Turntable speed

[IanG]

Can anybody please tell me what speed in RPM a locomotive turntable should rotate at ? I’m looking to use a high torque motor and gearbox fro eBay to motorise the OO Peco model

but want to get the correct rotation speed,any ideas?

[Paul H Vigor]

1 hour ago, IanG said:

Can anybody please tell me what speed in RPM a locomotive turntable should rotate at ? I’m looking to use a high torque motor and gearbox fro eBay to motorise the OO Peco model

but want to get the correct rotation speed,any ideas?

https://www.google.com/search?q=railway+turntable+uk+youtube&sca_esv=01d62422335794b4&rlz=1C1GGRV_enGB755GB757&sxsrf=ACQVn080MnqpWWMkHXoM6Yo4q7Klrstv0g%3A1709767721425&ei=KfzoZb_JGbSB9u8P6pWYmAU&ved=0ahUKEwj_gbyN5eCEAxW0gP0HHeoKBlMQ4dUDCBA&uact=5&oq=railway+turntable+uk+youtube&gs_lp=Egxnd3Mtd2l6LXNlcnAiHHJhaWx3YXkgdHVybnRhYmxlIHVrIHlvdXR1YmUyBRAhGKABMgUQIRigATIFECEYnwVIkCdQ-gRY1htwAXgBkAEAmAGKAaABgwaqAQM2LjK4AQPIAQD4AQGYAgmgAssGwgIKEAAYRxjWBBiwA8ICBhAAGBYYHsICCxAAGIAEGIoFGIYDwgIHECEYChigAZgDAIgGAZAGCJIHAzYuM6AHwBs&sclient=gws-wiz-serp#fpstate=ive&vld=cid:05d7fd9b,vid:My3vaLWLi6I,st:0

 

They don't hang about!

[DCB]

Basically the end of a turntable revolves at walking pace, say 3 mph,   I will work that out in RPM when I have a spare lifetime

Timing YouTube videos the York outdoor TT seems to take 6 blokes about 3 min for 180 degrees.  The Didcot  table 3 mins for 2 blokes to crank round The NRM about 80 seconds, Ferryhill 80 and   Pickering about 65 secs ,   Some TTs used vacuum power to turn, I think NRM is electric.   Starting and stopping are problems, especially stopping and several attempts to engage the locks were quite common,    What modern RTR especially DCC can't match is the precision with which they place a 66ft long  57ft WB V2 loco on what looks like a 6oft table

Edited March 8 by DCB

[DCB]

2 hours ago, Paul H Vigor said:

https://www.google.com/search?q=railway+turntable+uk+youtube&sca_esv=01d62422335794b4&rlz=1C1GGRV_enGB755GB757&sxsrf=ACQVn080MnqpWWMkHXoM6Yo4q7Klrstv0g%3A1709767721425&ei=KfzoZb_JGbSB9u8P6pWYmAU&ved=0ahUKEwj_gbyN5eCEAxW0gP0HHeoKBlMQ4dUDCBA&uact=5&oq=railway+turntable+uk+youtube&gs_lp=Egxnd3Mtd2l6LXNlcnAiHHJhaWx3YXkgdHVybnRhYmxlIHVrIHlvdXR1YmUyBRAhGKABMgUQIRigATIFECEYnwVIkCdQ-gRY1htwAXgBkAEAmAGKAaABgwaqAQM2LjK4AQPIAQD4AQGYAgmgAssGwgIKEAAYRxjWBBiwA8ICBhAAGBYYHsICCxAAGIAEGIoFGIYDwgIHECEYChigAZgDAIgGAZAGCJIHAzYuM6AHwBs&sclient=gws-wiz-serp#fpstate=ive&vld=cid:05d7fd9b,vid:My3vaLWLi6I,st:0

 

They don't hang about!

Looks like the speed model turntables revolve,  Like someone used a speeded up clock.

[31A]

Does this help at all (from 0:30 secs approx); it doesn't look like a constant rate of revolution:

https://www.youtube.com/watch?v=hnBrKC5BFdI

 

[wasdavetheroad]

7 hours ago, DCB said:

Basically the end of a turntable revolves at walking pace, say 3 mph,   I will work that out in RPM when I have a spare minute

About 6 minutes for a 65 ft to turn 360 degrees, or 3 min for 180 degrees.    Some TTs used vacuum power to turn.   Starting and stopping are problems, especially stopping an several attempts to engage the locks were quite common, 

I think waiting 3 minutes for a model turntable to rotate 180 degrees would drive me crazy. I want to turn the loco, not stand there waiting, 30 seconds seems a long time to me. I remember admiring a beautiful BLT at an exhibition. No trains moving so I asked when the next one was due. He looked at his watch and said '3 quarters of an hour, I am running the Saturday timetable.' It was Saturday. I replied, i like the trees and backed off rapidly. If i ran a real Sunday service on my layout there would be a couple of excursion trains and a curtailed local passenger service. No pickup goods, no shunting in the exchange sidings etc. 

