Is it true that the passenger steamers had the larger diameter drivers for increased speed? Camera was mounted on a tripod so the distance from each loco was EXACTLY the same…
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You are correct, Jim.
Larger drivers for speed and smaller for power and traction.
With out a dought. That is how the 999 hit 100 mph. Large dirvers.
Thanks guys…anyone know which steamer had the largest? And just how big were they on the Hudson J1E? In comparison, how large are they on the fastest diesels?
The Hudsons had 79" drivers…
The standard wheel on diesel is 44"
I was just at the Museum of Science & Industry in Chicago the other week. The 999 hit 112.5 mph with 86" drivers and needed a pu***o get going. It is displayed with smaller drivers that replaced the larger ones after the record speed run which incidently damaged the valvegear. The larger drivers wouldn’t fit underneath the running boards. Diesels use a traction motor that is geared to the wheels which makes diameter of the wheels irrelevent, passenger engines are just geared higher than freights. John[8D][:o)]
Jim,
Think of it like this. Let’s say that you have two locomotives side by side, one with 44" drivers and one with 79" drivers. Let’s also say that both drivers are turning at the same speed, 1 rpm for purposes of this. The circumference of each driver is given by the forumla pi*D, meaning that the 44" diameter drivers have a circumference of 138", and the 79" drivers 248". That means that every minute, the 44" drivers move 138" down the track, while the 79" drivers move 248". Assuming no slipping at 1 rpm, the 44" diameter drivers would be moving at 1.6 mph, and the 79" drivers 2.8 mph. Of course, the difference is much more striking with higher differences in rotational speed.
very good reply Ben. It would be pretty boring watching locos going 1 rpm tho wouldn’t it? John[8D][:o)]
Man, considering the weight of the valve gear and connecting rods of those fast passenger steamers, that was a LOT of mass thrashing around at high speeds! It’s a wonder everything held together! Yikes!!!
Thanks for the history and physics lesson!
Your cylinder has steam emitted, uses the steam and exhusts it about 3 times per second when in “company notch” the closest notch on the power reverser… aka; Johnson bar
One of the benefits of moving to diesel electrics was the fact that steam engines beat up the rail so bad because of all that weight pounding up and down. Modern trains don’t have that up & down motion. I always marveled at all that heavy machinery in motion also and wondered just how it stayed together. Inside the modern diesel electric is a reciprocating engine where the pistons stop at each end of the stroke tho, and reverse direction and stop at the other end to the tune of maybe 900 rpms. There’s a lot of mass there too. John[:o)]
The biggest drivered engines of which I’m aware were the Crampton locomitives designed by Isaac Dripps for the Camden and Amboy Railroad in 1849. The engine was a 6-2-0 machine with 8 foot diameter drivers. Actually there were 7 such engines 5 had the 8 foot diameter wheels and the other two were only 7 feet.
In 1848 Baldwin was offered $10,000 to build an engine for the Vermont Central to pull a passenger train at 60 mph. He delivered a 6-2-0 Crampton named the Governor Paine which had 6.5 foot drivers. The difference was in the lead truck. Whereas the first Crampton had a single 6 wheel lead truck the Baldwin engine had a 4 wheel lead truck with two more small wheels placed directly in front of the huge drivers. The driver axles and the two wheels of the “lead” truck were combined so that the weight of the engine could be shifted back and forth between the wheel sets. The engine is reported to have hit 84 mph on the straightaway - with the roadbed being what it was in 1849 that would have been one wild ride!
The motion of the pistons of any steam engine (be it a stationary engine or locomotive) when the pistons stop at the end of each stroke and then begin their return, is referred to as “Lost Motion.”
BillFromWayne
www.modeltrainjournal.com
Hey, it ain’t the size of the wave, but the motion of the ocean!
Jim, I’m not gonna get caught up in all the technical hoopla. Let’s just say my layout babes have ALWAYS preferred bigger drivers!!! Scale Niagara drivers here(click on pix to enlarge).
One of my babes admiring a scale Pennsy T-1 Duplex driver!! Both 1:48th scale:
[:D][:D][:D][:D][;)]
Jon, you bimbo! I actually thought of you when I originally titled this thread and decided you’d jump on it so I added the “Steamer Wheels” in parentheses…(wink)
But it does beg the question, “Once you get those Big Drivers pumpin’, how long does it take to stop 'em…???”
K, Now I have an additional pickup line for gals. “You are invited to my basement layout to see my big-drivered huffing and puffing steam engine and blow the horn.”
Sadly, the line probably won’t work.
Its wortha good slap in the face, Dave
Jim, I think the whole idea of the bigger drivers was that you weren’t going to get the thashing of valve gear due to the lower rotation rate of the drivers at speed X. Picture a 0-6-0 doing 60 mph, and the Hudson sighing along beside it on a parallel track. The 0-6-0 would be tearing itself to pieces, while the Hudson would be barely chuffing.
I’m not sure if that is what your last post meant?