Skip to comments.Caterpillar D7E: Move earth and save the Earth ( Hybrid Bulldozer...?
Posted on 06/12/2009 7:19:45 PM PDT by Ernest_at_the_Beach
On the way to a demonstration of Caterpillar's first hybrid dozer, I was expecting it would be one of the little ones, the kind used to dig pools and landscape suburban back yards. But looming up in the middle of Holt of California, a Caterpillar dealer outside Sacramento, Calif., was a huge beast, a massive yellow earth mover, the metal tracks of which came up to my waist. The Caterpillar D7E was a lot bigger than the little hybrid I was expecting.
A Caterpillar representative jumped in the cab and, metal tracks scraping up the clean concrete floor, pivoted the big dozer around and drove it out to the demonstration area, a field of dirt with one big hill, and strategically placed holes and trenches--not to mention a slalom course marked by orange pylons. As a dramatic start to the demonstration, the driver took the 56,669 pound D7E over the steepest section of the hill, the dozer's blade pointing up toward the sky. At the top, it neatly balanced on the crest before making its descent, demonstrating how easily it maintained control on this loose ground.
The D7E differs from traditional earth-moving equipment in that it uses a locomotive-style series hybrid drivetrain.
(Excerpt) Read more at reviews.cnet.com ...
Actually no, I'm an ex-logger from northern Wisconsin who went off to college and got two engineering degrees. We had our own R.B. in Baraga UP Michigan. Pettibone was cut from the same cloth.
The dozers are conventional, but I know the large dumptrucks are electric wheels with diesel/electric generators under the "hood".
The largest cable shovels and draglines are all electric connected directly to the grid with a big flexible cable drug along by a dozer.
I don't know how glass would work out as it is actually a "super cooled" liquid which gets softer as the temperature increases, it doesn't actually melt (go thru a phase change) at any particular temperature.
I had heard about GM working with high strength ceramics which have very good high temperature characteristics and can take compressive loading in stride. The down side is they are very brittle and are lousy in tension. I know they got some demomstration "proof of concept" prototypes running but what happened after that I lost track of.
I worked for a hydraulics firm that built vane pumps. We also tried ceramics for pumps that ran fireproof fluids as they generally have low lubricity. We found that it could work if a ceramic ring was shrunk fit inside a steel ring. That left the ceramic under a large compressive loading much like tempered glass. The problem was the vanes that slid along the inner surface of the ring. We tried just about every tool steel and heat treat we could think of up to titanium carbide but the wear rates were uniformly unacceptable. When you really think about what we had invented was an "inside out" grinding wheel which ate up the mating parts as fast as we could shove them into the pump!
Some things just aren't meant to be...
Why don’t they just run it on used french fry oil?
Ferdinand Porsche invented that type of drive train for his version of the Tiger tank. It was a bust, but he was pals with Hitler, so they built 100 of them anyway.
What a laugh...a D7 huge????
Try an 11.
D7 always impresses me as being in the upper range of medium duty. The D9 is what turns my head.
I've never seen a D10 or D11, I can only imagine the tingling sensation that would run up my legs at the sight of one of those behemoths.
Under the present-day definition, if it moves with something between the internal-combustion engine and the drive wheels, it is a hybrid.
Don't blame me, I didn't make up the rules.
Don't blame me, I didn't make up the rules.”
Ok.. give me a reference to saying that.. because basically that would make a regular car invented since the late 1880s.. a Hybrid vehicle.
On the horizon, solar bulldozers.....................
Cool, I was gonna make a Rachel Corrie reference,
and it was already here.
As have I, way back when I was watching some idiots with a small crawler trying to dig out a spring hole to make a little pond. They had an old "mucking bucket" that had two handles like a wheel barrow and appeared to be something that was made to be pulled by a mule or two. They had it rigged with about fifty feet of wire rope of dubious strength and with much sweat and cussing they had made some little progress. As they delved deeper into the muck thing came to a halt and the crawler was starting to lug down some. The property owner jumped behind the crawler and grabbed the cable as if to add his puny strength to the operation. I yelled to him to get the H### out of there and he stepped back as the cable parted at the bucket and faster then spit there was fifty feet of wire rope in an untidy ball right where he had been. We figured he would have lost both legs if he hadn't moved. The AH didn't even say thanks. After much digging they found the stump that had snagged their bucket.
As to the safety of hydraulics, energy is energy and power is power and it matters not whether it's tension in a cable or pressure in a pipe. If your focus strays for even a second when you should be paying attention you are risking injury or death. I've worked with hydraulics for over forty years and have seen a lot of near disasters. I've built test rigs and run them at pressures in excess of 100,000 PSI and fatigue tests to ten million cycles to verify strength requirements and still things break unexpectedly. When something literally breaks into pieces (pressure vessel failure) the pressure immediately dissipates and the worst that can happen is a shrapnel wound which is bad enough. Worse then that is if a hose develops a pin hole leak or a flange fitting stretches just enough to let out a flay fan shaped spray. Stuff like can cut you in half like a laser beam. If you've worked around earth movers you might know diesel engines. Part of the set up of the injectors is setting the "lift pressure" which involves a little test rig with a gage and a hand pump. You connect the injector to the test rig and pump it up, noting where the gage stops and a fine spray forms at the end of the injector. It looks soft and fluffy like a cotton ball. I saw a guy try to feel one with his finger as he pumped the rig up. Before I could say "stop" his finger was black and blue and grossly distended. The spray had broken the skin and he had given his index finger a subcutaneous injection of diesel oil. They wound up amputating the finger because there was no way to clean the oil out and his finger was infected. That was at about 1000 PSI, which is considered "Low Pressure" by most.
Electricians have a unwritten code they follow, "one hand for the job and the other in my pocket", not a bad idea.
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