Why not diesel electric trucks?

[schlep1967]

If a single diesel electric locomotive can pull 27,000,000 pounds, why has it not been scaled down to pull 20-40,000 pounds yet?

[whjco]

Quote Yes, I can imagine the drive train...look the last steam engines ever built. They were wildly complicated systems of gears, axles and shafts...and even there not all the wheels were powered. Steam engines do have the advantage that they can put out peak torque from zero RPM similar to electric motors.

I believe hydraulic has been used on some smaller railyard engines but it's not as efficient.

There is no "regen" with diesel locomotives. The available power is what the engine is putting out right now. If the engine puts out more power than the electric motors take up, it's wasted but since trains spend 95%+ of their time running at a steady speed, it's not a big deal. End Quote

Actually, the only steam locomotives that used gears to drive them were low-speed high adhesion locomotives like Shay or Heisler engines that were typically used in logging operations in the early 20th Century. Mainline engines use conventional steam chests, pistons, crossheads, connecting rods and side rods to power the locomotive. As for starting torque, a diesel-electric is much better at starting a train as compared to a steam locomotive. A steam locomotive has to have some movement before it can get a full charge of steam in the pistons. If you're fortunate enough to have an engine with a power reverse, you can charge the pistons to help get things going, but the mechanical reversing bar won't generally let the engineer do this.

As for electrical control in a diesel-electric locomotive, in the older DC powered locomotives the field windings for the traction generator and the traction motors are in series. A locomotive starts with the main power leads to the motors in series. As it picks up speed, the control circuit will momentarily drop load while the relays switch the motors to a series/parallel configuration. As the locomotive picks up more, the control circuit will again momentarily drop load and the relays will shift the motors into full parallel configuration. The load to the motors is controlled by a governor which will automatically reduce power output to the motors and with the traction motors and traction generator fields in series, there's never any excess power generation unless a control malfunction occurs. On locomotives equipped with dynamic braking, the traction motors become the generators and are loaded with a large resistor bank so that EMF is used for braking instead of mechanical brake shoes.

[8_1_Van]

Many countries and cities around the world have stated they will ban the sale of passenger vehicles (primarily cars and buses) powered by fossil fuels such as petrol, liquefied petroleum gas and diesel at some time in the future.

Phase-out of fossil fuel vehicles

[Joppy]

I'am retired from the mining industry and we had diesel electric haul trucks. The diesel powered a large generator that was mounted where the transmission would be. From there the power went to wheel motors, one for each rear wheel.

[rjstractor]

BenK wrote:
To answer the OP’s question directly…

Sure thing. Pretty easy to boot, but the solution will take much space

Take a Model 3 and say it’s battery/motor is a 50KW system

So just take a gas or diesel 50KW generator of the correct voltage and the fuel tank system to keep it going.

All the parts are readily available at most any hardware store…except for the DOT fuel tank. Junk yard would be the best source, or if money no problem…order a brand new one from any OEM

Then find the space to mount all that & the cabling/controls to manage it all

Maybe toss the battery’s to boot, but they would be needed for regenerative braking…or toss the batteries and use resisters to absorb the regenerative braking power & reject it as heat.

Hey !…maybe we’ve just solved Tusk’s Semi problem !!! :B

schlep1967 wrote:
If a single diesel electric locomotive can pull 27,000,000 pounds, why has it not been scaled down to pull 20-40,000 pounds yet?

Sure, do all that and you'll have a truck with the acceleration and gradeability of a diesel locomotive. 😉 50 KW is only 68 horsepower. That's why you would need that big battery.

[rlw999]

free radical wrote:

schlep1967 wrote:
If a single diesel electric locomotive can pull 27,000,000 pounds, why has it not been scaled down to pull 20-40,000 pounds yet?

Via motors have done that long time ago
100 mpg electric hybrid truck

https://youtu.be/4XHbQLfgI6g

Why dont GM do it?
Because they are controled by Oil companies that would lose lots o $$ if all trucks got 100 mpg ! :B

That's a plug-in hybrid, you can claim any gas mileage you want if you decide that the battery range is "free". The Prius Eco is rated at 58mpg, I don't think any full size truck is going to beat that if you don't count the all-electric range.

[free_radical]

schlep1967 wrote:
If a single diesel electric locomotive can pull 27,000,000 pounds, why has it not been scaled down to pull 20-40,000 pounds yet?

Via motors have done that long time ago
100 mpg electric hybrid truck

https://youtu.be/4XHbQLfgI6g

Why dont GM do it?
Because they are controled by Oil companies that would lose lots o $$ if all trucks got 100 mpg ! :B

[LanceRKeys]

As soon as they made one, everyone here would complain about lack of payload.

[stsmark]

or toss the batteries and use resisters to absorb the regenerative braking power & reject it as heat.
This is exactly what locomotives do, besides the wheel brakes on the cars.

