Print

Please login or register.
1 Hour 1 Day 1 Week 1 Month Forever
Login with username, password and session length.

[tassie48]

Hi Crew in a propeller shaft A frame is it important to have either bronze /brass bushings or bearings for the shafts to run in,  looking at friction and wear etc in the A frame housing area.  As in my new build LCS the shaft for the propeller exits the outer tube at the hull and just the prop shaft that has the prop on the end is exposed and supported just by a A frame housing, still learning tassie48

[Bunkerbarge]

You have to bear in mind that, unlike the stern tube bearings that have lubrication, the only lubrication the 'A' or 'P' bracket gets is from pond water and all its included impurities.  Invariably the material is either plastic, wood or white metal so significantly softer than the rotating steel shaft. For those reasons I would normally fit a bush to the bracket to reduce wear and tear unless the model is very lightly used and you lubricate it manually frequently. 

[John W E]

Hi there


To try and merge two topics into one as I note you ask for information about A frames on another topic.    So, for lubrication, I tend to go with Richard and his reply about inserts of bronze & soforth.   Before sailing my model, I lubricate the A frame support bearing with some 3 in 1 oil - just a little dab - to help it free off.


A frames I tend to make myself.   I made a jig up years ago and I only soft solder parts of the A frame.   There is only once I have ever needed to silver solder a P frame, as it happens to be, was on an IC engine hydroplane model - so soft soldering has always sufficed.   I know there was a guy on Ebay selling A frames but I cannot locate him at the moment, but I will put a link on when I do.


Couple of pictures of HMS Exeter's A frames.

[Geoff]

Please consider that its important that the propeller thrust is not taken by the A frame but the shaft proper where you should have a thrust collar and washers to transmit the load to the outer casing and thence the hull. If the thrust is on the A frame it will either distort it causing drag or cause a leak at the hull joint. A frames are only there to stop a shaft whipping!


Cheers


Geoff

[tassie48]

Thanks Crew I am going to build my own A frames and fit bronze bushings in them , bearings get clogged in time and bronze can can replaced due to wear if any , as Geoff said they are carriers to stop shaft whip and not so much load bearing to everyone whom contributed many thanks tassie48