I finally found the video, worked on one computer and not the other so i hope everyone can see it alright. Let me know what you think about this if you haven't seen it yet. http://www.constructionequipment.co...cclamp&articleid=CA6492062&videoID=1445587557
I think it looks smaller than the current D7's...is this technology going to be put into the other dozers eventually?
I dont know for sure, but safe to assume that this will be in all machines, or most of machines soon after all the bugs are worked out of this one. It does look smaller, but you dont need a torque convertor, trans, no more elevated sprocket, all this makes it look a lot smaller than the R series. I think what they are doing here is preparing for the next emissions due date. If you have an engine that runs a constant RPM all day long, you dont get the particulates in the exhaust with no acelaration. The generator on the engine and other electronic devices would monitor the amps going to the motors giving different speeds and torque abilities while the engine just purs prob around 1800 RPM's.
Ok, Here we go again, this dozer has been talked about and talked about on here, here's some links for you. CAT D7E Electric Drive Dozer Electric Drive Tractors!!!
there has been rumor that bobcat is working on a electric drive loader also i know its a skid steer but still electric drive just thought youd like to hear the rumor
I am a railroad engineer and electric drive motors have been used on locomotives for decades now. They eliminate all clutch problems and pull incredable loads. Two 3500 HP locomotives pull 12,000 tons of coal through the hills of Kentucky and East Tennessee.Biggest drawback I see is a time lag between throttle and machine response. Also you probably wouldn't want to use the electric motors around water as we can only operate in 3 inches or less.They also develope about 600 volts and a lot of amps which could make them a little dangerous to work on.
eray, so what is the cost to rewind those motors? Here is what electrics mean. Total electronic controls, very expensive to fix, very difficult to fix, designed in break points that will shut the machine down at a predetermined amount of operating time, and require very expensive dealership only overhauls. Many sealed not servicable components, like Ozdozer mentioned years ago. Expensive black boxes that are only replaced and not fixed. This is like the hybrid cars today, and the $4000. battery packs that last only so long. Did you know the CNC machine tool manufacture Mazak has a new system that recognizes if the machine has been moved? And if it sets then you have to call mazak service to enter the secret password to get it going again. I'm sure the new electronic/electric dozers will be the same. So say a state like California does not want that particular machine in the state because it doesn't meet some new standard. As soon as its GPS reports its new position, it will be sent the no start or no move signal. I read a deal years ago how machines had a system that if you forgot a payment the dealer would send a signal to lock the engine from starting. Lets say your on a hot job and they accidently shut it down on a holiday weekend? Or is was some paperwork mix up. One good thing, no more transmission overfill to keep it from slipping out of gear on a steep slope. Will they keep the same efficiency as a transmission? It takes power to convert to electric then back to mechanical again. With the cost of fuel I'd rather see that power on the tracks. So when are they going to use ball screws for the lift cylinders? They need fool proof idiot machines for the up and comming generation of operators. I hope they are installing high power sterio systems, and video games that the operator can play while sitting there as the machine does all the work. And like eray says, dangerous to work on. And they think there is a fire hazzard now. Wait till they have a few of them working around wood chips that light up. For sure the alternators/motors can not be air cooled, as there is alot of things like fir needles, leaves, wood dust etc. that gets in the nooks and cranys. They will be cheaper to make, alot less gears to produce. And how come its just a dozer, where are the electric excavators and wheel loaders etc? How come they always fool with the dozers? And as long as the high drives go by by its a good thing I guess. I hope Komatsu doesn't go electric. It will fizzle, like it did with Letourneau machines.
I would imagine they fool with dozers first because dozers are probably one of the simplest of mechanized earthmoving machines. And as for automatic shut-off after movement to another location, I am betting that that is some sort of theft-deterrent...although I can see why it would be a PITA.
About $30,000 to rebuild a traction motor. Not a big problem on a 2 million dollar locomotive, but I can see how that would be cost prohibitative on a dozer. Also you have to be very careful to immediately shut the throttle off if the machine stalls or the electrical current will "spot" the traction motor. Big problems. However in addition to the clutch you eliminate the need for a transmission. Of course that is cancelled out by the need for a generator. The locomotives have a self diagnostic panel built in which analizes any equipment failures and advises if you can correct it yourself and how to fix it.Of course very few problems on this equipment can be repaired in the field.
