Pennsy T-1 - How about this?

[tpatrick]

All you mechanical engineers out there, dust off your slide rules and consider this: The knock on the PRR T-1 was that it was slippery, especially at high speeds. So why couldn't they connect the number two and three axles with inside drive rods? Then they would have a four cylinder 4-8-4. It's slippery tendencies would be controlled by the more stable rear wheels, PRR trains would run even faster, the diesel would be vanquished and all would be well in the world. OK, maybe the diesels would have won, but it would have been a better fight![(-D]

[Anonymous]

The T-1 was designed and BUILT specificially to preserve the track.

By seperating the sets of drivers, better high speed was acheived without the intense pounding onto the track everytime the side rods came down.

The design was successful and further improved with the rebuild to a 4-6-4-4.

Engineers did find it to be a bit slippery which was pretty scary at times.

So. The theory behind the 2-10-4 or 4-8-4 is that the large sets of wheels and rods beat the track to death. The seperation of the drives and possibly additional power achieved from a second pair of cylinders may have alot to do with it's success.

Keep in mind there was no room for inside drive rods. Not to mention a mechanical nightmare. It was actually better that each set of drives did thier own power to the track and they would sometimes phase in and out from each other so. there it is.

[nanaimo73]

The ACE 3000 would have had its middle drivers connected that way. A great article on this is "Did we scrap steam too soon" in the June 1974 Trains. Were both pairs of drivers on the T-1 of the same diameter ? Was the T-1 quartered on the proper side or on the PRR side ?

[Anonymous]

The divided drive of the T1 (no hyphen, it was the PRR) was supposed to eliminate problems expected with extremely powerful 4-8-4s caused by high piston thrusts and dynamic augment of one set of drivers.

These problems did not manifest themselves with powerful 4-8-4s, so there was no actual need to divide up the power at the cost of an extra set of cylinders and valve gear.

PRR's Q1 4-6-4-4 was not an outgrowth of the T1, and was not successful. The Q2 4-4-6-4 was moderately more successful but was more slippery than the J1 2-10-4s. The Q2 was tested on N&W's Scioto Division against performance records of N&W's Class A 2-6-6-4s and did not come close to equalling the A in heavy tonnage service, even though it was heavier.

Old Timer

[eastside]

QUOTE: Originally posted by tpatrick

All you mechanical engineers out there, dust off your slide rules and consider this: The knock on the PRR T-1 was that it was slippery, especially at high speeds. So why couldn't they connect the number two and three axles with inside drive rods? Then they would have a four cylinder 4-8-4. It's slippery tendencies would be controlled by the more stable rear wheels, PRR trains would run even faster, the diesel would be vanquished and all would be well in the world. OK, maybe the diesels would have won, but it would have been a better fight![(-D]

Good that you say this half in jest. The T-1 came out in 1945. I think the epitaph for steam was written in 1939, with GM's FT diesels. In the diesel RR execs looked beyond just a change in hardware technology. They saw it as an opportunity to restructure their workforces drastically. Once they started getting diesels they was no turning back. Instead of having to cross-train their maintenance staff and crews on both steam and diesel and having to maintain separate maintenance facilities, they rushed to get rid of steam totally. Eventually they even got rid of the firemen. I look at the T-1 as a gallant but futile attempt to keep steam viable.

[Anonymous]

I had never heard that they were slippery at high speeds, but they were a bear to get started and up to speed with a train of any length. The idea of coupling the second and third drivers would somewhat reduce the tendency to slip, the coupling would need to be made to keep the front and rear pistons at 45 degrees from each other so as to make the power as smooth as possible over the entire rotation.

[CSSHEGEWISCH]

Robert Le Massena argued in "The Big Engines" in June 1968 TRAINS that steam locomotive development in the United States peaked in 1937. Development after that date was held back by World War II and the transition to diesels. The design of the T1, Q2 and S1 were part of a lot of last-ditch designs to hold back the diesel. Many were foiled by their own complexity in an attempt to incorporate too many advances in one design.

[nobullchitbids]

Even were such internal rods an improvement over the uncoupled design, in terms of performance on the rails, maintenance costs alone would have made them an unsupportable nightmare. Compare locomotives which did have internal rods -- three-cylinder machines like U.P.'s Nines or S.P's Overlands. Even though the Nines lasted almost to the end of steam (1954-55), they remained a maintenance headache, going only about 25,000 miles between shoppings toward the end. The Challengers which replaced them (and did last to the end of steam -- 1962) could go ten times that distance between shoppings.

