i'd like to build a couple small turntables to turn engines on a pt-to-pt layout using a 1/4" phone jack. I'm trying to keep the layout simple/inexpensive, such as using caboose ground throws. I'd be happy to manually turn the table, but am wondering about maintaining alignment. I thought about motorizing the table, but was wondering how difficult it would be to align it.
It seems to me that incorporating an indexing mechanism is probably the most complicated and expensive aspect of a turntable. I've read about mechanical, electrical, optical and geneva mechanisms for indexing.
how difficult is it to maintain table alignment if turned manually without a motor to hold it in place, or to align a table using a motor without indexing?
greg
greg - Philadelphia & Reading / Reading
LION thinks that you are on the right track. Problem is, that light you see at the end of the tunnel is attached to a locomotive!
Ah, Yes... a terntable. That is where the birds land for lunch!
LION thinks making it using an RCA jack as the pivot is a great idea, and remember many of those end of the line turntables were man powered to begin with. So spot your locomotive on the turntable, and push!
Oh, BTW, did I tell you that there is a manual lock to hold the turntable in place so that it will not turn when the engine is moving. A little slider that pushes a steel rod from the turn table to the track side will work just perfectly.
And BTW: If you are going to power the tracks via that RCA plug, then you can use two such rods, one on each side of the track so that the polarity will be correct when you try to move....
oppps. Wrong polarity, sorry about that!
ROAR
The Route of the Broadway Lion The Largest Subway Layout in North Dakota.
Here there be cats. LIONS with CAMERAS
I have a manual turntable that I built that uses a phone jack for the center pivot.
I used a wood block for the bridge and put plastic bridge girder sides on it and detailed it out with deck boards and handrails. Instead of using wheels at the ends to support the bridge, I used a couple of small hardwood shims. I put a coat of super glue on the bottom, then when the SG was dry I rubbed in some graphite. So what I have is a friction type slider that rides on the pit rails. I turn the table by hand and it stays put. I also connected an auto reverser to the power going to the phone jack and it works great.
Elmer.
The above is my opinion, from an active and experienced Model Railroader in N scale and HO since 1961.
(Modeling Freelance, Eastern US, HO scale, in 1962, with NCE DCC for locomotive control and a stand alone LocoNet for block detection and signals.) http://waynes-trains.com/ at home, and N scale at the Club.
You need to model a ladder from the bridge to the pit so that the crews can get down there to push the turn table.
One of our turntables ont he club layout is right near the edge. There is no indexing, just a small DC throttle driving a motor to spin the table. There's no hard stop on the throttle, but someone did etch in a mark at the setting which makes it spin at a prototypical speed. It has a large center off toggle for direction, if you are good you cna stop it perfectly first try, otherwise you can do what the real thing did and jog it back and forth for perfect alignment.
So with a nice up front installation where yoiu cna easily see the bridge and the stall tracks, there's no need for a complex indexing system. And putting a turntable way in the back of the layout, unless there is absolutely no other way you can do it, is kind of a waste, since it's a neat moving part that really shows off your locos, and to hide something like that in the back seems like such a waste.
--Randy
Modeling the Reading Railroad in the 1950's
Visit my web site at www.readingeastpenn.com for construction updates, DCC Info, and more.
Gandy Dancer, all you need to simulate a powered turntable is a vertical pipe on each end. The pipes should have an L at the top into a quick-acting valve (trigger handle type) and a length of hose terminating in a glad hand. The air 'kicker' would be invisible between the girders.
In use, the glad hand would be connected to the train line at the pilot or tender and train air would move the turntable.
The alternative is a long wood-beam handle at each end, but the people path is cluttered at one side and drops off to oblivion at the fascia on the other. If you do go that route, the turntable would only turn 180 degrees at a time and there should be a well-beaten path close to the pit on the fascia side.
The one turntable currently in operation on my layout is a small 'Armstrong' type, depends on friction to hold it in place and has no locking mechanism. The carrier wheels are spring-loaded, purely for electrical contact (and resulting automatic reversing,) while the bridge rests on pads between the girders.
Chuck (Modeling Central Japan in September, 1964)
thanks for the responses, i think my understanding and perspective have been elevated.
1) i hadn't thought about not using bogie wheels and using something that just slides on top of the ring rail out of view. This make the design much simpler and maintains alignment
2) i have to remember that using the 0-5-0 is really not such a bad thing. A manually turntable is simply a very practical part of the layout
3) at least with a turntable bridge, it can always be improved/replaced later
My turntable is a block of wood with a cut-down Atlas girder bridge glued to its sides. Finger-operated and, like the real ones, indexed "by-eye".
rrinker .....someone did etch in a mark at the setting which makes it spin at a prototypical speed. ....
.....someone did etch in a mark at the setting which makes it spin at a prototypical speed. ....
You might be surprised at what constitutes "prototypical speed", Randy. I was taking photos near the TH&B's Chatham St. roundhouse in Hamilton one day, when I hostler took a geep out of the roundhouse. The table was already lined to the proper stall, so he ran the loco onto the table, then the table moved. Boy, did it ever move! When it stopped, the loco rocked violently from side to side. I wouldn't have believed it if I hadn't seen it in person. I don't know if there was a malfunction or if somebody was simply in a rush and operated it in a manner other than that set out in the rules.
Here's a shot taken on a normal day:
Wayne
Back when Mark Newton was around, we had a thread about turntable speed, and came up with a ball park figure of 1 RPM. For steam locos, much more than that and the water in the tender cistern could begin to slosh back and forth - with potentially embarrassing results. Hard to explain how the tender rolled sideways off the bridge into the pit...
When they do the Reading Railroad Days atthe Railroad Museum of PA, when we have the modular layout set up, one of the non-stanard extra things they do at the museum is give demonstrations of the former Reading turntable they have installed and operating - they do use it to move equipment around the display yard. There seems to be at least two speeds on it, a fast traverse and a slow speed to jog it into final alignment. They usually don't spin it 360, but when it's moving at the traverse speed, it seems pretty fast - definitely the speed of the end of the bridge relative to the pit wall is quite fast.
I suspect what you saw them do was use the fast traverse speed, which by rule is probably supposed to only be used when there is nothing on the bridge. Probably would have gotten that crew in trouble had there been any officials around doing any inspecting. I can see what Chuck said, if it rocked the loco on its springs, it could have easily sloshed the water in the boiler or tender of a stem loco enough to roll the thing right off.
My Turntable was a Bowser kit. An option, which I also purchased was a motorizing kit. However, I don't have an indexing unit. I can't remember if one was offered; but, if there was I decided I would attempt operating without. I run my turntable with a hand held DC throttle. I can watch when the tracks align and that works pretty good. An indexing unit would be better; but, I will live without.
I also built a Diamond Scale turntable (I think that's who it was) for the club I belonged to a few years back. The club bought it and sprung for the whole unit; turntable, motorizing kit and indexing kit. It was a honey of a kit and really worked and looked good!
Previous to buying my Bowser turntable I also built a Walthers kit, which I found to be a piece of junk and returned to Walthers after I buit and detailed and it!
I think at the highest throttle setting, mine would make a complete revolution in about a minute.
NP 2626 "Northern Pacific, really terrific"
Northern Pacific Railway Historical Association: http://www.nprha.org/