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Drive systems for tractors.


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AS most of you know they have been running Diesel Electric drive trains sense the late 1920's. Most mine haul trucks except Cat have been diesel electric drive sense sometime in the 1960's. Cat couldn't get it right and finally enters that market with a gear drive in the 90's. But Cat started selling the D7E  diesel electric drive dozer in 09. Now they have the D6XE out. Are we going to see diesel electric drive farm tractors sometime in the near future? Infinite speed control without a transmission that can be difficult and very expensive to repair? 

For those not aware, diesel electric drive the engine runs a generator/alternator which in turns runs electric drive motors eliminating a transmission.

Rick

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The obvious answer is yes.  The not so obvious part is when.  There are supposed to be a lot of benefits to the diesel over electric drive.  Agriculture normally lags behind on technology like this.  I dont know if it is lack of $ in R&D with a up and down farm economy or they arent sure farmers will adopt the new technology.  Either way, this technology is being adapted to every other heavy off road use so it only makes sense it will find its way to agriculture sooner or later.

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It has been talked about for at least a decade now. I think it would eliminate much of the parasitic loss of a powershift or cvt transmission while giving all the benefits of full range full power transfer. At the same time if they could replace hydraulics with electric actuators they could lessen the power drag associated with pumping fluid, as well as the challenge of cooling the fluid. I personally think the first uses should be self contained units like combines, choppers and skid steer loaders.

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OK I haven't seen anything about this type of drive system in a tractor. 

Can't see why it would be more expensive? Transmissions are difficult and expensive to make. Lot of machining and on PS models . Looks like the D7R and D7E are about the same price.

Rick

 

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2 hours ago, billonthefarm said:

The obvious answer is yes.  The not so obvious part is when.  There are supposed to be a lot of benefits to the diesel over electric drive.  Agriculture normally lags behind on technology like this.  I dont know if it is lack of $ in R&D with a up and down farm economy or they arent sure farmers will adopt the new technology.  Either way, this technology is being adapted to every other heavy off road use so it only makes sense it will find its way to agriculture sooner or later.

Remember when rubber tires were said to poison the ground back in the thirties.

Dennis

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I believe Mason Dixon Farms was using electric to power a merger at one time that they made front mount on a reverse station tractor

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A lot of the locomotives also use gen sets, so you have two or three engines to supply only as much power as needed. Dodge was working on diesel electric pickups before Fiat bought them and shelved the whole program unfortunately. I personally think it's a great idea if they keep it simple and avoid needless complex control systems like a lot of the EVs have to deal with charging, braking and other issues. Could even move to linear servos and replace hydraulics.

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3 hours ago, billonthefarm said:

The obvious answer is yes.  The not so obvious part is when.  There are supposed to be a lot of benefits to the diesel over electric drive.  Agriculture normally lags behind on technology like this.  I dont know if it is lack of $ in R&D with a up and down farm economy or they arent sure farmers will adopt the new technology.  Either way, this technology is being adapted to every other heavy off road use so it only makes sense it will find its way to agriculture sooner or later.

I think the biggest issue is the cost. They can make anything they want, but they then need people to buy them. A 400,000 dollar machine better last a LONG while. Heck for me, a 50,000 dollar machine better last the rest of my life. Unfortunately most of the push has been for a pure electric vehicle which I think is a horrid idea considering the overloaded power grid as it is. Gas/electric or Diesel/electric is the way to go for the future I believe.

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I predict the total electric package will be integrated from lighting to GPS and drive train to make it cheaper for the mfg and as it gets old impossible to repair with out spectacular knowledge and repair aparatus. This crap will not come with a handcrank!

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4 hours ago, Stuffcollector said:

Around a pair of new Deere Hybrid loaders, 20 gal in 24 hr fuel savings over a Cat 982....And the guys like them better.

I saw the prototype of those hybrid loaders 5-6 years ago.  B-I-G loaders compared to everything else Deere makes.   Almost a gallon an hour fuel savings is good,  but how many gallons an hour does it burn?

A loader is actually not the best machine for fuel savings for a hybrid,  the constant changing of directions is convenient but tends to be at a higher rate to speed cycle times.  A constant variable speed machine, like combine, chopper, windrower would be ideal.

