Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

The Regular Stuff: Chat, Buy, Sell, Off Topic, etc. => General Discussion - Scale Model Gas Engines - Hit & Miss - Throttle Governed - Non-Compression – etc => Topic started by: eec1910 on December 20, 2020, 09:39:07 am

Title: Re: M91 help needed
Post by: eec1910 on January 20, 2021, 11:53:58 am

Hello all,
Finally got round to have a look at the M91 again and have filed some metal
of the latch out lever, after the fourth time of filing it now runs ok.
Thanks again for the help.
Cheers Trevor.

Title: Re: M91 help needed
Post by: Adirondack Jack on December 23, 2020, 12:46:57 pm

This is the issue I had also, and I did two things. I pulled the weights off and insured the Governor arms were perfectly centered in the notches where they rest in the flywheel, and I loosened the collar on the crankshaft that the Governor mechanism is anchored to, and shoved it firmly toward the flywheel and snugged it down.  That piece determines the geometry of the travel of the arms. If it’s not fully against the flywheel, the arms crash on the latch out mechanism and knock it off center.

Title: Re: M91 help needed
Post by: MaytagMama on December 22, 2020, 04:28:04 pm

I had the same issue with mine. I had to file it down to keep them from rubbing.

Title: Re: M91 help needed
Post by: eec1910 on December 22, 2020, 03:41:35 pm

I've had another look at my M91 and found that the governor weights when they expand
are hitting the latchout lever,can anyone give me a reason why they would do this ?.
The only answer i can come up with is to file some off the lever what do you think ?.

Thanks again for the replies,
Trevor.

Title: Re: M91 help needed
Post by: Raphael on December 21, 2020, 07:17:37 am

Bonjour Trevor,
I would be happy if this video I made on my M91 a while ago would help you (sorry, in French) :
https://www.youtube.com/watch?v=Ynns8w7lBYY

Title: Re: M91 help needed
Post by: Adirondack Jack on December 20, 2020, 07:40:55 pm

Note the end of the crank is slightly recessed in the flywheel. Note the Governor bits attached to the crank as close as possible to the flywheel. If they slip, it crashes the Governor

Title: Re: M91 help needed
Post by: Adirondack Jack on December 20, 2020, 07:30:38 pm

My guess, having been through it, is the Governor mechanism has slipped in its position on the crankshaft, allowing the mechanism to crash. Check to see that the Governor bits attached at the crank are out as far toward the flywheel as possible.

Title: Re: M91 help needed
Post by: RedRyder on December 20, 2020, 02:37:59 pm

Make a video of this action in slow motion and study it.
You will likely see what is hitting the lever and when.
If you don't see it, publish the slo mo so we can study it.

Title: M91 help needed
Post by: eec1910 on December 20, 2020, 09:39:07 am

I have been trying to run my M91 the past few days and have a problem which i can't solve,
every time the engine fires and runs the latchout lever comes loose,always to the on off
switch end of the engine.
The allen screw which holds the lever in place has been tightened and makes no difference,
has anyone come across this problem before or can give me help in solving it.

Thanks Trevor
(eec1910).