New Cat D9 Dozer Replaces D9T, Lowers Maintenance Costs

Updated Feb 6, 2021

Cat has replaced the D9T with the new D9. As a next generation dozer, there are some foundational changes to the structure of this machine to discuss, but most of what’s new focuses on reducing O&O costs, including a new torque converter and maintenance improvements.


The Cat D9 is powered by a 440-net-horsepower C18 engine.The Cat D9 is powered by a 440-net-horsepower C18 engine.

As we’ve discussed several times over the last year or so, Cat is in the process of a lineup-wide refresh of its dozers.

They started back in 2018 with the introduction of the first of these new next-generation dozers, the D6 and D6 XE. The company then followed that up with replacements for most of the small and medium dozer lineup with the new D1, D2, D3, D4, D5 and D7 models over the last 12 months.

And now we’ve got our first next-gen large dozer, the new D9, which is replacing the D9T.

A hallmark of these new next-gen models has been a new cab, but the new D9’s got a bit more going on than that when it comes to upgrades. Specifically, much of this new dozer’s development was focused on saving you money over the course of the life of this machine.

But before we get into the specifics of the D9, as we’ve done with all of our coverage of next-gen Cat dozers, we have to take a second and acknowledge the new model name on this machine.

In 2017, Cat decided to stop using letters in model names to denote new generations of machines with the hope of making every machine lineup within the company a little bit easier to understand.

Within the dozer lineup, this was actually a little more complicated because not only were letters being used to denote generations of certain models, they were also being used to denote different sizes of the same dozer model.

An example of that being the three different kinds of D6 dozer that you could buy at one point.

So, under this new naming convention, the D9T is now just the D9. If you want a more thorough explanation of this new way of naming dozers, check out our video on the new D4—which used to be called the D6K2. In that video we get more into Cat’s thinking behind this change and how it clears up the product line a bit.

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A next-gen D9

Now, because the D9 is a next-gen dozer, there are several important changes made to this machine that while not outwardly apparent, as Cat dozer and mining product expert Todd Cole outlined, are still very significant to the platform.

“Electrical architecture, reduction of ECM, some changes to the frame that are really minor, [but are important] for manufacturability and interchangeability with different configurations and commonality too with some of the large dozer families,” Cole says. “The more parts we can utilize, the less variation [there is between models] and [that is] really a benefit to the customer, to the dealer and to us.“

Beyond bringing the D9 in line with other next-gen dozers, the other focus for Cat on this new model was total cost of ownership, and that’s an important consideration for this machine specifically because it is a large machine that is used in pretty rough production environments.

Plus, thanks to its size and a wide range of blades and attachments available for it, it can be used for several different tasks across multiple industries.

“So depending on where you are in the world, it is a mining machine. In North America, it’s probably more viewed as heavy construction. But it definitely sits in that land in between two continents,” Cole says. “We’re in waste, we’re in stockpile applications, heavy construction, wood chip, ripping applications, trap loading with loaders, and of course mining and production dozing. So we’re in everything. If you had to break it up, looking over the last 20 years, [it’s] 25% mining, 40% is heavy construction/general construction. And the remaining pieces are that specialty, the industrial, the rental, the waste, so I would call it the Swiss Army tool of dozers.”

Obviously return on investment and total cost of ownership are always important, but they’re paramount when plugging a machine into these severe environments. And to that end, Cat says it has reduced TOC by reducing fuel costs, reducing maintenance time and cost and through a few production boosting technology features.

New specs, same performance

But let’s start with that reduction in fuel cost, because what makes this interesting is that it’s not achieved through an Eco engine mode or some other software feature that might constrain performance. It’s a hardware change.

The new D9 is powered by a 452-horsepower Cat C18 engine. Now, that’s the same engine that powered the D9T and though Cat’s spec sheets rate the new D9 a bit higher in terms of horsepower than its predecessor, it’s a negligible amount and Cole actually tells me it probably has more to do with differences in the testing done to find that rating and small differences in what rpm peak horsepower is achieved at rather than real world performance differences.

Another important spec apart from horsepower that is higher on this machine is operating weight. The new D9 weighs in at 110,225 pounds, while the D9T weighed in at 105,539 pounds. However, it’s also another change that hasn’t impacted performance.

So, despite the fact that the D9 is heavier and technically has more hp, in terms of raw power, the D9 isn’t all the different from the D9T.

“We did make some changes as I mentioned, we moved some weight around. There’s a new radiator guard and some slight changes really to the frame for manufacturability. But there is not what I call meaningful change to the weight of the machine,” Cole says.

