Speed reducers

[Derek Warner]

on Sunday, March 30, 2003, daipowell wrote
"they are geared with Master Airscrew gearboxes to give 150 rpm"

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Thanks for that Dai [and Brett for his comment] & during the week I managed to purchase the 05 Model @ 3.5:1 ratio

I suppose my real issue here now is the input gear pinion bore is 0.124" [one thou under 1/8"] but my motor shaft is
3.00 mm which is 0.118" - so maybe three strands of 0.003" wire in a triangular pattern & high build LOCTITE

The brochure nominates no lubrication required for the gears or bearings [but can oil lube bearings if reqd] - I found
the baby bearings are [single Z sealed] one side only & sounded pretty rattly dry [no evidence of assembly lube]
which seemed a little strange so I lightly lubed the bearings which eliminated the rattle and intend to lube the gear
set at final assembly

I note that your gearbox's have an output speed of 150 RPM, however Decoys 05 model is the primary speed reducer
being 1500 RPM in & an odd 415 RPM out [allowance for friction etc] so did you consider lube to the bearings or
gear set a necessity?

Again thanks for the tip on these units as my segmented tooth belt primary reduction required too much belt tension
for the brushless induction motor limited current draw - Derek

[Dai Powell]

Hi Derek,
Glad you were able to get the gearbox over there ok, you
mention how they sound noisy, yes I found they sounded very noisy
and just packed them with some white marine motor grease that I had
for my outboard motor (That quiets them down, I hope it doesn't
thicken up and go hard,[never thought about that I was just trying
to shut up the noise]) now I'm worried, I may have to clean them out
and put light oil in instead............Dai

[dragoncity]

Well Derek ! , how about refitting you Wiper Motor :-) Fully sealed, extremely quiet, enought grunt to overcome
almost any tension. I have acouple of those gearboxes and was thinking of using them in the Industry, but
space (beam) considerations stopped that train of development. The gearboxes are very robust and should last
a fair while.

And remember these are aircraft gearboxes so should be AIR-cooled !!

[Dai Powell]

Good on ya Brett, I recon the "Banana oil" has got to be the way to
go, I can't get any oil out of Iraq, but there are plenty of bananas
in the carribbean........Dai

[Derek Warner]

Last couple of days we have seen postings of banana oil as a recommended lubrication for gearbox's!!!!!!!

From my limited knowledge of such things I thought it was banana skins that were used, but to clarify
a few points and one is that I am a devoted fan of windscreen wiper motors [WSWM], but

1) in Decoys hull set-up the WSWM would be going in reverse when Decoy was going ahead - all to do with
a single ball bearing in a dimple located in the end of the armature shaft that accepts the thrust of the EMF
created when the fields get excited [electrically that is]

2) so with the 12Vdc WSWM running on 6Vdc in reverse my borrowed digital multi meter confirms a ranging
current draw from 1>1.8 amp and you can see the motor output shaft speed increase & decrease by eye

3) WSWM were never designed to go backwards & I acknowledge that the speed issue is less noticeable @
12Vdc, but my speed controller is limited to 7.2Vdc

so I rest my case - Derek

NB - note for Dai - Australian bananas have been voted best in the world by an international body, but not sure
if it was by the WHO, UNESCO or the United Nations [or OPEC]