Dozer575's un-substantiated rant. Hello, Dozer575. As per usual, you have thrown a lot of words up in the air as being fact and presented not one shred of proof of what you claim. Why not electric drive dozers? They have had FULL electric face shovels, stripping shovels and draglines for 60 or 70 years with no major dramas. Why should it not be possible with much more advanced technology to make a viable electric drive dozer? C'mon, wise guy, give us the REASONS. Why should they have 'designed in break points that will shut down at a predetermined amount of operating time'? What a load of crap? Has it ever occurred to you that there might be a HUGE lawsuit against ANY company that deliberately did anything like that? Not to mention the fact that there are laws against that sort of planned obsolescence. Why should they have GPS location shut-down systems just because one state or another does not want them in that state? Why would any state not want them? Have you been pedalling your anti-Cat propaganda to them in your spare time when you're not being a PITA here? You prattle on about power loss converting from mechanical to electric and back again. What about the power loss through a normal mechanical direct drive/torque converter/powershift tranmission? Why is drawbar HP always less than flywheel HP? Or have you figured out a way to make that not count? Cooling as an issue has been dealt with long ago and there have been totally sealed alternators and AC electric motors for many decades now. Or have you had your head in the sand conveniently ignoring this technology? Quote: "So when are they going to use ball screws for the lift cylinders? They need fool proof idiot machines for the up and comming generation of operators. I hope they are installing high power sterio systems, and video games that the operator can play while sitting there as the machine does all the work." Unquote. Nowhere that I have seen yet is Cat claiming that the operator will only have to sit on the bank under a shady tree or will have to sit in the machine with nothing to do while the machine does all the work. I would love to be able to take my PC/laptop to work and do all sorts of things on it while that nice new self-controlling Cat electric drive dozer did it all on its own and I still get paid for my time. I wish. LOL. Quote: "And as long as the high drives go by by its a good thing I guess." Unquote. Back to your old, tired theme again, Bob? When are you going to admit that the Cat high-sprocket drive dozers have achieved a market penetration way beyond any other manufacturer in history, especially in the higher end of the market, where you have been predicting for as long as I have known of you that they would fail? Get real. Admit that you're flogging your own dead horse and have been wrong all along. I'll bet you're not man enough for that. Bob, may I suggest that you go and get yourself a life somewhere and stop posting your utter rot here and on other forums.
jiihaa! word Deas! :drinkup Dozer575, welcome to the new world, gone are the ccu:s and direct drives... you where wondering where the electric excavators and loaders are, ok, Deas all ready mentioned some of them, but also almost any large mining equipment use electric drive. part of the problem why dozers burn up is the leaking oil mixed with collected dirt, i think the problem will be a little bit smaller with electric drives. electric drive has less rotating parts and friction= more power to the ground. electric parts and motors can also be water cooled like any other engine -> you can transfer the fire dangerous heat to a radiator. the thing you wrote with the lift cylinders was ridicolous or plain stupidity... even if a machine has electric drive it still can have a hydraulic pump or plenty of them. and the gps part of the story??? ***? Dozer575 you shouldn't look at those scifi movies, they are bad for you! did you know that Komatsu with some aliens from Mars are developing a dozer without under carriage! it will hover around on lazer beams!
Go, Sparffo. Hi, Sparffo. I have one thing to say. GO, SPARFFO!!!!!!!!!!!!!!
I'm guessing that Bob works for Komatsu :beatsme Perhaps a night watchman or maybe in the janitorial research and development department
Ya know, I've been around dozers for a long time, and I still have no love nor respect for a D7 size machine. I've run plenty of them, and always found myself wishing for a D8 or a D6 size unit to perform what I was doing. Betwixt and between, that's what I call a D7 size dozer. Too little for bigger jobs. Too big for smaller work. Throwing electric drive into one doesn't help my opinion, nor putting it back into low drive either. Now we wait for real world test comparisons on power, fuel economy, and other metrics.
