On this day, June 19, 1876, British steam locomotive designer Sir Nigel Gresley was born.

[mahatmakanejeeves]

2. Until now, I thought I was the only person at DU who had even heard of it.

There are quite a few video clips at Youtube posted by people who seriously know their way around a machine shop.

And good morning.

Southern Pacific 4-10-2 Valve Gear Test 3

SP5004
380 subscribers

7,614 views Jul 20, 2017
Close-up of the valve gear motion in a test for a 1.6" (1.6007 :-p ) scale Southern Pacific 4-10-2. There have been several attempts to get the project off the computer screen and into the real world with out success. Yet.

On a normal locomotive with only 2 cylinders, the crank pins are set 90 degrees apart from each other. This means a power stroke every 90 degrees of rotation of the drivers.

Right-hand Cylinder 0.0/360 degrees.
Left-Hand Cylinder 90 degrees.
Right-Hand Cylinder 180 degrees.
Left-Hand Cylinder 270 degrees.
Right-hand Cylinder 360/0.0 degrees.

This makes for a very evenly timed "chuff" sound from the exhaust.

Chuff. Chuff. Chuff. Chuff. Chuff. Chuff. Chuff. Chuff. Chuff.

On a locomotive with 3 cylinders such as a Shay the crank pins are set 120 degrees apart. This means a power stroke every 60 degrees of rotation of the drivers whihc again makes for a very evenly timed "chuff" sound from the exhaust.

Chuff. Chuff. Chuff. Chuff. Chuff. Chuff. Chuff. Chuff. Chuff.

However, on these locomotives the Center Cylinder had to be raised up to make room for the Engine (aka Lead) Truck. This put the Center Cylinder at a 9.5 degree angle.

The locomotive is considered "right-hand lead" thus the first power stroke is the Right-Hand cylinder and the Right-Hand crank is at 0.0 degrees.

Thus the order of the cylinders is Right, Center, Left and the power strokes occurred as follows:

Right-Hand Cylinder 0.0/360 degrees.
Center Cylinder 50.5 degrees.
Left-Hand Cylinder 120 degrees.
Right-Hand Cylinder 180 degrees.
Center Cylinder 230.5 degrees.
Left-Hand Cylinder 300 degrees.
Right-Hand Cylinder 360/0.0 degrees.

This gave the locomotive a very unique "stuttering chuff" from the exhaust.

Chuff.Chuff...Chuff. Chuff.Chuff...Chuff. Chuff.Chuff...Chuff.

Gresley valve gear, O-scale 4-12-2

Train Kitchen
634 subscribers

37,706 views Mar 22, 2019 #trainkitchen #oscale #proto48
O-scale Sunset Union Pacific 4-12-2, working 3rd cylinder & Greesley valve gear


#trainkitchen
#oscale
#proto48

Not impressive enough? Try this three-cylinder Caprotti valve gear demonstration.

7 1/4” gauge Duke of Gloucester

The Steam Workshop
11K subscribers

14,517 views Sep 3, 2018
This is our rebuild project of the 7 1/4” gauge Duke of Gloucester. Built by the late Dennis Evans, she’s a full 3 cylinder Caprotti valve gear masterpiece and we are proud to be trusted with her rebuilding. For more information like us on Facebook, follow us on Instagram or visit our website page for this loco. www.steamworkshop.co.uk/portfolio/sw-rebuild-no-17/