Hub motor conversion

[Zlatan]

Building a sub aqua scooter ( a dpv, diver propulsion vehicle by rights) and wanting a motor of around 500w with an output speed of around 300rpm. I,ve been looking at hub motors and they seem to offer exactly that capability,( much cheaper than any others) but I want to spin the shaft not the diver...Is it possible ( and how if so) to configure a hub motor to spin central shaft ??? Anybody any ideas.. Thanks in advance.

 

[Alan Quay]

Not easily, as the wires come out of the centre. You could use the spinning hub to drive something with a belt though.

Sent from my HTC 10 using Tapatalk

 

[Zlatan]

Thanks Alan.
Wanting to keep all drive inline...so scooter is more torpedo shape..Hub motor would be right diameter, to bolt to housing radially and some have cyclic gears to get rpm where I want them...Running a propeller so cant run direct drive. Built one already with a cordless drill motor ( and its gearbox, variable speed/ clutch) but its a bit down on power..Hub motors as I,m sure you know can be bought upto 1.5kw with all required bits very cheaply...and those without gearboxes still have required rpm..( but very large diameter to generate torque)

 

[Zlatan]

Or perhaps somebody knows of a 1000w brushless cordless drill...which would be perfect
.( most cordless drills are under 400w..well under in some cases)
The one I,ve built is great for pool use but underpowered in sea)

 

[Danidl]

Thanks Alan.
Wanting to keep all drive inline...so scooter is more torpedo shape..Hub motor would be right diameter, to bolt to housing radially and some have cyclic gears to get rpm where I want them...Running a propeller so cant run direct drive. Built one already with a cordless drill motor ( and its gearbox, variable speed/ clutch) but its a bit down on power..Hub motors as I,m sure you know can be bought upto 1.5kw with all required bits very cheaply...and those without gearboxes still have required rpm..( but very large diameter to generate torque)

Hi
Correct me if I am wrong but do not hub motors have two parts. 1 a central section which is bolted to the fixed element E.g the forks and through which the cables go and 2 a rotating element the hub to which the wheel rim is attached. Either removing the rim if fitted an attaching the propeller to this hub perhaps using the spoke holes meets that requirement .
Since you will only have access to one of two bolts the bracket would need to be very strong
I doubt however whether the motor is waterproofed. The windings will have been encased in epoxy resin so should not short out but the iron in the core and particularly the bearings will not not have been treated and will corrode . In the intend ed use these are basically splashproof . Continued immersion will allow water through whatever grease seal is present.
Motors intended for underwater use might use hydrostatic bearings, where the rotation creates lift and moves the rotating surfaces apart

 

[Zlatan]

I mount motors in a aluminium tube ( approx 1cm larger than motor) concentrically, in which are welded bulkheads contained ip68 glands for control cables. Switches are magnetic. Simply on or off. Units have to be disassembled to alter power. ( which was another question)there are no holes to outside...apart from propshaft which has an O ring type stern tube. Bulkheads are to contain water in rear comparment should stern tube fail( which they do) I have 3 compartments. Power. Control and battery. An O ringed lid bolted to front completes unit.. I have also built one using a seadoo dolphin case. ( a pool toy with a 50 w motor) but using a 400 w 24 v cordless drill.
I want to build a 1000w unit...The plastic casing of seadoo wouldn't cope with heat build up...hence usiing alloy tube for current project..
Any input would be appreciated. I,m fine with mechanical side, O rings , glands, stern tubes but power control is another matter...
Also considering building one using an old jet ski impellor, could use direct drive motor on that.( Impellors run at engine speed, props are always geared down)

If interested google " Seabob"...They are about £10 k...( and weigh 28kg for F5 and 35 for F5s...per weight dearer than a Ferrari? Or superyacht.. ( a 1 tonne car would cost 2.8 million to same pricing) .They are awesome tho...again if interested google " Subwing". Definitely most fun you can have at 3 mph..but that needs a boat...capable of 3mph !!!! and a driver willing to sit at 3mph !!! First easy...second way harder..

 

[Deleted member 4366]

Just what the doctor ordered:

http://www.gngebike.com/36v350w-48v500w-2015-gen-2

The crank runs at up to 100 rpm(48v version). The primary ratio is 3.3:1, which means the motor shaft is close to 300 rpm. The shaft is round with a key slot, so it should be easy to couple it with a shaft clamp arrangement.

 

[Zlatan]

Yep almost...but do you think the motor shaft would absorb the pushing forces from propellor ? A hub motor has to take side ways forces ( when bike cornering) The motors from scooters and crank drives I don't think will have a thrust plate built in ?? ( a drill must otherwise you couldn't push into materials)
But thanks ..and it could be made to work using a thrust plate/ bearing built into stern tube...
Big thanks tho....for simplicity needs to be a hub motor...but that has inherent wiring problems...??? Thought it might be possible to power motor through hub rather than shaft...probably not ?

 

[Deleted member 4366]

You'd have to put a thrust bearing/plate on the shaft.

 

[Zlatan]

Yep I would...thanks for help..

and pin shaft in two places....one pin for prop other for shaft to thrust plate...with shaft pushing motor ( as it does with cordless drill and hub motor) it does make job simpler.. but nowts simple...

Cheers.. Too cold to use it at moment so no rush..