Betwixt and between. Hi, Surfer-joe. I suspect that is why Cat picked the D7 to be the test bed for diesel-electric power, 'cos it is betwixt and between, neither your elbow nor your armpit. It's less likely to cause their share prices to fall radically if it doesn't set the world on fire. How-wevver, looking at the succes of the electric drive dump trucks, bigger face shovels and draglines and the long history of electric and diesel-electric locomotives, I honestly can't see any reason why it can't be made to succeed. Anybody who knows anything about electric motors knows that they usually produce their greatest torque at or very near stall. What better characteristic could you ask for in something like a dozer - torque output rising as the drive motor slows? D8Bob, did you get that?
Sufer, I agree about the D7 size dozer, kinda a big cat feel with no push. I was very impressed with a D6 the first time I ran one.
Thanks Deas :Banghead You just made me spray Jack N Coke from my nose
No idea again. Hello, Dozer 575. Nobody that I know who has any idea of what they are talking about would claim that a D7 has 'no push'. What I think Surfer-joe was referring to is that the D7 is just not big enough for big jobs and too big for the smaller ones. It falls into a sort of no-man's land which leaves it out of its class in most applications. IMHO, it stll makes a pretty good agricultural contracting machine for all but the heaviest clearing and big dam-sinking/pond building. Back when I was a little tacker, they were a VERY popular agricultural contracting machine, especially for clearing timber when fitted with a tree pusher and timber canopy. They saw the IH TD18's pretty much right out of business around where I grew up so they must have had something going for them.
Shocking waste. Hi, RollOverPete. You need to develop more discipline and self control. You realise, I hope, that that is a shocking waste of Jack. Alcoholics Unanimous would just about ban you for life for that. And such waste in these hard times is almost criminal. You could have given it to some poor soul who has had to give up his share of Jack so that he can afford his crack fix 'cos he's not smart enough to realise that the Jack will do him less harm. LOL.
Deas, you are so right! After reading all the specs on the D7E, I realized that Cat did their homework on this tractor. With the torque characteristics of electric drive, this machine should have some serious grunt. I do believe that if Dozer575 had actually read all the specs on this machine, he would not have made a bunch of gratuitous objections to electric drive. I am looking forward to production and cost specs on the D7E after some real-world use.
Looking forward. Hi, Pushblock. I'm looking forward to it too. I think it was Lashlander who said the he had worked over in Russia with a Russian guy who operated a Russian-built diesel-electric drive dozer that ackshully performed quite well. Now if the Russkies can do it,................. And we KNOW that diesel-electric dump trucks have been doing quite well for years. It's only a matter of gearing to get it down to dozer-type speeds. Electric and diesel-electric locomotives have been doing it forever but that fact apparently didn't sit well with the agenda being pushed by the gentleman in question so he didn't mention them, other than to enquire about the cost of re-building a traction motor. Then there have been the 'kings' of volume earthmoving, the face and stripping shovels and the big draglines, almost all full electric. They apparently didn't fit in with his agenda either so they got the same treatment. I was a little surprised by the respnse from OzDozer over on the ACME board when he rubbished the concept. For me, I'm interested but I'm also in 'wait-n-see' mode.
Never a boring day on these forums. Dozer575 - What you are referring to is called "KOMTRAX" and it is standard on many Komatsu machines. It has the ability to geo fence, meaning that if you set up the parameters with your pc/laptop using gps coordinates, your machine will not start if it is moved out of the described area. Individual states cannot limit what machines operate in their states as they do not have access to the KOMTRAX system, only the registered owner has that access. And as far as the dealership or bank shutting down your machine for non payment, that will only happen in really extreme cases. Go ask a lawyer about what is involved in that process ..... As far as electric dozers go - I hope Cat does well with them, the push power should be incredible, and all with potentially lowered emissions to boot. What's not to like? (and yes I am indirectly paid by Komatsu)
How much is Copper$$$$
has anyone of you american guys any idea of when the electric D7E comes on the market?? i have heard they are testing it in usa running on about 3000 hours now and when it hits 6000 hours it should be ready and after that they might make the 6 size the same
I would like eray , given the engineering background, or any other member with the relevant knowledge to indicate whether there is a role for Hydrogen to play in the new generation of machines to come. I think those of us who continue to believe that the status quo, with fossil fuel as the main power source for the propulsion of any wheeled machine or vehicle is kidding themselves. There is no question that the oil has a very limited life span. A. It is running out. B. All of the major economies will be carbon trading by one method or another sooner than later to avoid cataclysmic climate change which has already commenced without a shadow of a doubt. I know that BMW has for the last ten years been experimenting with Hydrogen as the main fuel source for vehicle propulsion. I am wondering whether any other member has any further information which might be of assistance.
