[Howie]

Hi everybody!

i'm a 29 year guy from Norway that have recently gotten into EV's. For about a half a year ago, i bought my first EV, a Tesla Model 3 long range.
after falling in love with the car, i started thinking about making things switch over to electric "fuel".

i have an 2008 model "SW LTD ZL12F" chinese wheel loader with a problematic 4-cyl diesel engine. it's noisy as F, and decides to stop working when i need it at most.
so i started thinking about making it EV. but before i start doing anything, i feel i have to ask someone if it's an viable project at all.

the wheel loader has an converter that gives it 4wd and high/low gears. the ICE is connected with an axle to the converter. on the opposite side of the ICE, there is an hydraulic pump also connected with an axle.
so my idea was to just rip out the diesel engine, and put in an Nissan Leaf or Mitsubishi miev motor and weld the diff, so i get power to both the hydraulic pump and the converter.
the engine output rpm is around 2200 at max, and that give me a top speed of around 20km/h.
range is not something i'm conserned about, since at most i use it for about an hour at a time. usually to plow snow in the winter.
does this sound like a project that is worth starting, or is it doomed from the start?
i'm an electrician, so electricity is not a problem. neither is some electronics working.

Greetings from Howie (Håvard)

 

[brian_]

If by "axle" you mean "shaft" (a common translation issue), then I think I understand the plan. The issue that I see with it is that this system would require the motor to run fast enough to run the hydraulic pump all of the time, while the torque converter wastes much of the power from the motor to drive the wheels. It will work, but it won't be efficient. Ideally one motor would run the hydraulic pump and a separate motor would run drive the wheels... without a torque converter.

 

[Howie]

If by "axle" you mean "shaft" (a common translation issue), then I think I understand the plan. The issue that I see with it is that this system would require the motor to run fast enough to run the hydraulic pump all of the time, while the torque converter wastes much of the power from the motor to drive the wheels. It will work, but it won't be efficient. Ideally one motor would run the hydraulic pump and a separate motor would run drive the wheels... without a torque converter.

yeah... my english is not the best and you was thinking correctly.

the power steering is also driven by the hydraulic pump. so i think i need the pump to be running constantly.

if i were to remove the converter, would i need some gear reduction to lower the speed? or is an EV motor powerful enough at that low speeds? (20km/h / 12 mph)
the machine is weighing around 3000kgs (6600 lbs),

 

[brian_]

Your English is fine, Howie... and infinitely better than my Norwegian!

the power steering is also driven by the hydraulic pump. so i think i need the pump to be running constantly.

Everything hydraulic needs to work all of the time, so yes, with the design of that hydraulic system the motor for the hydraulic pumps needs to run continuously. That's why it would need its own motor, if the torque converter is not used.

if i were to remove the converter, would i need some gear reduction to lower the speed? or is an EV motor powerful enough at that low speeds? (20km/h / 12 mph)
the machine is weighing around 3000kgs (6600 lbs),

There already is gear reduction between the torque converter and the wheels, although it may not be enough for a motor that you would want to use.

If the tires are about 3 metres in circumference (the size isn't given in the description that I found) then at 20 km/h the axles are only turning about 110 revolutions per minute, but the engine is turning about 2200 RPM, so between the torque converter and the gearbox and the gears in the axles there is about a 20:1 reduction ratio. At top speed, most of that is in the gears, not the torque converter.

The engine is rated to put out 37 kW at 2200 RPM. That combination corresponds to 160 Nm, and common EV motors can produce that at any speed from zero to about one-third of the way up to their top speed (e.g. the 80 kW Leaf motor produces about 280 Nm at any speed up to about 2800 RPM, and can produce the full 80 kW up to 10,000 RPM). The torque converter increases the torque (and reduces the speed), so the more slowly you drive the more torque is available to the wheels; the 280 Nm of a Leaf motor multiplied by the 20:1 or so of the gearing would be enough even when starting off from stationary, without any additional multiplication by a torque converter.

The idea of locking the differential in an drive unit salvaged from an EV might work: it would give you a lot of gear reduction (e.g. about 7:1 in a Nissan Leaf), but too much. It won't have to quite match the engine speed (because the torque converter always reduces the speed by at least 10%), but for the outputs (which normally go the the car's wheels) to turn 2,000 RPM would correspond to about 250 km/h with typical car tires... far faster than the car goes, because the corresponding motor speed is way too high. Does the loader have a two-speed gearbox, for "hi/low gears"? The speed might be okay if you run it in high gear at anything but extremely low speed.

