Power/Torque Upgrade for Heavy Duty Soundsystem Trike

Hi Folks,

 

I hope this is in the right section. I have seen a post on a similar theme come up on here but I think our Trike is that much heavier it's going to require a different solution. I wondered if anyone could give us some advice?

 

We have a cheap Chinese trike that we bought second hand for transporting our mobile soundsystem. The soundsystem weighs about 270kg so the total weight we are pulling is that plus an adult rider plus the trike itself. It's fitted with a 48v motor and parallel differential gear - see photos.

 

It's been coping okay on the flat but really struggling up hills. Recently the diff has started making a grinding noise and failing under load. An additional, perhaps separate problem, is that there is no control of the motor speed - it's either on or off and the gearing is geared for speed rather than torque so it really struggles to pull away when stopped. When it's moving it goes unnecessarily fast. Where we live is hilly and often we are using the system on demonstrations/events where people are walking - we don't need speed, just steady power.

 

Clearly we are overloading it. We would like to upgrade the motor and replace the diff, ideally with something that is geared for more torque, or has a higher torque motor, and which we are able to better control.

 

I have spoken to a friend and bike shop owner who suggests putting in a Bafang mid drive motor in and leaving the rear axel alone. My worry with this is that (a) the diff is still making a grinding noise whether or not it is engaged, (b) this would only drive one wheel since the pedal drive is connected one side of the diff © the chain may not cope with such high torque (total wight could be up to 400kg).

 

I can think of three main options:

 

1. Replace the motor and diff with something similar to what we have already.

- I have found some people on ebay selling this motor but no diff (and they've not replied to my questions) and on alibaba, I've found this which looks equivalent - again they have not answered my questions. Does anyone know where I could buy something that could work?

 

 

2. Install a bafang bbshd 1000w mid drive motor kit with a 40T chainring.

- Remove existing motor and diff entirely (this would also mean replacing the rear axel) - solving problem (a)

- Replace rear axels and fit a samagaga differential with sprocket (or similar) - solving problem (b).

- Run the strongest chain I can find - solving problem ©?

 

3. Install a sprocket and chain drive motor (sorry, not sure on terminology)

- Rather than a motor with an integrated parallel diff like we have, we could fit something more like this.

- Obviously this would also mean replacing the rear axel and adding something like a samagaga diff.

- This option would imo be the most work as we'd need to fabricate new motor mounts etc. - but if it's hands down the best option we'd do it.

 

Does anyone have any other ideas? Can you advise on what we should do or where we can source parts? Our budget is around £500-1k.

 

Many many thanks in advance!

 

Nate

(total wight could be up to 400kg).

Welcome to the forum.

 

Think you need a Ford Transit

Have a look at this. It uses a large geared hub-motor on drop-outs in front of the differential axle. It has normal derailleur gears to the motor so you can always get a comfortable pedal speed. There is a sprocket mounted on the disc side using the disc brake fittings and a separate chain from there to the axle with a 2: 1 ratio, so the motor runs at double the speed of the rear axle -similar to your jack-shaft arrangement, but using a motor instead of a bare axle. A motor like a MAC from ww.em3ev.com already has massive torque, and with the 2: 1 ratio or whatever ratio you want, you can get all the torque you need. A BBSHD motor is minuscule compared to a MAC, and I doubt that it would give you a robust solution.

 

The differential is a commercially available one for pedicabs. I can probably get details if you get stuck.

 

https://www.pedicabshop.com/cargo-bikes/ecocargo-cargo-bike.html

 

Here's Andrew, the owner of Maxpro/H7 using one of his cargo trikes to transport our stand at the 2013 NEC bike show.

Edited September 24, 20205 yr by vfr400

Welcome to the forum.

 

Think you need a Ford Transit

 

We had one... didn't have enough torque

Have a look at this. It uses a large geared hub-motor on drop-outs in front of the differential axle. It has normal derailleur gears to the motor so you can always get a...

 

Thanks vfr4000 - yeah I was looking at the maxpro site - I don't see any pics of the setup you describe though - it sounds awesome - and possibly similar to the ieni cycles design? - Again, not really the detailed pics on that site either - at least not enough for me to build something similar - I'm interested in particular in how they attach the drive chainring on other side (opposite side to the cassette) of the motor. Yes, if you have details of the diff or any other parts that'd be a huge help - thank you!

Thanks vfr4000 - yeah I was looking at the maxpro site - I don't see any pics of the setup you describe though - it sounds awesome - and possibly similar to the ieni cycles design? - Again, not really the detailed pics on that site either - at least not enough for me to build something similar - I'm interested in particular in how they attach the drive chainring on other side (opposite side to the cassette) of the motor. Yes, if you have details of the diff or any other parts that'd be a huge help - thank you!

Your photo isn't very clear, but it looks like all you need to do is replace your jack-shaft axle with a hub-motor, as long as you have enough clearance for the outside diameter. Then you can chuck the old motor or use both.