New torque converter

So, let’s move on to what is different and that is fuel cost. Cat says you can expect to save 5 percent in fuel costs with the new D9 over the D9T, not due to engine enhancements or power modes, but due to two other powertrain updates: a new torque converter and a tweak made to the transmission.

The new torque converter on the D9 implements a stator clutch and that clutch is where the majority of the fuel savings is coming from.

As you’re likely aware, like the clutch in a manual transmission, the torque converter allows the engine on a vehicle with an automatic transmission to spin almost independently of the transmission and it essentially converts engine rotation into machine movement by pressurizing transmission fluid and then directing the flow of that fluid into the transmission.

The stator is really at the heart of the torque converter and it’s in charge of optimizing fluid flow between the two halves of the torque converter: the turbine on the engine side and the impeller or pump, which is on the side that connects to the transmission.

The stator allows for torque multiplication and plays a huge role in fuel efficiency because it effectively governs the efficiency of the torque converter and thus the powertrain. And you can increase the efficiency even further through a clutch that allows the machine to engage or disengage that stator.

“So when you go into the push, the stator clutch then will lock up and you get that torque you need. Then when you get to the part of the cycle where you back up, the stator will come unlocked. [During] maneuvering and light blade loads you don’t need that stator,” Cole says.

Plus, the stator clutch engages and disengages automatically. No input is needed from the operator.

But improved efficiency isn’t the only benefit of a stator clutch.

“The big thing to note is ‘Well why not just put a freewheel stator in as some of the other large dozers in the past have?” Cole says. “We get the ability to also put that stator locked back up in the case of retarding. So going back down a hill, you don’t want the machine to run away, the engine actually can help hold it back. That stator provides additional retarding capability, so we’re kind of getting the best of both worlds with that feature.”

With that 5 percent reduction in fuel cost brought by the stator, Cat says you can expect your material moved cost to drop by 3 percent.

“So it’s great because it pays the customer every day. Somebody is paying for every gallon of fuel. If you take that 5% put it over 4,000 hours at a customer site, you’re talking in excess of 2,200 gallons of fuel. So do the math. I mean, it’s big,” Cole says.

Improved maintenance

The other substantial improvement on the D9 is maintenance costs. Specifically, Cat is saying it has reduced maintenance costs by 4 percent and the first reason behind that reduction is a fully integrated Auto Lube system that requires fewer greasing points.

“It has an 8-liter tank, so you should have no problem running every bit of a month at a customer site,” Cole says. “And a great thing about the Cat Auto Lube system is it’s integrated into the design of the tractor. It also has an auto shutoff feature. So the lube guy can hook up to the machine, fill the tank, and then it’ll kick off when it’s full. Some designs require us to watch it because otherwise you end up with a massive pile of grease covering your tractor and all over the ground. And that’s just really not okay.”

“The lift cylinders that are on the radiator guard, those used to be greased, they’re no longer greasable. They’re greased for life,” Cole adds. “That’s actually a carryover design from the D7E.”

Engine oil pan capacity is also larger on this machine and Cole says the D9 in most applications should have no problem getting to 500 hours before an oil change is needed. Plus Cat has extended some of the powertrain filter change intervals all the way up to 2,000 hours, and they’ve included continuous fluid level monitoring.

“So we used to have you turn the key on, do the gauge sweep on it, it says okay to start. So that just gives the confirmation on the compartment level, that the fluids are in good position. So now we’ve taken the next step of while the machines running it monitors the level of the engine oil, the coolant, powertrain and then the fuel tank. So you still have safety net that when the low oil pressure comes on, you get the event “operator shut down now.” This is prior to that, where if that tank compartment is running low, you’ve got some warnings. So it’s really a chance to avoid some maintenance costs.”

As a safety and maintenance feature, Cat has also added secondary retention pins on the belly pan of the D9.

“So lowering that belly pan, sometimes so much debris can be packed in there, that the guy or gal getting it down, it can be a problem. So they’ll pry it down but you’ve got to be careful to not let it swing down. So now there’s about a 2-inch catch in there that allows it to get some movement.”

Rounding things out on the improved maintenance features on the D9 are new powered access ladders and a new radiator guard design that gives you a larger clean out there on the right side of the machine that also provides tool-less entry.

“With the new guard design, even an operator can open it up, get in there, you can blow it out, you can vacuum it out,” Cole says. “All dozers at some point are going to need to have a really good clean out. Debris gets packed in there, it’s just such a tight area to get rid of all the heat. So that’s another advantage that will help drive down ownership cost and the dozer.”