Also, the third rod of a Nine is unbelievably difficult to get at -- why do you think a steam locomotive remains the only one of man's machines with its working parts on the outside?

Finally, it was not just maintenance costs which killed steam. Diesels eventually became thermally more efficient -- a greater percentage of their energy output is converted to work -- and with the development of MU connections, crew costs became drastically reduced as well. On a steam locomotive, there really was no substitute for the men in the cab; two cabs meant four men -- who all had to be paid.

[JimValle]

We have to remember that the T1 had an integrally cast one piece engine bed or frame.
It would have been impossible to fit internal rods on that account alone. Actually, all high speed divided drive locomotives had a tendency to be slippery. I have a video showing the front unit of UP's Challenger slipping like mad on Altamont Pass while the rear unit remained stable. UP engineers were much more comfortable with the Big Boys as they were beautifully balanced and almost never slipped. The Q2 slipped too if the engineer was ham-handed with it . Both T1 and Q2 were successful if they were in good working order and skillfully handled but the Pennsy guys were just accustomed to much simpler and more robust motive power and the diesel onslaught didn't allow time for extensive modifications.

[marknewton]

QUOTE: Originally posted by JimValle


We have to remember that the T1 had an integrally cast one piece engine bed or frame.
It would have been impossible to fit internal rods on that account alone.

Numerous 3-cylinder engines - engines with a middle rod and crank axle - were built with cast engine beds. It would not be impossible to couple the two engine units on a T1 in this manner, as you assert. It would be complex, difficult to maintain, and possibly negate the whole divide drive concept, but it could be done.

[wccobb]

A more plausable "pie-in-the-sky" fix for the PRR T1 would be a large sprocket on axles 2 & 3 and a chain drive. Most of these components are available. You'll fine one set on each side of the larger bulldozers. (Grousers not required).
All these pipe dreams not withstanding, there are two advantages of the diesels which the steam locomotive cannot touch: Steam locomotives cannout MU & steam locomotives have no dynamic brakes.

[CSSHEGEWISCH]

To wccobb: Have you also been reading "Articulated Locomotives"? The sprocket and chain drive arrangement sounds like it was borrowed from a Schwartzkopf locomotive. Most of those were on light narrow-gauge operations, though.

[heynav99]

I rode behind a T1 in July 1947 on the "American" enroute from New York to St Louis. There wa no slippage that I noticed while i was in the diner having breakfast or any other time. But we rolled along at a fast pace even though the train was a long one made up of heavyweight cars. There were few opportunities to catch a look at the front of the train even from the last car because of the lack of curves. But a T1 at speed was a sight worth waiting for.

[marknewton]

QUOTE: Originally posted by CSSHEGEWISCH
The sprocket and chain drive arrangement sounds like it was borrowed from a Schwartzkopf locomotive. Most of those were on light narrow-gauge operations, though.

Sentinel in the UK also used chain drives on a range of locomotives and railcars, some of which were large-ish standard-gauge designs. For an example of a large, heavyweight standard-gauge steam loco with chain drive, see Bulleid's "Leader" class 0-6-6-0 built for the Southern Railway in the UK.

http://www.xs4all.nl/~alexz/trein/leader2.html

[wccobb]

The PRR T1 is NOT an articulated locomotive. Thus, axles 2 & 3 will remain rigidly "in line" at all times, one of the basic requirements for a successful chain drive.
The starting TE of a PRR T1 is given as 58,300 lbs on PRR tracing D-437564. The Tractive force of PRR T1 No. 6110 was given as 65,000 lbs (Baldwin Locomotives magazine, December 1942, p.5)
The drawbar pull of a Caterpillar D11R is in excess of 330,000 lbs (current Caterpillar web site). That's 165,000 lbs on each track and it is the track which takes the force from the drive train (sprocket) through the shoes & grousers to the ground.
Read that: one track (drive chain) from a Caterpillar D11R can "absorb" all the "power" from 2.5 PRR T1 locomotives.
Even the most casual glance at the several photographs of the T1's cast frame in the Baldwin Locomotives magazine is suficient to clarify that there is no linkage possible between axles 2 & 3. (We may be very confident that could it have been done, the guys of PRR woulda done it !!!!!)
The next "nutty-railfan" assignment: design MU capabilities into the PRR T1 and install dynamic brakes.

[marknewton]

QUOTE: Originally posted by wccobbSteam locomotives cannout MU & steam locomotives have no dynamic brakes.

