Diff steer, how does it work?

DPete · Jun 3, 2009

Anybody know the basics of diff steer? I have an 02' D6R rented this week it's my first experience with diff steer as I'm used to the older D8's with steering clutches. The machine will turn with the trans in neutral if the lever is applied so the power must go through the diff prior to the trans. Nice machine by the way.

CM1995 · Jun 3, 2009

That's a good question. I have a diff steer D6N and a hystat D5. I prefer the diff steer over the joystick anyday. To me the diff steer has better, more responsive control than the joystick. (also has to do with it being a heavier tractor as well

)

I am sure we have some folks that know exactly how it works, I am interested to learn as well.

ih100 · Jun 3, 2009

It's a bit like the old controlled diff steering that cletrac, fowler, track marshall used. The big difference is that instead of the regeneration between tracks being initaited by braking oe track and transfering drive to the other side, the Cat system uses a hydraulic motor to rotate the gears of the differential and initiate speed difference. This is also how you can do a neutral turn while out of gear. The T's with diff steer have an auxilliary pump specifically to power the diff, as on the R's and N's the main pump wasn't as efficient at steering when too much was going on with the blade, due to not enough flow.

Hope this helps.

td25c · Jun 3, 2009

Thats interesting ih100.I dident know how the cat differential steering worked.on a IH td25c The ring& pinion have planetary gear sets on each side of the ring gear.They are controlled by 3 disc & caliper assemblys per side.one for high range,low range,and the last is the brake.They are nice for full power turns when the blade is loaded.Sorry to highjack the thread DPete talking about an IH dozer.

LonestarCobra · Jun 3, 2009

IH 100 is right. The hydraulic steering motor spins planetary sets. When in gear, they speed up one side or the other and you never lose power to either track. Best I remember, they can speed the tracks up to about 2 mph difference. Cat had problems back when they came out with the diff. steer D8 not having enough steering power due to sharing the pump with the blade. The added a steering pump later and fixed this problem. They did not learn from their mistake because in the later series of D6R's they tried it again with no success. That D6T is a darn good machine, and they are sure selling cheap around here with the economy like it is.

DPete · Jun 3, 2009

I noticed today you can't always lock one track if you want to like if you need to miss a stake or need to turn sharp. For the most part I am impressed. We had a D5N on our last job with finger tip steering, herky jerky to operate and to light for the ripping we needed, 6 way blade was handy though. I'm new to the smaller crawlers

DPete · Jun 3, 2009

Construct'O · Jun 3, 2009

My D6H ia a 1988 model i believe the first years for diff steer.Is has been great.After 16k hours on the machine i went throught the final drive and had to do some workon the plantery gears and park brake which is on the right side behind the final drive.

The thrust washer in the plantery gear came off and was wearing on the gear cage and inside plantery gear for the diff steer.They came out with an update which i replace mine with,which is suppose to have solved the problem.

They are easy to take apart.Break the track,pull the dead axle and take out two rows of bolts and pull the final drive and the brake and inside diff steer pplantery gear togather.Or you can split them and leave the diff steer and brake on the machine.

Pete you need to get to moving some dirt the blade looks to be ready to rust down.I know it's a rental.Tell them next time you want one with a shiny blade at least

ih100 · Jun 4, 2009

TD25C, I've never had the pleasure of even seeing a 25 this side of the pond, I doudt many made it over here. Did the big TD's have steering clutches for tight turns as well as the 2-speed, or was it a diff? I was never clear on that.

Dpete, you'll find that how tight you can turn depends on the ground conditions and how much you're pushing. Personally I never found the N's much more manoeuverable than H's with clutch steer.

Hjolli · Jun 4, 2009

LonestarCobra said:
IH 100 is right. The hydraulic steering motor spins planetary sets. When in gear, they speed up one side or the other and you never lose power to either track. Best I remember, they can speed the tracks up to about 2 mph difference. Cat had problems back when they came out with the diff. steer D8 not having enough steering power due to sharing the pump with the blade. The added a steering pump later and fixed this problem. They did not learn from their mistake because in the later series of D6R's they tried it again with no success. That D6T is a darn good machine, and they are sure selling cheap around here with the economy like it is.

Does that mean that the D6H´s did have that extra pump and the 6R´s didn´t?

Anyway, I was driving a D6H some years ago, real great steering performance.
The 6R I drove later was pretty good too, but somehow I felt that the steering was a bit sluggish.

John C. · Jun 4, 2009

The TD25C and D used big half shoes that clamped onto disks hooked to the planetary sets. Set the brake on the planetary disk and you had one speed, release it and you had another. There is an extra disk on each side with associated shoes that actually stops the output axles from turning. The steering levers had detents for speeds and all the way back locked the brake. I worked on one in my time.

The TD25E had a modular set up that was like the Komatsu power pod. The cross shaft and all the planetaries could be picked out of the machine in one piece. I've seen one apart but never had the pleasure of actually working on one.

The differential steering in most of the machines that have it is based on two power inputs. Use only one input and the machine goes straight. Turn the second input one way and the left track spins faster than the right track. Turn the second input the other way and the speed of right track is faster.

The older Cats with one hydraulic pump steered fine as long as you didn't try to pick up the blade or ripper at the same time.

I started working on diff steer Komatsu machines in 1994. When did Cat come out with their diff steer models?

