ArvinMeritor, Wal-Mart to make diesel-electric drivetrain

Yah yah yah.

Now if they could get Cat and GE together, we might have something.

Besides the benefits you've listed, you would also save on the energy wasted as heat in gearboxes and differentials, which adds up at higher HP applications. You'd also have fewer lubes to change on the vehicle, which on Class-8 trucks amounts to some hefty amounts. 5 gallons for the engine oil is typical. A couple gallons in the transmission. A gallon (or more) for each differential/axle.

FWIW, I think that having some of the braking energy captured in compressed air would be better for fast restarts of a diesel engine than a hydraulic accumulator. Hydraulics suffer from those temperature problems -- eg, thin in the summer, thick in the winter. You should see what a bear it is to start a farm tractor here in Nevada in the winter when the temp is about 0F. Block heaters certainly help the engine, but a heater for the hydraulic fluid tank (or rear axle) can really change how fast you're able to spin an engine over. Hence my vote for air over fluid.

Diesel-electric loco's handle this by putting the energy from regen braking into huge resistor banks cooled with fans. The same could be done on trucks once the energy capture systems are full.

A substantial engine is still required to generate the power, but yeah, you'd eliminate some fluid maintenance. Not eliminate it, though. Also, if there were individual electric drive motors, the'd require substantial periodic maintenance.

An air start system or electric storage is probably more practical, but not for temperature reasons you state.

Electric motors can be made to require very little maint. I've got 4 irrigation motors over 100 HP (the largest being 200 HP) and the most I have to do is change the bearing lube once per year (each year is over 2,000 hours of run-time on these motors) and I'm done. These things sit out there on wellheads year round in the weather and they survive just fine. Each bearing takes about 5 gallons of turbine oil. I'm sure that the maint on drive motors can be reduced even further with better bearings; eg, using the best tapered roller bearings and good synthetic grease and I'd wager the maint intervals could stretch even further.

BTW2 on the hydraulic system: the other reason I'd avoid hydraulics is that when you have a high pressure hydraulic system, you have leaks. I've never, ever seen a piece of equipment come on this farm that didn't develop a hydraulic leak sooner or later, even with all the proper maint and fluids. They're a messy pain in the chops, but it is a given in farm equipment that hydraulics are necessary, so one has to tolerate the leaks even after fixing them.

The upshot is that for a truck, the diesel->electric idea has a lot of merit. No more transmission issues, the trucks would become safer in marginal road conditions with computerized tractive control, the safety of the truck increases due to regenerative braking, which could be used in town/cities, where they often currently outlaw jakes, and I haven't thought about it too hard, but I'd wager that with really aggressive engineering, the weight of the tractor could be reduced too.

The mileage would go up too if the regenerative braking energy capture could be used to get the truck+cargo off the stop line. This is where the hybrids get most of their fuel savings, so it follows that trucks based on the same idea would see similar savings.

Trains on roads (18 wheel lengths). Proven concept. Works. Efficient. Safe.

Diesel-electric is a fine way to go.

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Discs on trucks are actually more dependable than drums, think of it this way as drum brakes get hot the drum expands causing the shoes to have to travel farther to make contact(fade) allowing more air into the gap creating a climate for faster heating. With Discs the rotor heats up swells up actually making for better braking as the discs are applied. If I remember correctly the fade rate on drum brakes is exponential from a 4 percent loss from the first application. Bendix is in a whole different class of equipment than Meritor.

The upshot is that for a truck, the diesel->electric idea has a lot of merit. No more transmission issues, the trucks would become safer in marginal road conditions with computerized tractive control, the safety of the truck increases due to regenerative braking, which could be used in town/cities, where they often currently outlaw jakes, and I haven't thought about it too hard, but I'd wager that with really aggressive engineering, the weight of the tractor could be reduced too.

It seems that the engine could be engineered differently as well. If all it's doing is driving a generator, the engine can be optimized for a very narrow RPM range. A mechanical transmission likes a broader power-band, but with electric, it can be a nice, steep spike. That should help with fuel efficiency, size and weight, I would think.

The cost of adding on 10 of these beauties to your rig is how much?

where's my flying car?

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