Steam & Excursion > Running a 3-cylinder locomotive on two cylinders?

This Al Haij photo of UP 4-10-2 #8801 at Yermo, CA in 1938 turned up in the Jeff Moreau collection at the Southern California Railway Museum.  The locomotive appears to be under steam, but it also looks like the cylinder head of the center cylinder is missing.  Was it possible to cut out the center cylinder on a 3-cylinder locomotive and run it on just two cylinders, or is something else happening here?  Yermo had a roundhouse, but wasn't the site of a major shop complex as far as I know.

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It's technically possible, remove the valve actuation linkage, lock the valve in null postion, remove the
connecting rod to the drivers but the locomotive use out of Kelso would be as a helper going East and
why would you use a "lame" locomotive for that purpose. Not to mention the work would be almost
impossible without a shop. On the other hand maybe it blew the center head and is waiting for a tow
back to LA.

Out 

That class of locomotives were eventually remodeled into a 2 cylinder configuration. Could that be an early test?

https://www.steamlocomotive.com/locobase.php?country=USA&wheel=4-10-2&railroad=up

Would the third cylinder be cast into the frame?

If so, conversion to 2-cylinder might leave that artifact.

ts1457 Wrote:
-------------------------------------------------------
> Would the third cylinder be cast into the frame?

These engines had built-up, not cast, frames to which two-piece cylinder castings were bolted.
>
> If so, conversion to 2-cylinder might leave that
> artifact.

This is clearly a bad order engine.  If a conversion they wouldn't have left the stuffing boxes on the piston valves and Gresley valve gear for a center cylinder to be maintained.

-LD



Edited 1 time(s). Last edit at 11/30/24 13:54 by LarryDoyle.

Converting a three cylinder engine to two cylinder engine would not only removal of the center drive piston and valve mechanism, but also removal of drivers from their axles and reinstalling them 90 degrees ("quartered"} on each axle.  They are 120 degrees offset on a three cylinder machine.

-LD
 

LarryDoyle Wrote:
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> Converting a three cylinder engine to two cylinder
> engine would not only removal of the center drive
> piston and valve mechanism, but also removal of
> drivers from their axles and reinstalling them 90
> degrees ("quartered"} on each axle.  They are 120
> degrees offset on a three cylinder machine.

Thanks, makes sense.

The conventional 90-degree phasing delivers 4 power strokes 
per revolution.  With 120-degrees between cranks, on 3-cylinder engines,
you get 6-power strokes per revolution.

Typically, you'll find the center piston connected the 2-axle of a set of drivers.
Also, because of 'clearance' conflicts, the no. 1 driver axle will have an offset
formed into it's driver axle --- to allow ample clearance for the main-rod powering 
axle #2.

it is difficult to access ( properly) the moving parts of the 3rd cylinder.
A  3-cylinder loco looks GREAT on "paper";  but, in service their down-time 
became onerous... and even with extra attention, when powering heavy freights,
the ""weakest link in the system" was all the parts associated with that 3rd cylinder and 
axle.   

A question for this situation:  How would you shut-off stream from the throttle, from being
wasted out the #3 cylinder --- if the intent is to be self-propelled to destination?
Unless the boiler steam is under pressure, you'd have no power to the 'good' pistons..

The extra maintenance required to maintain 3-piston/cylinders doomed them for ever 
gaining dominance in the "states".  Foreign RRs had better luck, but their train-weights 
were 20% of a typical American freight train.   When put against American mountsins 
and grades, the 3 cylinder machines soon faded in populatar.

Articulated locos, like 4-6-6-4s were much easier to keep "in service":
Perfomed flawlessly, and spent more time "out on the road", earninhg money .
 
​W.



Edited 3 time(s). Last edit at 12/02/24 03:14 by wcamp1472.

The gentleman on the left front seems to have a wrench in hand. Could be a man up on the locomotive higher up on the left side doing a repair?

Looks like she is only one engine length from the turntable behind her and may have recently arrived. Doubtful she goes anywhere before some repairs are made.

The picture is dated 1938.  Utahrails shows the following: LA&SL 8800-8808 were built as three-cylinder locomotives; converted to two-cylinder locomotives in 1942-1943 and renumbered to LA&SL 5091-5099.  If accurate, the pictured loco was still three cylinder, but what is that big round dark area where the third cylinder head should be?  Interesting discussion.  Maybe the  8801 was the test bed for the later conversions?

JBWX  



Edited 1 time(s). Last edit at 12/01/24 16:03 by jbwest.

>  Maybe the  8801 was the test bed for the later....

How could a two cylinder engine with cranks set at 120/240 degrees reliably avoid "dead centering" on start of a movement. 

And, why would it still have Gresley valve gear?

-LD



Edited 1 time(s). Last edit at 12/01/24 16:38 by LarryDoyle.

I'd bet that the 3rd piston and main rod are getting re-habbed,
and are on a workbench in the roundhouse.