CascadeScaper · Jun 6, 2009

I've been on a 6H and 6R, never noticed too much between them in terms of steering response but will agree the 6H was a tad bit quicker/smoother.

ironhorse · Jun 10, 2009

hi, im new to the site and have a question but do not have any posts, so i am asking it here with no means to hijack your thread.
how many yards will a d6r widetrack push?

railrider · Apr 11, 2010

Hello, I'm new here also. From what I found, it will push anywhere from 4.84 to 7.35 cu. yards, depending on blade type, but that may be for regular tracks. Hope this is helpful.

railrider · Apr 11, 2010

Question: Several of us are trying to solve problem on D6r (9pn1899). Machine has rebuilt final/axle on right. Transmission, left brake, and bevel gear all rebuilt. New axle on left. Machine would not move. Checked pressure, it was 0. Found gear broke gear inside transmission pump. Replaced pump, speed sensor on torque, and two temp sensors. Pressure holds about 400 range, but left final acts like brake is on. It will move, but not correctly and lugs engine. Two ports on top of brake, one reads zero, the other 400 range and I can control pressure reading there with service brake. Put new solenoid in priority valve. When you try to steer, a small hose from block on side of main hydraulic pump that goes to relief valve under main control valve assembly on right of machine jumps very hard. Pressure on block exceeded 5000 psi gauge. Removed hose, blew through both directions, hose o.k. Removed steering motor with counterbalance valve attached. Reconnected hoses, ran machine. It seems to turn fine, both directions (but it's not under load.) They ordered new steering motor and new counterbalance valve and two relief valves that mount under main control valve assembly. I suspect the relief valve that has the "jumping" hose connected to it, they suspect the steering motor/counterbalance valve. Any advice would be greatly appreciated.

JASON M · Apr 11, 2010

DPete said:
I noticed today you can't always lock one track if you want to like if you need to miss a stake or need to turn sharp. For the most part I am impressed. We had a D5N on our last job with finger tip steering, herky jerky to operate and to light for the ripping we needed, 6 way blade was handy though. I'm new to the smaller crawlers

I remember when Cat came out w/ that silly fingertip control. They threw that motorized assassin at me on demo. After I ran it, I quarantined it to a place on the jobsite where nobody would see it, so they wouldn't try to use it! That design was destined to kill an innocent bystander........ dangerous!

I don't see the big difference, operating anyway, from a D6R to a D6T.

I don't see the big improvement in the D6T model; have run both of 'em......... and I'm not nearly ready to scramble out to locate a D6T, because it's supposed to be better; haven't seen the improvement, from an operatoring standpoint.

CascadeScaper · Apr 11, 2010

6T is a bit faster in the blade from my observations. Other than that, I couldn't feel much difference between the two.

AmerIndependent · Apr 12, 2010

railrider said:
Question: Several of us are trying to solve problem on D6r (9pn1899). Machine has rebuilt final/axle on right. Transmission, left brake, and bevel gear all rebuilt. New axle on left. Machine would not move. Checked pressure, it was 0. Found gear broke gear inside transmission pump. Replaced pump, speed sensor on torque, and two temp sensors. Pressure holds about 400 range, but left final acts like brake is on. It will move, but not correctly and lugs engine. Two ports on top of brake, one reads zero, the other 400 range and I can control pressure reading there with service brake. Put new solenoid in priority valve. When you try to steer, a small hose from block on side of main hydraulic pump that goes to relief valve under main control valve assembly on right of machine jumps very hard. Pressure on block exceeded 5000 psi gauge. Removed hose, blew through both directions, hose o.k. Removed steering motor with counterbalance valve attached. Reconnected hoses, ran machine. It seems to turn fine, both directions (but it's not under load.) They ordered new steering motor and new counterbalance valve and two relief valves that mount under main control valve assembly. I suspect the relief valve that has the "jumping" hose connected to it, they suspect the steering motor/counterbalance valve. Any advice would be greatly appreciated.

Not trying to jack this thread- maybe one of the mods can move it?

In response to your questions railrider, my first question would be: where’s the old pump? Pump gears usually don’t break without a reason, rather, they are the victim of oil starvation or debris in system. This evidence is crucial to getting to the bottom of your problem.

Also, be advised that this is a differential steer tractor meaning the hydraulic system which powers steering motor is a separate oil system from the power train. The mechanical part of the steering shares oil with the brakes, transmission, torque converter and that pump you just replaced and this is where I would suspect the culprit is.

I would not spend another dime without examining the pump and carefully inspecting screens and filters. If you'd could, post pictures so we can try and analyze what's in there. Feel free to contact me directly.

LDK · Apr 12, 2010

JASON M said:
I remember when Cat came out w/ that silly fingertip control. They threw that motorized assassin at me on demo. After I ran it, I quarantined it to a place on the jobsite where nobody would see it, so they wouldn't try to use it! That design was destined to kill an innocent bystander........ dangerous!

The finger tip steering is good if it is set up correctly. I had a new 6N that was not right when it was delivered, CAT came out and re-calibrated it with a laptop and it was fine after that. I have run 5M's and N's that would snatch, re-calibration sorted those out too.

activeorpassive · Apr 15, 2010

How does diff steer work?

Very well.

Diff steer, how does it work?

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