Drivetrain selection for an electric drive system

Hi all, I am designing an electric drivetrain for a three wheeler (tuk tuk) using a BLDC motor and controller. I am powering this with a lithium ion battery pack. I am currently using a chain drive with a single reduction gear to transmit power to the rear wheels. I would like to know the best transmission option for my scenario. I have considered using chain drive/ toothed belt drive / direct gear arrangement (sort of a single reduction gearbox) for this purpose.

It would be great if I can get some advice on the drivetrain selection with regards to efficiency, maintenance, ease of sourcing/manufacturing, costs etc. Thanks in advance!

If a single speed chain reduction can provide the gearing you require then that will be the simplest and most efficient.

As evidenced by its widespread use on bicycles and motorcycle. Anything you can do in your design to keep it clean and lubricated will increase efficiency, service life and reliability

Thank you for your replies.

I was considering shifting to a gearbox with a single reduction as it will require least care in terms of frequent maintenance. Also, isn't the efficiency of a gear system better than a chain drive? Please clear this point.

Thank you!

In my opinion, chain drive is the way to go.

Its cheaper than a properly sized geared belt/HTD drive and the components are readily available if you need to replace sprockets and chain. I would try to design around standard shaft and bore sizes where possible so that you can easily replace components without custom boring or machining.

The efficiency of a properly designed chain drive is quite high and comparable to spur gear and belt drives (within a few per cent).

Engineering and fabricating a custom gear drive would likely be the most costly of the options and unless you really want to do it just for fun ( sometimes that's enough ), Id go with a chain drive.

The one caveat is that chain drives arent ideal at super high speeds without dedicated lube system. Find a horsepower rating table for roller chain (all over the web) and note the speed and power ratings and lubrication recommendations. In truth, roller chains are abused beyond their limits and maintenance largely ignored in many cases on go karts, dirt bikes, etc and they hold up very well. A reasonably cared for properly designed chain drive will last a very long time. Be sure you account for the ability to tension it properly by making your motor mount adjustable.

My two cents....happy building!

Chain drive is actually one of the most efficient gear reduction systems, in addition to being easily regeared if you want to change ratios down the line.

Thank you for your suggestions and views.

The efficiency of a properly designed chain drive is quite high and comparable to spur gear and belt drives (within a few per cent)

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From my preliminary research, the belt drives seem to have heating issues and tend to wear out pretty quickly requiring frequent replacement, unless I go for kevlar reinforced belts which are quite expensive but still have heating issues. My application is to drive for ~8-10 hrs on a daily basis in conditions involving dust and frequent water logged roads (water and particle ingress is prevalent). This might require continuous maintenance for the chains but in case of a gearbox, it seems to be lesser.

Please let me know what you think.

The one caveat is that chain drives arent ideal at super high speeds without dedicated lube system

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My application has a top speed of 55 km/hr that translates to ~650rpm. Will a chain drive handle this for a longer lifetime? (assuming I select the correct chain and tension it properly)

Chain drive is actually one of the most efficient gear reduction systems, in addition to being easily regeared if you want to change ratios down the line

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Thank you for this view. But in case I have a single gear spur arrangement, how difficult will it be to change ratios later?

Punx0r said:

As evidenced by its widespread use on bicycles and motorcycle. Anything you can do in your design to keep it clean and lubricated will increase efficiency, service life and reliability

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Sure, will keep this in mind if I continue to use a chain drive!

robinhood said:

But in case I have a single gear spur arrangement, how difficult will it be to change ratios later?

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The distance between gear centers will vary with ratio, and it's difficult or impossible to change without remanufacturing parts. Chains are easy. They're tolerant of imprecision and wear, and they remain more efficient than gears until they are quite worn out. Replacement sprockets and chain are inexpensive. You can use a chain case to reduce maintenance and keep things cleaner.

Have you ruled out the use of a front hub motor for your trike? That might be the simplest, quietest, and lowest maintenance option.

robinhood said:

My application is to drive for ~8-10 hrs on a daily basis in conditions involving dust and frequent water logged roads (water and particle ingress is prevalent).

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That's probably going to be a HUGE battery pack.

Or a small one that can be charged at a very high rate so you aren't sitting idle charging most of the day. LTO might work.

Or several smaller swappable ones, and a central charging station they're kept at that you regularly visit to swap out.

amberwolf said:

robinhood said:

My application is to drive for ~8-10 hrs on a daily basis in conditions involving dust and frequent water logged roads (water and particle ingress is prevalent).

Click to expand...

That's probably going to be a HUGE battery pack.

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Yeah, no kidding-- I missed that detail. There's no way an electric tuktuk with that kind of endurance will be as economical as a normal gas powered version. What's the goal here? Demonstration of the possibilities, or something practical?

Chalo said:

robinhood said:

But in case I have a single gear spur arrangement, how difficult will it be to change ratios later?

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Have you ruled out the use of a front hub motor for your trike? That might be the simplest, quietest, and lowest maintenance option.

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A front hub motor is an option, however for my application, I would need >5kW hub motor which is turning out to be expensive, also due to the fact that the trike is being steered by the front wheel, I'm afraid it might affect the vehicle dynamics in terms of steering, a lot.

Could you give me some links to resources about chain tensioning and other chain drive design/maintenance parameters? It would be great to read about them!

Thanks in advance!

amberwolf said:

robinhood said:

My application is to drive for ~8-10 hrs on a daily basis in conditions involving dust and frequent water logged roads (water and particle ingress is prevalent).

Click to expand...

That's probably going to be a HUGE battery pack.

Or a small one that can be charged at a very high rate so you aren't sitting idle charging most of the day. LTO might work.

Or several smaller swappable ones, and a central charging station they're kept at that you regularly visit to swap out.

Click to expand...

Not really huge, I'm powering it with Li-ion packs that weigh around 30kgs, chargeable in ~6-8hrs. Thanks for the other suggestions, I will take note!

Chalo said:

amberwolf said:

robinhood said:

My application is to drive for ~8-10 hrs on a daily basis in conditions involving dust and frequent water logged roads (water and particle ingress is prevalent).

Click to expand...

That's probably going to be a HUGE battery pack.

Click to expand...

Yeah, no kidding-- I missed that detail. There's no way an electric tuktuk with that kind of endurance will be as economical as a normal gas powered version. What's the goal here? Demonstration of the possibilities, or something practical?

Click to expand...

When I mentioned 8-10 hrs, I meant to say the entire operational time in a day. The distance covered wouldn't exceed 125 miles a day which seems to be normal. I'm still working out the economics, but just figuring out the possibilities as for now. Trying out different motors and drive-train arrangements. Most of the suggestions here have favored the use of a chain drive which I am already using. Will try playing around with the gearing to obtain optimum performance characteristics!