Steam locomotives were built with an equivalent to dynamic brake, known variously as Le Chatelier counter-pressure brakes, repression brakes, or water brakes. Commonly fitted to locomotives for steeply-graded mountain lines or rack and adhesion lines, examples may still be seen in service today.

http://www.smrailwayhobbies.co.nz/tr%20abt%20railway%20loco.jpg

The vertical brass pipe behind the chimney is one of the two brake exhaust pipes.

All the best,

Mark.

[marknewton]

QUOTE: Originally posted by wccobb
Even the most casual glance at the several photographs of the T1's cast frame in the Baldwin Locomotives magazine is suficient to clarify that there is no linkage possible between axles 2 & 3.

As designed and built, no, there isn't. If the requirement was to have coupled the 2nd and 3rd axles with rods, there is no technical reason that a cast bed couldn't have been designed and built to accomodate this feature. As I noted before, GSC produced a number of cast beds for three-cylinder locos with a crank axle. The same problems apply to that design, and were successfully overcome.

GSC were capable of casting an engine bed with integral saddle, cylinders, cylinder back covers, steam passages, air reservoirs, slide bar brackets, motion brackets and air compressor brackets - I seriously doubt that making provision for rods and crank axles would have been beyond them. I don't know whether you've ever seen a GSC cast bed "in the flesh" ? I worked for six years on the rebuilding of a steam loco with one, and I can tell you that they are an amazing example of advanced foundry work.

QUOTE: (We may be very confident that could it have been done, the guys of PRR woulda done it !!!!!)

It could have been done, and was.

http://www.chapelon.net/cgi-bin/i/pics/plm151a_1.jpg
http://www.chapelon.net/cgi-bin/i/pics/plm151a.gif

I'm equally confident that the Pennsy did not couple the two engine units for the reasons outlined in previous replies - the intent of the divided drive concept was to reduce piston thrust and reciprocating /rotating mass, thereby reducing dynamic augment. Read Ralph P. Johnson's various papers and articles for a better insight into the divided drive concept and it's aims. Coupling the two engine units would compromise these aims.

QUOTE: The next "nutty-railfan" assignment: design MU capabilities into the PRR T1 and install dynamic brakes.

The dynamic brake part is easy as; fit Le Chatelier brakes. MU is harder, obviously. But if you're prepared to accept a fireman on each loco, then something along the lines of British or European push-pull equipment would give you steam MU capability...[:)]

[GP40-2]

wccob,

If you look at the graph for the drawbar pull of the D11R, the 330,000lbs is extrapolated back to 0 mph. If you extrapolate an AC4400's power back to 1 mph it equals 1,600,000 lbs of pull.

Unless Caterpillar has found a way to bend the laws of physics, this represents an adhesion of 143% since the D11R only weighs 230,000 lbs fully operational.

The 0 mph pull of 330,000 lbs is not realistic because the dozer will spin its treads before this figure is reached. I've heard this called "digging coffins" because if the operator doesn't stop, the dozer will dig trenches deep enough to bottom itself out. Another dozer will then have to pull it out. It's similar to why the AC4400 never produces 1,600,000 lbs TE at 1mph; it runs out of adhesion way before that.

If you look down the page, you will see the D11R has a maximum operational pull of 148,500 lbs with a single tooth ripper.

Not to nit-pick, but your comment about the drive train of the D11R "absorbing the power of 2.5 PRR T1s" is not exactly true either.

Drawbar pull is a force, not power. Power is a force over a time interval. If you look at the D11R's drawbar graph, it's drawbar pull at 7 mph is zero! 0lbs pull = 0 HP. At 7 mph, the T1 hasn't even started to rev up.

The D11R does have more low speed pull than a T1, but it has much less total power. The drive train on a T1, however must be built to withstand 5,000 to 6,000 maximum horsepower, so any chain/belt drive would have to be engineered to that specification, not the D11R's lower power.

[Paul Milenkovic]

One piece of the puzzle is that engineers "cured" the T1 high speed slip problem by running with somewhat reduced throttle and later cutoff.

Think about it. For efficient use of steam, and you have to make good use of steam at high speed, not just for fuel saving but because your boiler will run out, you need wide open throttle so as much as boiler pressure gets to the cylinder, and you need maximum expansion (early cutoff). The T1 poppet-valve gear should have been quite capable for controlling cutoff.

Also think that your cylinders are set up so that at low speed start, you are running very late cutoff (full steam pressure through the full piston stroke), and the wide-open throttle steam pressure should be barely enough to slip the wheels so you get enough cylinder area and steam pressure to get max starting tractivie effort.

One of the things that happens as you increase speed is that the maximum tractive effort declines somewhat. If you are running at high speed full throttle, early cutoff, you are getting a pulse of high piston force that tapers off as the steam expands.