[ktmrfs]

jdc1 wrote:
You wouldn't need the generator system to charge the battery 100% of the time. Both the Clarity and Volt are plug-ins. You wouldn't need a 70kW battery pack either. Half of that would suffice.
https://www.nationalpump.com.au/calculators/guide-to-choosing-generator-to-motor-size/

I don't have a clue what size generator would be required to run an electric motor equivalent to say a 454 ICE engine. But, I'm thinking a smallish diesel generator to charge a 30-40KW battery pack that propels the electric motors. Would we see a huge increase in fuel economy? Would the total drivetrain outlast those of ICE vehicles? Or, would the whole thing be too much to ask for?

unless it is set up as a hybrid with the engine cycling on and off like conventional hybrids, fuel efficiency would be worse than just ICE drive. You don't get something for nothing, running any ICE engine constantly to turn a generator to run electric motors is overall going to be less fuel efficient than ICE and transmission along. Diesel electric trains/boats etc. sacrifice max fuel economy for the ability to better control and start the train etc. not for max fuel efficiency.

And even in the senerio above, in town fuel economy could improve significantly with regenerative braking, without that to recovery kenetic energy fuel economy would suffer.

[jdc1]

You wouldn't need the generator system to charge the battery 100% of the time. Both the Clarity and Volt are plug-ins. You wouldn't need a 70kW battery pack either. Half of that would suffice.
https://www.nationalpump.com.au/calculators/guide-to-choosing-generator-to-motor-size/

I don't have a clue what size generator would be required to run an electric motor equivalent to say a 454 ICE engine. But, I'm thinking a smallish diesel generator to charge a 30-40KW battery pack that propels the electric motors. Would we see a huge increase in fuel economy? Would the total drivetrain outlast those of ICE vehicles? Or, would the whole thing be too much to ask for?

[valhalla360]

jdc1 wrote:
I think the OP was thinking along the lines of a Chevy Volt or Honda Clarity. Use the EV drivetrain, and a diesel engine as a generator. Makes PERFECT sense to me.

Chevy Volt is a completely different animal and designed to serve a different purpose, even if some of the parts superficially are similar.

It uses batteries most of the time for daily commutes while being charged at night. Only on longer trips does the ICE kick in to supply power allowing for effectively unlimited range. Effectively for most people 80-95% of miles it's a battery electric vehicle and it suffers less than ideal efficiency when the motor does kick in but for most that's a good trade off.

A diesel-electric locomotive doesn't use a battery bank for propulsion. If it's moving the ICE is providing the power, just transmitted via electrons.

PS: I believe Ford has a Plug-In-Hybrid F-150 which is similar in purpose to the Volt.

[BenK]

To answer the OP’s question directly…

Sure thing. Pretty easy to boot, but the solution will take much space

Take a Model 3 and say it’s battery/motor is a 50KW system

So just take a gas or diesel 50KW generator of the correct voltage and the fuel tank system to keep it going.

All the parts are readily available at most any hardware store…except for the DOT fuel tank. Junk yard would be the best source, or if money no problem…order a brand new one from any OEM

Then find the space to mount all that & the cabling/controls to manage it all

Maybe toss the battery’s to boot, but they would be needed for regenerative braking…or toss the batteries and use resisters to absorb the regenerative braking power & reject it as heat.

Hey !…maybe we’ve just solved Tusk’s Semi problem !!! :B

schlep1967 wrote:
If a single diesel electric locomotive can pull 27,000,000 pounds, why has it not been scaled down to pull 20-40,000 pounds yet?

[jdc1]

I think the OP was thinking along the lines of a Chevy Volt or Honda Clarity. Use the EV drivetrain, and a diesel engine as a generator. Makes PERFECT sense to me.

[valhalla360]

JRscooby wrote:
I always thought the idea was traction. Steel on steel is pretty slick. Can you imagine what driveshafts would look like if used them to drive all the wheels?
Years back, sitting around a campfire, burning some illegal substances we discussed driving a pump with engine, to power hydraulic motor on each wheel. Would not have the regen of electric, but hydraulic motor lighted than electric, pump lighter than generator. And with valving, the engine could run idle, or most efficient RPM. As speed increase some motors freewheel

Yes, I can imagine the drive train...look the last steam engines ever built. They were wildly complicated systems of gears, axles and shafts...and even there not all the wheels were powered. Steam engines do have the advantage that they can put out peak torque from zero RPM similar to electric motors.

I believe hydraulic has been used on some smaller railyard engines but it's not as efficient.

There is no "regen" with diesel locomotives. The available power is what the engine is putting out right now. If the engine puts out more power than the electric motors take up, it's wasted but since trains spend 95%+ of their time running at a steady speed, it's not a big deal.