Six Cylinder Steam Locomotives???

[NWP SWP]

Did a six cylinder steam locomotive ever exist? Not a triplex locomotive but a duplex or articulated that has a third cylinder on each driver set.

[7j43k]

I've never heard of one in the US.  And, in the rest of the world, there weren't that many duplexes of articulateds.

I think it would have been a problem to run the extra piping.  On a regular three cylinder loco, the "piping" is all in the cylinder saddle.  Pretty much.  But once you start running steam pipes around elsewhere, it could get pretty crowded.

And if yer gonna say: "What about the triplexes?" in response, be reminded that the triplexes were piped just like regular mallets, except they ran another set of low pressure pipes to the tender.  Pretty much like a steam booster on a trailing truck.

 

Ed

[M636C]

NWP SWP

Did a six cylinder steam locomotive ever exist? Not a triplex locomotive but a duplex or articulated that has a third cylinder on each driver set.

 

There were four that I can think of....

 

A 2-8-0+0-8-2 Beyer Garratt built for the London and North Eastern Railway. This had three cylinders with Gresley conjugated valve gear each end, and was built in 1925. It lasted into British Railways days (past 1948) but was withdrawn well before the end of steam.

 

Three 4-6-2+2-6-4 Beyer Garratts for the New Zealand Railways Numbers 98-100. These were found to be too powerful for the draft gear of the freight vehicles of the time, and were expensive to maintain. They were taken out of service and the engine units were converted into six three cylinder Pacific type locomotives which ended up being numbered 95-100. These lasted into the 1960s.

 

I can think of two eight cylinder locomotives:

 

The Tasmanian Railways had three eight cylinder Beyer Garratts, 4-4-2+2-4-4 express passenger locomotives. These had four cylinders at each end with the inner valves actuated by rocking levers from the outside Walschearts valve gear.

 

One of these left the track due to excessive speed on a curve at Campania north of Hobart while still fairly new, and the class was withdrawn. The boilers were later used as spares for three 2-6-2+2-6-2 freight locomotives built at the same time.

 

The New Zealand Railways built a locomotive commonly known as "Pearson's Dream", a sort of 2-6-6-2 mallet articulated but with the rear cylinders under the cab. This counts because each engine unit had Baldwin Vauclain Compound cylinders (purchased years earlier but never used) so the loco as a whole had eight cylinders, four each end. The rear cylinders exhausted directly to atmosphere via a stack at the rear of the coal bunker. It was used as a pusher engine on the Rimutaka incline which had Fell centre rail adhesion and braking, although this loco wasn't so equipped.

 

It didn't last long.

 

Peter

[NWP SWP]

So nothing in the US like a SP-2 but articulated?

[Overmod]

The simple articulated was developed in part to address the maintenance and operational issues with large three-cylinder power of the '20s.  The advent of better 2-cylinder balancing and the N&W and Alco approaches to stabilizing the front engine of a high-speed 'Mallet chassis' got rid of any particular reason to use inside cylinders, cranked axles, etc. and some of the issues requiring their use (e.g. tight British clearances) did not apply meaningfully in North America.

Had compounding taken off again in the wake of stayboltless-firebox development we might have seen a return to 'multiple three-cylinder engines'.  An example of a nominally six-cylinder engine not yet mentioned is Chapelon's 160 A1 (with 2 of the cylinders acting as one, so from the steam's point of view a 5-cylinder) which used the multiple cylinders and an interesting version of jacketing and reheat right at the end of modern steam.

[M636C]

Overmod

The simple articulated was developed in part to address the maintenance and operational issues with large three-cylinder power of the '20s.  The advent of better 2-cylinder balancing and the N&W and Alco approaches to stabilizing the front engine of a high-speed 'Mallet chassis' got rid of any particular reason to use inside cylinders, cranked axles, etc. and some of the issues requiring their use (e.g. tight British clearances) did not apply meaningfully in North America.

Had compounding taken off again in the wake of stayboltless-firebox development we might have seen a return to 'multiple three-cylinder engines'.  An example of a nominally six-cylinder engine not yet mentioned is Chapelon's 160 A1 (with 2 of the cylinders acting as one, so from the steam's point of view a 5-cylinder) which used the multiple cylinders and an interesting version of jacketing and reheat right at the end of modern steam.

 

I should have said something about 160A1 but it demonstrates one of the basic problems with inside cylinders, that things get complex when something requires replacenent or even inspection.

 

I understand that in his interview with Gresley, Holcroft recommended against what became the standard "Gresley" conjugated gear arrangement because of the difficulties in coping with valve rod expansion and the fact that this threw the setting of inner valve out of alignment with the outer valves.

 

Gresley's response was he was less worried about the accuracy but was impressed by the ease of access to both the gear and the inside valve and piston with that arrangement.

 

Having Gresley gear on the rear engine of an articulated (or even a Duplex) would make access to the valve gear, piston and valve difficult.

 

People who complained about the access to the rear Franklin gear on a T1 might have been happy they didn't have Gresley gear on the rear engine.

 

Peter

[7j43k]

Cough cough.

Additional Walschaert valve gear on UP 4-12-2's.  To replace Gresley.

Cough cough.

 

ed

[7j43k]

I could mention that there were 6 steam cylinders in the late production Lima rotary snow plows.  Not locomotives, of course.

Ed

[M636C]

7j43k

Cough cough.

Additional Walschaert valve gear on UP 4-12-2's.  To replace Gresley.

Cough cough.

ed

 

Ed,

 

The original poster wrote:

"So nothing in the US like a SP-2 but articulated?"

 

and I was answering his exact question.

 

There were three cylinder locomotives with three outside Walschearts valve gears before Gresley put his gear in his big 2-6-0 No 1000 in 1920.

 

Balldwin in particular supplied three cylinder locomotives with two outside gears on one side to Thailand in the 1920s, where I saw one preserved in 1985. Baldwin 60000 in Philadelphia also has that arrangement.

 

Using that valve gear arrangement would avoid valve gear complications on an articulated or a duplex, but the centre cylinder and valve on the rear engine would still be hard to get at, worse in a duplex, but still behind the hinge on an articulated.

 

Peter

[hardcoalcase]

Baldwin built a 4-10-2 (#60000) that had three cylinders, the center one ehausting to the two outside ones.  It was built as an experimental test unit to see if there was enough interest from the RRs to warrant further development, while several RRs did test it, none were impressed enough to place orders.  

In 1933 the locomotive was donated to the Franklin Institute Museum in Philadelphia where it still sits today.

Here is the wiki link:

https://en.wikipedia.org/wiki/Baldwin_60000 

Jim