For those whove spent time in these: GP35, 38, 40, ....?

For my money, EMD’s best and worst locos built are the SD9s and GP60s.

Because of their ride characteristics, the SD9 was referred to as a “Cadillac” where I worked (SP)or “Shellvilles.” This was a regional term that applied to them as to a branch line they operated on.

And they would flat PULL, too! With an 1800 hp prime mover powering 6 big traction motors, they were the only diesel electrics I have operated that had no “short time rating,” so if it would move at all, it was impossible to hurt. Two of them compared to a single 3600 hp SD45, there was no comparison. They’d out pull them each and every time.

They did have some restrictions on them for servicing some industries where only a Geep could handle the curvature, so they saw mostly road switcher service by the time I happened along. As road switchers they were even better, equipped with the RL24 brake schedule to the end of their days.

They did have one quirk that was a little uncomfortable. In drag operations on a grade, all the stacks would emit a flame from them that kind of developed a cycle to each. I never saw this on the geeps, though, and was harmless. The thing is, with roots blowers (they weren’t turbocharged) there was a build up of carbon. There were “carbon trap caps” that needed to be serviced at regular intervals, and this was dangerous because they would emit embers that can and did start fires, if maintenance was sloppy or deferred.

As for ride characteristics, the 180 degree about face belongs to the F40PH.

Short wheelbase + stiff trucks + 79mph = they’d beat your brains out. Seriously. When you did a 300 mile run with them under you, you’d be physically fatigued from the energy spent just to stay in your flippin’ seat. This is definitely a ride characteristic that applies equally well to the GP60.

When speaking of pulling power in drag operations they weren’t worth a damn. Wouldn’t hold the rail at all, designed primarily for flat land high speed running with intermodal service. Which is why they shouldn’t have wound up in mountain pool freight, but they did.

Today, it must be said that GE locos are superior to all, even though being said just started every hogger who ever had to run any of the various GE U-boats spinning in their graves.....

That’s just the way I see it, though…

There wasnt a GP locomotive made in any horsepower, even low horsepower like the GP7 that wasnt slippery and in my opinion rough riding.

And in comparison, every SD type locomotive I was in would hold the rail like grim death and with one exception ride better then their 4 axle counterpart.

Some locomotives the guy you were talking with might have had newer slip detection but given a horsepower difference of as little as 500 and both locomotives being in the same series, I doubt there would be much difference in noticable slip tendencies from say a 35 vs a 38 or a 40.

Another thing that makes a difference in individual locomotives is wheel diameter, for example if one traction motor had been changed and the wheel was a half inch larger or smaller, even though they shim the spring packs to compensate that axle will have a tendency to slip.

Every SD 45 I was ever on rode horribly, I swear they had scratched paint on the side of the cab from rubbing the right of way fence.

SD 40s although very similar in most ways rode much better, I cant explain why but most engineers will verify that.

even today, the newer locomotives dont ride one bit better than a well maintained SD40 with properly maintained suspension, except those are getting more rare each day.

I cant tell you how many times I have tried to get that 9th notch out of the throttle wishing I had just a bit more horsepower.

I think what gave/gives the SDs their advantage was/is the fact that you have six axles and six traction motors pulling. And 12 wheels providing contact points with the rail for greater traction over four axle units. The down side can be that the rigid three axle trucks can tend to spread rails on sharper curves and switches not designed for these types of trucks, such as on branch lines. But most railroads accepted the SDs just fine.

A four axle unit will tend to slip the wheels easier with just 8 wheel contact points. But keep in mind two things. Every locomotive seems to have its own personality, even in regards to when it will begin slipping. Also, the only piece of equipment that comes standard on a diesel locomotive is the frame. Everything else are options and are built to a customer's specs. This includes the electronics. It wasn't common for a railroad to custom order how many amps were delivered to the traction motors, and how fast. But this aspect can be modified. I have seen the electronics and switches in a Geep fire wall changed out to either make an engine load slower or faster. Many examples of Geeps also had a selector switch in the cab to control traction motor "loading" for either swiching service or road service. Again however, this wasn't the answer for every situation, and again, every engine had its own personality.

I'm sure more guys will post more info for you here. Leave this up a while. I gotta go to work.

I never heard that complaint about the GP35, from crews that operated them on the Penn Central. It was the GP40 that was most reviled by them. The general complaint was that while they were runners, they weren't much good at slow speed, such as loading at a tipple. But that kind of thing generally separated the hogheads who ran the flatlands and those who spent their time in the mountains. My personal thought there was that if the 40's didn't have 'creep' controls, they would just naturally not be good at sustained low speeds. That would be true of any high-horsepower unit. It might also be indicative of the propensities of the 645 diesel versus the 'pushed' 567. 2500 gross horsepower was about as far as the old block could be taken (considering that it was originally designed to produce 1350-HP, roughly half). The power curve of the 35, fell off very quickly once the air was increased through the brake systems, thus making it better suited to slow speed operations.

We who operated the 567 in the switcher configurations knew it to be entirely reliable and very well suited to slow speed operation. It'd run all day under ten miles per hour without complaint, with very few amp spikes, and consistent torque generation.

The 45's were all power, great under load, and low amp users. Where they would be trouble was when they had a runner who would jump around on the throttle. That long crank just couldn't take sudden fluctuations on the speed. That was the biggest maintenance headache with the 45. I knew a runner on the PC, who praised them to the skies. Considering that was on a railroad that had the poorest maintenance performance of any, that was really saying something. But he told me of having one by itself in a coal branch yard for a few days, and it was a nightmare. The biggest problem was its loading time, longer than most units, and that it would 'jump' and then have to be braked hard to prevent an excessive speed surge. Spotting cars at truck loaders was 'an adventure' according to him.

A friend on the Western Maryland thought that their SD35's were the best engines they had, though he never elaborated as to why he thought that.

Dunno