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5 minutes ago, DOCTOR EVIL said:

I saw the prototype of those hybrid loaders 5-6 years ago.  B-I-G loaders compared to everything else Deere makes.   Almost a gallon an hour fuel savings is good,  but how many gallons an hour does it burn?

A loader is actually not the best machine for fuel savings for a hybrid,  the constant changing of directions is convenient but tends to be at a higher rate to speed cycle times.  A constant variable speed machine, like combine, chopper, windrower would be ideal.

10 gal hr...I think right at an 8 yd bucket, pretty good for that size machine moving almost non-stop.

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As the manufacturers run into the efficiency wall with engines, they are turning to the powertrain for performance gains. And it's a whole new world. 

The new Cat XE loaders, whether electric or CVT drive are showing 20%+ fuel efficiency gains over their powershift brethren. The hybrid 336 excavator that stores and reuses swing energy, same thing. 

Existing technologies such as the electric drive have been vastly improved. Cat always pointed to the drawbacks and limitations of the electric haul trucks and stuck with mechanical drive. Those limitations have been addressed. Between customer expectations and emissions laws, they will only get better. 

I expect we are just seeing the tip of the iceberg in the things to come. Power transmission has been largely ignored in the mobile equipment market, but not anymore.

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4 hours ago, rcb said:

A lot of the locomotives also use gen sets, so you have two or three engines to supply only as much power as needed. Dodge was working on diesel electric pickups before Fiat bought them and shelved the whole program unfortunately. I personally think it's a great idea if they keep it simple and avoid needless complex control systems like a lot of the EVs have to deal with charging, braking and other issues. Could even move to linear servos and replace hydraulics.

 

Most of the genset locos IIRC are rebuilds using the existing frame and maybe the cab with everything else being new. Most use 3 engine generators and only run as you said what they need. Last I read the 5.9 diesel was the engine if choice. Mostly being used for short runs and as yard switchers.

That pickup? Was it going to be a straight diesel electric drive or a hybrid?

4 hours ago, oleman said:

I predict the total electric package will be integrated from lighting to GPS and drive train to make it cheaper for the mfg and as it gets old impossible to repair with out spectacular knowledge and repair aparatus. This crap will not come with a handcrank!

Hate to tell you this but the hand crank hasn't come with a tractor for some time. Change comes to everything eventually.

2 hours ago, Cattech said:

As the manufacturers run into the efficiency wall with engines, they are turning to the powertrain for performance gains. And it's a whole new world. 

The new Cat XE loaders, whether electric or CVT drive are showing 20%+ fuel efficiency gains over their powershift brethren. The hybrid 336 excavator that stores and reuses swing energy, same thing. 

Existing technologies such as the electric drive have been vastly improved. Cat always pointed to the drawbacks and limitations of the electric haul trucks and stuck with mechanical drive. Those limitations have been addressed. Between customer expectations and emissions laws, they will only get better. 

I expect we are just seeing the tip of the iceberg in the things to come. Power transmission has been largely ignored in the mobile equipment market, but not anymore.

I agree, it's coming.

Rick

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10 hours ago, oldtanker said:

AS most of you know they have been running Diesel Electric drive trains sense the late 1920's. Most mine haul trucks except Cat have been diesel electric drive sense sometime in the 1960's. Cat couldn't get it right and finally enters that market with a gear drive in the 90's. But Cat started selling the D7E  diesel electric drive dozer in 09. Now they have the D6XE out. Are we going to see diesel electric drive farm tractors sometime in the near future? Infinite speed control without a transmission that can be difficult and very expensive to repair? 

For those not aware, diesel electric drive the engine runs a generator/alternator which in turns runs electric drive motors eliminating a transmission.

Rick

This is the direction Tesla should be going with their experimental truck

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31 minutes ago, Gearclash said:

I wonder if precise ground speed control is an issue with diesel electric drive?  Even hydros have that problem. Slow down going uphill, speed up going down hill. 

I wouldn't think with today's computerized controls that it would be a problem but who knows?

 

Rick

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51 minutes ago, Gearclash said:

I wonder if precise ground speed control is an issue with diesel electric drive?  Even hydros have that problem. Slow down going uphill, speed up going down hill. 

Not these days. Output speed is monitored and input power is matched to what is necessary for the load applied.

