Clearing a Path

Even before the turn of the 19th century, farmers had started to add thick, metal blades to the fronts of their tractors to help them plow their fields. While it was a dramatic improvement over horse-drawn implements and manual labor, it was just the beginning. By 1904, Benjamin Holt introduced the industry’s first “track-type tractor,” and the crawler dozer industry was born.

Holt, who was then president of the Holt Mfg. Co. (which later became Caterpillar Inc.), developed his “caterpillar tracks” in response to traction problems  most farmers experienced in a variety of soft grounds.

The tracks spread the weight of the heavy machines over a larger area than a conventional tractor — producing a lower ground pressure that kept the machine from sinking into the mud. Over the years, the machines grew from those first mid-sized track-type tractors into the enormous machines we know today.

“As time went on, smaller-sized dozers were still being built, but manufacturers were starting to increase the horsepower and operating weight of their machines,” says Joel Fritts, senior product engineer for Caterpillar’s small track-type tractor product group. “They continued to add more and more larger models to expand the product lines. The goal was to be able to get more work done — to push more material and heavier material faster and more efficiently.”

Today, heavy-duty bulldozers can be seen on jobsites everywhere, leveling terrain in order to make it fit for construction. However, much of the construction itself is actually performed with much smaller dozers. Now, several manufacturers produce lines of compact and small dozers to cater to the needs of a variety of customers. Notable players include Caterpillar, Case, Komatsu, John Deere, New Holland and Rayco Mfg., among others. And as the accessible space in residential areas continues to shrink, the market for smaller options is only getting bigger.

Dozer Details

As one of the most fundamental machines in construction, tracked dozers are also one of the most straightforward by design. Technological developments resulted in more powerful engines, more reliable drivetrains, better tracks and improved visibility, in addition to the incorporation of hydraulics and automated controls.

“Over the years, dozers have become more efficient, more operator-friendly and offer a much greater degree of ergonomics,” says Ed Warner, product manager of dozers for Komatsu America Corp. “Mechanical linkage has been replaced by hydraulics and electronics, reducing operator efforts and improving control. Today’s dozers also offer improved maintenance features and on-board self diagnostics.”

But still, the two most critical components of any dozer, large or small, are the blade and the undercarriage. Essentially heavy metal plates installed on the front of the machine, dozer blades are available in a variety of shapes and sizes for conventional crawler dozers. However, the 6-way, or power-angle-tilt (PAT) blades, have become the industry standard for almost every small-end and compact dozer on the market. Named for its six possible movements (raise, lower, angle right, angle left, tilt right and tilt left), the multi-purpose blade allows operators to accomplish a variety of tasks.

“On the small end of crawler dozers, the 6-way blades are the standard; it’s when you go up in horsepower and weight that you get the other blade configurations,” explains Rusty Schaefer, marketing manager for Case Construction Equipment. “For full-size dozers, you have outside push beam straight dozers [power-tilt blades], outside push beam dozers that use a semi U-Blade, in addition to full U-Blades or land clearing and waste blades. There are various blade options that are developed for specific applications, but for small dozers the power-angle-tilt is the standard.”

The track and undercarriage assembly is the other critical component of any crawler dozer. Undercarriages are differentiated by the footprint the track provides for the machine and by the level of traction, or tractive effort, dictated by the ground conditions. In sand, for example, tracks are going to spin easier than in clay, where tracks will usually be able to dig in and grip for better traction.

Depending on the application, manufacturers offer standard, long, wide and low ground pressure (LGP) undercarriages. The distinction between the styles pertains not only to the width of the shoe, but also the track gauge, or the distance between the center line of the sprockets on either side of the track. The longer the track on the ground, the easier it is for an operator to control the grade or the position of the blade. For more flotation, wider track gauges are used in conjunction with a wider, larger shoe — allowing increased productivity on slopes and in softer ground.

“Customers have to look at their application and select which type of configuration fits it best,” Schaefer says. “If you are working in all hard conditions, you just need a long track or extra long track. And in strictly soft conditions, you will go with an LGP. But for a mixture of those conditions, then they might choose a wide track because the wider your shoe, the more accelerated your undercarriage wear is going to be.”

With an LGP, ground pressure could be as low as 3.5 psi, so an operator can ride a 15,000-lb machine in areas where he couldn’t even walk without sinking. According to manufacturers, the crawler dozer market (large and small) is split roughly evenly between long tracks, wide tracks and LGPs, in terms of industry volume.

Sizing Up the Market

Depending on the manufacturer, the horsepower range for light-duty crawler dozers can spread anywhere from 60 to just over 100 hp, but manufacturers contend that operating weight is a better gauge. Small conventional dozers range from 14,000 to 20,000 lbs, while compact dozers typically weigh less than 14,000 lbs. Dozers falling into these two categories are said to account for more than 50 percent of the North American market.

“One of the big selling points for compact dozers is that even though you can physically push more dirt with a larger machine, the amount of work you can get done in a day is almost identical,” says Galen Miller, product manager for Rayco Mfg. “The smallest conventional dozers can push a little bit more, but they can also be more cumbersome and not as agile or maneuverable with their turns. That is really where a smaller compact dozer can make up time and productivity.”

The growing market has also allowed customers of other compact machines to graduate up to a compact dozer, either from a mini excavator or a skid steer. Rayco’s 87-hp C87D Compact Super Crawler, for example, weighs only 9,200 lbs and has a 86-in. 6-way articulating blade, so operators can work in confined areas that are not accessible with larger machines. The C87D also features joystick controls and a cab-forward design unique to Rayco, which simplifies the operation of the machine and provides high visibility to the dozer blade. Rayco’s dozer is also the only compact dozer available with steel tracks direct from the factory.

