Merlin locos

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funandtrains
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Post by funandtrains » Mon Jun 16, 2014 1:38 pm

From what I see there are still plenty of working Merlins around so most must have ran well, a pity that a few duds were sold to people. I actually seem to see more Merlins running these days from the 1980s than Roundhouse so either they have worn well or more are being restored. I have a Merlin Monarch which runs just as well as my Roundhouse Billy which less than half it's age.
Cheers, Steve

big-ted
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Re: Merlin locos

Post by big-ted » Fri Mar 18, 2022 5:53 pm

I've recently acquired a late model (outside frames & loosely simulated valve gear) Monarch. The electrics are in need of a bit* of a tidy up, so I plan to remove the old 25MHz receiver & install modern stuff. One thing I can't figure out is where the batteries are supposed to go? Unlike the Mayflower, which had the servo in the cab on the right hand side and the batteries under the footplate, Monarch has the servo under the footplate. My loco had a very crude plastic box to house the batteries added to the rear of the cab that definitely isn't original.

I don't really want the batteries visible through the cab windows if I can help it, as they would be if I used the space freed up by removing the large receiver. So far my best option seems like 4 NiMh AAAs, taped together in a custom shape & squeezed in the cab on the right hand side between the boiler & cab. Trouble is, I'd have to permanently tape & solder up my own pack to have them in a diagonal configuration. A flat pack won't fit in front of the lubricator, & a square pack will be really tight between the cab & the boiler. I can make my own pack, but this then means I can't charge the cells individually.

The other option is a pair of 18650 cells. Am I nuts to consider putting lithium batteries in a live steam loco?

*This is a big under statement.

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pandsrowe
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Re: Merlin locos

Post by pandsrowe » Sat Mar 19, 2022 9:41 am

Any chance that you could mount them as a flat pack to the underside of the cab roof?
My Roundhouse Billy has this arrangement and works quite well in an otherwise very cramped cab.
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GTB
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Re: Merlin locos

Post by GTB » Sat Mar 19, 2022 12:37 pm

big-ted wrote: Fri Mar 18, 2022 5:53 pm The other option is a pair of 18650 cells. Am I nuts to consider putting lithium batteries in a live steam loco?
I also wondered about fitting 4 x AAA in a flat pack under the cab roof, as it is common in Roundhouse steam locos. That's where they are in Lilla, which isn't particularly spacious in the cab dept. We usually look down on model locos when running them, so the battery pack is less obvious under the roof.

If you are prepared to make a new mounting bracket, modern servos are small enough that you could probably relocate the servo into the cab, put a square battery pack under the cab floor and fit the receiver up under the cab roof.

I don't have any experience with Li-ion cells in model locos, so can't help you assess the likely risk of using them in a live steam loco.

High operating temperatures will reduce the operating life of any rechargable cell, but NiMH cells are more resistant to high temperatures and with Li-ion cells there is also a risk of thermal runaway. From what I've read, LiFePO4 cells are recommended as an alternative to Li-ion cells in high operating temperatures.

Regards,
Graeme

big-ted
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Re: Merlin locos

Post by big-ted » Sat Mar 19, 2022 4:12 pm

On this generation of Merlin loco, the Mayflower & Major included, the gas tank is in the roof between the cab windows, & the receivers of the time stuck to one side of it. I could definitely fit a square pack in the space freed up by relocating the receiver, (Deltang receivers are much smaller) but the batteries would be very visible through the cab windows. Relocating the servo is an option, but would require some drilling off the original chassis to mount it which I'd like to avoid.

I'm just stumped as to where the batteries would have been originally!

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artfull dodger
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Re: Merlin locos

Post by artfull dodger » Sat Mar 19, 2022 9:33 pm

On both my Mayflower and my late run Major, there was a four AA battery pack under the cab footplate between the frames rails and behind the rear driver axle. Receiver was mounted on one side of the butane tank. I no longer own the engines, so I have no pictures to share. A modern four AAA rechargeable battery should be able to hidden on the engine I would think. Might need recharge a bit more often than a AA battery back, but much easier to hide. My Riverdale coal fired Elke uses four AAA batteries for its RC receiver power.
Silly NT's.....I have Asperger's Syndrome!

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Re: Merlin locos

Post by big-ted » Sat Apr 02, 2022 3:35 am

I owe this thread an update. Everything is installed:
IMG_20220401_181633.jpg
IMG_20220401_181633.jpg (976.03 KiB) Viewed 3965 times

Deltang receiver on the left behind the power switch. Not yet fixed in as I still need to set servo trims. 4 AAA batteries soldered & taped together & placed on the right hand side in front of the lubricator. Servo for steam regulator/reverser on factory location under the footplate.

I'm not at all concerned about the battery capacity. The four AAAs in my Roundhouse loco (same receiver, two servos) last for ages.

Fingers crossed pics of loco outside in steam tomorrow, although the weather isn't looking great.

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Re: Merlin locos

Post by big-ted » Sun Apr 03, 2022 12:25 am

Well, the weather held off beautifully today so ladies & gentlemen, meet Myrddin:
IMG-20220402-WA0006.jpeg
IMG-20220402-WA0006.jpeg (1.3 MiB) Viewed 3918 times
The timing is way out on one side, & the set screw holding the return crank to the axle is stripped, so I'm going to have fun with that. Getting it out will be one thing but I suspect finding a replacement will be even more tricky. Anyone know the size of the set screw these locos used?!!

A small steam leak from one of the banjo bolts on the lubricator, & I think the gas filler valve needs cleaning, as it seems to take ages to fill the tank, but both of these should be easily sorted. It actually ran really well in spite of these issues!

Note the plates are made by me. The loco was missing it's builders plates, so I've no way of knowing the works number. By all accounts these numbers were a bit arbitrary anyway, so Myrddin's plates have been left blank.

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