• GP-35"s

  • Discussion of Electro-Motive locomotive products and technology, past and present. Official web site can be found here: http://www.emdiesels.com/.
Discussion of Electro-Motive locomotive products and technology, past and present. Official web site can be found here: http://www.emdiesels.com/.

Moderator: GOLDEN-ARM

  by dgvrengineer
Is anyone familiar with the major problems with the GP-35 that made them unpopular with many railroads? Was it the 567D being pushed too far to get 2500HP or the 16 step transition that was hard to maintain?
  by MEC407
From what I've heard, the issues were mostly electrical. There are some GP35s still running with their original engines, still rated at 2500 HP, almost 50 years old, so that doesn't strike me as a sign that the engine wasn't capable of reliably producing that amount of power. A lot of railroads did de-turbo them, but I think that was mainly done to reduce maintenance costs, especially when the units were being used to do a lot of switching. We've also seen railroads do that with GP40s, SD40s, GP50s, etc., which is another sign that it has less to do with the 567 and more to do with the railroad simply not wanting or needing a turbo for a particular type of service.
  by RickRackstop
The main problem of that era was wire insulation. All the controls used relays which were wired together with plastic insulated wire which over time would dry out and crack. On the MP36 "package" diesel generator unit I remember that in the control room seeing all the wires connecting the relays all covered up with heat shrink tubing. Then there is the D32 DC generator that was probably at its limit at that power rating now if you could get a good used AR10 alternator that would help the situation enormously. Back in 1964 - 66 I worked for a company that manufactured magnet wire (ironically on GE machines) that was just starting to use synthetic varnish that would allow thinner coatings for more turns on the pole pieces and could stand higher temperatures. No doubt this allowed for higher power locomotive such as the 40 series to replace the GP35's.

As for the 567D3a engine one problem that developed was leaks in the seal plate between the head pots that if rewelding didn't fix EMD had a "policy adjustment" program to replace the entire engine block with a new E crankcase. If the original crankcase has lasted this long their isn't going to be a problem. As far as the MP36's are concerned all the controls and and governors are replaced with micro processor equipment and the D4 engine ran at about 2900 hp at 900 rpm driving a A20 alternator.
  by Bright Star
Last summer, I saw an GP-35 in fresh paint with not only the original controls and wiring-but with the SEARCH wiring still in place !!!

Both BARCO and Genisco Technology supplied retrofit kits (piloted by an axle mounted speed sensor) to replace the as-built transition scheme on the GP-35.

When the transition equipment was out of adjustment, the sudden dropping and return of load would just beat the hell of the engine-especially the top deck.

As with the D&M C425M's, the extra 500 hp (and the turbo that allowed it) was of little need/use in the secondary assignments these locos found later in their service life.

  by MEC407
Bright Star wrote:Last summer, I saw an GP-35 in fresh paint with not only the original controls and wiring-but with the SEARCH wiring still in place !!!
Was it Conway Scenic Railroad's "new" GP35 by any chance?
  by Bright Star
No-not Conway Scenic. The unit was bright red.
  by Engineer Spike
A good number of GP35s have become cores for GP38 rebuilds. Metro North has some, Housatonic has removed the turbos from some. The a while ago I saw a 35->38 rebuild at CPR Cote-St.-Luc Diesel Shop. The BN GP39 program kept the turbos, but have -2 electrical systems. When I worked there, I never looked, but they must have gotten alternators.

For a quick and dirty rebuild, would the reduction to 2000hp negate some of the steps of transition, if the D32 was kept?
  by scottychaos
im curious..and I do have some survival numbers for three railroads that owned GP35's,
so im going to work up some data:

NYC - had 31 GP35's, 1 survives, that's 3%
EL - had 36 GP35's, 2 survive, that's 6%
PRR - had 119 GP35's, 19 survive, that's 16%

That's pretty low for GP's..

