Re: Ang.:Re: [electricboats] Sizing motor for 45-50’ boats

(sorry if this is a repeat - I posted it 8hrs ago and it never showed up)

I have also spent a lot of time looking for thrust bearing options.  That Python Drive looks like a great solution where there is room to fit it.  Looks like it will leave some room in the wallet too. 

Thunderstruck uses a trailer hub with tapered roller bearings.  It's a good simple and inexpensive solution for small setups (<30hp?).   I think this is the hub they use:

https://www.agrisupply.com/trailer-hub-capacity/p/25669/?sid=asf10&eid=Easf10&zmam=77232640&zmas=1&zmac=1&zmap=25669&eid=gl020116&sid=google&gclid=Cj0KCQiAyoeCBhCTARIsAOfpKxg-UWWx-rrzYMZA1hBZLyEhEjTr2oVK21ludtM8zMI49vR0KLRQ3D8aAgkUEALw_wcB

One issue with these is setting the pre-load on the bearings.  If you have changed the wheel bearings on a car you know what this is about.  Thunderstruck does it by using a fixed collar and bushing on the prop side of the bearing and another bushing on the other side that is held in place by the tapered bushing that holds the toothed belt for the reduction gear pulley.  It's a simple setup with only a few parts and some simple machining on the shaft.

I am fabricating my own belt drive reduction gear for my boat (12kW motor) and I am going to use a trailer hub that's one size larger and available in stainless steel (with a price premium of course).  This is what I am using:
https://www.etrailer.com/Trailer-Hubs-and-Drums/Kodiak/KH84545S.html

I am going to use a threaded split collar on the shaft to set the pre-load on the bearing.  My shaft will be a more complicated machining (including a threaded section) but I think it will be a better way to set and hold the pre-load on the bearings.   The two parts I have to make are the shaft and the bushing.  Both will be stainless steel.  The hub will remain stock with no machining.  The bearings are standard hub bearings you can get anywhere.   All the parts except the bearings will be stainless steel.  And the bearings will be in the grease.  The bushing will have the OD sized to fit the grease seal on the hub that takes the place of the standard cap when it is used on a wheel.  It's a standard grease seal but I had to hunt a bit to sort out fitting it in the hub. 

This could easily be scaled up for larger applications.   These hubs come in at least two larger sizes in stainless. 

The bearing, reduction gear assembly, and motor will mount to an aluminum plate similar to what Thunderstruck does.  I was going to use a piece of c-channel and that would work well but I wanted more flexibility in the pulley sizing to be better able to fine tune the reduction ratio and the c-channel limits the diameter of the gear pulley a bit.  I am still sorting that part out but I am aiming for about 3:1 for the reduction.  The world of timing belts and pulleys is vast and has been difficult to get a handle on so far. 


Dan Pfeiffer

 

On 2021-03-15 11:29 pm, Carsten via groups.io wrote:

Of course you'll need a double bearing for axial loads in forward and reverse...

Sendt fra Yahoo Mail på Android

På tir., den 16. mar. 2021 klokken 10:47, Carsten via groups.io

<Carstensemail=yahoo.com@groups.io> skrev:

Hi, Steve

 

Consider to make your thrust bearing with a high quality spherical roller thrust bearing, eg. of SKF brand. This can accept torsional forces much better than ball thrust bearings.

Then you don't need the expensive solutions with a lot of rubber (which needs care and replacement when worn).

 

The tooth belt drive (not V-belt, which introduces higher radial forces to the shaft) can be mounted either before or after the thrust bearing.

The housing for the thrust bearing should best be mounted close to the cutlass bearing, to minimize torsional bending of a long shaft.

 

Could you please post some photos of your existing setup of the shaft and cutlass ?

 

Have you considered which prop you will use for your new setup ?

Going electric has a lot of torque at low revs, which is very useful during maneuvering, so the prop should have less pitch and larger diameter, imho.

 

Carsten

 

 

Sendt fra Yahoo Mail på Android

På tir., den 16. mar. 2021 klokken 4:52, Steven Borg

<steve@theborg.family> skrev:

I'm in the process of planning and installing a Hyper-9 motor at 154V with a battery bank of 48 280Ah 3.2V LiFePO4 batteries I received from China. The motor is rated to be plenty powerful to replace my 100 HP Diesel (which has been removed).  I'll keep everyone posted when it's installed.

In the meantime, I have a related question (maybe for ChristopherH?) around thrust bearings.  I've decided to use a belt drive (like the photos above, but for a single motor and gear.  But without the transmission I had planned on using (with integrated thrust bearings), I'm going to need to anchor the propshaft to the boat.  

Christopher, what inline thrust bearing did you use?  I'm trying to determine if I should build out a thrust bearing somewhere along the prop shaft, or whether I should integrate the thrust bearing into the engine mount, either before or after the belt pulley driving the shaft.  Also, if there's a pre-made thrust bearing for boats, I can't seem to find them (except large ones for giant ships). Does anyone know what they'd be called, so I can search for them.  (Yes, this is an embarrassing, totally newbie, question to ask, but I just can't seem to find them, so have been debating whether to just engineer my own from bearings off Granger or McMaster-Carr).

I'm not sure those questions even made sense, but that's where I'm starting...  Still trying to figure out the best way to get this done!  

This has been an amazing thread!  Thank you!