Hydrogen as a fuel. Hi, Aussie Nick. Like you, I have heard of a fair bit research with the use of hydrogen as a fuel. From what I can gather, there is little problem with its potential as a fuel. Generating it in big quantities is proving a little difficult, especially in a mobile ituation such as in a vehicle, although much progress has been made in this area too. The real snag with hydrogen is safe storage and transport as it is highly volatile and extremely disruptive if it explodes. That is why any form of containers with aqueous liquid in them are banned from aluminium smelters and some other similar places. Such containers, if dropped into the melt, can sink into the molten metal before the liquid in the container gets hot enough to turn to steam. When it does turn to steam, often after the container itself has melted, it can result in a steam explosion. This is usually followed immediately by a hydrogen explosion as the oxygen and hydrogen in the liquid are separated and the heat of the melt triggers the hydrogen. As I understand it, that is what happened to the Simsmetal plant in Melbourne about 20 years ago when it was blown apart with some loss of life. I've also been told that that was the cause of the Hindenburg airship disaster. Most current airships use helium to inflate the air vessel as it is much more stable. I also will be watching future developments.
Hi all , I was reading the local farm rag the other day and it had a story on a forklift in the states (I think in the US forces but dont quote me) that ran on hydrogen. It used 0.75 litres per our of water to make the hydrogen and that was it. I cant find the paper to quote all the particulars but it was in the farm weekly (formerly Elders weekly) and sounded very interesting. Maybe you guys in the US would know more?
In order to keep this thread on somewhat on topic there is a new thread for Hydrogen Fuel here:
I am glad to see the Aussies so steamed up about hydrogen (pardon the pun). I was hoping we would have some input from some of our non-indigenous members.
sorry but what has hydrogen fuel got to do with the D7E electric?????:Banghead:Banghead:beatsme:beatsme
The point is that the electric drive could possibly be powered by something other than a diesel engine. If the right power plant was developed to turn the alternator it could eleminate the diesel. Kinda thinking out of the box. How about a nice little reactor? Feed it a couple little uranium pills and you're good to go for 20 years
I was hoping that there would be a direct Hydrogen power plant replacing the Diesel motor. Grunk The point of the discussion is that the oil is terminal ....... very shortly, hence the diversion to alternative power plants such as electric motors and others including hydrogen. Hydrogen does not need to be extracted from coal or oil . Just turn on your tap and you will extract plenty of it. Every time you take a shower you are using Hydrogen. Water is made up of two hydrogen atoms and one of oxygen.The pollution factor when hydrogen is used in a combustion process in the atmosphere is close to zero as the byproduct from that process is water or H2O. The problem is extracting the Hydrogen from the water which means separating out the Oxygen atoms which requires energy. The other problem I can see in burning Hydrogen in a piston engine is that after ignition the piston chamber is full of water .So how does that affect the lubrication of the piston rings?
I think eveybody listens to too much TV. http://www.worldnetdaily.com/news/article.asp?ARTICLE_ID=59991
ahhhh now i saw the light ha ha i think its a fantastic idea you make that dozer then i will drive it:usa
You watch tv, listen to the radio. All that article says is it's a theory, so why not still try to develop other more efficient, less harmful ways to get around? Maybe I missed the point but if hydrogen can be used as a fuel why not? It sounds to me that you're just another bobcat ron who unless they have a use for it or even like it then it must be junk or just not worth bothering with. Why don't you try to be at least a bit positive?
So is the global warming and climate change all a THEORY. Except it is more an up and comming religion that is going to remove all your libertys, and cost ya a bunch of new taxes. Do we ever have a day when it is not mentioned in the news media? CO2 tax is a commin. I read in the Wallstreet Journal today, how there is talk about bringing the good old 55 speed limit back. When we are stuck to that, I'm sure those fuel guzzling Jets will still be pumping out the tons of polllutants they do everyday, and sucking the fuel at so many tons per hour. The whole of this enviro movement is to remove your and my toys, not the ones of the big boys.
