Three cylinder steam engines

[timz]

Never have tried to figure out BLW 60000’s valve gear-- try

http://cwrr.com/Lounge/Reference/baldwin/baldwin.html

There’s a side view drawing, which you’ll have a hard time deciphering. Maybe the text will explain.

[HARVEY_GEORGE]

I had experience with Baldwin built 4-6-2s in Thailand in the '70s when they were in service. Originally they were used on the premier passenger trains. By the time I saw them they were working local service due to the introduction of newer engines. They had equal size cylinders with the steam chest to the left of the middle cylinder. There were two sets of Walschearts motion on the left side. The chug was heard in a synchopated beat. They must have been successful because all other locomotives purchased about the same time were long retired.

[M636C]

21. Walschaerts valve gear is used, with an independent motion for each cylinder, but all controlled by one type B Ragonnet power reverse gear. The valve for the left-hand cylinder is operated from the left-hand main pin and crosshead in the usual way. The right-hand valve receives its lead from the right-hand cross-head, but the link for this cylinder is operated through a transverse shaft, by means of a connection to the left-hand crosshead. The return crank on the right-hand main pin is set to operate the valve for the inside cylinder, and this valve is given lead through a connection with the inside crosshead. The arrangement of the links, arms and rockers through which these connections are made, is shown in the accompanying drawings. The valve motion bearer is a single steel casting supporting practically the entire valve gear.

Reading this in conjunction with the side view of the valve gear Fig 13a at the link Timz provided above:

So my interpretation is:

The left side is straight Walschaerts.
The right side is basically Young gear as used on the UP 7000 4-8-2s driven by the LH crosshead.
The middle is Walschaerts driven from the RH crosshead

That might not be strictly correct but it has made my entire week - Many Thanks

M636C

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[daveryan]

The center cylinder is cranked to a driving axle, with the connection located between the frame members. It is angled in order to provide clearance. There were simple, as well as compound versions of this arrangement, but the compounds generally proved impractical in North American use. All survivors in this country are simple engines, as far as I know.

Surviving examples include Alton & Southern 0-8-0 no. 12 in Kirkwood, MO; Baldwin 4-10-2 no. 60,000 in Philadelphia; Southern Pacific 4-10-2 5021 in Pomona, CA; and Union Pacific 4-12-2 9000, also in Pomona.

[M636C]

Wizlish wrote the following post 6 days ago:

I do not know how the control was arranged on 60000; perhaps Mike (wanswheel) can find something definitive. My naive idea would be to have a ‘trim’ control on the center cylinder that would allow it to be adjusted separately from the LP cylinders, but then have all the gears worked running by the same power reverse. Fortunately the engine still exists and someone doing research could at least in theory gain full access to the cab and running gear, and watch the result of adjusting the controls that are there, with HR video running to observe the valve spindle motion outside and inside, to see how the trick is done.

While I’m not sure how they do it, the test results in the data at Timz’ excellent link show a fixed relationship between cutoff of the HP and LP cylinders.

60000 started with the cutoff at 80/50 (80% on the HP, 50% on the LP) and this varied downward with the fixed difference of 30% between HP and LP except below 50% on the HP it fell to 40/20, so 20% difference.

How this fixed ratio was arranged between the gears isn’t clear (to me anyway) but it was acheived with a single power reverse.

M636C