The crank-end of the main rod has two brass blocks that 
are crankpin bearings for the mainrod.  While in service, it's
hard to access the adjustable strap, as the brasses get worn.
The packing set for the piston is virtually inaccessible, once everything
is in place, 

And it's hard to replace the cylinder-packing, without removing the piston 
and rod.  ( "cylinder-packing" is roundhouse term for 'piston rings').
But, the packing's parts are more numerous & complex than automotive piston rings.

Being connected to the 2nd drive axle means that the angular movement 
through the crank circle, makes wider swing of the main rod, increasing 
the wear at that crankpin.   On conventional 2- cylinder locos, good "mainrod geometry"
calls for as long a mainrod as possible ---- to reduce the 'angularity' of the mainrod.
And longer bearing life for  their main rod crankpin bearings.

So, I'd guess this was a common practice...
I don't know why they're working outdoors.

​W.


 



Edited 1 time(s). Last edit at 12/02/24 03:07 by wcamp1472.

In reply to LarryDoyle's question on dead-center null.

(A hypothetical question...  No railroad ever tried 2-pistons at 
120-deg of separation..)

But here goes a response to a hypothetical situation..

Each crank is separated from the other 2 by 120-deg of arc.
If the center crank is missing its Main Rod, then the other 2 
are still powering ---- the steam supply to the center cylinder 
must be blanked-off--- and the 2 remain separated by 120-degrees.

If the drivers are not re-keyed for 90-degree separation on their crankpins,
then the 120-degree separation means that a piston at a dead-center 
( piston at a cylinder head ) will always have it's mate at 120-degree 
position, thus a dead-centered engine would have it's other piston 
powered by steam, but late in its stroke.

The engine would not be stalled.
However, it's train hauling capacity would be severely curtailed, and 
not able to move many cars.

As I say, I doubt any 3-cylinder loco ever operated on only 2 of its original cylinders,
and the drivers still keyed at 120-degree separation.

With 90-degree keying for drivers on the same loco, there's 4 power strokes
for each driver revolution... and the possibility of having a driver at its dead-center,
and weaker at starting.  With 6-power strokes per revolution, you'll never 
have a loco stalled on a dead center.

With 3 cylinders at 120-degree 'phasing', then there's 6 power strokes per 
revolution. 

Keeping that center cylinder, it's cranked axle happy and well lubricated
was a constant fight.  How UP kept a fleet of them running must have
very costly in numbers of man-hours keeping the fleet hauling freight.

​W. 

​



Edited 3 time(s). Last edit at 12/02/24 18:43 by wcamp1472.

The 1938 date on this photo matches the period when LA&SL was having serious problems with the three-cyliner design. Gordon McCulloch wrote the following in his self-published book, "The History of Union Pacific Steam."

"Over time, the 8800s had worsening problems with the inside main-rod bearings. Much of that situation was a direct result of wear at the pivot points of the Gresley valve gear. Excess wear led to lost motion, which led to a shift in admission valve timing, which led to premature cutoff on the retract-strokes, and a delayed cut-off on the extend-strokes. That altered timing promoted rod pounding from excess admission of steam before the valve reached its cut-off point.

"Another result of the rod pounding was loosening of the bolts that attached the cylinders to the frame, resulting in alignment problems and cylinder breakage. These issues led to appreciable out-of-service time. As alluded-to above, the rod pounding was mostly attributable to uncorrected issues with the center valve gear. Apparently, fixes applied by the railroad on the center gear were temporary at best. Long term corrective solutions might have been applied over time if not for the evolution of large four-cylinder simple articulated freight engines by the late 1930s. Three new CSA Challengers were converted to oil and sent to the LA&SL in 1937, in part due to issues with the 8800s.

"By the late 1930s, LA&SL was looking for any solution to salvage their investment in the 8800s. Two had been sitting for months in 1941 with their cylinder and valve assemblies broken off the frame. A rebuild program was finally begun in 1942 under which all ten would be rebuilt at the Los Angeles shops to two-cylinders, then being renumbered as 5090-5099."

Don Strack

When builders made Demo models as a sales tool in the late 1920s/early 30s,
Lima had great success with their early 2-8-4s and how they outperformed 
existing 2-8-2s.  The 2-8-4s performed superbly with greater pulling power,
while burning less coal and water.  Early tests in the Berkshire Mountains,  
had the single 2-8-4s pulling the same trains as were pulled by double-headed 
2-8-2s, and did it in less time, over the road, burning less coal and water.

Such performance produced orders for many Lima 2-8-4s, and Erie RR had
many 2-8-4s which were made by Alco.

Baldwin sent a demonstrator around the county: a 4-10-2 , 3-cylinder engine,
with a water-tube firebox.   The complex Baldwin 4-10-2, # 60,000, never produced 
an order for a single copy.  60,000 now resides in Ben Franklin Musuem's 
halls, and is rolled back and forth for about 30 feet.

