Project to re-take Steam Rail Speed Record

[Hughlysses]

Since the only reference (that I noticed) to "gearing" was the drive wheel OD.
I assume that absence of projected mods for changing the linkage to the drivers means that the original stuff is safe at (comfortably beyond) 130?

The drive wheels on this thing are 84 inches in diameter, the largest used in the U.S. apart from some much earlier experimental stuff.  Most big passenger engines had drivers no larger than 80 inches.

In petrol head terms, they're the equivalent of a 2.54 to 1 rear end.   

[Tman]

I am in trucking as is all of my family so trains are a bad word here, but this is a cool project!!!!!!!!!!!!!!!

[panic]

The missing variable is the ratio of the linkage from the piston to the drivers...

[Hughlysses]

The missing variable is the ratio of the linkage from the piston to the drivers...

That's the stroke.  Think of a steam locomotive (most of them anyway) as a vehicle with the wheels mounted on the ends of the engine crankshaft.  ATSF 3463 has a 29-1/2" stroke, which compared to other large steam locomotives could be called "moderate".  

I did some comparison calculations just to see how this locomotive compares to some other fast steam locomotives.  One famous high speed run was made by a Norfolk & Western Railway "J" class 4-8-4 doing testing on the Pennsylvania Railroad back in the 1940's.  Now a J only had 70 inch tall drivers (maybe equivalent to a 3.54 auto rear end gear) but it managed to achieve 110 MPH.  It also had a longer 32 inch stroke.  110 MPH wasn't considered all that fast in general, but it was very fast for a locomotive with relatively small driving wheels, which put its horsepower peak at a lower speed (say 45 MPH or so) which was good for the moutainous territory it operated in.  One of the design features which enabled it to safely operate at high RPM was the use of Timken high-strength, light-weight main rods, connecting rods, piston rods, pistons and cross heads.  The N&W J steam locomotive was turning 528 RPM at 110 MPH.  

For comparison, the ATSF 3463 with its 84 inch drivers would be turning only 520 RPM at 130 MPH, and it would have a significantly lower piston speed because of the shorter stroke.  The information on the website states they will also equip it with alloy rods and reciprocating parts.

[panic]

Sorry, senior moment...

[Hughlysses]

No problem.  It does take some mental adjustment when going back and forth between cars and steam locomotives!

Here's a cool animation of the driving gear of a steam locomotive to show you what pieces they have to work with:



The pink color indicates steam being admitted to the cylinder; the blue color indicates exhaust steam leaving the cylinder.  There's one cylinder on each side of the engine and each of them is "double-acting" (unlike internal combustion engines which are "single acting").  One revolution of the drive wheels gives you four power pulses from two cylinders.

[mallard126]

you seem to have got a bit wrong with regards to mallards record the record is 126.5 MPH. and another thing if one of the six A4 owners wanted to go for the record they could easily take it back as an A4's terminal velocity light engine is 140 MPH and with a standard six coach train could be able to hit 135 MPH and i would also like to know where the record attempt will be happening if you know.

p.s if you have ever visited the east cost line in the UK the you will know that to get out of the London terminus kings cross you have to go up a 1/76 tunnel called gasworks and Copenhagen and the LNER pacific's could get going out and up the tunnel (with the help of a banker if necessary) and gain speed on it with relative ease and the A4's have conjugated valve gear so that at any one point there was power going to the wheels so in other words the loco that "might" break the record is going to have to do a good job if it wants to keep it from a Gresley pacific and keep it!          

[Seldom Seen Slim]

Mallard, I'd appreciate it - and so might many of our Yankee Forum members, I expect - - if you'd help translate your comments into American from the Brit-speak you've given us.  I can figure out many of your words, but some of them leave me wondering.

For instance, what's a "banker" with reference to a steam train?  Is a "Gresley Pacific" a type or brand of locomotive?  There are a few more phrases or words that could use a bit of Americanising, too.  Interesting stuff -- just not as understandable as I'd like.  Thanks.

[Malcolm UK]

Mallard, I'd appreciate it - and so might many of our Yankee Forum members, I expect - - if you'd help translate your comments into American from the Brit-speak you've given us.  I can figure out many of your words, but some of them leave me wondering.

I am a British speed guy and I find it difficult to understand the 'rail speak'.

I think that there was a challenge in there, that any of the owners of an operating A4 locomotive (Mallard is not currently in running order) could easily take the record back from any 'new' American steam locomotive. 

[Stan Back]

I know a guy that will want to race it with a diesel pickup.

[Speed Limit 1000]

I know a guy that knows a guy...

[4-barrel Mike]

I know a guy that will want to race it with a diesel pickup.

 

Mike

[salt27]

I know a guy that will want to race it with a diesel pickup.

 

Mike

I don't care to be part of a pizzing match but that right there is funny.   

  Don

[Hughlysses]

Mallard, I'd appreciate it - and so might many of our Yankee Forum members, I expect - - if you'd help translate your comments into American from the Brit-speak you've given us.  I can figure out many of your words, but some of them leave me wondering.

For instance, what's a "banker" with reference to a steam train?  Is a "Gresley Pacific" a type or brand of locomotive?  There are a few more phrases or words that could use a bit of Americanising, too.  Interesting stuff -- just not as understandable as I'd like.  Thanks.

I think I can translate most of it.  Regarding your questions- "banker" in British parlance is the same as a "pusher" in U.S. parlance: a second locomotive at the rear of the train pushing to help the train get over a steep grade.  Sir Nigel Gresley was a British locomotive designer who designed the A4 class, of which the locomotive named Mallard is a member.  "Pacific" is a steam locomotive with a 4-6-2 wheel arrangement: 4 guiding wheels at the front, 6 large diameter driving wheels in the middle, and two carrying wheels under the firebox.  So "Gresley Pacific" refers to a steam locomotive of the Pacific wheel arrangement designed by Sir Nigel Gresley.  

Mallard126- Pardon me for rounding Mallard's speed up from 126.5 MPH to 127.  Mallard overheated the big end bearing on the inside main rod during its 126.5 MPH record.  It couldn't have continued for long at that speed.  I'm very skeptical an A4 could sustain 135 MPH with a train.  Hopefully the CSR guys will get the chance to break the record, and then we hopefully we get the chance to find out if an A4 can do 135 MPH or not.

[4-barrel Mike]

I don't care to be part of a pizzing match but that right there is funny.   

  Don

Nah, just pokin' a little fun.

Mike