Hi Jeremy,
I haven't seen and efficiency vs HP or torque graph from Browning, but my gearbox is rated to 5.9kW, which is matched fairly well for my 5.5kW system. I have run my boat above 5kW. The next model down in the Browning 3000 product line is only rated to 3.6kW and would not be appropriate for my set up.
I've been providing the same specs that Browning has published. If you have access to better data, I'm sure that many people here would appreciate a link or a copy of those detailed performance specs.
Fair winds,
Eric
Marina del Rey, CA
--- In electricboats@yahoogroups.com, "Jeremy" <jeremy_harris_uk@...> wrote:
>
> Out of interest, what is the power level for that 97% efficiency? My experience of measuring power losses in smaller gearboxes (specifically the Mitrpak range of right angle drives) tended to show that the losses were fairly fixed in terms of power, so the efficiency ranged from around 1% at very low power levels to around 98% at the maximum rpm and torque that the gearbox would accept.
>
> The specific gearbox I was looking at would handle around 300 watts maximum at the relatively low rpm I was working at (so lower than its absolute maximum power capability by a fair margin), but had a fixed power loss of around 20W when cold, dropping to around 14W when warm. At normal operating power of around 100W the efficiency was between 80 and 86%, whereas at the maximum power I was using of around 300W the efficiency could be as high as 95%.
>
> I switched to a belt drive in order to reduce the high fixed losses associated with a gearbox (most of the losses seem to come from friction in the bearings and seals at low torque levels). I'd be interested to see an efficiency vs rpm and efficiency vs torque plot for these gearboxes, as I suspect that they may well be way poorer than 97% efficient over a significant part of their acceptable operating region.
>
> Jeremy
>
> --- In electricboats@yahoogroups.com, "Eric" <ewdysar@> wrote:
> >
> > Another option is a Browning 3201 gearbox. The ME0907 should bolt directly to it. They have a built in thrust bearing, 97% overall efficiency including bearings and seals, 10,000 hours MTBF and come in 10 different gear ratios. To me, a single component that handles everything (reduction, thrust, motor mount, etc.) helps keep it simple.
> >
> > Fair winds,
> > Eric
> > Marina del Rey, CA
> >
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