We at Construction Equipment are privileged to have had a front-row seat for significant milestones in the development of Gradall products.
In January 1994, for instance, we worked with Gradall to compare a new XL 5200 crawler excavator with its 880E predecessor in a series of in-the-dirt performance tests. The XL Series was a milestone for Gradall, because these machines marked a fundamental change in both the company’s design philosophy and marketing strategy.
Before the XL, Gradall machines were long famous for their fine-grading performance and were used primarily in that niche market. The new XL design, however, combined that distinctive grading performance with trenching, truck-loading and lifting capabilities that rivaled those of conventional excavators.
Our testing on that occasion found the thoroughly re-engineered XL machine, with its new high-pressure hydraulic system, to be some 85 percent more productive at basic earthmoving tasks than its predecessor. Reflecting on that spectacular increase, the headline of the resulting article in Construction Equipment asked: Is This Really a Gradall? Said Gradall at the time: Buyers no longer need to compromise earthmoving and lifting production for exceptional grading capability.
Then, in August 2003, a Construction Equipment Field Test compared a second-generation XL model, the XL 4100 II highway-speed excavator, to its XL 4100 predecessor. We had another milestone machine on our hands: Not only did the Series II exhibit further notable gains in productivity, but it also incorporated a new boom, new boom cradle, further refinement of the XL hydraulic system, a complete overhaul of the upper cab, and, for the first time in a highway-speed model of this size, only one engine (not two, as in past) to operate both the carrier and the excavator. And the new color scheme first appeared.
In mid-February, we were once more in the dirt with a Gradall machine, this time with a fourth-generation XL machine (the new XL 4100 IV highway-speed machine) that, again, represents a milestone in Gradall technology. The big changes this time are in the undercarriage (the “truck” portion of the machine), which now is equipped with a fully automatic transmission (a first for Gradall), a completely new remote-drive system, and a more powerful Mercedes engine that meets Tier 4-Interim emissions standards. (Download full specifications.)
The new model’s refinement, though, doesn’t stop with these major innovations; refinement pervades the XL 4100 IV’s overall design. All of Gradall’s highway-speed models—XL 3100, XL 4100 and XL5100—have advanced to “IV” (Series-4) status, with the smaller, 160-inch-wheelbase XL 3100 IV available in 4 x 2 and 4 x 4 configurations, and the larger models, with a 171-inch wheelbase, available in 6 x 4 and 6 x 6 configurations.
When Construction Equipment asked Gradall for the loan of a new Series-4 machine that we could place in the capable hands of the Gradall experts at Local 150 (International Union of Operating Engineers) for evaluation, the company arranged for its Burr Ridge, Ill., distributor, Finkbiner Equipment, to deliver a new 6 x 4 XL 4100 IV to Local 150’s training center in Wilmington, Ill.
Local 150 operators Sean Poyner and Chris Tomblin, both instructors for the Local’s Apprenticeship and Skill Improvement Program—and both long-time Gradall operators when working for contractors—spent the better part of a chilly, mid-February day with CE editors while investigating the new features and capabilities of the XL 4100 IV.
Power-train changes
Rated at 245 net horsepower, the new six-cylinder Mercedes OM926 engine in the XL 4100 IV has 16 more horsepower than its Series-3 predecessor. The new engine’s selective-catalytic-reduction (SCR) system, which controls emissions of nitrogen oxides, requires the addition of a 10-gallon tank for diesel exhaust fluid, which can treat around 250 gallons of fuel.
“The exhaust of these new XL machines,” said Bill Thomas, vice president excavator products for Gradall, “is almost as clean as the air entering the engine.”
Although Gradall did use a power-shift-type transmission in its 1985 G3WD, the standard transmission for the company’s highway-speed models in recent years has been a nine-speed Eaton Roadranger coupled with a hydraulically actuated Spicer clutch. That arrangement is replaced by the Series-4 AutoDrive system, which uses a fully automatic, six-speed Allison 3500 RDS transmission with a lock-up converter.