Lets compare to some other GP's before the dash-2 line:
DL&W - had 20 GP7's, 4 survive, that's 20%
PRR - had 270 GP9's, 49 survive, that's 18%
NYC - had 160 GP9's, 38 survive, that's 24%
PC - had 265 GP38's, 133 survive, that's 50%
NYC - had 105 GP40's, 62 survive, that's 60%
PC - had 175 GP40's, 114 survive, that's 65%

not totally scientific, and not the full population of all locomotives, but yeah, its safe to say there was something negative about the GP35 specifically.
and we cant use age as a factor (saying the GP35 is older than the GP38 and GP40, therefore we should expect less GP35's due to age)
because the GP7's and GP9's are older than the GP35, and they have a higher survival rate..
and also now, 50 years later, the 1963 to 1966 production for the GP35, compared to 1966 to 1971 for the GP38 and GP40, isn't really a factor anymore.
a 5 year difference, 50 years later, doesn't mean much.

http://gold.mylargescale.com/scottychao ... rkcentral/" onclick="window.open(this.href);return false;
http://1stclass.mylargescale.com/Scotty ... Survivors/" onclick="window.open(this.href);return false;
http://www.american-rails.com/" onclick="window.open(this.href);return false;

  by MEC407
Many of NW's GP35s seemed to survive much longer than those of the other railroads, despite having high noses which are viewed unfavorably today.

I'm not sure how many are still in service today, but as recently as 10 years ago there were around 16 of them operating just on Pan Am Railways alone, and I know there are a few shortlines who still have some.
  by NorthWest
Are the survivor lists only in relatively as-built form? As noted earlier many units have been rebuilt to eliminate the electrical issues.
It'd also be interesting to survey surviving GP30s as they were more successful. These higher-horsepower units were less attractive to short lines and for secondary service (though the GP35's quick loading was appreciated in the yards) and so were scrapped when done with road service while the GP7s/9s survived on other jobs.
  by Typewriters
My understanding is that the major problems with the GP-35 were the transition program switch (used to switch through the many steps of field shunt and also used to control transition) and problems with commutation of the generator. I just read yesterday on a website that Western Pacific experienced serious trouble with its GP-35 units, and derated them to 2000 HP until a factory modification program was carried out.

I have read of grumbles with the shunting indexing motor in ALCO C-628 units, an exactly comparable part to the transition program switch in the EMD SD-24 / GP-30 / GP-35 / SD-35 / DD-35 / DD-35A. (The C-420 and C-424 also had this device. The C-425 used the GT-598 generator and didn't need to protect it with many small stages of field shunt.)

I know of at least one aftermarket product intended to replace the transition program switch (the solid state Genisco Transition Programmer) and get rid of problems such as one might expect with a complicated yet delicate electro-mechanical device. These apparently did not sell very well - I have no idea if EMD developed a similar but internal fix for this problem.

Of course, generator commutation problems were one part of what pushed the development of alternator-rectifier transmission.

-Will Davis
  by Allen Hazen
I have a vague recollection that at one time the Santa Fe had a rebuilding program for GP-35 which included replacement of the DC generator with a traction alternator: I assume EMD AR-10. Is this true? Would EMD have been happy selling alternators to install in existing units? … It does seem like an obvious (though perhaps expensive) way of solving many of the electrical problems with the as-built GP-35.
  by mp15ac
I don't recall reading that Santa Fe replaced the DC generator for an AC alternator, but I have read that they did do major rewiring of their GP20's, 30's, and 35's. They also added 645 components to the 567 prime movers. Its interesting to note that they were still mainline power right up to the BNSF merger.

  by Allen Hazen
Mp15ac-- Thanks for correcting me. (Chalk it up to the fallibility of my elderly memory.)
I **think** I remember that SOMEBODY installed an alternator in a GP-35 to produce something functionally more like a GP-40. Alaska Rail Road, maybe? (Or another instance of my memory being… creative.)
  by Allen Hazen
O.k., maybe I ***wasn't*** being creative on that last one.
http://www.alaskarails.org/glance/complete-roster.html" onclick="window.open(this.href);return false;
gives a roster of ARR locomotives (steam and diesel… and maybe you could even say "straight electric" for the two slugs). Look for the 3051, which started life as the 2503. Heavy rebuilding after a wreck, from which it emerged as effectively a GP-40-2. Since no sane person would try to put 3,000 hp into the original d.c. generator of a GP-35, this must have involved installing an alternator. (But it was a one-off, wreck re-build: no evidence, therefore, that this was part of any general attempt to eliminate GP-35 electrical issues.)