Gentleman, This thread needs to stay on topic. This forum is founded on straight talking and honesty. Stick to the subject and don't get personal. Alternative fuel discussion here:
aaaaaahhhhhhhhhh jeez...
If Climate change is a theory come over here and look at the rivers Murray and Darling. It was 19 degrees Celsius (65F) here in Melbourne in the Middle of Winter the other day. No mate that ain't no theory
thinking outside the square Diesel electric should work well in a dozer, for the same reason it works well in face shovels, trains, shipping, and submarines. I have some familiarity with the shipping systems. In them D/E gives high torque power at the most efficient engine speed, the ele then being used to spin the prop. The most common usage of D/E in shipping is in icebreakers, where it is the power of choice because it has the ability to withstand shock loads better than conventional gear driven systems. That's gotta be a benefit in a dozer. D/E systems are more efficient at turning engine HP to shaft torque by a factor of about 20%. That is D/E is considered to hold around 98% of engine torque, whereas gear driven systems are about 70%. So 20% more torque in the water. 20% more torque at the tracks from the same engine would be nice too, assuming you beef the weight up to use it. An engine 20% smaller putting the same power on the ground while operating at it's most fuel economical setting sounds good too though. Next benifit is speed. In a gear driven system you have to wait for the gears to stop turning one way before reversing them to go the other. Powershift speeds this but the cost is increased wear. Those old direct drive transmissions lasted forever because of the delay involved in swinging the main clutch, forward/ reverse lever, and often a gear change as well. How long does it take the light to go on on off when you hit the switch? Does the wiring wear out when you do it? The principal is exactly the same. Then we come to durability. Throw out the costs assosiated with converters, transmissions, bevel gears, brakes, clutches etc. Add one DC generator. They have a service life of around 20,000hrs for a good one, not counting the bearings which are a hell of a lot cheaper and easier to replace than a tranny rebuild. And you don't have to rely on an operator pulling dipsticks and putting oil in to keep it from dismantleing itself. There are none. Replace the bearings every 5000 hrs in a scheduled service and forget about them again. So I have no doubt that D/E systems can power a dozer better than any existing system. Whether Cat's can is a different matter. I remember the fuss and naysayers when the first Liebherr hydrostatic dozers appeared here. The people who said loudest it couldn't work in a dozer cause it was different to an excavator were Cat.
Dc/ac Hi, Trackfanatic. I agree with most of what you say and, while not out and out disagreeing with any of the rest of your post due to lack of knowledge, I reserve the right to disagree if further information leads me that way. As I understand it, the Cat D7E diesel/electric dozer is all AC with AC induction drive motors. The system in its current form appears to have double reduction gears on the output shafts of the electric motors. The power is then fed to planetary reduction hubs in the sprockets. That is still a fair gear train, although I grant you there is no powershift or direct drive transmission, torque converter or steering clutches and brakes. Personally, I like the idea but I'm reserving judgement until more information and bums-on-seats experience is available - or until Cat or a Cat dealer offers me the chance to play with one in some serious dirt. Just my 0.02.
Murray-Darling river complex Hi, Aussie Nick. Pardon me if I'm perhaps a little ill-informed here as I do live some few hundred miles away from both those rivers but I thought that the main problem with the Murray-Darling system was the amount of water NOT allowed to flow through it due to all the various impoundments that had been constructed. Not the least of these would be the Snowy Mountains scheme in N.S.W. and Cubby Station here in good old QLD but there are many other smaller impoundments that have a cumulative effect in reducing the systm's flow to a trickle and even to non-existence. JUst my 0.02.
Fair enough Deas. I hadn't looked at the Cat system and just assumed that they'd have done it similar to what I've seen. I'm no expert but have some experience, and assumed wrongly.