 

The sprocket on the left side is screwed to the motor using the 6 disc brake screws, i.e. the motor has a sprocket instead of a disc. You could probably modify a gear out of a normal rear gear cluster - dremmel out the I/D to fit and drill the 6 holes using a disc rotor as a template/drill-guide.

Your photo isn't very clear, but it looks like all you need to do is replace your jack-shaft axle with a hub-motor, as long as you have enough clearance for the outside diameter. Then you can chuck the old motor or use both.

 

Okay, yeah, if there's clearance that'd be nice solution. If not we can move the crossmember. We'd still need to change the rear axel though and add a diff (?) - hard to see in the pic but the pedal/chain driven sprocket on the axel is fixed-mounted so pedal drive only turns the wheel on that side of the diff.

 

The sprocket on the left side is screwed to the motor using the 6 disc brake screws, i.e. the motor has a sprocket instead of a disc. You could probably modify a gear out of a normal rear gear cluster - dremmel out the I/D to fit and drill the 6 holes using a disc rotor as a template/drill-guide.

 

Okay, cool, that's really easy.

Doubt you will do a diff and shafts and the motor in your budget, samagga is the off the shelf option, have used once, very well made and heavy duty but to machine the shafts to a non standard length added to the cost

The east German guy has disappeared that made a cheaper option seen in the pic below

A high power mid drive will be a problem stability and steering become frantic even with just 100nm 36 v extra torque motor from em3 and with just one wheel rear drive dangerous

Doubt you will do a diff and shafts and the motor in your budget, samagga is the off the shelf option, have used once, very well made and heavy duty but to machine the shafts to a non standard length added to the cost

The east German guy has disappeared that made a cheaper option seen in the pic below

A high power mid drive will be a problem stability and steering become frantic even with just 100nm 36 v extra torque motor from em3 and with just one wheel rear drive dangerous

 

There's also this diff on ebay - doesn't use a splined half shaft so a lot cheaper/easier to produce the shafts - but it also doesn't look a patch on the quality of the Samagaga. I'll get a quote from Samagaga. Leaning towards one of them plus a Mac hub motor now.

 

Steering? Yeah, this thing is HECTIC to ride when fully loaded - not helped by the current motor speeding it forward when it switches on and a long delay between braking and the motor cutting out. It's probably a separate thread but I'm thinking 20" fat bike forks (custom long steerer tube) and large fat road tyre on the front to increase stability in cornering. ...priority now is drive train.

The German diff is what i used in the picture the shafts require flats and a pin through the shaft ,

doubt it will take the power of the bbshd.

But mine was pushing fat tyres and only three speeds with a 36 tooth lekkie but the low speed control was excellent walking pace up to 10mph over that it was hang on and close eyes also had stopping problems even with 3 disc brakes

The German diff is what i used in the picture the shafts require flats and a pin...

 

Do you have a name or anything for the East German guy? Anyone else know of him? Weird that he'd totally disappear... possible for various reasons tho.

 

This diff is a similar price to the ebay one and looks pretty hardcore. No technical data though - appears to be bolt on rather than splined (?) which would make DIY production of the shafts a lot easier. I'll contact and see if they have any info.

If he's Polish rather than East German, it's Andrew, the guy in my photo, who I know. If I remember, I'll phone him tomorrow and find out what diffs he uses.

https://www.ebay.co.uk/itm/Dreirad-Pfautec-Kynast-Differential-schwarz-Montageanleitung-mit-Bildern/124316344035?_trksid=p2485497.m4902.l9144

this is the same one

sound system my ass

 

thats just big enough for a family bbq in a housing estate

If he's Polish rather than East German, it's Andrew, the guy in my photo, who I know. If I remember, I'll phone him tomorrow and find out what diffs he uses.

Thanks!

https://www.ebay.co.uk/itm/Dreirad-Pfautec-Kynast-Differential-schwarz-Montageanleitung-mit-Bildern/124316344035?_trksid=p2485497.m4902.l9144

this is the same one

 

Okay, interesting - looks exactly the same as the other ebay one I posted which says it's in Ireland - cheaper postage from Germany tho .

sound system my ass

[ATTACH type=full" alt="38474]38474[/ATTACH]

 

thats just big enough for a family bbq in a housing estate

 

That's a beast! Good to see they're observing social distancing.

I spoke with Andrew (Maxpro) today. He said that if your wheels are compatible, he could make a differential axle for you for about £300. There are some cheaper options depending on what you have. He'd be happy to talk to you about it. If you want to go ahead, I can provide his private contact details.

I spoke with Andrew (Maxpro) today. He said that if your wheels are compatible, he could make a differential axle for you for about £300. There are some cheaper options depending on what you have. He'd be happy to talk to you about it. If you want to go ahead, I can provide his private contact details.

 

That'd be amazing. Yes, please do pass me on his contact details. Thanks so much for doing that.