Couplings

[BattoParticipant @batto]

I have noticed that in all the models I've seen pictures of recently the motor to shaft coupling is a universal joint type but I remember from my MFA Spearfish/K&B40 model of 40 odd years ago that I had to be sure to get the thrust acting on the outboard end of the shaft in order not to load up the motor, and for that I used a pin coupling. When I built my "Henry" recently I ditched the supplied UJ coupling and replaced it with a pin coupling so as not to load up the steam engine bearings. Anyway (stop rambling man!) I was wondering if, with electric motors, thrust on the motor is not a problem or do people just accurately set up the coupling and prop so that there is no end float on the prop shaft or perhaps leave the the motor end of the coupling loose to a sliding fit?

[BattoParticipant @batto]

[Ray Wood 3Participant @raywood3]

Hi Batto,

I think you'll find the thrust from the prop only goes as far as the lock nut & washer onto the stern tube, no thrust gets as far as the motor 😀

Regards Ray

[Dave MilbournParticipant @davemilbourn48782]

It's very difficult to do this when you use a "solid" coupling or one with a rubber centre-part. Huco U/J type couplings aren't really up to the revs which brushless motors can give them. That said, I've had no problems with brushless types when using rubber couplings. Pin couplings are hard to find these days anyway – unless someone knows better?

Dave M

[Colin BishopModerator @colinbishop34627]

I've not found it too difficult on my SLEC Huntsman kit. to take the thrust on the tube using a rubber coupling. Basically I fitted the prop with a washer behind it and slid the shaft up the tube. If the motor is aligned properly then you should be able to slide the rubber coupling up and down along the motor shaft and propshaft with a bit of leeway.

With the propeller against the tube end then tighten the fixings of the coupling on the shaft and then on the motor at which point the end of the tube will be takling the thrust as intended. Hope this is clear!

Colin

[BattoParticipant @batto]

Dave you can get pin couplings HERE but they're the only ones I found – I was looking for all-metal units originally but they don't seem to exist now.

[captainslogParticipant @captainslog]

I am glad this came up. i use a hugo u/j coupling all the time. what is th sequence of fitting them correctly please? from the motor shaft to the prop. Is it "brass insert/coupling/ brass insert/ then washer and 1 nut before the shaft then shaft/washer/1 nut then the prop. the reason i ask is because sometimes after i have gone astern a few times then sailed home i have found that my prop shaft will move back and fore as if it has loosened off. am i doing something wrong please? thanks keith

btw batto, i have a couple of pin type couplings somewhere, use them for my ic motors back in the 70s i will try and look them out for you, they could be anywhere mind. iff i find them will pm you, your welcome to them

[Malcolm FraryParticipant @malcolmfrary95515]

A the inboard end of the shaft, if the locknut is not securely locked against the face of the coupling, it will move. Having a washer between nut and lock object prevents proper locking. The place for the washer is between the nut and the prop shaft tube outer. It needs a spenner on both the coupling and the nut wound firmly against each other for locking to happen. Same at the prop end if the prop is valued.

[captainslogParticipant @captainslog]

thanks malcolm, I do like my props as it helps to get the boat back , its just i think i need a refresher course as i havnt bothered with my r/c boats for a long time, too busy building flying things. must start digging out my old mags and take a leaf out of glynne guests pages. Or even "don careless" do you remember him?

keith

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