You would need to check the calculations and make your own decision, but I think that it's likely that a reasonably large salvaged EV motor (such as the one in a Leaf) would be suitable as a direct replacement for the engine and torque converter, as long as your battery can provide enough power for the motor to operate as designed.

Whatever your design, I don't think that you need to worry about weight - that Changchai 4L68 engine weighs 260 kg by itself, and you need substantial weight on the back of the machine to counterbalance what you pick up in the bucket.

 

[Howie]

first off: thanks for great feedback. you have given me some good ponts to consider.

Does the loader have a two-speed gearbox, for "hi/low gears"? The speed might be okay if you run it in high gear at anything but extremely low speed.

correct. there is a dual gear where the low gear is the most used. the turn joint does have some wobble to it due to worn bushings. it's terrible to run at high speeds.

i think i have to research a bit more on the loader itself, to see how things would fit if i were to remove the gearbox. i do think the brakes are interconnected with the converter, but not sure in what way.

 

[brian_]

correct. there is a dual gear where the low gear is the most used. the turn joint does have some wobble to it due to worn bushings. it's terrible to run at high speeds.

i think i have to research a bit more on the loader itself, to see how things would fit if i were to remove the gearbox.

I was thinking of removing the torque converter but keeping the gearbox. There is the possibility of using a transmission salvaged with the motor from an EV, and removing the loader's original gearbox - that would probably work out for overall gearing if it can be arranged.

i do think the brakes are interconnected with the converter, but not sure in what way.

That would be interesting - let us know what you find.

 

[Howie]

I was thinking of removing the torque converter but keeping the gearbox.

that is one unit with the function of both it seems. I climbed under today to see how things would be in terms of usable space, and as far i could see, there is a shaft from the diesel engine, going to a square box, that i assume is both the gearbox, and the torque converter. from there, it is two shafts going out to front and rear axle/differential
i see that there is 2 hydraulic hoses going from the gearbox/converter assembly to the diesel engine, so i have to investigate what function that is. can't find it on any picture of the engine on google.

luckily for me, the frame and the gearbox is separate, so i won't have to dismantle the whole machine fo remove the gearbox.

if i remembered the dimensions of the leaf motor assembly correctly, i think i can fit that under the cabin where the gearbox is now, which would give me space in the engine compartment for batteries.

That would be interesting - let us know what you find.

of what i could see, the brakes are only connected to the gearbox mechanically, presumably to disengage the converter when the brake pedal is depressed

the next thing i need to investigate is how i will solve the need for hydraulics. i think that another ev-motor would be totally overkill.
i do think that a normal VFD (variable frequency drive) would be capable of running DC voltage, then i could possibly just use an off the shelf small AC motor to drive the hydraulic pump. some calculations may be needed to figure out how big of an motor i need

 

[brian_]

that is one unit with the function of both it seems. I climbed under today to see how things would be in terms of usable space, and as far i could see, there is a shaft from the diesel engine, going to a square box, that i assume is both the gearbox, and the torque converter. from there, it is two shafts going out to front and rear axle/differential
...

luckily for me, the frame and the gearbox is separate, so i won't have to dismantle the whole machine fo remove the gearbox.

if i remembered the dimensions of the leaf motor assembly correctly, i think i can fit that under the cabin where the gearbox is now, which would give me space in the engine compartment for batteries.

So the gearbox is a torque converter housing, reduction gearbox, and drop box (gearbox to transfer the drive down to the shafts which go the axles) all in one. Without the torque converter that's effectively the same thing as the transfer case in a traditional 4WD truck; you may be able to use a transfer case if you can find one which works in the desired orientation (outputs below input), if you don't use a Leaf transaxle.

the next thing i need to investigate is how i will solve the need for hydraulics. i think that another ev-motor would be totally overkill.
i do think that a normal VFD (variable frequency drive) would be capable of running DC voltage, then i could possibly just use an off the shelf small AC motor to drive the hydraulic pump. some calculations may be needed to figure out how big of an motor i need

I agree - an EV drive motor is far more than needed; something out of a forklift might work. Electric forklifts have a pump motor for exactly this purpose, but you would need more hydraulic power to run the loader than a typical electric forklift would have. A typical VFD can apparently be used with a DC supply, perhaps by bypassing the rectifier on the input.

If you can find specifications for the hydraulic pressure and flow rate that tells you the peak power required.