[Buhar]

8 hours ago, DCB said:

Basically the end of a turntable revolves at walking pace, say 3 mph,   I will work that out in RPM when I have a spare minute

About 6 minutes for a 65 ft to turn 360 degrees, or 3 min for 180 degrees.    Some TTs used vacuum power to turn.   Starting and stopping are problems, especially stopping an several attempts to engage the locks were quite common, 

I did some sums with the 3mph rate and got 45 secs or so for 180 degrees turn by hand. A little longer to allow for getting going and slowing down.

Alan 

[daltonparva]

When you wire the motor, don't just use an on/off switch, use an old cheap controller or put a change-over switch between the layout and turntable motor using your existing controller: that way you can make it go as fast or as slow as you want, and you can change direction.

Edited March 7 by daltonparva

[Mol_PMB]

I'll put this in metric units because I suspect the use of imperial units in the various calculations mentioned above is causing confusion.

65' is about 20m. The circumference of a 20m diameter circle is pi x 20 = 63m.

A brisk walking pace is about 1.8m/s. So if the end does move at about walking pace (which seems reasonable) it would take 63/1.8=35 seconds for a full revolution. Half-way round (a more common operation) would be 17.5 seconds. Agreed you need to add a bit for starting and stopping, but 3 minutes seems excessive.

[goldfish]

Better to stay in imperial. I make 3mph to be 4.4 ft/sec. A 65 ft turntable has a circumference of 204.2 ft. So one revolution takes 46.4 seconds. So 1.29 rpm.

 

In reality it can take a lot longer : - https://www.youtube.com/watch?v=fLL-SExCHTc (2:36 - 4:39)

 

 

Edited March 7 by goldfish

[31A]

I've always thought mine was a bit fast, so out of interest I went and timed it.  It takes about 42 seconds to turn through 180 degrees.  It's driven by a home made gearbox using Meccano gears and a 9v motor from an old reel-to-reel tape recorder.  It's supposed to represent a vacuum driven turntable although I haven't got around to making the vacuum bits (or the handrails).

 

https://www.youtube.com/watch?v=cI53GOhwJZM

 

 

[Michael Hodgson]

I understand the Garsdale one could go faster before they stockaded it?

[daltonparva]

This is a link to a Heljan turntable that had gone faulty, as they usually do. I fitted a decoder so that I could control it like a loco, and reworked the ring contacts/wiring so it didn't reverse polarity and cut out the sound half way round. A dual frog polarity reverser sorted that out. Please excuse the poor quality video, I'm no David Lean and It is a cheap crappy camera; and if the steam sound hiss is too overbearing just mute the sound (it starts muted, you have to switch the sound on). There is a bit in the video where I show how slow you can turn it for lining up the tracks, which you can do on 12v DC with a transformer as I said in my previous post if you aren't going digital.

 

 

 

Edited March 8 by daltonparva

[LNER4479]

Grantham's 70ft turntable takes about a minute to revolve 180 deg. It feels / looks about right to me. It runs off an independent power supply so you just leave it running and can be moving something else around on the shed whilst it's in operation.

 

This was first test, 9 years ago. It's long since been detailed and finished! And please don't play the video with the sound turned up - it really isn't THAT noisy!! (one of those where the camera microphone is picking up any sound going).

 

[sncf231e]

Slow (i.e. not too fast)

Regards

Fred

[Porcy Mane]

Hand turned. You could always time this one.

 

 

[zarniwhoop]

47 minutes ago, Porcy Mane said:

Hand turned. You could always time this one.

 

 

Looking at the you tube timings, I make that about a minute for the actual 180 degree turn - and that is with 4 guys pushing it. Preceded by a stop for the fireman to get off first, then about 20 seconds while the loco crawls to the middle of the table.

[Clive Mortimore]

10 hours ago, 31A said:

I've always thought mine was a bit fast, so out of interest I went and timed it.  It takes about 42 seconds to turn through 180 degrees.  It's driven by a home made gearbox using Meccano gears and a 9v motor from an old reel-to-reel tape recorder.  It's supposed to represent a vacuum driven turntable although I haven't got around to making the vacuum bits (or the handrails).

 

https://www.youtube.com/watch?v=cI53GOhwJZM

 

 

 

[Porcy Mane]

No, no, no.  You need the accordion version followed by a mass banjo ensemble.

 

 

Edited March 7 by Porcy Mane

[DCB]

The biggest issue I have with model turntables apart from they are generally far too big , is they move too stiffly  I keep plotting how to make a decent motorised table  but then again my hand operated  cut down Dapol  table is a model of a hand operated table so maybe a powered one would be less realistic.  Current plan revolves (Pun intended) around some Ford Escort wheel bearings  I acquired,      Present terminus one is a 75 or 80 ft Triang and as I don't have anything bigger than a Duchess to turn another 65 ft like the middle station will suffice

[IanG]

Thanks for the replies I’ve decided to go for 1RPM and use a speed controller to slow down when aligning as I really can’t be bothered to try to make up a indexing system!