It's an odd feeling running that D7E, you will be driving along at one speed and the engine speed will go up and down matching the HP output to what is needed to maintain speed. Drive the blade into a pile and the tracks will continue at set speed but engine will climb.

Same with a Challenger tractor that has the CVT, roading the tractor at 35 MPH, the engine will drop down to 12-1300 RPM while maintaining speed. MPH drops a bit and the engine will start to pick up and trans shifts down as needed.

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After posting it did occur to me that electronic controls would take care of the speed consistency.  Anybody know how the energy loss compares in a mechanical drive system vs electric?  I have always wondered.  A true hydro is pretty bad for losses, as is a torque converter.  The big selling point of IVT tech was presumably to have the infinite speed variation of a hydro without so much loss. 

For what its worth the Volvo wheel loaders have an electronic speed limiter on them also.  Hit 30 mph and the engine starts to slow down on its own.  

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36 minutes ago, Gearclash said:

After posting it did occur to me that electronic controls would take care of the speed consistency.  Anybody know how the energy loss compares in a mechanical drive system vs electric?  I have always wondered.  A true hydro is pretty bad for losses, as is a torque converter.  The big selling point of IVT tech was presumably to have the infinite speed variation of a hydro without so much loss. 

For what its worth the Volvo wheel loaders have an electronic speed limiter on them also.  Hit 30 mph and the engine starts to slow down on its own.  

I'm not sure what the total efficiency of the system would be, but the generator and motor would each probably be less than 80% and there will still likely be losses in reduction gearing. It would be interesting to compare the different types of drive systems. I'm sure that it will be better than hydros but maybe not as good as gear drive? 

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The step up in efficiency is shown in the fuel savings, in the Cat 988 size machine you can buy either mechanical or now electric drive. The electric drive is supposed to feel more powerful,(I haven't run one yet) and is reportedly saving 20% in fuel running side by side with the mechanical drive.

In a machine that will burn 250+ gallon of fuel in a day, that is pretty big $$.

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In the mining industry, electric drives are used to power the large draglines and face shovels, feeding off the main power grid. In the past, I was involved in the maintenance of these big beasts where everything was on the massive scale. On the BE 1370 walking dragline, fitted with 300' boom, 100 ton capacity bucket and weighing about 2500 tons, they were fitted with 4 500hp motors to make them walk, 4 to hoist and another 4 to drag the bucket in. To swing the machine, another four 500hp motors were used. All these functions used very high reduction gearboxes to create massive torque. For example, the rotational speed from the propel boxes would have been about 1 revolution per minute. By using electric drive systems, transmitting power is easier through cables than heavy mechanical drive systems. I had a look over an oil drilling rig once which was operating in extremely remote and tropical jungle conditions and to drive the drilling head, eight 500hp engines were set up side by side and connected through drive boxes to one very long driveshaft with many universal joints. The main reasons for the mechanical drive would have been because of the hot wet conditions and also, the complete rig had to be dismantled down into small sections so that it could be transported by helicopter between drilling sites (300 loads just for the rig itself) Below are a few of my photos of a dragline and face shovel along with a Komatsu  model 930 300 ton truck with one of it's wheel motors / final drive removed for replacement. The tyre fitter checking wheel nuts gives a good indication of scale. Incidentally, 3 full shovel buckets of material would fill this Komatsu truck.

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17 hours ago, Stuffcollector said:

10 gal hr...I think right at an 8 yd bucket, pretty good for that size machine moving almost non-stop.

WOW, I expected much higher Gallons per hour than that.  The percentage of off throttle time is really reflected in fuel usage.

I know back when I was loading trucks most of the day at work your driving style made a huge difference in fuel use.

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Cattech, is there much info yet as to the difference in the hours or cost of scheduled rebuilds of those larger articulated wheel loaders?

My thoughts are that hybrid applications will first appear in high-hour applications where current fuel consumption is a bigger factor.  Those applications tend to pay very close attention to operating costs.  Case in point, the custom manure haulers is where the first CVT transmissions began to be sold to customers in Fendt & AGCO tractors.  Higher transport speeds and brakes helped.  Tighter emissions laws provided the added efficiency boost for the European diesels using DEF soon after that.  It had been said that some of those Fendts were saving over $100 in fuel per day over the Deere's they replaced.

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