Three Cylinder Steam Locomotives
Okay – So I found something new (for me) – three cylinder steam locomotives! At first when I saw this topic, I thought of the 3 piston Shays built by Lima. But, the locomotives shown here are built by ALCO and are rod locos rather than geared.
New Haven had a class of 3-cylinder heavy 0-8-0 switchers, class Y-4. Here is #3601, built in 1924. This was the second of ten of the Y-4’s: roster listing 3600 – 3609, all built in 1924.
Here’s NH # 3602 – the third of the class.
NH #3605 was first provided with a long haul Vanderbilt style tender – this appears to be a builder’s photo. The class Y-4’s were originally built as road locos and were all delivered with these large road tenders. Other later photos of #3605 show it with the smaller more standard switching tender as shown in the previous pics.
Here’s a picture of NH #3605’s headlight. (Headlight still exists!)
The Y-4s were followed by six Y-4-a’s, numbered 3610 – 3615, built in 1927. This is #3611, the second of the Y-4-a’s. New Haven typically mounted the headlights in the center of the smokebox front above the pilot, but it looks like they moved the headlight to the top of the smokebox on #3611.
Here we get a look at NH #3614 – another Y-4-a. (Headlight in the center.)
Here’s NH #3615 – the last of the Y-4-a’s shown with a large road tender. Again, I believe this is a builder’s pic. The Y-4-a’s were all delivered with this version of tender for road service, and then the tenders were switched out for cut back tenders as shown in the previous pics
But the Y-4’s weren’t the only NH class of 3-cylinder steamers. Class R-3’s, 4-8-2 mountains, were also built by ALCO with 3 cylinders. Three Class R-3’s were built #3550 – 3552, in 1926. Here’s NH #3554 a class R-3-a. Check out the water heater on the top of the smokebox, and the two air pumps on the pilot. Class R-3-a consisted of 10 locomotives from 3553 – 3562 built in 1928.
So how did the 3 cylinder locomotives work? Here you see a cross section of the front of a 3-cylinder steamer. The two typical cylinders sit on either side below the smokebox, in front of the drivers, with the valve cylinder directly above. As expected, these cylinders drive the side rods fastened to the outside of the drivers. In the center of the diagram, above the pilot and below the smokebox, you see the third cylinder with the valve cylinder on the left. I’m not sure if the 3rd valve cylinder is stealing steam pressure from the outside valve cylinder on the left, or if a separate steam line runs down through the smokebox. This cylinder drives a main rod attached to an eccentric in the axle of the main driver. So in lieu of quartering the attachment of the drive rods, these rods were set at 60 degrees differences. While the typical 2-cylinder locomotive has 4 chuffs per driver rotation, these locos had six chuffs! Very interesting if you’re setting up a sound system for your model steamer.
Here you can see the center cylinder on the left with the piston rod attached to the drive rod.
The drive rod had to be designed to move above the axles of the front drivers, and then drop down to the main driver to the axle eccentric. The valve gear had to be squeezed sideways between the two outside cylinder valve gear. As you’ll see later, this arrangement caused heavy loading on the bearings of this third drive – especially on larger locomotives.
This pic gives a great view of the center cylinder. So…Why a 3-cylinder rod steamer? The third cylinder not only increased horsepower (by roughly 50%), but also added tractive effort. The 0-8-0’s were tested at roughly 60,000 lbs tractive effort which was more than a lot of 4-8-2’s and 4-6-4’s of the same time period! (USRA 0-8-0’s are listed with a little over 50,000 lbs tractive effort. I’m not sure I fully understand all the added tractive effort – I’ll have to check it out later.) The drawback was that maintenance on the third cylinder was a bear. It wasn’t designed any different from the other two, it was just getting access to it – crowded between the other two cylinders and under the smokebox! The three-cylinder locos were deemed “Roundhouse Queens” because they sometimes spent more time in the shop than in service.
New Haven wasn’t the only user of these 3 cylinder locos – Here’s SP #5042, a 4-10-2, class SP-3 built by ALCO. ALCO delivered ten of these class SP-3’s to the SP in 1927, numbers 5039 – 5048
SP #5021 is one of the few remaining 3-cylinder locomotives. It’s in a permanent display at the Fairplex railway exhibit in Pomona, California. 5021 was part of the SP-2 class, predating the SP-3 class. ALCO delivered 23 of these in 1926, numbers 5016 – 5038. And prior to the SP-2s were the SP-1s – 16 were built in 1925 numbering 5000 – 5015.
Here is one of UP’s 3-cylinder steamer, #9000, a 4-12-2, built by ALCO in 1926. UP took delivery of 10 of these in 1925 #8000 & 8800-8808. The first group was relatively unsuccessful not only because of the maintenance issues, but also because of the heat build-up on the eccentric bearing (the 3rd cylinder drive). The UP worked with ALCO to try and alleviate some of the problems, and the second group of 15 was delivered in 1926, #9000 – 9014. Still, a third group of 15 was delivered in 1928 numbered 9015 – 9029. The 4-12-2’s were know for “straightening out” curves! Most were moved to service out west where the lines ran straighter.
The Alton & Southern RR took delivery from ALCO for #12 another 0-8-0. #12 is another of the few remaining 3-cylinder steamers. (I believe the front end pic and 3rd cylinder pics above are from the static display of #12.)
Wabash bought 5 class K-5 Mikados, 2-8-2’s, 3-cylinder locos from ALCO in 1925, numbered 2600 – 2604. These engines were relatively unsuccessful, and the boilers were used for a rebuild into 4-6-4 Hudsons, class P-1, in 1943 & 44 (without 3 cylinders). In this pic of #2601, you can just pick out the 3rd cylinder behind the steps on the pilot.
So, the 3-cylinder experiment in the US was only modestly successful. Some of the 0-8-0 switchers had long lives, but most of the larger locos suffered from the drawbacks of maintenance and difficulties in overheating in the bearings of the 3rd drive. The 3-cylinder steamers were much more successful in England and a few other countries overseas. It’s funny how with the amount of time I spend looking at steam locos and steamer technology, I can just stumble upon the 3-cylinder efforts recently. But it is certainly a fascinating effort by ALCO in the mid to late ‘20s.