Union Pacific FEF-3 4-8-4 Northern type steam locomotive, by Smokebox

[mrennie]

O my!! my eyes drooling!!!!!

I wish that from Berkshire likewise animation.....


NKP

There's similar animation on the Consolidation but with the FEF-3, I'm aiming at raising the bar higher. The power reverser and brakes are examples of that. Basically, if it moves on the real loco, I'll try to make it move on the model too, although I can't promise that I'll manage to cover absolutely everything.

[RvA944]

what no vibrating cotter keys............. pfffffffffffffffff

[mrennie]

what no vibrating cotter keys............. pfffffffffffffffff

Hmmm .... now there's an idea

[mrennie]

Here's a technical question for the experts:

If a steam locomotive is running forwards, is it possible, even with a power reverse gear, to suddenly pull the Johnson bar into reverse and set the driving wheels turning in the opposite direction?

I don't have the DLC, but I've been told that the German BR52 does this. To my mind, it doesn't make much sense. Wouldn't that be like driving along in your car and suddenly trying to put it into reverse gear without first stopping? My guess is that, because of demanding the reverse gear to fight against the force of the moving valve piston, you'd wreck something, like the reverse gear cylinder perhaps, or bend the reach rod, or perhaps the levers and rods of the reverse gear, wherever is the weakest link between the Johnson bar, reverse gear and the piston valves themselves. I'm just wondering if what the BR52 does is realistic and should I try to do the same thing, or would that be unrealistic and a waste of time?

[hertsbob]

Here's an uneducated answer.
http://www.annesleyfireman.com/id4.html

Now was the time to see what the mighty 9F could really do, if we got the road we would fly along .45 50 55mph and I believe topping 60mph. coming down Ashby bank, if the outer distant was against us (you had maybe 2 or 3 seconds looking through the trees ) GOD HELP US! Steam brake on, tender brake on, steam sanders on reverse gear hang on the whistle and pray that you had woke up the guard so he could use his brake!

I've always read that quote to imply that in extreme circumstances going into reverse, as it were, was a legitimate-ish way of extreme braking... Possibly not relevant, but I don't see why I should start being relevant now.

[mrennie]

Here's an uneducated answer.
http://www.annesleyfireman.com/id4.html

Now was the time to see what the mighty 9F could really do, if we got the road we would fly along .45 50 55mph and I believe topping 60mph. coming down Ashby bank, if the outer distant was against us (you had maybe 2 or 3 seconds looking through the trees ) GOD HELP US! Steam brake on, tender brake on, steam sanders on reverse gear hang on the whistle and pray that you had woke up the guard so he could use his brake!

I've always read that quote to imply that in extreme circumstances going into reverse, as it were, was a legitimate-ish way of extreme braking... Possibly not relevant, but I don't see why I should start being relevant now.

Thanks Bob, I think it is relevant. I suppose that's like using the gears in a car to aid in braking (using the back pressure in the cylinders as a braking force). If it were too extreme, just like breaking the gearbox in a car if you were doing 70mph and went into 1st gear or reverse, in a steam loco you'd probably bend or break something else (I've read about main rods getting bent). The real question, though, is whether you'd ever be able to get the driving wheels to turn in reverse while the loco is moving forwards (in a car, you'd probably burn the tread of the tyres straight away - in a loco it would probably be as bad as, or maybe worse than, the flat spots you'd get from locking up the driving wheels).

I hope someone who knows will chip in at this point. I'll give my brain a rest and get back to adding more nuts and bolts.

[OlPaint]

The would definitely make a great "Hollywood" movie effect...Something that the likes of Casey Jones might have done just before the Cannon Ball plowed into the stalled freight train. But a stunt none the less.

OlPaint

[Ericmopar]

Actually...
When I'm diving into a station too fast with a Black 5, I have indeed put it into reverse, about 40%, and opened the throttle some to aid in stopping in time.

Whether or not that is possible in real life...

[mrennie]

It appears that it is possible in real life. You could close the throttle, allowing the Johnson bar to be hooked up all the way into reverse, then slowly and carefully open the throttle to admit live steam into the cylinder to push against the oncoming piston, slowing it (and the locomotive) down. It has to be done carefully to avoid building up too much live steam pressure in the side of the cylinder that the piston is moving towards (the piston is making that space smaller and that further increases the pressure). Apparently it should be done with the cylinder cocks open to avoid the danger of blowing the caps off the cylinders. I've also been told that if the reverse force is able to overcome the inertia and friction of the driving wheels (which is what is pushing the piston towards the live steam end of the cylinders), it can indeed reverse the direction of rotation of the driving wheels and make them spin backwards (reverse wheelslip) while the locomotive continues, because of the train's momentum, to skid forwards.

To be able to do this, and other things (including precise control over the force feed lubricator handle), I've disabled the automatic animation of the driving wheels and substituted it for my own control algorithm, so that I can do whatever I want with the driving wheels, motion, valve gear etc. That means I can do proper, realistic wheelslip (making them spin faster as they lose traction), wheel lockup, and reverse wheelslip.

[ozinoz]

Mike has been hiding his talents under a bushel and holding out on us

Check out his Farcebook page - first off a beautifully animated 844 at 80mph and secondly, and more excitingly, finally fully syncronised wheel slip with exhaust, with selectable operating conditions, brake lock up, glowing brake embers and finally modeled cylinder failure through thrash And, to top it off, promised of more goodies to come...





Grant

[mrennie]

It took me several tries to get the algorithms debugged, but I'm pretty satisfied with how they work now. There are a couple more tweaks to do but nothing major.

I'm going to do some screenshots for RSC, but in the meantime, here are a couple showing what I've been doing today - more plumbing and the manual blowdown valves above the mudring.

2013-11-25_00001.jpg

2013-11-25_00002.jpg

[bpetit]

Reality Check!

[RAILSOHIO]

I just watched the video on the FB page,and THAT is how a steam loco should operate. The sparks are a great touch,but the ability to slip/spin the drivers is much overdue in this sim. Before airbrakes,steam engines were slowed/stopped with the reverser,and its great to see this working well.

[ozinoz]

I'm going to do some screenshots for RSC, but in the meantime, here are a couple showing what I've been doing today - more plumbing and the manual blowdown valves above the mudring.

Ahh - but does the blowdown valve blow down ? Something long missing from US steam. Not so much a problem in the UK with decent water, but in the US, thats a whole other ball game

Continue to be utterly amazed

[mrennie]

Ahh - but does the blowdown valve blow down ?

It will do, yes