Step into the cab of a new Gehl 40-Series skid-steer loader—as we did on a recent visit to the company's Madison, S.D., facility—and you can take note of a few design details that reflect the thoughtful engineering of these new machines.
As you step across the bucket, notice that the optional new Power-A-Tach coupler is electrically—not hydraulically—actuated, an interesting approach to automated couplers. If you brush against the top of a tilt cylinder as you enter the cab, no worries. The top pivot of these cylinders now uses a greaseless composite bushing, which means no more grease stains on pant legs. And as you settle into the cab's new suspension seat, take note that elbow room is plentiful, gauge panels are angled to reduce glare, control handles are ergonomically styled and optional climate-control ducts are molded unobtrusively into the cab's interior panels.
CE editors visited Madison in mid-September to work with the Gehl engineering and marketing folks to compare the design and performance of the company's new 40-Series machines with those of their 35-Series predecessors. The test site was the company's new training area, adjacent to its ever-expanding production facility, which now also produces all models of the Mustang skid-steer line.
We talked first with Marvin Joray, director of engineering; Tracy Lammers, senior project engineer; and Bob Lewandowski, engineering test coordinator, who gave us an overview of design differences between the two series. Then, a walk-around with product manager Kelly Moore and marketing services coordinator Lori Heidecker filled in the details. According to Moore, the four new models (4640, 4840, 5640 and 6640), with standard rated operating loads from 1,500 to 2,400 pounds, compete in a market segment that accounts for an estimated 70 percent or more of total skid-steer sales in North America.
A primary goal in replacing four of its 35-Series models (4635, 4835, 5635 and 6635) with comparably sized new machines, says Moore, was to expand the company's potential in this important market. Aiming for that target, he says, meant engineering the new 40-Series models with enhanced performance and greater comfort and convenience for the operator. Of course, says Moore, the timing for replacing the four 35-Series models, introduced in the mid- to late-1990s, was influenced by the requirement to incorporate Tier-II engines in these model sizes.
We picked the center two models from the new 40-Series line (the 4840 and 5640) for evaluation. We ran these new models against their predecessors, the 4835 and 5635, in four exercises: excavating, truck-loading, trenching and traveling. You can pick up on the details of the comparisons in the test summary section of this report, along with some thoughts about the results.
But for a thumbnail version of the results here, the new models, on average, exhibited 22 percent better productivity in the dirt-work comparisons. And, as it turned out, they had a 22-percent average fuel-efficiency advantage, based on the excavating and trenching exercises. Skid-steers, of course, are utility machines, not production machines, but the numbers, we think, do serve as an index of sorts for relative performance differences, as well as for potential operating-cost savings.
At the heart of the new 40-Series design is the Deutz 2011-Series diesel engine, which replaces the previously used Deutz 1011-Series. Like the former engine series, 2011 engines are completely oil cooled and circulate their lubricating oil through a "conventional" cooling system that includes an external, oil-to-air heat exchanger. The 2011 engines also reflect similar overall architecture, but they have significantly higher injection pressures (for emissions control), as well as appreciably larger displacements.
Specifically, the 4840 uses the four-cylinder, naturally aspirated F4M2011 engine, rated at 60 net horsepower, compared with the 4835's three-cylinder, turbocharged BF3M1011F with 57 horsepower. The new engine is nearly one liter larger in displacement than its turbocharged predecessor (3.1 versus 2.2 liters) and produces 7 percent more flywheel torque.
Likewise, the optional turbocharged version of this engine (BF4M2011) used in the 5640 is larger than the four-cylinder, turbocharged BF4M1011F in the 5635 (3.1 versus 2.9 liters). Again, horsepower ratings for these two engines are close, 80 net for the 5635, and 82 for the 5640. Engine torque, though, is up 13 percent in the 5640. For more specifications, go to constructionequipment.com.
Although the servo-controlled Eaton pumps and Poclain radial-piston motors in the drive system have been tweaked for greater efficiency in the new models, the significant change in the drive train is simplification inside the chain case. The 35-Series machines used an idler system for adjusting the chains, necessitating opening the case to gain access. The 40-Series machines, by contrast, use a simple "bow-tie" chain configuration, and adjustment, should it become necessary, is handled externally by sliding the axle housings on their mounting bolts. The new design, says Gehl, reduces components in the chain case by 25 percent. The cases are sealed, of course, and the chains run in an oil bath.
The most significant structural change for 40-Series models is the new ROPS/FOPS (roll-over/falling-object protective structure). The basic design of the new structure is borrowed from the larger "muscle-series" machines, the 7610 and 7810, which have standard rated operating loads of 3,400 and 3,675 pounds. As applied to 40-Series machines, the enclosure is some two inches narrower than that for the 7000-Series, but still about 1.5 inches wider than the enclosure used on the 35-Series.
The new ROPS/FOPS (besides having more interior room, a contoured roof that sheds water rearward and a sound-attenuating headliner) is a Level-II-certified structure, as was that of 35-Series models. "Level-II-certified" means that, in the test lab, the structure must deflect three top hits from a 500-pound steel cylinder (10 inches in diameter and 23 inches long), dropped from a height of 17 feet. In terms of energy absorption, says Gehl, that's about eight times more than a Level-I-certified structure, which must withstand three hits from a 100-pound, 10-inch-diameter steel ball.
Although the 40-Series maintains the company's Powerview load-arm design, introduced with the 35-Series, the load arms on the new models do use a redesigned "knee," the point where the basically horizontal and vertical sections of the arm are joined. According to the company, the new design yields more strength, as well as providing a styling enhancement.
