“We’ve tried as much as possible to keep the machine simple, but that isn’t easy when you have a model with the features available on the 95Z7” --Gary Bell, vice president, Kawasaki Construction Machinery America (KCMA).
Kawasaki’s Z7 Series wheel loaders are, indeed, the most technically advanced in the company’s history, with a long list of new features aimed essentially at greater overall efficiency. Z7 technology has so far been applied to three models in the company’s extensive wheel-loader range (85Z7, 90Z7 and 95Z7), and Construction Equipment recently had the chance to borrow the first 95Z7 available in North America for a day’s evaluation with professional operators Chris Tomblin and Lucas Scanlon at Local 150’s (Operating Engineers) training facility in Wilmington, Ill.
Kawasaki 95Z7 Specifications Summary
Engine: Isuzu 6WG1
Horsepower (net): 388
Operating weight: 75,790 lb.
Transmission type: Powershift
Speeds: 4 Foward, 3 Reverse
Hydraulic flow: 89.8 gpm
Hydraulic pressure (main): 4,554 psi
Linkage design: Dual Z-bar
Bucket capacity (std.), heaped: 7.3 cubic yards
Although much has changed on Z7 models, says Bell, the company’s fundamental design philosophy remains at the heart of the new machines.
“We try to keep everything as durable and traditional as possible with this kind of machine,” says Bell. “Fortunately, the Z7 Series’ Intellitec control system combines advanced machine ‘intelligence’ with an intuitive operational simplicity, which means that the machine itself can determine factors within its operating environment and react appropriately, without the operator having to change settings, push buttons, or flip switches.”
CE editors met KMCA’s Mike Dixon, regional product support manager, and Sam Crawford-Shelton, market administrator for KMCA, at Local 150’s facility—some 40 miles southwest of Chicago—where Dixon began the day by explaining the new model’s features and controls to Tomblin and Scanlon. Tomblin then moved the 95Z7 from the shop to the first work site, a stockpile of extremely heavy, wet, sandy material that the operators would load into an articulated dump truck.
New Z7 control features
Tomblin’s first comment when arriving with the machine was how rapidly it shifted as he traveled the quarter mile or so to the site.
Dixon explained that the Z7 Series has a number of new electronic control features, among them a Flex Shift system that automatically alters shift points based on speed and load. The purpose, he said, is to optimize cycle time and to save fuel. He added, though, that a “shift delay” feature that lengthens shift intervals can be selected through the machine’s monitor if the operating situation demands.
Dixon also pointed out the “shift hold” button on the right console, saying that the button can be used to prevent the machine from automatically shifting to a higher gear, for instance, when climbing a long, steep grade. He also showed the operators how to use the monitor to activate the torque converter’s automatic lock-up feature, which provides direct drive in gears two through four to increase travel speed and boost fuel efficiency.
The transmission, said Dixon, features a manual-shift mode and two automatic-shift modes—Auto 1 and Auto 2—which operate the same, except that Auto 2 does not downshift to first gear. Both automatic modes start the machine in second gear as a fuel-saving measure, he said, and downshifting to first gear in any mode is easily done with one of two switches on the bucket lever.
During the truck-loading exercise, Tomblin experimented with the automatic shift systems and preferred Auto 2.
“Even though allowing the machine to downshift to first gear gives the wheels more bite,” said Tomblin, “first-gear operation also has a tendency to spin the wheels. If that happens, then you’re backing up over depressions that disrupt the loading cycle.”
To counter just that situation, said Dixon, the 95Z7’s Intellidig feature is designed to minimize wheel spin by balancing rimpull and hydraulic power, thus preventing the machine from pushing into the pile too aggressively. Our observation as the 95Z7 worked in the stubborn material was that it exhibited not a hint of wheel spin.
Also new for the Z7 Series, said Dixon, is Kawasaki’s Simulload system, which allows simultaneous operation of lift and tilt functions until the boom attains maximum reach (about mid-way in the lift cycle). Above that point, the system provides tilt priority to speed bucket action. Complementing this feature is the Quick-Cycle system, which automatically speeds the boom-raise function and delays transmission up-shift when the machine is approaching a truck with a loaded bucket.
Tomblin liked the simultaneous operation of lift and tilt: “When working in material like this, the tires tend to collapse a bit when you go into the pile, so I usually just pick up the boom a bit. This system makes it easy to keep the loading process smooth.”
Dixon further explained to the operators that the 95Z7 has two “de-clutch” modes, selected with a switch on the right console. When the left pedal is depressed with the switch in the “L” (level) mode, the transmission begins to de-clutch before the brakes fully apply. In the “H” (hill) mode, the brakes fully apply before the transmission disconnects, preventing rollback when negotiating a hopper ramp.
“I think the de-clutch feature is very useful, because it lets you bring up engine speed for good hydraulic action without pushing through the brakes,” said Tomblin. “I understand the reasoning behind giving the operator a choice, but I found very little difference in actual operation between the two settings. Could be that more experience with the machine would make the difference more distinct.”
