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Model Railroading > Peco LK-55 Turntable Kit - with VIDEO!


Date: 11/19/11 02:17
Peco LK-55 Turntable Kit - with VIDEO!
Author: Focalplane

The LK-55 turntable from PECO is a reasonably priced alternative for HO/OO modelers who baulk at the price of ready made motorized units, which seem never to be available when you want to buy them!

Rather than wait for a suitable turntable to come onto the market, I thought that the kit would be worth a try. It has turned out well and I thought a brief review with photos might be helpful to other TO members. A search revealed no history on TO for this device.

First a brief background. I have limited space in an apartment so my model is basically an 8 foot long working diorama of a 1950s British steam “shed”. This allows me to build a detailed model with lots of locomotives and an out of sight “system” served by the “shed”. Operations will effectively take the role of the superintendent, organizing the roster for the day, servicing the returning locos and “putting them to bed”. Operations will include panic situations like a failed axle box or looking for a freight locomotive to take the Saturday holiday special! With a roster of up to 20 locos, the layout is being wired for DCC.

Now, the turntable. Because it is such an important part of the layout design, it had to be built first and a lot of research went into the plan and the mechanics for motorizing the turntable. There are quite a few resources on the web so Google can help a lot here!

PECO’s instructions are well written in four languages with useful diagrams. Assembly was not difficult. I cut a perfect circular hole in the baseboard using a Dremel Trio (highly recommended tool) and gauged how the turntable well should sit in the hole in order to align (in height) with the tracks. To effect this I had to cut a gasket in cork sheeting bought at the local DIY store.

The bridge was easy to assemble as well though the railings were damaged in shipping the kit. They were easily repaired. The bridge spins on a central hub in the base and if there is a weakness in the design it is that the base is not sufficiently rigid to take stresses and strains associated with motorization and uneven weight distribution of an OO gauge tender locomotive (which are always biassed toward the drivers). More on how to improve this later.

Building the kit is the easy part. Motorizing it is much more of a challenge. I opted for a kit supplied by a British company, but I think the same kit is also available in North America. This consists of a motor, gearbox, worm and gear, shaft, battery pack, wiring and switch. The quality of the components is “average” but with some modification I was able to make the system run effectively if a little noisily.

The key areas to focus on are as follows:

1. The lack of rigidity in the plastic well. The hub has a lot of slack without significant stiffening. If I was starting over again I would modify the construction of the well with some out of sight plasticard stiffening. My retro stiffening is a lot less esthetic and it’s just as well that you can’t see it!

2. The two shafts from motor to bridge need secondary “bearings”. I used simple brass strip to make mine which probably contributes to the noisy operation.

3. The two gears on the shafts (worm and gear) are a push fit. The worm is very tight, the large red gear started to slip and had to be keyed. Again this would look much better if I had known that from the start.

4. Finally, consider using an old variable DC power supply. I am testing the device with an MRC Tech II 1400 which is overkill. Hornby train sets come with a very cheap rheostat controller which would make more sense. I am sure similar controllers are available in North America. Having a variable speed control is effective as the system does not have any locking device to align the tracks. Whether the turntable was hand operated or used the locomotive’s vacuum system you would expect a gradual acceleration and deceleration.

Should I ever do this again I would think seriously about the noise of the system, including a quieter motor and better bearings for the shafts. There are still a couple of things I can do, including packing the plastic gearbox with the right sort of grease and oiling the bearings so that they run in faster.

Calibrating a realistic speed of rotation was done by referring to the hand operated turntable recently installed on the West Somerset Railway. A YouTube video of No. 88 being turned showed that a 180º rotation took 1:25 minutes with the complete time from entering to leaving the turntable at around 5 minutes.

No description would be complete without photos.

1. The kit is completed and the hole has been cut. A good fit, not too tight but no slack either. Note that no other track has been laid.

2. All the approach tracks have been laid, using the correct Code 75 strips to align the rails. The well comes in this unrealistic pale plastic and cries out to be weathered! You can just about make out the cork gasket that raised the turntable to match the tracks' height.

3. The view I wasn't really expecting to share as it is not how I would have finished it off before I found out how much stiffening was required. Also, the wiring is temporary. The important operational aspect of this is that there is no play or slop in the system.



Edited 3 time(s). Last edit at 11/20/11 02:49 by Focalplane.








Date: 11/19/11 02:24
Re: Peco LK-55 Turntable Kit
Author: Focalplane

4. A close up of the motorized mechanism. The plastic gearbox had one set of gears removed, otherwise it would be way too slow. The white plasticard on the red gear is holding a very small key in place which was drilled into the shaft. Next time I would do this before fitting the assembly in place! The strip of wood on the right was glued to the well with CA glue to provide much needed stiffening.

5. The test rig. I had already airbrushed the well to start the weathering process. With the turntable wired up it was time to turn some locomotives. The MRC Tech II 1400 controls the turntable motor.







Date: 11/19/11 07:36
Re: Peco LK-55 Turntable Kit
Author: calsubd

I know you're going to show us more, please, Ed



Date: 11/19/11 09:12
Re: Peco LK-55 Turntable Kit
Author: Jeff_Johnston

Very nice tech user report! Thank you for your efforts. And how long is the track?

As a suggestion, if the turntable drive motor is 12 volts DC, power it by the DCC system. Hook an inexpensive decoder to the motor and program an address for the turntable motor, perhaps posted on a small signboard next to the turntable.

An operator runs the loco onto the turntable, selects the address, uses the cab throttle knob (or buttons) to run the bridge at whatever speed is desired, then reselects the loco to run off. Saves you messing with another power pack and such.

Just a thought. I saw this done on a layout near Chicago and it worked great.

Jeff Johnston
www.trainvideosandparts.com



Date: 11/19/11 09:33
Re: Peco LK-55 Turntable Kit
Author: Focalplane

Jeff, that is a good plan and I have read about it. My test rig is just that and a simple decoder would work just as well, particularly if the speed was limited using the appropriate CV. It would have the added advantage that the dcc controller would have to switch from loco to turntable to loco again, saving the embarrassment of accidentally derailing the locomotive by turning the wrong throttle. The good news is that this would be easy to retrofit at some future date.

I am not sure I can show any more photos at the moment as I am moving on to the switch motors. It has occurred to me that a short video might be a good idea, but my only video camera is an iPod Touch and I would have to rig up a temporary tripod for it.

The track length is 11.7 inches which translates to 81ft in HO, 74 ft in OO. The latter is just long enough for the largest British steam locos. On the other hand my SP steam locos are too long!

Thanks for the comments!



Edited 1 time(s). Last edit at 11/19/11 09:38 by Focalplane.



Date: 11/20/11 02:26
Re: Peco LK-55 Turntable Kit - MOVIE added!
Author: Focalplane

I have taken a 2 minute uninterrupted sequence with my iPod Touch (mounted on a "tripod of sorts") of LMS Royal Scot 46165 entering the turntable, being rotated through about 165º at scale speed and then reversed off the table onto a different road.

The motor noise is annoying and I am going to have to see if running with grease in the gearbox will make an improvement. Otherwise I may go back to the drawing board with a better motor and decent metal gears and bearings. That being said, the noise is actually less than others I have heard that come ready to run out of the box and cost a lot more and look decidedly less prototypical. Decoupling the motor from the baseboard would reduce the noise but increase the risk of sloppy running, something I have now managed to avoid.

You may also hear a couple of clicks - these are the current contacts beneath the turntable bridge that change polarity in an appropriate "dead zone"

Does anyone know what type of grease I should use?

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