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Gearbox Identification Help

Posted: Mon Jul 26, 2010 1:05 pm
by martinwinlow
Hi All,

I'm trying to help someone without WWW access (who lives 200 miles away) to convert their PbA pack to Lithium for better highway performance and need to know the gear ratio of its gearbox before potentially wasting any more time on the project if the motor/gearbox is not capable of a good 55mph top speed. I could try marking the wheel and motor shaft and count the relative number of turns but I'd rather try it the easy way first.

Can anyone ID the gearbox in the attached picture? It is a single speed (ie fixed) one whose output is connected to the rear axle differential, in this case, with a very short prop shaft. It is attached to an ADC 4001A motor and both are installed in a Daihatsu HiJet (aka Piaggio Porter) micro-van. The motor is dated '02.

The image is taken from the offside and is looking under the van at the rear, near-side wheel. You can see the bottom of the diff just below the brush (rear) end of the motor.

Thanks.

Re: Gearbox Identification Help

Posted: Mon Jul 26, 2010 1:37 pm
by EVan
I think the easy way would be to count the turns. Even if you identify the type of gearbox there could be any choice of ratio in it.

Re: Gearbox Identification Help

Posted: Mon Jul 26, 2010 3:42 pm
by martinwinlow
EVan, Thanks for that... if you are right about having a choice of gearing, it raises the possibility of changing the ratio for a higher top speed - the trade off being poorer acceleration. Which brings us back to a positive ID of the gearbox so we can investigate altering the ratio with the manufacturer. The key issue at the moment is improving the vehicles top speed. I think it was designed for a trundle-about-town scenario, not highways... 40mph or so max.

Regards, MW.

Re: Gearbox Identification Help

Posted: Mon Jul 26, 2010 6:00 pm
by retepsnikrep
Can we not help them directly by getting them to join this forum and post on here.

Re: Gearbox Identification Help

Posted: Mon Jul 26, 2010 8:26 pm
by ChrisB
I dont think they have tinterweb access :wink:

ChrisB

Re: Gearbox Identification Help

Posted: Wed Jul 28, 2010 6:55 pm
by jonathan jewkes
Your friend should certainly not spend any money on Li-Ion batteries until he has sorted out his top speed problem. You have said that he wants to achieve 55mph
Li-Ion may have the potential to give slightly better performance because of its lighter weight - but this will be offset because for any given voltage and Ah capacity it won't deliver any more amps than lead-acid (and probably a lot less). Therefore top speed and especially acceleration are unlikely to be any better with Li-Ion than with Lead. The main advantage of Lithium is greater range for a given weight of battery.

You haven't said what voltage system it is, or the max current the controller can handle. But from the picture the motor looks to be a similar physical size to that fitted to the Elcat (of which I have one). The Elcat is based on a vehicle of very similar size and shape to the Daihatsu HiJet. (Poor aerodynamics!)
My Elcat will just about go at 55mph drawing 300A from an 84v pack. However the Elcat has a manual gear-box and I need to be in 5th gear to go this fast. However in this gear it can only pull away very slowly from standing on the flat, and not at all on any gradient. For normal town driving up to 25-30mph I use second gear.

Although your friend may perhaps be able to alter the ratio in the gearbox, whatever he chooses will be fixed. So it may be impossible to find a ratio which will give adequate acceleration and hill-climbing ability as well as a top speed of 55.
Though it may just be possible if the motor is big enough and the battery pack and controller can supply enough amps, without anything overheating.

At first, just see if you can get sufficient acceleration and top speed with lead-acid (don't worry about the range at this stage - it may well be very poor). If you can't, then you have to consider alterations - some or all of a bigger motor, higher voltages or a higher current controller. But if you can, then (and only then) spend money on Li-Ion to get a decent range.