What was the typical operating speed (RPM) of a turntable in a modern (1940’s) large railroad’s steam locomotive terminal? Was there a significant difference in speed with or without a locomotive?
Thanks,
Mike
It would be a fraction of an RPM, and depend on the length of the table. Most electrically driven ones did have variable speed, so they could slow down as they got near the stall they were stopping at, which had more to do with it than whether they were loaded or not.
Turntable Speed–FOREVER–well that is when you are standing in the hot summer sun waiting on it . [:)] That also hold true in the winter on a very cold day. [:(]
I have one that goes both 45rpm and 33 1/3 rpm.
Mine’ll do 78 [:D]
Seriously, though, when moving something weighing upwards of 100 tons (or more), speed is not important. Plenty of locomotives got driven into turntable pits. I’d hate to dump one by spinning it too fast.
I don’t know the rpm but the Western Maryland Scenic Railway was really spinning the locomotive when they were turning the train. I was amazed at how fast it seemed to go with the locomotive on it. It had to be doing better than a revolution a minute.
Powered turn tables could mostly be regulated within a given range, many had reduction geared drive mechanisms for power. As Larry states, nobody wants to be the one that put an engine in the pit. The IC’s Johnson Yard [In Memphis] turntable was as fast as a slow walk, and the Southern’s was a little faster, but a smaller diameter.
I know for a fact that the IC’s Pit could hold 3 SD’s but the last one had to be stacked.[;)]
The ones powered by the crew pushing a bar at each end wouldn’t be going very fast.
The real concern on an Armstrong turntable, once you get it moving, is stopping it. Unless you’ve done it, you may not believe how much momentum a narrow gauge mikado on a turntable has when it seems to be turning slowly. [:0]
Depending on the point at which the strong-arms began to stop the bridge, it might have been a hefty surprise! Ideally, if they took six or seven steps at the beginning to accelerate it to a steady speed of rotation, they would have taken that many to stop it. I would imagine that the experienced ones knew as much.
I would imagine a powered turntable could rotate an engine 180 deg in about one minute, give or take 15 seconds.
Warp speed
way to slow when your cab-forward needed to be turned and the train you were helping was waiting on the main!!! oh well its not called “railroading” for nothing!!!
Depending on the power of the motor running it, most turntables need between two and three minutes to finish a 180 degree turn. Any faster is unsafe, and well…[B)] I watched the now-gone CN table in Ft. Erie, Ont, which turned ex-Wabash N&W F7s in just over two minutes. I also watched Western Maryland Scenic’s table in Frostburg MD, and it needed three minutes to spin their 2-8-0, admittedly heavier than a Wab/NW F7. But, you can get lots of photos of the engine while it was turned! Finally, the East Broad Top’s “armstrong” table is kinda slow. Again, though that means more photo angles, and opportunities.
DC ELECTRIC MOTORS ARE ALL DIFFERENT SIZES AND TYPES. THE WAY ITS CONNECTED TO DRIVE WHEEL(s) ,GEARS ARE DIFFERENT SIZESTEETH CONFIGURATIONS,DIAMETERS AND SO ON. GIVING A DIFINITIVE WITHOUT ALL THESE BEING CONSIDERED:IMPOSIBLE![}:)] THE ARMSTRONG AT THE HENERY FORD MUSEAM WAS A BLAST. WE TURNED A PLYMOTH 0-4-0 AND OVERSHOT BUT IT WAS GOOD AND EVERYONE LAUGHED. THE USSUAL CONTROLER FOR THE TURNTABLE IN TIMES PAST WAS THE SAME AS ONE USED ON AN INTERURBAN OR TROLLY. IT BASICLY CONTROLLED DC RESISTORS BY MANUALLY ROTATING THEM IN AND OUT AND THIS DICTATED POWER USSAGE. LIMITING POWER![alien]
That would be Revolutions Per Hour not minutes., RPH, LOL
How come nobody has mentioned the 4 turntables of the San Francisco Cable Car System? There are three in the streets and one in the carbarn.
My only experience was with the Vermont Railway [former Rutland Railroad] turntable at the Burlington, VT, engine terminal in the late 1960’s. I was a teenage railfan and was startled to see it turn at about 3 RPM when empty (I timed it with a watch). I’m sure it wasn’t turning that fast when I rode an SW-1500 on it (out of the roundhouse, turned on the table, and then out onto the lead track) but it still seemed to be up around 1 RPM. I’m pretty sure the turntable was 85 or 90 feet long since it could turn the Rutland’s 4-8-2’s. The other distinct recollection I had about the 3 RPM turning speed was the noise – it sounded like something was scraping on the pit walls, although it could have been a bearing or even a much smaller noise amplified by the turntable bridge structure.
Okay, all you wags. There is one way to find out the speed of a turntable, and at least two ways of measuring it. The turntable that once turned 4000-class “Big Boys” in Cheyenne is still in place and operational, an in use.
So, the thing to do is ask Mr. Steve Lee and/or his staff, to conduct a couple of turns of their table. One measure of speed is the pecentage of a full 360-degree revolution per minute, and the other is the speed of one end of the table along the edge of the pit in miles per hour. Thus you would have an RPM, and an MPH, figure for the table.
For scale modelers of the steam era, this is a serious and long debated question.
Someone can run with this ball. MR Staff, Local fan/reader in Cheyenne, or Denver? Mr. Lee, if you’re reading this?
(Don’t look at me, i’m halfway around the world).
i was one of the lucky teenagers that went to rail camp a fue years ago, and on the last day we got to ride on the turntable at steam town. i dont reamber how fast it was but we didnt get sick or even notes it so it cant be that fast but someone dose need to ask Mr. Lee how fast his turns
From those two figures, you could figure out how long the turntable was![;)]