Diesel/Electric Tractors

[brain55]

I know in large ship applications they are using super-conductor motors and generators which can be a third of the size and weight of conventional copper wound, not to mention their 99% efficiency. With various rare-earth conductors super-conduction can be acheived with industrial refrigerants no need for liguid nitrogen or oxygen anymore. One just has to weigh the cost versus weight and efficiency.

Brian

 

[nspec]

I'm not even going that far. Awesome technology, but I'm just talking run of the mill setups on supply boats, tugs, ferries, etc... It may cost more, but on a dozer, think of all that you eliminate - no torque converter, no reduction gears, no steering clutches, etc.... Plus, you eliminate probably 30-50 gallons of hydraulic and gear oil on the dozer.

Once battery technology improves, you'll also be able to store excess energy that you create as well. I know one of the companies was playing around with a diesel electric excavator. They had a generator that produced energy every time the thing would swing and then send it to the storage bank to be used in the next cycle. Really neat stuff.

 

[Birdhunter1]

Allis Chalmers in the 1950's had a hydrogen fuel cell tractor that would pull a 2 bottom plow, there used to be a video of it on youtube but it is gone now. My guess is the oil companies and government saw it and pulled it so we don't start some sort of trend to a greener tractor, but I am kinda a conspiracy nut anyway (actually the guy that had the video's is no longer a youtube user, maybe he was bought off I don't know). Go to youtube and search 'Allis Chalmers Electric Tractor' and there are several videos where guys have taken G model AC's and converted them to battery powered electric drive.

 

[SPYDERLK]

What? Neither the generator nor the electric motors is 100% efficient, so there is clearly loss of power being transferred from the engine to the wheels. It's hard to find any numbers, but in one IEEE paper I found the highest generator and motor efficiencies shown are about 90% each, or 81% for a pair. Some systems were substantially less.

The question is whether electrical transmission loss is more or less loss than with mechanical or hydraulic systems. On that I have no clue.

Terry

Youre right. At the simplistic level at which claims are promugated it is perfectly valid to attribute no advantage ... essentially 1:1. As brought out later youll see that there is MUCH more relatively straightforward optimization that can be done with electrical drive and electronics so that even 1:1 at a specific task will win out overall. ... And you can push above 90% with well designed electrical main components. -- And to near 100% with superconducting as mentioned. But there goes simplism again. What about the cost of keeping it cold? And what about the mechanical parts? All considered, as things advance to the limits of Physics we may reach 95% in a mobile system.
larry

 

[CobyRupert]

Hint: Look at the speed torque curve of a DC or variable speed AC motor versus trying to get that through a burning clutch or a hydro pump. Hydro is probably pretty good, but a still a lot more wear and heat.

 

[Sysop]

Trains on average haul more weight than any construction equipment or tractors and they have used diesel electric generation to power their locomotives for years. It is the most efficient use of the fuel once you get above a certain amount of weight.

 

[houstonscott]

It's the lack of rolling resistance that make trains efficient, not the diesel electric configuration. That configuration eliminates a transmission and its weight too.

HS

 

[Sysop]

It's the lack of rolling resistance that make trains efficient, not the diesel electric configuration. That configuration eliminates a transmission and its weight too.

HS

They had diesel gear and hydraulic drive between the current generation diesel electric and the older steam engines of which there were even diesel variants). They opted for the diesel electric because it was most efficient of all other forms of power transmission from the engine to the ground, rolling resistance wasn't a factor in in the progress of locomotive locomotion since all used the same tracks. I guess you could say newer tracks have less rolling resistance due to better manufacturing and installation processes, but I don't think that would have enough influence on the situation to matter. All the stuff that makes up the generators and drive motors actually outweighs what a geared transmission would. Freight train engines are heavier now than ever before.

 

[GManBart]

Trains on average haul more weight than any construction equipment or tractors and they have used diesel electric generation to power their locomotives for years. It is the most efficient use of the fuel once you get above a certain amount of weight.

Absolutely....because you can adjust the engine/generator parameters to maximize fuel efficiency (and electrical generating efficiency), and leave them there, rather than change in response to speed, elevation, and load changes. Maximize those two things, then store essentially all of the power you generate, rather than blow a lot of it out the exhaust stack.

 

[Sysop]

I think eventually we may see similar systems on smaller tractors, but it is still many years off.