When I looked over 60,000 I was astounded at the firebox construction:
each side had long, flat rectangular water boxes'  with what looked like 4" diameter
vertical circulation pipes the formed the side walls of the firebox.  The tops of the 
vertical tubes curved, and were connected to a long, steam-drum at the top of the
firebox.  

There might have been 50 or so vertical pipes, monunted in a staggered 
row pattern, to squeeze-in as many firebox tubes as possible.  Below each tube 
in the rectangular water-box, was an individual brass 4"-diameter wash-out plug...
with standard 12 threads-per-inch, tapered threads.  So, at boiler wash-out time
( every 30 days), workers had to remove and replace about 100 washout plugs.

Anyway, after sending their demo-model around the country, it never produced 
an order single order for a duplicate from Baldwin.

Together with 3 cykinders and crank axles, the water-tube fire boxes, a theoretical 
class of duplicates would spend most of every month being maintained while 
in the roundhouse --- truly a "working-man's friend"...

The Berks had a design fault that wasn't appreciated until in service...in that 
at fast track speeds they pounded the ROW and became rough-riders.
Fast track speeds were tge result of large grate areas, and free-steaming boilers.

The engines were soon found to be 'rough-riders'.  Partly beacuse the Main driver
and the 4th driver had massive counterweights, and as recent postings on T/O 
explained:  counterbalancing was its own 'art'.... and took years to perfect.

A contributor to the rough-riding was that the counterweigted drivers were very 
near the center-of-mass of the loco structure.  In aircraft that "center" is called 
the center-of-gravity.  

Whatever moves the 'centers', moves ( shakes) the whole "structure".
With steamers, the solution led towards moving the Main Driver, forward,
from #3 axle, to the #2 axle,  The Main Driver is where the piston rods's
power strokes are connected to the drive-wheel power scheme.
If you moved the power imbalances further away from the center-of mass,
you would reduce shaking the whole engine.

But, that meant moving the cylinders well ahead --- to preserve the long Main Rods,
and less-sharp angles.  So, to support tha greater weight at the front of the locos,
they used 4-wheel 'pilot' trucks.... 

Thus, was born the very successful design: the 4-8-4!   The design was easier 
on the roadbed, and allowed bigger engines, larger drivers & speeds approaching
100 mph --- all thanks to the superb performance increases of the earlier 2-8-4s !

​W.
 

donstrack Wrote:

> The 1938 date on this photo matches the period
> when LA&SL was having serious problems with the
> three-cyliner design.

Thanks for the insights, Don. From the comfort of the armchair, the obvious play would be to keep ahead of the wear on the Gresley gear through preventive maintenance before the cascade of horrors took the engines out of service, but it probably wasn’t that simple.

The biggest challenge is the conventional  arrangement for 
the bearing at crank-end of the mainrod.... the cranked 2nd axle.

The 2nd axle of the drive system has 3 section construction:
two axle-halfs and a 3-piece, middle crank.  The 2 arms of the crank
are massive: they not only transmit torque to the drive system, but also
have to keep the 3 pieces 'square' during high steam pressure, when 
lugging a freight uphill.

So, it was before the perfection of 'rolling-element' bearings, and 
the bearing at the crank was two blocks of brass, separated by about 
an inch --- to allow for future 'tightening' as the brass blocks wore from 
the friction and pressure from the steam powered 3rd piston.

To re-tighten the two brass blocks, a large 'U' shaped metal 'strap' surrounds
the outer of the two brass blocks.   You can see the arrangement 
on any steam loco with non-roller bearing Main crankpins.   

So, the U-shaped straps have elongated bolt holes, to allow occaisonal
tightenting of any 'lost motion' between the crankpin and its two bearing 
blocks.  You have to loosen the bolts clamping the outer bearing-half, 
force the loose bearing tighter to the crankpin ( but, not TOO tight!) .

Then you gotta' retighten the 'clamp bolts' .... That's easy for conventional 
main bearing crankpins.---- it's virtually impossible when the strap and the 
clamp bolts are situated between the two Axle-crank arms, surrounding 
the 3rd crankpin.... and you're under the engine, in very cramped conditions ...
the cranks are large and the axle is lined up with all the other axles.

Even with ratchet wrenches and socket extenders, it's nearly impossible to
access the straps,and you need to position the crank in one specific position 
of the locomotive.  

All very difficult to keep tightened.  
Every trip, of one-hundred miles, loosens-up and causes. wear to the two 
brass bearing blocks.  Then, get the engines over pit and get the mechanics 
under there, again.

​W.







 



Edited 1 time(s). Last edit at 12/05/24 14:38 by wcamp1472.

Another interesting feature of the BLW 60000 is that she is a compound.  The inboard was high pressure and the outboard cylinders were the low pressure cylinders, which would have made for a goofy sounding exhaust beat.

While the UP's  3 cylinder 4-10-2's turned out to be problem children, the UP 9000 class 3-cylinder 4-12-2's managed long careers, as did the SP's 4-10-2's.