“The new automatic transmission was a matter of convenience,” said Thomas. “Because most dump trucks used by contractors and municipalities these days are automatics, it’s getting more and more difficult to find drivers who can handle a manual transmission.”
Driver convenience aside, additional benefits of the new automatic, says Gradall, are a higher top speed (60 mph, versus 55 mph for Series-3 machines) and faster acceleration from a dead stop. Push-button control allows the transmission to shift in a completely automatic mode, or to be manually controlled with up-shift/down-shift buttons. The system further allows limiting the highest gear attainable in the automatic mode.
Behind the transmission, all Series-4 models use an all-new transfer case. (In the past, only 6 x 6 models used a transfer case.) During highway travel, the transfer case receives the transmission’s input and sends it to the machine’s powered axles. Axles front and rear, powered and non-powered, are all heavier (more carrying capacity) than those on the Series 3, contributing to an enhanced lift chart for Series-4 models.
As evidence of the latter point, Poyner, using a Gradall pavement-removal bucket, picked up a 10-foot section of concrete barrier wall and extended the load over the side to the boom’s maximum extension. In his experience, he said, earlier Gradall models couldn’t have done this.
Practical remote-drive
Gradall’s highway-speed models have always had a remote-drive system that allows the operator to drive the machine from the upper cab. Prior to the Series 4, however, the system used a somewhat complex arrangement of twin hydraulic motors driving through power-take-offs into the manual transmission. By contrast, the new Series-4 remote-drive system uses only a single hydraulic motor that drives directly through the transfer case, thus eliminating use of the transmission and PTOs.
“The new remote-drive system is simpler, more reliable, and more powerful than the previous system,” said Thomas. “Previous machines had a very strong but slow low gear, and a very fast but weak high gear. Everyone wanted something in between, which the new system provides.”
The new system, like the predecessor system, has two maximum-speed ranges, which are 2.5 and 5.0 mph in the new model, selected via a switch on the instrument panel. In either range, says Gradall, the machine has the same amount of power to propel itself across most job sites or along roadside ditches, even in soft soil, without the need to downshift—a common practice with previous models.
A closer look
As Gradall’s Thomas explained the features of the new machine to Poyner and Tomblin during an initial walk-around in the Local 150 shop, Poyner commented on the machine’s shortened tail swing. Thomas explained that the original XL 4100 had a tail swing of 9 feet 3 inches, which was reduced to 8 feet on subsequent models.
“That’s a huge feature,” said Poyner, “because when you’re sitting on a highway doing work, you could be a foot or more into the live lane with a machine this size.”
Thomas pointed out that while the upper-structure frame had changed slightly to accommodate emissions-control hardware, the upper deck and cab are essentially unchanged. In the cab he pointed out controls for adjusting the hydraulic system between “dig” mode and “grading” mode and for switching the electronic joystick controllers among three operating patterns—“Gradall,” “SAE,” and “John Deere.”
“The ability to quickly switch between operating patterns is a real bonus for us as we work with students who prefer one pattern over the others,” said Tomblin. “Using the rotary dial in the cab to switch patterns beats having to switch around quick-connect hoses in a panel outside the cab on earlier models.”
Both operators also noticed a change in the machine’s optional bucket carrier system, which allows securely transporting a second bucket on the deck. The system’s upper bracket (which is attached to the underside of the boom and used with a chain and a second bracket to move the bucket onto and off the deck) had been moved forward. The repositioning, said the operators, would reduce the possibility of the bucket banging into the corner of the upper cab during removal.
Other features that Thomas pointed out on the tour: radial tires; 24-volt electrical system, with 12-volt power provisions in both cabs; standard auxiliary-hydraulics valve; convex mirrors for seeing front tires from the upper cab; flexible fenders; clam-shell-type hood over the engine (in the carrier) providing wide open access to the engine and to the stacked cooling package (radiator, transmission cooler, and charge-air cooler); filter in the hydraulic system’s add-oil circuit; and standard adapter bracket (at the end of the boom) that allows interchanging buckets among all Gradall models.