Thus far, the largest market for compact dozers is rental, since many contractors are unable to justify owning a smaller-sized dozer full-time — but want to rent one for jobs that require access to tight, compact quarters. Case’s line of small dozers (including the 550H, 650K, 750K and 850K) feature operating controls that are engineered to be simple to use, which not only boosts productivity, but also makes the dozers ideal for rental needs.

“Small contractors and rental houses always require small dozers because they are easier to use around a new home or building and to work in tighter quarters,” notes Warner. “But they also require the same versatility as their bigger brothers, and now designs are such that more power and more versatility has been incorporated into the smaller machines.”

Komatsu’s KomStat Series small dozers feature an efficient Proportional Pressure Control (PPC) joystick, which provides precise, responsive hydraulic control of the dozer blade by applying hydraulic output in direct proportion to control lever movement. In addition to the KomStat Series, which range from just under 16,000 lbs up to around 20,000 lbs, Komatsu also incorporates a lightweight, compact design into its D21A-8 and D21P-8 compact dozers. Each weighing less than 10,000 lbs, the two dozers allow contractors to use the same trailer used for skid steers, while remaining inside the weight limits for a commercial drivers license (CDL).

In addition to transportation concerns, weight is also an important consideration when it comes to productivity. Most manufacturers agree that sufficient weight is required to push material, but some say that it’s more of a combination of factors, including traction, weight and horsepower.

“Whenever one of those three things is lacking, it limits the amount of material you can push,” Miller says. “If you don’t have the weight to get the tracks to dig in, then you can’t utilize all of the horsepower. Even if you have plenty of horsepower, you can end up spinning the tracks without enough weight to push the machine down to get traction, or if you don’t have enough aggressiveness in your pads.

So when you buy a compact dozer, you’re physically going to be able to push less.”

But another important factor to consider, according to Fritts, is how a customer actually measures their productivity. While some customers define productivity by how much volume they can move in an hour, others look at how quickly they can get their entire job completed from start to finish. Depending on the situation, the appropriate machine could weigh anywhere from 8,000 to 20,000 lbs.

“With small dozers, you’re not trying to move a large amounts of material from Point-A to Point-B,” Fritts points out. “You’re trying to maneuver the machine around to move small amounts of material (or for fine grading) in a smaller environment. So in those situations, you don’t need a heavier machine. And horsepower just governs how fast you can move the material — it’s the amount you’re trying to push at one time that dictates how much weight you need to have in the machine.”

But that’s not to say size doesn’t matter. Heavy dozers are still known for unmatched ground hold and mobility through rough terrain, converting their weight and power into enough tractive effort to push massive amounts of heavy material. And since weight still plays a significant role in this equation, several manufacturers have kept their small dozers pretty big — at least from a compact perspective.

Case’s small dozers range from about 14,000 to 20,000 lbs in operating weight and range from 67 to 96 hp, with lengths of available track on the ground from 78 to 93 in. Caterpillar’s smallest line of track-type tractors (the D3G, D4G and D5G) ranges from 16,000 lbs to just over 20,000 lbs in operating weight, while John Deere’s J-Series (made up of the 450J, 550J and 650J) is also at the cusp of heavy-duty classification, with models from 16,000 to 19,750 lbs and 70 to 99 hp, depending on track configuration.

Tracking Down Other Options

At first glance, compact track loaders (also called rubber track loaders or all-terrain loaders) seem to have at least a few of the distinguishing characteristics of a compact crawler dozer. In the last 15 years, these rubber-tracked loaders have carved a niche for themselves as a versatile machine, able to perform grading and landscaping tasks across a variety of difficult ground conditions. And with the added benefit of being able to leave delicate surfaces such as sidewalks and manicured landscapes undisturbed, it begs the question — why not just get a track loader, instead of a small or compact dozer? According to manufacturers, it comes down to a “jack of all trades” argument.

While track loaders might be a more versatile machine — able to utilize a wide variety of attachments — when it comes to straight dozing and grading applications, everyone agrees that there is still no comparison. Throughout the industry, tractive effort, grading ability and overall stability are all far superior on crawler dozers, which according to Case’s Schaefer, allows a small dozer to be dramatically more productive than a compact track loader in certain applications.

“With a dozer, you’re able to dig out harder material than what you can with a compact track loader and the slope capability is also greater,” notes Schaefer.

“In addition, the operator sits further away from the blade on a dozer, so he has the ability to control the grade more easily. And it’s not always the case that a track loader will exert less ground pressure than a small crawler dozer. You have to look at the weight of the machine and the length and width of the track. Some [dozers] can be as low or lower than a track loader. It all depends on the configuration.”

In addition to a variety of worktools, compact track loaders can also utilize a 6-way blade attachment for grading and plowing applications. This can be a good fit for customers who don’t do as much dedicated grading. But according to manufacturers, since the blade is mounted on the loader arm, track loaders also don’t benefit from the ruggedness or precision of grading offered by a crawler dozer.

“There is no question the name of the track loader market is versatility, but small dozers have a few unique qualities that distinguish them and give them a real niche in the market,” Miller says. “In order to offset the weight of an attachment or a bucket full of a dirt, track loaders are constructed more rear-heavy — which takes away from their grading ability because it just doesn’t have the same weight distribution. And as a result of that weight distribution, you’re simply not going to push as much, or have the same productivity with a track loader set up with a 6-way blade, that you can with a dedicated small dozer.”

Nick Zubko is associate editor of Compact Equipment.

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