The irrigation was always a strain on the Murray Darling system, but despite this the system was managing to cope. A believe two years ago the Darling stopped flowing altogether and the flow in the Murray has declined in spite of a flush out of lake Mulwala,which is partly associated with pestulent weed destruction. Melbourne's water supply declined to 29% a few weeks ago (Despite drastic reductions in consumption over the last three years) and the State Government has commissioned the construction of a desalination plant. Lake Eildon is a skeleton of its former self and it is impossible, almost, to take a power boat through some sections without ripping out the keel and prop. I believe that some of the dams in Brisbane were also under some considerable stress.
here is a video from conexpo about the D7E http://www.constructionequipment.com/index.asp?layout=nocclamp&articleid=CA6551310
diesel over electric diesel over electric power is so well proven, im surprised its taken this long to see itself into th h.e. market! perhaps im wrong, maybe the dust dirt is going to play a factor! but someone had to get there feet wet with this proven source of power. the mine shovels have been using this electro source for ,what , 50 years? i hope weve advanced a little since then!even if the electro thing works for the best, you still get ur diesel noise, smell, and grunt!!!! if this does work out, my opion would be, komatsu is going to be on this like a teenage boy on a cute blonde girl! i wish cat the best on this effort! im sure all the other h.e. mans. are watching this very carefully!its all good! progress is progress! i see many posters here to claim the old stuff was better built! and maybe so,but we have to move ahead! any of you guys want to start a fire in the boiler of ur tractor before you work? if ur doin a little pokin around the farm, thats one thing! most of the guys in here are triyin to make a living pushing dirt! damn ive babbled too long, deas is gonna be pissed! lol
I would say the old stuff was very well built, so much so that improvement via complete redesign of the powertrain will be hard to justify. Performance is something that is measured in thousands of hours, not video clips. Just my opinion..
Olddirt Red this thread for some reviews of the machine. And NO, I do not work for Cat. Just a lowly contractor.
I have already read those, I am not dissing this thing, all I am saying is what we have been used to worked real well and lasted a long time under the most trying of operators and rough conditions. To beat that is going to take some doing, although it is completely possible. I am not against this at all, just pointing out the hurdles cat must jump over without a mistake. I am also quite sure they know exactly what this all means. Like in pitch, you can't win crap if you don't get the bid. As for this big change in drivetrain, you gotta start somewhere. Maybe this will be the new standard. I don't believe I would like to be the guinea pig, although it would be fun if someone else paid for it. I am no different than you, just expressing my opinions. Hopefully not to po anyone too.
I do have to agree with Dozer575 about the quality and type of operators coming out of the pipeline. Had a kid showed up here looking for a job, not that I was looking for any help in these wonderful economic times, informed me he was a third year apprentice, and informed me that he refused to operate any equipment lacking air conditioned cab, stereo and GPS.
My thoughts: The motors and converter had better be water cooled cuz a lot of you guys operate in some dirty dirty conditions. As much as those black box electric controls will cost a ton to replace for certain, electronics have come a long way and they really make problem diagnosis faster and more accurate. I recall a 6H i was considering buying, except it had an overheat condition in the tranny. The dealer had spent countless hours tearing it apart, replaced nearly every seal, pump, cooler, valve body inside the tranny. They simple could not get it to stay cool. Sucked for them, cuz anytime someone was looking at buying it, it would overheat. Even in near freezing temps in Ontario. Anyway, all i can say is modern powershift trannys are so complicated ,sometimes you get problems that can't be diagnosed. With any luck, this new drive system will eliminate that. They've been moving trains, ships, and cars for years now with electricity. Its the next big thing. Personally, i really like the idea.
drivetrain! so true dirt!!!!! we will, just have to see whaat they do!
dirsel over elecetro i guess we can only see where the the new d-7 is going to go!i believe cat will make this idea really come aliveeeee!time will tell! id love to hear some other coments on this drive system!!!!!
Some place in this thread or the other one, there is a link to an article calling this new D7 a hybrid. Does Cat call it a hybrid? Looking at the various sources that give the definition of hybrid vehicles, I cannot say that I clearly understand what the definition is. Generally, the definition seems to be a vehicle that is powered by more that one power source such as a gasoline engine and an electric motor. And specifically, this would mean that either the engine could propel the car directly through a transmission, or an electric motor could propel the car directly by taking power from batteries. So hybrid vehicles have massive battery banks. But I don’t think that a vehicle such as a diesel-electric locomotive could be classified as a hybrid because they cannot shift back and forth, running on just the electric motors or just the diesel engine. The engine and motors must work together in a way that has the alternator (or generator) and the electric traction motors acting as a type of transmission in which voltage and amperage can be varied to modify drive torque and speed. The same would have been the case with LeTourneau motor scrapers and wheel dozers. I assume that this is the basic system used on the new D7. But to really clarify this, I am wondering if the D7 has battery banks beyond what would be needed to just start the diesel engine, and if power is taken from the batteries to drive the traction motors under some circumstances.