On the road
After Poyner had taken the XL 4100 IV for a drive on the county roads around Wilmington, we asked for his impressions.
“To be honest, I’m not a big fan of the automatic in a truck, but I could see where this transmission would be dynamite if you’re working block-to-block in the city with lots of stop lights—it would save a lot of wear and tear on the clutch. But, given some time, I might come around to liking the automatic.
“I will say that the higher top speed makes a huge difference. With the older models, about all you could get was 53 mph with a tail wind; this one you can do 60, and it does make a noticeable difference.
“Acceleration is marginally better, and the ride is no worse—but it’s a Gradall, not a Cadillac, and it’s suspended to be stable when working. Everything considered, this one is much better on the road than the Series 2 I’m used to driving.”
In the dirt
After both Poyner and Tomblin had used the machine to trench, grade, load trucks, lift a 10-foot section of barrier wall, and maneuver across Local’s 150’s inside operating arena in remote drive, we solicited their thoughts and comments.
“I was impressed by its digging power,” said Tomblin. “It does seem to have more power, compared with the older machines.”
Poyner agreed: “There was no let-down in performance; I could notice an increase.”
Gradall’s Thomas told us that the added digging power that the operators noticed results primarily from hydraulic tweaks in the boom and bucket hydraulic circuits and from revised geometry of the bucket adapter, which is now forged, not fabricated, to handle the added working forces.
Along with added digging power, the operators also said the machine delivered more precise control:
“I liked being able to slow down the digging motion with a switch in the cab,” said Tomblin. “The slower fine-grade mode would be useful when digging around an obstacle, like a fire hydrant. The engine continues to run at high speed, so you have all the power you need, but you don’t have to be concerned that you’re going to stall the engine.”
Another feature Tomblin liked was the machine’s capability to use the bucket in a face-shovel configuration:
“I was really impressed with the feature of being able to spin the bucket around. If you’re unloading black dirt from a truck to place behind a curb, you could just come it at the tailgate and scoop into it—you’re not jamming all the material up against the gate.”
Changing buckets, however, was a topic of conversation between the operators and Thomas. The operators’ question was one Thomas had heard before: Why no hydraulic quick coupler?
“We’ve been working on the development of a coupler and also working with suppliers to develop it,” said Thomas, “but running more hydraulic lines down the inside of boom is a problem. Electric is not an option, because of the boom’s constant motion.”
Marty Ahrendt, a principal in the Finkbiner dealership, agreed: “Many customers use attachments requiring hoses in the boom; adding a coupler with another set of hoses in there would require some trade-offs.”
Remote-drive power
For both operators, however, the standout feature for the XL 4100 IV was its new remote-drive system:
“The remote travel from the upper cab is fantastic,” said Poyner. “On Series 2 and 3 machines, in a soft-ground situation, you’d have to take it out of high range, because it just wasn’t working; it just wouldn’t move. You’d have to rock it back and forth in low to get it to roll. But this new machine has no problem in soft ground in high range.”
Tomblin agreed: “Sometimes you’d have to lock the differentials to get the machine to move in soft ground. With this new machine, there’s no issue. You can leave it in high range and still move. It has really good speed from the upper cab.”
Summing up
Any further observations?
“I liked the other paint scheme better, but the yellow’s all right,” said Poyner.
Gradall’s Thomas says the color change was a judgment call: “We had some comments that the gray blends in, so we decided to go with a high-visibility paint. It has excellent coverage—more solids in it—and we use a new powder-coat system to paint before assembly.”
Overall, Gradall’s new XL 4100 IV received excellent marks from the operators:
“Sean and I are both long-time Gradall operators,” said Tomblin, “and we were anxious to give the new machine a try when we heard it was coming. Lots of new features compared with the Series 2 we have here at the training center; it’s much more user friendly.”
Said Poyner: “It’s a good-looking machine that seriously outperforms the Gradalls we’ve known in the past. It’s a machine that Chris and I wouldn’t mind running every day.”
