Trims on Radio Control

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markoteal
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Trims on Radio Control

Post by markoteal » Thu May 23, 2019 8:37 pm

Hello - still not got a garden to put a line into - trying to get my fix of steam by running my Millie on blocks - recently had its regulator servo replaced- all good but on the last steam up, the servo isn't quite travelling enough to close the regulator off - If I loosen the screw that attaches the reg to the servo, the reg can move that little bit more to close.

I've tried to re-attach the grub at that point but the angles wrong - I'm guessing that while the loco and transmitter have been stored away, something may have pushed against the trims on the transmitter.

2 questions:-

1) What is a trim? are they the little sliding things on the transmitter
2) Which one should I fiddle with - don't want to b@gger them all up

I know I should be submitting photos with a request like this but I'm working away from home 5 days a week at the mo - I will have another go this weekend and send some pics

@tom - I may need a trip to see you one day soon!
Where did I put that uncoupler?

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Re: Trims on Radio Control

Post by markoteal » Thu May 23, 2019 8:44 pm

Ok - this is a pic of a similar transmitter to what I have -- I think I use the LH stick for the regulator - so if I want to extend the travel of the servo, which bit do I fiddle with?
trans.jpg
trans.jpg (43.19 KiB) Viewed 6018 times
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Re: Trims on Radio Control

Post by Busted Bricks » Thu May 23, 2019 9:13 pm

You have the dual rate switches on the top/sides of the TX. The reduce/increase travel. The trims are next to the joysticks. All they do is adjust the center position of the servo. If you want to extend travel you need to move the pushrod out one hole in the servo arm (or fit a longer arm).

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Re: Trims on Radio Control

Post by tom_tom_go » Thu May 23, 2019 10:14 pm

Hi Mark,

Good to hear from you and happy to help.

Maybe a WhatsApp call via video to show me or drop it by next time you are down?

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Re: Trims on Radio Control

Post by markoteal » Sat May 25, 2019 7:35 pm

Cheers Tom - I’ll have a run ( on blocks tomorrow and will video it - hopefully!!!!!) - will be in touch
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Re: Trims on Radio Control

Post by cncmodeller » Sat May 25, 2019 10:38 pm

The trimmers are really more use to aircraft modellers when you need to adjust the flight characteristics of a model by say adding more lift to the elevators,
it saves having to keep dismantling the plane to adjust the servos plus you can do it in flight, the more exotic transmitters can save these adjustments for different models.

John

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Re: Trims on Radio Control

Post by tom_tom_go » Sun May 26, 2019 9:49 am

Just as useful for servos in live steamers as well rather than having to adjust linkages although I have learned that you should try and get as close as possible to the setup required before using trim.

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Re: Trims on Radio Control

Post by Paul_G » Sun May 26, 2019 11:34 am

From the factory my Lady Anne wouldn't allow the regulator to fully shut even with the trim (digital on my Tx) fully adjusted.
Simply resetting the trim to the centre position, undoing the grub screw & ensuring the regulator was fully closed before tightening the grub screw solved the problem at the first attempt & so in your case it sounds as if something else is amiss. The fact that the angle of the linkage won't allow the grub screw to tighten up is wrong & that needs addressing before trying to mask the problem by adjusting the trims. They are really only for fine tuning.
Can you post a picture of the linkage assembly?

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Re: Trims on Radio Control

Post by FWLR » Mon May 27, 2019 9:21 am

I have every sympathy with you with the problem on your Rx. I went through the same problem for months. But Tom has sorted it now. He does know his stuff on such things....

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Re: Trims on Radio Control

Post by Chris Cairns » Mon May 27, 2019 11:40 am

Radio controlled regulators on Roundhouse locos not fully shutting off has been a regular occurrence in both the West & East of Scotland 16mm NGM groups. We've had to change a few internal 'O' rings (available from the factory).

Many of the loco manuals (not the Millie one) including the following information -
Roundhouse Engineering wrote:REGULATOR NOT SHUTTING (R/C models)
The steam regulator seating and seal can, after a period of time become worn or compressed so that when the lever on the radio control is fully closed, the locomotive still moves. To overcome this, a trimmer is fitted to the transmitter. This is the small lever at the side of the main control lever and is set at the factory to the top of its slot. As wear takes place in the regulator, it can slowly be moved down the slot to compensate. When it reaches the bottom, it is time to reset it to the top and adjust the linkage between the servo and the regulator in the cab. If adjustment does not cure this problem, the internal '0' ring is probably damaged and requires replacement. Contact the factory for further advice.
http://www.roundhouse-eng.com/ss06.htm

Part of the problem is that Roundhouse state to fully close the regulator between operating sessions, thus that 'O' ring is going to be compressed all the time. I leave my R/C regulators partly open between operating sessions but I loosen the safety valve/filler plug once pressure has dropped to prevent a vacuum forming.

I recently obtained a pre-owned Millie which has an R/C regulator & been having problems with the regulator not fully shutting off. I found that running the Millie on blocks (do not have an outdoor layout at present) to get the wheels to stop on shutting off the regulator was not accurate enough, and had to adjust it whilst running on track.

Chris Cairns

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Re: Trims on Radio Control

Post by FWLR » Tue May 28, 2019 7:31 am

Thanks Chris for your time in replying with this information. It's good to know that.

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Re: Trims on Radio Control

Post by markoteal » Tue May 28, 2019 1:26 pm

Thanks for all your replies - had a steam up at the weekend and managed to adjust the linkage length - the linkage has a screw end at the bottom which in effect tightens it up - this allowed me to put the reg at a closed position and get the grub screw through the hole and re attach the linkage.

Chris - have seen your point above and you are spot on - when the reg is closed the wheels do turn a little on the blocks - but when I place it on the track it holds still - especially when its attached to a heavy coal wagon slomo that it usually pulls around to keep it under control.

I just need to sort my track to run it around on!
Where did I put that uncoupler?

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