Local 150’s Scanlon summed up both operators’ take on the 95Z7’s hydraulic action: “I thought the hydraulics were really fast on the machine—no problem there.”
The Z7 Series is the first of Kawasaki’s loaders to use a load-sensing hydraulic system, which incorporates variable-displacement pumps and an open-center valve, a design, says KMCA’s Bell, more typical of hydraulic excavators than wheel loaders.
Kawasaki’s opinion, says Bell, is that the open-center design, versus the more common closed-center, is more responsive and provides better feedback to the operator. Overall, says Bell, the new variable-displacement system uses horsepower more efficiently, providing better performance at lower engine speeds and allowing a more cost-effective cylinder design. The 95Z7 also increases main hydraulic pressure by more than 1,500 psi, compared with its predecessor’s fixed-displacement, gear-pump system.
Preference for the “power” mode
The design feature most discussed by the Local 150 operators was the 95Z7’s ability to boost its engine speed by a significant amount to increase power.
If the machine needs only a short burst of power—for negotiating a steep grade or for getting through a spot of particularly hard digging, says Kawasaki—the operator can push the Quick Power button (on the tilt lever), which stays engaged until the transmission shifts. For sustained higher power, the operator can engage the machine’s Power Mode switch on the right console.
“We want to give the operator the flexibility to get good fuel economy,” says Bell, “so the Z7 Series provides the choice of selecting a ‘normal’ operating mode or a ‘power’ mode. The system defaults to its normal mode.”
Given the material and conditions on site, both Local 150 operators preferred to operate with the power mode switched on. As noted, the machine was handling heavy material in both the truck-loading exercise and a load-and-carry exercise, the latter of which required the 95Z7 to traverse an initial flat segment of approximately 500 feet, make a 180-degree turn at the base of a 70-foot uphill ramp (estimated at a 3-to-1 slope), travel up and over the ramp, then return along the initial flat segment.
As an experiment, we asked the operators to use the 95Z7 in both its normal and power modes during the truck-loading exercise. We also asked them to do the load-and-carry exercise in three stages, each involving several runs: 1) with the torque-converter lock-up disengaged and normal engine mode selected; 2) then add converter lock-up; 3) then engage power mode. We timed each operator as he worked, then averaged their times in each event.
Based simply on the time required to perform these tasks (assuming the material moved to be equivalent), we noted an 8-percent average gain in productivity during truck loading with the power mode switched on, a 7-percent average gain with converter lock-up during load-and-carry, and a further average advantage in load-and-carry of 6 percent with the power mode engaged.
“When we were doing the load-and-carry exercise,” said Tomblin, “I thought that the machine was a bit lagging when you first took off with the load in normal mode and again when negotiating the ramp.
“Comparing performance in its normal mode without the converter lock-up engaged, to its performance in power mode with the lock-up on, there was a significant difference. The machine gained probably two miles per hour on the flat segments of the haul, and its hill-climbing ability was excellent. With the power mode engaged, I was in third gear when I turned onto the ramp, and the machine didn’t downshift until about the crest of the hill—which was a long pull.
“When we were loading trucks without the power switch on, the machine dug into the pile and did the job, no problem. But to be honest, I preferred running with the switch on—then the machine has all kinds of power.”
Scanlon was of like opinion: “The power mode made a difference in both truck-loading and the load-and-carry. In conditions like we had today, I’d be inclined to keep the power mode engaged. In other situations, the economy mode might be fine, but in applications like this, I think you need the extra power.”
Both operators also gave the 95Z7 high marks for acceleration in the power mode. Kawasaki has designed the engine-control system to recognize how much throttle can be efficiently utilized in a given situation, then to adjust engine speed to that optimum level without jeopardizing acceleration. In addition, if the engine is running at normal temperature, the hydraulic fan is slowed or stopped to divert added horsepower to the drive train during acceleration.
Operator’s station, serviceability
A newly engineered cab for the 95Z7 uses redesigned viscous mounts, added insulation, and redesigned seals to bring interior sound levels down to 72-74 dB(A), says Kawasaki. The new cab features full-length glass doors, adjustable right console, and a new monitor that allows setting operating parameters, viewing rearview camera images, and investigating diagnostic codes.
“The cab is roomy and very comfortable,” said Tomblin. “I thought that using the monitor to set boom kick-outs and to change the setting on the converter lock-up was quite easy. It wasn’t difficult to navigate; everything is there for you.”
Both operators thought the 95Z7’s service access was convenient and safe: “Chris and I were both impressed with the serviceability aspects of the machine,” said Scanlon. “It’s wide open—the way the fenders swing out and lock and the inner panels hinge up and lock—you don’t have to be concerned about panels shutting or falling on you. You can get to service points with no problem.”
“It’s a very solidly built machine,” said Tomblin. “It’s well put together and has all the bells and whistles that an operator might want.”