How did push-pull work with the old equipment?

A question I have about the "P" units is what was done with the traction motors? From what I know (which isn't everything), they are geared directly to the axles and moving a diesel-electric would mean the motors would have to spin as well. For a short tow this sounds OK, but were they actually left this way for thousands and thousands of miles?

Wouldn't this represent un-needed wear and tear as well as more rolling resistance?

Everyone: I rode many times on this equipment when it was in service from the early 70s to the late 90s. I think it was a clever idea to convert perfectly usable electric coaches to diesel with the method the LIRR used. John Scala describes some of this in his book DIESELS OF THE SUNRISE TRAIL. I remember that the FAs used the original prime mover with the traction motors disconnected. I remember them occasionally even sending up sparks in full tilt once in a while. The conversion to a small diesel generator was an interesting variation with a concrete block added for ballast weight. The MP15s converted to a switchable power-pack as well as a straight locomotive was also a clever move by the LIRR. The LIRR got many years of useful service from this concept. MACTRAXX

And originally, before the days of the MP15's, we had the C420s on the powered end:


Dave

Srnumber9, look at it from the LIRR's point of view. The 1500's were purchased for freight. As freight declined, they didn't need as many 1500's as before. The "P" mode gave them a new life and quite a long one on the LIRR. Could the wear and tear being towed around be any worse than being on some railroad pulling freight?

It was a smart move and worked perfectly. Not only did it provide the Hotel power necessary, it provided safety for the Engineer in collisions (think about Bellport on that one) and above all else if need be, provided motive power for a train if the road engine was down. Maybe the cars were dark, but if the train was moving, who cared?

From an economical stanpoint..the 1500's in "P" mode burned approximately 150 gallons of fuel in a 24hr period. A DE/DM providing the same Hotel or now HEP on a train sitting static in a yard during the same 24hr period burns 300 gallons of fuel.

It was win/win on that one and a testiment to the ingenuity of the LIRR's MofE Dept. of the past.

So much for the newer engines being more fuel efficient lol. Damn, they burn twice as much fuel sitting than the MP15s burned in action? Crazy

My question is less "why?", but more "how?".

Did the LIRR leave the traction motors geared to the axles, or is there a way to disengage them so the axles freewheel seperately from the motors?

It's kind of a general question: Let's say a railroad museum in Massachusetts finds a first generation diesel in Arizona and gets it there by having it hauled in several freight trains. Do those motors spin for over 2,000 miles, or do they disconnect them?

To be blunt: is there a "Neutral"?

Nope, no neutral. Unless you pull the motors out, they're geared to the wheels.

I think a few French motors had gear ratios that could be quick changed (including while standing at a station, IIRC) but I know of no US unit that had this.

I'd imagine the wear and tear of a locomotive in dead tow wouldn't be much as long as the maximum speed isn't exceeded. Unlike a car*, the gearbox will always be under lubrication, and the loads on the gearbox are low. EMUs run all the time with dead motors (for whatever reason) and it doesn't hurt them. Given the stronger design of a locomotive gearbox, I'd imagine it's no issue there at all (I can't see why it would be).

You'd be causing some commutator wear, but if it were enough to kill the motor/brshes, likely the motor wasn't going to last much longer anyway...

I'd be more worried about any currents generated from free wheeling the motors like that, which could be a hazzard, but nothing that couldn't be dealt with.

Was it lack of a suitable HEP locomotive that kept the LIRR from simply recabbing the MP-72/75s into diesel control units? Though I guess the REAL cheap way out in the case would have been to rewire the MU controller for diesel operation Though, would 3 notches really be too few? (I'd be curious if anyones ever studied time in X notch in typical commuter service)

* Oh, yes. You're not supposed to tow your car on it's driving wheels because all modern transmissions don't circulate lubricant without the enginer running. On an automatic, this is easily fatal to the unit in a few hundred miles at highway speeds because there's no lubricant washing over the released cluch packs to cool them...

Dave, amazing on the pic at Port Jeff because the whole area is developed now. Funny off to the right, you see the 251 Oakland Ave. Medical Center building, which is still there today. Yes, areas did change drastically since the 70's.

Nasadowsk wrote:Was it lack of a suitable HEP locomotive that kept the LIRR from simply recabbing the MP-72/75s into diesel control units? Though I guess the REAL cheap way out in the case would have been to rewire the MU controller for diesel operation Though, would 3 notches really be too few? (I'd be curious if anyones ever studied time in X notch in typical commuter service)

What is a HEP locomotive?

Srnumber9, there is no neutral on the 1500's that disengages the the ring gear from the pinion on the motor. Any wear and tear that would occur would be more within the motors themselves..commutators, brushes, etc. But those are items that would wear anyway if they were used for traction, so what's the difference. The bearings are constantly lubricated with an oil bath whether towed or under power.

It's not like the 1500's were just towed around for a joy ride. They were performing a real important function providing power for the cars and a control stand to operate push-pull...so any expense due to wear and tear would be justified.

They didn't have locomotives that could provide both hotel and traction allowing for a homemade cab car on the opposite end. They used what they had and it worked.

Phil pointed out that modern automaic transmissions cannot be towed in neutral for very long due to lack of lubrication.....older automatics front oil pumps driven by the engine and rear oil pumps driven by the output shaft when it is turning regardless whether the engine is running or not. Traction motor bearings are always lubricated on the 1500's, so it does not matter.

The DE/DM's are more fuel efficient on the road..than the 38's were. But not "mile for mile". It's like this..a Geep hauling an average train of five cars and a P engine to Montauk burned about 450-500 gallons of fuel. The P engine would burn around 75 gallons on the same trip for hotel power. The DE/DM's being a traction/HEP capable unit burns around 450-500 gallons for the same weight train...but in this case is more efficient due ot not having a separate unit just for HEP.

A Locomotive Supplying HEP "Head End Power" aka Hotel power.

Hi Neil:

I went back north for a visit in 2001, just before 9-11 and photographed at Port Jeff. New high level platforms, pedestrian crossover, restored depot, new track layout, new yard east of the station area . . . . stores and buildings all over! Couldn't believe it was the same place!

You'll notice this was the original configuration for push-pull service: power packs on the east end and powered units on the west end. Some time later they switched the positions.

Dave

Long Island 7285 wrote:A Locomotive Supplying HEP "Head End Power" aka Hotel power.

Thanks.

I think GM dropped rear pumps on automatics in the mid 60's on the powerglide. AFAIK, the THM 350 and 400 never had 'em, nor did the Ford C4/C6, or the infamous Mopar 727 an 904...

Lots of automatics before this had rear pumps, which was more or less to allow push starting of the car, which a modern automatic can't do. The EPA didn't like this (at least once the catalyst came around), and the rear pump cost money anyway, so it got tossed...

Of course, it creates numerous issues with having a transbrake on a Powerglide

HEP is not the same thing as Hotel Power. Hotel Power is the power being supplied to the coaches coming from a remote source, such as a P-engine or Power Pack. A HEP equipped locomotive can provide power to the coaches in addition to traction, without the need for a "remote" power source.

Joe