Nope, no hybrid of any style here and Cat does not call it one. Strictly Diesel electric, no batteries other than for starting the Diesel. I also think that automotive has totally missed the boat by not doing the same thing that Cat has done here. As I understand it this is also an AC arrangement. That is going to make it tough to adjust voltage and current to modify torque and speed. Diesel electric locomotives are not thought of as hybrid either. They are strictly Diesel electric also.
Hybrid and AC That is not true anymore, with inverters AC has as good if not better control than DC today. With AC you have full torque through a large RPM range of the motor by controlling the volt Hz relationship. AC motors can be more efficient and easier to maintain than DC. This dozer could also be listed as a series hybrid. That is a vehicle that a motor powers an electrical gen. source and that either powers batteries and/or an electric motor. Most cars are a parrallel, that the combustion motor can either power the vehical and/or charges batteries, and the electric motor can power the vehicle. Below is a link to a Cat document that they are calling it a hybrid drivetrain. The newer trains are also calling themselves hybrids. GE released a train a few years ago they were calling a hybrid due to it had battery packs that on braking would be charged up for later use. The DOE worked with both Ford and UPS to develop a hydraulic hybrid. It uses a pump attached to the drive shaft that under braking pumps fluid into a nitrogen filled tank to store pressure and upon take off the flow is reversed and the pump is used as a motor. This boosts th vehicle on take off. I think hybrid is just the new catch phrase of the day. These use to be called Diesel electric or gas electric. http://www.cat.com/cda/files/1577483/7/179PR09 D7E - Press Release & Images.doc
Thanks for that information Greg and Nothinbetter. According to that link to Cat, they do call the new D7E a hybrid. I do agree that the term hybrid has become a catch phrase. The term has become fashionable as a component of the green movement. I don’t know if that is the intent with the new D7E, but the green movement has become very popular as a marketing objective. I am wary of products that are developed and marketed to be green because that objective has no clear definition and often forces the design to compromise other aspects of its performance in order to meet a green objective. Green housing would be an example. As I mentioned, I looked at several definitions of the term hybrid. According to one definition, a diesel-electric locomotive would be considered a hybrid even without the new feature of storing dynamic brake energy in batteries for reuse powering the traction motors. However, calling a straight diesel-electric drive a hybrid does seem like the furthest stretch of the definition, and seems motivated by the ability to use the term as a marketing tool. I am not reaching any conclusions based on this issue as it pertains to the new D7E. I am sure that it will get a chance to clearly prove itself to completely objective users who will evaluate it in hard terms of first cost, operating cost, maintenance cost, and performance. What I really find interesting is that Cat suddenly makes this radical departure in drive train design. If this is truly the way to go, won’t everything go this way? If so, it seems amazing that drive train preference could just turn the corner overnight. Diesel-electric drive has been around for a long time, but it has only been applied to certain classes of equipment. Locomotives generally have settled on diesel-electric, but even with them, there has been considerable application of diesel-hydraulic drives. Back when Letourneau was building diesel-electric Tournapulls and Tournadozers, he must have thought that was the way to go. A lot of people must have asked Cat why they were not jumping on the Letourneau bandwagon. What would Cat have told them?
Some of the reasons we may be seeing this now are cost and tech advancement. Even though inverters have been around for a while it's only been the last 10-15 years that in this application AC motors have surpassed DC motors. Cost have also come down on inverters by probably 5 or 600 %. I know drives that use to cost $2500.00 - $3000.00 now cost $500-$600.00 (I'm sure the drives on the D7E are much larger than what I'm refering to). Now these have come down in cost to the point that even houshold washer machines, clothes dryers, airconditioners, and larger air compressors have inverters. These newer drives are also much smaller, and can do in some cases 100 times the amount older ones did. As computer chips get more powerfull and cheaper, this has helped the drives come down in cost and size. I know in the past drives were expensive and so were repairs. Now in some cases a drive a few years old can be replaced with a much better unit cheaper than they can be repaired. So it may now pay on smaller machines to make this work where in the past it looks like only high HP machines (mining trucks, shovels, trains etc). Even with that the D7E it sounds like is going to cost 20% more than a D7R. The payback on a Hybrid car from what I have read is about 8 years with $3.00+ a gallon gas. I also wonder why the parallel system is used in cars and not the series like the D7E and trains. Seems like a lot of extra weight and mechanical loss to add a transmission.