The new ladders are electric over hydraulic and allow operators to lower the ladders from ground level, climb up and into the cab and then raise the ladder back up.


Moving on to the undercarriage of the D9, this is essentially the same high-drive suspended undercarriage you’ll find on a D9T.

“The elevated sprockets have been around really since the 80s. And it has made some changes over time but really when you get specific to this program, we’ve got it pretty well dialed in,” Cole says. “So no significant change to the undercarriage, the roller frames, the final drives, the idlers, the rollers, the track, push arms, blades—the working end of the dozer is unchanged.”

And while the undercarriage components are the same, Cat will be offering a new undercarriage option on the D9 in the general duty undercarriage. So you’ll have three options to choose from: General Duty, Heavy Duty PPR and the Heavy Duty Extended Life Undercarriage with Dura Link or HDXL.

Cat says the HD XL can boost undercarriage life anywhere from 20 to 40 percent thanks to that Cat patented and more robust Dura Link link design along with larger diameter bushing, track roller, and sprocket segments.

New cab

Beyond changes to the electrical and the frame of this machine, another part of bringing the D9 in line with the rest of Cat’s next-gen dozer lineup is the cab.

Inside the cab you’ll find a cloth air-suspension seat, an intuitive control scheme and a new 10-inch, high-definition touchscreen display.

“If you get in the cab today of a [D9T,] there’s at a minimum two screens on there. So one thing you’ll notice is that we brought everything from those two screens into one large 10-inch touchscreen display,” Cole says. “So if you can navigate your smartphone, you can figure out how to work this touchscreen. … It gets used also as a monitor for some of the camera systems so your ripper, your rear view that’ll show up right there in the center. You can do neat things like turn lights off individually just through the touch on the screen. So if you have a truck dump application, or you’re trying to get somebody’s attention, or you’re blinding someone, touch a button and you can individually control every light on that machine.”

Another nice touch inside this new D9 cab are two dials, one for throttle and the other for pre-selecting your gear.

“Most operators want to doze in first gear forward, then back up in second. But there can be applications or other operator preferences where you want to go to, say, just first to first and then be able to go first to second,” Cole says. “So without having to go in and set all that up [in the display], it’s a lot quicker through the touch of a button, using the auto upshift, downshift features. So it’ll be different. But it makes it easier on the operators, to use some of the technology and things that are baked into the machine.”

Tech assists

Another big element of this machine is the available technology on it and the options include 360-degree vision, automatic ripper control, AutoCarry and Automated Blade Assist.

360-degree vision is a four camera system that stitches together—you guessed it—a 360-degree view of the machine. Some call this a birdseye or overhead view ofthe machine and its nearby surroundings. You can monitor this 360 view from a dedicated display on the right side of the cab.

Cole noted during our talk that this isn’t a detection system, it’s just a vision system. So it won’t detect objects or people in your path and warn you. It’s meant more for operators trying to get a better view in front of the blade or behind the ripper.

Automatic ripper control, meanwhile, not only automatically maintains consistent ripper depth to avoid track slippage, it also automatically raises and stores the ripper when you’re done with it.

The AutoCarry feature automates the lift of the blade. Like ripper control this is really helpful in reducing track slippage and it improves load consistency which in turn increases your productivity and efficiency.

Then there’s Automated Blade Assist. With this option you can create preset blade pitch positions for load, carry and spread tasks.

“So we have a dozer pushing material. Generally we come into that cut, we want to load that blade up. And then on a dual tilt machine with those dual pitch cylinders, we can actually lay material back, hold that material and you can push up to 5 percent more material of dual tilt,” Cole explains. “That requires the operator constantly putting input into those tilt cylinders to cut, carry and dump. So with the push of a button, Auto Blade Assist gives you the ability to use that feature repeatedly with operator comfort.”

Another change with auto rip and auto carry is that previously, because the technology behind these features essentially monitors the same things in engine load and traction but on opposite ends of the machine, they were a package deal—all or nothing. Now they’re available separately.

Of course you can also equip this machine with Cat Grade with 3D machine control. Plus, in the near future, you’ll be able to equip the D9 with remote control.

“If you look at our bigger dozers, we’ve had that for a while. The D11 has a semi-autonomous tractor system…we’re not to that space yet in the D9. Going back to where we started this call, the D9 is a little bit everywhere. So remote does have a does have its play in some of the market out there. So we really wanted to finish out the product line by getting remote control in there,” Cole says.