rubber secondary suspension. Instead of a simple vertical stack of rubber pads, with a pair of chevron-shaped rubber pad sets were oriented sideways, supported at the outside edges by a flat rectangular block. The revised secondary suspension and bolster required the use of the taller swing hanger design from the clasp-brake Blomberg truck. This design may have been intended to soften the vertical ride, which was stiffer with the rubber pads than with the original leaf springs.

EagleChampion1 Wrote:
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> There is also a later variation of the Blomberg 4
> Axle Truck called Blomberg - P delivered on
> Southern Railway GP40-X Models #7000 to #7002 in
> 1978, and on Amtrak F40PHR models #325 to #328 in
> September 1979 geared for a 103 MPH as Test Beds.
> Then Amtrak received production Blomberg –P’s
> on Amtrak F40PH’s #329 to #360 from August 1980
> to December 1980 geared for a 110 MPH and on all
> remaining new F40PHs delivered starting in 1981 to
> include Amtrak #361 to #409 from April 1981 to
> January 1988 geared for a 103 MPH. The Blomberg -
> P trucks came with a different rubber secondary
> suspension. Instead of a simple vertical stack of
> rubber pads, with a pair of chevron-shaped rubber
> pad sets were oriented sideways, supported at the
> outside edges by a flat rectangular block. The
> revised secondary suspension and bolster required
> the use of the taller swing hanger design from the
> clasp-brake Blomberg truck. This design may have
> been intended to soften the vertical ride, which
> was stiffer with the rubber pads than with the
> original leaf springs.

Indeed a softer vertical ride compared to the compression rubber springs introduced with the Dash 2 series was the purpose. It is officially known as the inclined rubber suspension, using a pair of rubber springs on each side of the truck that sit in a pocket in the spring plank and a wedge looking block sits between the two spring sandwiches and compresses them with most of the deflection occurring in shear of the rubber. It has more than twice the static deflection that the rubber compression springs (so half the stiffness) but that is still only 1/2 the static deflection of the original design leaf springs. The development of the low profile elliptic springs, which have similar static deflection, replaced this suspension in production and became the standard arrangement for single shoe brake GP trucks.

Dave

Interesting discussion! From Blomberg-Ms to Blomberg-Ps and the back to the elliptical springs (but with the hydraulic shocks) as especially found under--say--the EMD F59PH and F59PHI psgr units, and certain classes of GP50 units (the BN GP50s being the most prolific frt units I can think of off the top of my head?)...