At the end of the lift arms is one of the 40-Series' most innovative structures: the new electrically activated Power-A-Tach coupler. The optional new coupler can be installed at the factory or in the field to accommodate universal-type attachments. Gehl engineers had designed a hydraulically actuated coupler, says Moore, but favored the simpler electrical design, which could better protect itself from binding caused by debris, lack of lubrication or misalignment.
The Power-A-Tach system uses a sealed, 12-volt, motor-and-screw arrangement to power the coupler mechanism. The system has an override clutch that is designed to ratchet if binding occurs, and also uses an electrical overload device. Large red tabs at the top of the coupler indicate to the operator whether the locking pins are in the retracted or engaged position. But, says Moore, no matter what coupler system a machine may use, it's always good practice to visually inspect the locking pins for proper engagement.
Small, but notable structural design items include reconfiguration of the loader towers, redesign of the rear bumper and reconfiguration of the grab handles at the lift-arm knees. Instead of being square with the knees as on the 35-Series, the handles have been angled 45 degrees, enlarged and canted inward, making them much more ergonomically friendly. Also, grab handles have been added at the front inside edges of the ROPS/FOPS structure to assist in exiting the cab. The new rear bumper, which serves as the optional weight kit, provides more protection and incorporates a step and an integral hitch for jobsite towing chores.
Gehl obviously spent lots of design time on the new 40-Series cab. A new suspension seat, for instance, adjusts to operator weight, and a brand-new air-conditioning/heater/defroster system is factory-available for the 4840 and larger models. The new system provides higher airflow, internal ducting (in the cab's side panels) and adjustable louvers. Side-window and cab-door options are new, as is the "door-open" sensor, which locks out loader-arm and tilt cylinder functions when the door is ajar. It's a simple way to help the owner avoid damaging the door, says Moore.
The vertical instrument panels on the forward ROPS/FOPS posts have been angled to reduce glare, and an automatic engine-shutdown system is now standard equipment, activated if the system senses high engine temperature or low oil pressure. The new panels also incorporate electrical circuit breakers, and the 40-Series' electrical system has been extensively overhauled, with more breakers to distribute electrical loads and new harnesses that offer "plug-and-play" capability for quickly adding electrical accessories. Halogen work lights, front and rear, are standard on the new models.
Although the 40-Series offers three control options (the "hands-only" Gehl T-Bar, hand/foot or dual-hand), the Gehl system is chosen about 70 percent of the time, says Moore. Control-lever handles, no matter which of the options is selected, now use ergonomically designed grips, which use integral push buttons to activate the new Hydraglide ride-control system, two-speed travel system or horn (all options).
When fitted with a two-speed system, machines are equipped with a retractable, three-point seat belt, and the restraint bar is now infinitely adjustable in small increments, up or down, to more easily accommodate operators of all sizes.
Everything considered, we think these new 40-Series models take a significant stride forward from their worthy predecessors in terms of technical design and operator amenities.
Overview: We conducted the excavating, trenching and stockpile-loading comparisons at the Gehl training facility in Madison, S.D., where the soil is primarily a moist loam. All test machines had fewer than 300 hours. The 4835 and 4840 used their standard oil-cooled Deutz diesel engines, a three-cylinder turbocharged and a four-cylinder naturally aspirated, respectively. The 5635 and 5640 used their optional turbocharged four-cylinder Deutz engines. Bucket width was 70 inches for the smaller machines, 74 inches for the larger.
Operators for the comparisons were Gehl product manager, Kelly Moore, and test technician, Lance Lund. In each comparative test (except the speed trials), both operators ran both machines for an equal time. We checked fuel consumption by topping off the tanks with fuel weighed across an electronic scale, after the machines had returned to a designated fueling area.
The summary percentages indicate the "advantage" that each 40-Series machine had over its predecessor, that is, the 4840 compared to the 4835, and the 5640 compared to the 5635. The relative differences in productivity and fuel efficiency (material/distance moved per gallon of fuel) are specific to the conditions encountered during the Madison test.
Observations: We came away from the test with two basic thoughts. Because the hydrostatic-drive systems and implement hydraulic systems are virtually identical between the new models and their predecessors, could it be that the Deutz 2011-Series engines (with larger displacements and more flywheel torque) drive these systems more effectively and, thus, become prime contributors to the observed increases in productivity? Could it be, also, that gains in fuel efficiency are the result of better fuel management in these new Tier-II engines?
|4840 Advantage||5640 Advantage|
|Productivity: 30%||Productivity: 29%|
|Fuel Efficiency: 29%||Fuel Efficiency: 24%|
|In the excavating comparison, we timed the operators as they dug basement-entry ramps and loaded spoil into a waiting tandem-axle truck, which was weighed to determine payload.|
|4840 Advantage||5640 Advantage|
|Productivity: 22%||Productivity: 30%|
|Fuel Efficiency: 17%||Fuel Efficiency: 20%|
|In the trenching comparison, each set of test machines operated side-by-side for a set time, then the operators switched units and duplicated the run. Trench depth (36 inches) was continually monitored. All test units used a standard-flow auxiliary-hydraulic system with identical Lowe trenchers.|
|4840 Advantage||5640 Advantage|
|Productivity: 11%||Productivity: 14%|
|As the truck returned from its weigh-in runs with spoil from the excavating test, we stockpiled the material and then used it for the loading comparison. In this exercise, the machines worked from the pile, reversed a short distance, then turned 90 degrees to the truck.|
|Rated capacity (std.)||1,700 lb.|
|Rated capacity (opt.)||1,850 lb.|
|Available||1 st Qtr. 2004|
|Rated capacity (std.)||2,000 lb.|
|Rated capacity (opt.)||2,300 lb.|
|Available||1 st Qtr. 2004|
|*Suggested list prices for base units with 12.00 x 16.5 HD flotation tires, as of 7/1/04.|