High Drive Dozers

[Scott]

 This is just a general question for anyone who has expirience with Cat high drive dozers. Are they really all they're made up to be? Cat has stuck with the design for 30 years (?) and  claims many great things about it.. I've herd a lot of negative things about them though like it makes the dozer more tippy on sidehills and the track wears faster due to more flex points. They don't seem to be losing any customers though. Any comments?

[beenthere]

If you were ever operating a dozer on a slope and trying to back up and at the same time trying to keep the tracks from running off the sprockets, you would really appreciate this 'invention' that CAT has. :D  I doubt that CAT would part with the patent on that idea, nor sell it to someone else. When in reverse, backing up a steep hill or bank, with the conventional crawler, the lower track on the ground is loose (tight on the top) which means it can get out from under the carriage rollers. When that happens (turning), all at once the track comes off the sprocket and putting it back on a slope in zero degrees wasn't my idea of a fun time. I didn't let that operator back on that crawler - ever. If one notices it soon enough, one can manuever around carefully to run it back on. Takes time and patience.

The high sprocket keeps the tracks tight on the ground, whether in reverse or forward. So turning won't scrape them off the sprockets. I don't know anything about 'roll-overs' or wear, but doubt they out weigh the advantages. I think CAT is way ahead of the crawler game with these. I toured the Peoria plant the year they first came out with the high drives. I have noticed they have been expanding into other size crawlers right along.

Just my 2 cents. Others may have a lot more information.

[OneWithWood]

Yup.  I can vouch for what beenthere says.  It isn't any more fun when the temp and humidity are in the high 80s and 90s at the bottom of a muddy pond either! ???

[L. Wakefield]

   OK, time for a dumb question. When you say 'high drive' do you mean the ones where the track has a physical triangular shape imposed by the idlers or rollers or sprockets? I've seen that but had no clue why they would make it like that. How does that work? Is it kinda like a 'hook' that automatically takes out the slack from the running surface? Or are there additional tensioners in it? I didn't look at it close, but I *have* had the experience of putting tracks back on a small crawler. No, it's not fun at all.  lw

[beenthere]

lw
The high sprocket is the drive sprocket (i.e. high drive). The loose section of track is either in front of or behind the high drive sprocket, but the track remains tight between the front and back sprocket. Draw some pictures and it should become more evident. The rear sprocket was (is) the drive on 'conventional' crawlers.

[Tom]

I looked into buying a High Drive cat D6 back in 1984 and the sales talk for them then was mostly maintenance. The High drive put the working parts of the tractor where the mechanic could get to it in the field.   It was also supposed to keep the drive mechanisms out of some of the dirt.

I don't remember anyone telling me that it would work better than a conventional track.

I was just before buying one when the salesman asked me what company I represented.  I said "me".  He said well if you see something that you are interested in, I'll be in the office.

That's when Ford sold me the 555A Tractor/loader/backhoe and the little 1910 farm tractor.  Cat probably did me a favor since I think I've gotten  more use out of the rubber tired hoe than I would have the D6.

[Norm]

I like the high drive on them and would use it if the terrain called for it. Here in Iowa we don't have a lot of steep terrain so the conventional drive system is fine. I guess it boils down to what your going to use it for.

When I was looking at excavators the cat dealer couldn't have been ruder if they tried. Kind of like what Tom experienced when they found I wasn't a big company they could have cared less if I bought one. Link-belt went out of their way to work with me. I'll probably be buying a dozer next year and will give their competition a serious look.

[ScottAR]

One main advantage is the elmination of the bull gears in the final drive and planetaries in their place.  In the older dozers, the bull gear took the full power of the machine on one tooth.  
The planetary spreads the load out making final drive failure a lot less common.  The final is up outta the muck and trash.  There are machines with 30,000+ hours roaming around with the only things replaced in the final being bearings.  

When one repairs a final on a high drive, one takes off the "hub cap" and begins.   Removal by a good mechanic takes 4-5 hrs.  
A low drive begins by jacking up the machine and breaking the track.  A good mechanic takes 1-2 days on a low drive.  

The tipover thing is mostly hearsay.  If one looks under the bodywork, the powertrain sets just as low if not lower than a convential track machine.  The top of the valve cover is about even with the operator's feet.  

The comments on Cat dealerships I hear is common, but I have not found this at my local dealer, J.A. Riggs in Jonesboro.  I talked with a salesman at our local county fair for nearly two hours about a backhoe and nearly everything else including the weather.  
Enough blathering...

[logloader1]

The high drive comes in at least two confingrations.  One for steep ground and one for dirt work, I think.  For logging on steep ground the high drive (sets more forward than dirt one) lets you turn on steeper ground.  It is much more stable.  The high drive has about 25% more rail than standar low drive.  So when it comes time to re-rail one grab your pocket book.  But at the same time the ground speed is much higher so skididng production is much higher.  I know of one logger who is able to skid at least 5-6 loads a day in steep ground using a D-5 with a grapple.

[SwampDonkey]

They're big Tonka Toys for big boys. Wonder how many woodlots have been slaughtered to pay CAT  ;D

[Scott]

 The Cat 527/517 track skidders are really impressive. I guess they really perform on the steep slopes and soft areas where wheel skidders can't work.

[Hunter]

I used hi-track dozers alot, I have been an operator for 12 years. The hi tracks are easier to work on and alot easier to clean the tracks.
I have had cat D-7's on slopes so steep they will slide long before they will role over. You would be really surprised how steep they will go. I have to get a blade full of dirt to keep good traction and stop the sliding.
I like them and they can really get stuff done. If you get one in the LGP(low Ground Pressure or Wide track) they can really run in softer stuff. We had a D-6 LGP and it seems like it would walk on water, Not quite, but I took it alot of places and pushed alot of 627's out of some really soft stuff.
Hunter

[SwampDonkey]

I hired a D-8 to scarifiy ground for tree planting and the operator got off the site somehow and ended up in a spring hole, which was the head of a brook. Needless to say he had to go fetch an escavator to fish him out.  :D  :D ABANDON SHIP!! :D :D The crazy nut. Just gotta shake your head sometimes.  ;)

[Scott]

 A lot of the dozers in Alberta are LGPs. They use them on oilfield projects and on the muskegs. Some of those dozers are equiped really nicely (angle blades, winches, full forestry guarding, wrap around guards, tri link track, ice grousers, etc) I'd love to get my hands on one but the price of a D6 high drive rarely falls below 200 grand.