Could it be that at high speeds, full throttle, early cutoff for efficient high-speed running, and with the light rods, that they were getting a bump in tractive effort with each piston stroke that was causing the wheels to break free in a slip? Could it be that cutting back on the throttle and delaying the cutoff produced a somewhat lower and more even peak thrust of tractive effort?

I also read the Champelon was always at war with his locomotive crews for not running wide open throttle and properly hooking up the gear -- he criticized crews for wasting fuel by using the throttle to control power. Maybe the crews knew what they were doing and the limitations of highly-expansive working in high speed operation.

[Leon Silverman]

If anyone wants to see how complicated a three cylinder steam locomotive is, you can visit the Franklin Institute in Philadelphia, Pa. I suspect that Baldwin Locomotive Works donated the engine because they could not find any customers to buy it. It is a 4-10-2.

[wccobb]

Yes, there are inside side rods on the Champelon 2-10-2. And the rear cylinders are not located per "standard" American practice. They are at a considerably raised elevation, quite probably to allow space for the inside side rods. Likewise quite probably were the "slide rule guys" at Altoona to adapt this modification to the PRR T1s, they could go just a couple inches or so higher and put all the siderods outside the frame !!!!!
The 330,000 lb drawbar of the D11R is NOT an extrapolated figure. Among other things, it is an engineering design requirement. Every component in the D11R is designed strong enough that it can do what it needs to do for that drawbar figure. There are two track groups, one right side and one left side, each providing 165,000 lb of the drawbar. Each drive sprocket is capable of handling 165,000 lb. Each track link is capable of handling 165,000 lb. Painting them other than Caterpillar yellow does not decrease their strength. Installing them on a steam powered "vehicle" with PRR lettering does not decrease their strength. There is a rather famous photograph from the 1920s showing a tug-of-war between a then-new Milwaukee Road electric locomotive and two Milwauke Road steam locomotives. The electric locomotive won. And the results would have been the same if the length of chain used were replaced with of a length of D11R track links. It's still the same 165,000 lb strong. And D11R track links would not have broken were two Milwaukee Road electrics been on one side and 2.5 PRR T1's on the other. (So OK, use 2 T1s and one E6 and I'll leave the good guys at Caterpillar to demonstrate how their D11R can produce a 330,000 drawbar.)
There are problems with all of these solutions. None of these solutions could have been used with the "existing" T1 frames. Of course GSC could have produced new frames that incorporated whatever changes the "slide rule guys" at Atloona wanted. Of course GSC would expect to be paid. The cost of the new frames is most probably a smaller part of the total cost of the very major job of changing frames. Very early in this thread, Highiron2003ar correctly observed: "The T-1 was designed and BUILT specifically to preserve the track". (Truer words wuz never spoke !!!). Each of these solutions is a significant compromise of that design criteria.
An alternate solution which has thus far eluded notice is that the Pennsy could have followed the example of the N&W. The N&W filled the frames on their J's (4-8-4) with lead. Were the Pennsy to follow suit with the T1's, the weight on drivers - in theory - could be doubled. A straight forward answer that could have been done with the existing T1 frames; requires no new parts, no revolving parts, extremely little (if any) maintenance, and it in all likelyhood the most cost effective of the lot. Make the T1 so heavy that it's impossible to slip the drivers. Unfortunately, this is not consistant with : "The T-1was designed and BUILT specifically to preserve track".
I beleive we may safely assume that the "slide rule guys" at Altoona knew of the leaded frames on the N&W and knew it was not suitable for their PRR. Likewise we may assume those "slide rule guys" knew of the LeChalerier and other sorts of resistive braking and found them not suitable for their PRR. And likewise the various methods of remote control for a single steam locomotive were known and were found not suitable for their PRR.

[GP40-2]

I'm not questioning the strength of the CAT components, what I'm questioning is whether the D11R can actually develop that much pull in the real world. I've been around plenty of construction sites and have operated smaller CAT dozers in the past. The treads do increase the traction, however, dozers can, and will spin their treads on a hard push/pull.

Like I said, I don't believe the physics supports the D11 producing 143% pull over its operational weight.

[feltonhill]

N&W J's did not have lead added to the frames. This was done to the low pressure engine of the Y5-Y6's when the booster valve was added in the early 1950's. The engine weight was increased from about 582,000 lbs to about 611,000 lbs. The J's always had 288,000 lbs on the drivers, no lead necessary.

