Case 850K dozer
| June 12, 2007 |
Hydrostatic drive dozers have become the norm, but Case Construction Equipment engineers were unconvinced that hydrostatic powertrains could provide contractors with Case’s traditional strength: its PowerTurn steering system, which allows operators to carry a full blade of dirt through a direction change. And Case customers were clear on that point as well: If the company was going to introduce a hydrostatic drivetrain for its dozers, then it was essential that PowerTurn capability be retained. According to Rusty Schaefer, marketing manager, that meant looking at hydrostatic drive systems in a whole new way.
The result was a new Case-designed hydrostatic-drive system. “This hydrostat drive was specifically designed for our new K-series dozer line,” Schaefer explains. “It’s an electronically controlled hydrostatic system with a straight-tracking control feature. In essence, the electronics control the dozer so precisely that wherever you position the machine, that’s where the machine will go without any additional operator input. And that straight tracking doesn’t vary by load. It’s a great tool for increasing productivity and reducing operator fatigue at the same time.”
Another nice feature the PowerStat system gives K-series dozers is full counter-rotation. “So these machines have the maneuverability required to allow you to work on congested jobsites and in tight areas,” Schaefer adds.
He says traditional hydrostat drives have been sized to take 100 percent of a machine’s power through both sides – when they tried to route power through just one track, they only managed to get about half of the potential horsepower to the ground. This made full-blade turns problematic.
“But with our PowerStat, we’ve sized our hydrostatic components much larger to take more of the available hydraulic power through one side,” Schaefer says. “That does several things: it lowers the operating system pressure while you’re doing much of the operation. Also, when it comes to turning, you can put almost all of the power through one side. So we’re still able to maintain the advantage we had with our PowerTurn technology. We can’t route all the hydraulic power to one track, but we can get a higher percentage of the power to a track.”
Pulling power is important in dozing applications, and Schaefer says Case engineers were determined to retain that feature with the new hydrostat-drive system. “You can see this reflected in the drawbar pull of this machine,” Schaefer says. “In stumping and hard dozing applications, these machines will push hard with ample low-end torque.”
Undercarriage design tweaks enhance PowerStat capabilities
On a warm summer day, we met with Schaeferat Northern Michigan Equipment, based in Traverse City, to conduct a K-series walk-around and test run. Right off the bat, it was apparent that although Case designers have made radical powertrain changes to this new dozer line, they were also careful to preserve many popular features that Case customers have come to know and depend on.
That philosophy starts up front. All K-series dozers are still powered by Case’s CDC diesel engines. The two smaller dozers (650K and 750K) have the four-cylinder, turbocharged engine, while the 850K features the six-cylinder, turbocharged diesel.
Taking cues from the H-series dozer line included retaining the older dozers’ comfort levels and ease of operation. “We know contractors have a hard time getting good operators,” Schaefer says, “and good operators are looking for dozers that allow them to work better. Ease of grading is a typical application. So our redesign included improving sight lines from the cab to the blade and the areas behind the blade. The dashboard and the dozer’s nose are tapered in dramatically to ensure those good sight lines, regardless of the situation you’re in.”
Realizing that undercarriage improvements could enhance the PowerStat’s straight tracking capability caused Case designers to add an additional bottom roller, which increased the 850K’s overall track length to 93 inches.
At the same time, some simple design characteristics were added to the undercarriage, including a noticeably more open profile. The undercarriage itself now has an extremely high taper, and the track frame covers are also tapered at a high angle. These high taper angles allow the undercarriage to shed any excess mud or material off a lot easier. “In a lot of areas where you’re working in freeze conditions, those tracks have to be cleaned every night,” Schaefer says. “And some operators can spend up to an hour a day cleaning out the undercarriage. But with this new design, any accumulated material will fall off a lot easier when the machine is working, making it much easier to clean around the sprocket areas and the main frame when the day is done.”
On-the-spot blade pitch changes, tilting cab among new serviceability features
Design work in other areas gave K-series dozers improved serviceability for routine maintenance checks, engine/powertrain repair work and on-the-job blade adjustments. Case engineers added a built-in pitch-changing tool mounted on top of the blade, which moves it forward or backward from 52 to 60 degrees, to perfectly match the type of material you’re working in. “If you want to roll your material more you can tip the blade back,” Schaefer notes. “Or if you want to carry a bigger load you can tip it forward. It’s a nice thing because you don’t need any special tools and it’s infinitely variable, so you can set it to your own personal preference.”
Serviceability access was improved by adding a swing-out front grill for easy access to the radiator and front of the engine compartment. Additional swing-out side shields on the engine area provide full access to the remaining portions of the engine compartment and allow for easy daily maintenance checks.
One notable new feature is an easy-tilting cab design that allows fast access to the all-hydrostatic- drive pumps and components. “You don’t have to get in there for daily maintenance,” Schaefer says. “But if you have major repair work required, it only takes about 10 minutes to tip the cab over and out of the way.”
Michigan contractor takes hydrostatic step
Once our walk-around was complete, it was out into the Michigan countryside with Northern Michigan president Jeff Dohm, sales rep Rick Smith and Schaefer to visit Tim Fisher, president and owner of Fisher Corporation. Based out of Traverse City, Fisher has been in business since 1972, doing site prep work and digging basements. His operation is small by choice. On the day we visited him, Tim was digging a basement on his week-old 850K.
Fisher has been running Case dozers in the abrasive Michigan soil since he founded his company. Like many Case customers, he’d resisted hydrostat machines as they came into the market. “I knew I was going to have to upgrade to a new dozer,” the soft-spoken Fisher says. “In fact, I’ve spent the last four years trying to figure out which model I wanted to replace my existing Case dozer with. I was testing various models, and the transition between what I was used to for all those years with Case and hydrostatic machines wasn’t real comfortable for me. I do more than just push dirt. I do a lot of stumping too, because this is a heavily forested region of the country. But there always seemed to be a power loss when it came to getting stumps out of the ground.”
Fisher says productivity is number one with him when it comes to judging equipment. “I’m used to very fast dozers,” he notes. “And to get good speed, you have to have good hydraulics.”
Ask Fisher about specifics and control is the first thing he mentions. “I like the way the operator can control everything from one spot,” he says. “You’re not reaching all over for the controls. Minimum effort is required to control the blade. Overall machine feel is very smooth and natural. It’s not cumbersome at all.”
From our partners
People often ask us why they can’t use hydraulic oil in their off-highway equipment. They’re interested in saving money, and…