cat d7e in regards to all the responses about diesel over electric, i was wondering if anyone here knows if letourneau was still toying with this set up, seeing that they started the research! we gotta love that company!!! talk about r+d! they really should be the "cat" of today!!!!!!!
Counter As far as "toying" with it, no. If you mean are they still producing diesel-electric drive as they have been for over 50 years, yes. Here is a bit of info. http://www.letourneau-inc.com/mining/features.htm and here http://www.letourneau-inc.com/mining/pdf/50_Series_Brochure.pdf Letourneau and Cat have been managed in different ways over the years, and that has led each of them to where they are today. RG had many ideas that were ahead of the reliable technology to make them work. When the company was bought out in the 50's or early 60's by Westinghouse, the company had the potential to grow and rival Cat, but due to choices made that was not to happen. Once Letourneau got away from Westinghouse, they were far behind Cat in market share, and have never been able to recover that. They have done a good job of sticking with the things they are good at, like the large loaders.
One of the illustrations that I have seen of the D7E shows the front idlers as sprockets that appear to be identical to the drive sprockets in the rear. Why is that? Those front sprockets are not driven are they? I assume that they are acting only as idlers. But what would be the reasoning for using sprockets as idlers? The only place that I have seen that practice is on those little Chinese dozers that are being imported. With them, I had assumed that they merely decided to save the cost of tooling up for front idlers when they could just use another of the existing sprockets used to drive in the rear. But I can’t see Cat doing it for that reason. Has any other crawler manufacturer ever used a second item of the sprocket for the idler?
Tracklayer I do not know where you saw that, but I can assure you the front idlers are normal, unless you get the system one option, then they are just skinny, but in no way look like a sprocket.
Jerry, I saw it over on ACME a few months ago in a thread that Swishy had started. I guess the sprocket in front must have been some of his artistic license.
on the model that they had for demo it looks like a normal idler with very small teeth mad it...... a question was asked about it and its there form track alignment of some sort
diesel over electric on the d7e dont know about the idler being an issue here! still would love to hear some guys who have ran the d7e!!!!!!!!! we all need to knowwwww
This is what I was referring to regarding the idlers. I thought Swishy used Cat illustrations of the UC with this spoof. Maybe not: http://www.antiquecaterpillar.net/ACF_v2/showthread.php?t=12030&highlight=d7e
does any of you guys know if they are starting the sale of the D7E???? on cats website it is allready lined up together with all the other dozers it seems to me that it is possible to purchase it now
the first production run doesnt start until october of this year and it will replace the D7R II in 2010
I got to run one a week ago today. It seems to me that it will be a good machine. It was comfortable and very quit and it was also operator friendly. It had loads of power also. It was suprisingly smooth, I am used to the high track but I still like the conventional style. the visisbility was also better than what I thought it would be. The hydralics were a little too fast though.
i agree with d6peg on all that he said that is exactly how i felt when i had the opportunity to run one for about 25mins at a CAT demonstration, i wish i had the opportunity to run it a little more you know double the hourmeter or something but i think they said the hydraulics were adjustable to meet the operators skills and ability
hey thanks for the input!!!! we all love it! you be one of the lucky guys to tell us!! perhaps the dealer can come out and adjust the hydraulics! ive heard ,that when new , the the hydraulics are set at max levels.
No need to have the dealer adjust it. The settings are all electronic, and can be set on the control panel by the operator. You can even save profiles for different operators. Say one guy likes the fast blade, and another likes it slow, you can program it so you select who is operating and his settings for that and other items come on, then when you run it later, your own settings come on. The fast settings work good with the GPS, and with a fast finish hand.
that still is wayyyyy cooolll! its like the automtive design of man and wife drivers of suv"s two or more settiings of seat and peddle positions!