[nobullchitbids]

For Leon Silverman's, and anyone else's, benefit who is interested, the 4-10-2 at the Frankline Institute is quite unique: In addition to being a 3-cyl. job, it has a water-tube boiler -- exactly the reverse of the vast majority of railroad locomotives but quite common in marine use. If memory serves, this boiler was rated at 330 pounds of pressure! Which was huge for its day.

I understand that the reason the Franklin locomotive did not sell was road resistance to the water-cooled concept, and not rejection of 3-cylinder design (the maintenance problems of that were not appreciated until later). As I understand the opposition, the fear was that a water-tube boiler, in a railroad application, could not (for all the vibration) be maintained with integrity. Sooner or later, the thing would leak, and irreparably.

In the marine application, the machine is riding on a cushion of water, not on unyielding steel rails, so the vibration problem does not arise, at least to the same magnitude. Water-tube boilers are quite good at pushing ships around.

[eastside]

QUOTE: Originally posted by nobullchitbids

For Leon Silverman's, and anyone else's, benefit who is interested, the 4-10-2 at the Frankline Institute is quite unique: In addition to being a 3-cyl. job, it has a water-tube boiler -- exactly the reverse of the vast majority of railroad locomotives but quite common in marine use. If memory serves, this boiler was rated at 330 pounds of pressure! Which was huge for its day.

I understand that the reason the Franklin locomotive did not sell was road resistance to the water-cooled concept, and not rejection of 3-cylinder design (the maintenance problems of that were not appreciated until later). As I understand the opposition, the fear was that a water-tube boiler, in a railroad application, could not (for all the vibration) be maintained with integrity. Sooner or later, the thing would leak, and irreparably.

In the marine application, the machine is riding on a cushion of water, not on unyielding steel rails, so the vibration problem does not arise, at least to the same magnitude. Water-tube boilers are quite good at pushing ships around.

A third strike might have been that it was compounding, a feature that wasn't very popular in the U.S.

[Anonymous]

First, the 60000 was water-tubed, not water-cooled.

It embodied too many radical concepts in one machine. From a maintenance standpoint, the particular design of water-tube firebox on the 60000 used something in excess of 200 washout plugs, each of which would have to be removed and replaced once a month at boiler wa***ime. The normal firetube boiler on a large engine might have 30 or so such plugs.

The center cylinder was always a maintenance problem in the US, more so than overseas. It's possible that it was as much a culture problem as anything else; enginehouse workers in Britain were always accustomed to going in between the frames to accomplish maintenance chores which were always outside in full view and handy to get at on a two-cylinder locomotive with outside valve gear. There is a 4-6-0 on display in one of the London museums that shows on each side a main rod, crossheads and piston rods to a set of outside cylinders, and of course the side rods. But reading the mechanical description of the locomotive reveals that it is a 4-cylinder compound with Walschaert valve gear; this means that not only are there two more cylinders, piston rods, crossheads and main rods connected to a crank axle, but there are two complete sets of Walschaert valve gear between the frames.

I don't know that the compounding feature of the 60000 would have been found that objectionable;

But that particular boiler design and the center cylinder would have been, and obviously were, enough to kill the thing commercially.

Old Timer

[gmstm]

I remember reading in Trains many years ago about the T1 and the N&W. The quote from the N&W man was "We tried to make an engine out it, but we couldn't." I think this was reality winning over theory.

[Johnstone]

I think the problem with the T-1 was to do with eqalisation. What the T-1 should have been was two 4-4-0 locos back to back. The adhesion and riding properties of these is a matter of record. What you actually got was the equalisation for a 4-8-4 applied to two separate locos, a recipe for disaster. Check for yourselves, the equaliser between the second and third drivers is easy to see.

[Anonymous]

QUOTE: Originally posted by Johnstone

I think the problem with the T-1 was to do with eqalisation. What the T-1 should have been was two 4-4-0 locos back to back. The adhesion and riding properties of these is a matter of record. What you actually got was the equalisation for a 4-8-4 applied to two separate locos, a recipe for disaster. Check for yourselves, the equaliser between the second and third drivers is easy to see.

I take it you're refering just to the wheel arrangement, and not suggesting a sort of center cab configuration with two separate sets of fireboxes, boilers, etc?

I think you're onto something, but what I would suggest is a pair of "reversed" 4-4-0's (0-4-4's?) back to back, with the two sets of pistons centered back to back, or even one larger set of pistons driving both the forward pair and trailing pair of drivers.

[Anonymous]

Sorry, but from my viewpoint, equalizing the two engines together would make for smoother riding than two sets of equalizers. Could you please explain you conclusion :)?

Sincerely,
Daniel Parks