Design Overhaul Transforms Gradall's 4100

Sept. 28, 2010


This side by side placement of the new XL-4100 Series II (left) and its predecessor, the XL-4100 (right), shows major design differences. The boom cradle, quite large and mounted rearward on the XL-4100, has been repositioned nearer the midpoint of the new model's boom, and the boom's tilt drive has been simplified. The upper cab resides on the right side of the XL-4100's boom, but on the left side of the new model's boom. With no upper engine, the Series II machine has much more compact upper structure, allowing enhanced visibility.
Cabs for the Series II machine are brand new, larger, and feature a clean, precise design.
Weighing in. The XL-4100 Series II test machine carried 13,480 pounds on its front axle and 33,320 on the tandem. The XL-4100 weighed in at 10,170 pounds front, and 36,440 rear. With 52 inches between rear-axle centers, the federal Bridge Formula allows only 34,000 pounds on the tandem (without a permit). Advantage to the new model. The Series II 6x4 chassis uses a Meritor FG-941 front axle with greater capacity than that of the 4100 (14,600 versus 13, 200).
The Series II has a slightly higher rated top speed (53.4 versus 52 mph). Its new transmission, an Eaton Roadranger RTX-14609B FWD 9-speed, has an oil cooler and filter that the 4100's Fuller RTO-11908LL didn't have. A new two-plate, hydraulically actuated  Spicer clutch replaces the 4100's single-plate, mechanical design.
The 4100 Series II begins the second of its two test runs. The operators seemed to make an easy transition between the two cab positions.

In the trenching comparison, operators Bob and Mike Warner each used the 4100 and the Series II, equipped with 0.625-cubic-yard buckets, to open 60 feet of trench, 6 feet deep, in extremely sandy soil. We timed the machines as they worked, measured excavations, then projected per-hour production rates. The Series II tuned in an advantage of approximately 13 percent, the result (in round numbers) of loading 9 percent more material into the bucket on an average cycle (0.85 versus 0.78 cubic yard), and of cycling 4 percent faster. The new model's increased digging forces and greater swing torque account for its superior performance.

Hydraulic refinement and greater swing power likely account for the faster cycle times turned in by the Series II.
Truck Loading

In the truck-loading comparison, operators Mike Warner and John Moulton alternately occupied the controls of both test units to load a tandem-axle dump truck six times with each machine. The test resulted in 69 cycles for the 4100 and 75 for the Series II. The material was sticky clay that ranged widely in moisture content. We timed the machines as they worked and weighed each truckload to determine payload. Based on projected hourly production rates, the new model produced about 6.5 percent more—the result, in this instance, of its faster cycle times.

Electronic control of the more powerful engine in the Series II machine allowed Gradall to dial in an optimum work-power setting.
Fuel efficiency

To determine fuel efficiency, the two machines worked for 90 minutes, digging in sticky, wet soil and simulating a truck-loading motion, that is, loading the bucket, swinging 90 degrees while booming up, then dumping. We checked total fuel consumption using auxiliary tanks weighed across an electronic scale, then determined the per-hour rate. The operators then loaded six trucks with each machine using the same material. From the test, a tons-per-hour production rate was calculated for each machine. Using this number and that for hourly fuel consumption, we calculated fuel-efficiency (volume of material excavated per gallon of fuel). In this application, the tons-per-gallon numbers were 72.45 for the 4100 and 71.76 for the Series II—all but identical.

Buckets for the Series II (from 0.5 to 1.25 cubic yards) have stronger cutting edges and teeth to handle increased breakout forces-and will fit the 4100. Tree-limb-shear and thumb-grabble attachments are new for the Series II and not compatible with the 4100. Gradall buckets can be pinned in a "speed" or "power" position, but few are repositioned in the field from their factory-set speed position.
Breakout Force and Boom Lift

We checked bucket breakout force and boom-lift capability by pulling against an electronic strain gauge, to which we chained, respectively, the bucket lip (via a tooth, top) and the boom (via its lifting hook, bottom). In both tests, the new model was superior, delivering 14.6 percent more breakout and 14.5 percent more lifting power, the latter with the boom level and retracted. (Lifting force was 20.5 percent greater with the boom extended.) Greater breakout force results from tool-cylinder linkage changes and from higher cylinder pressure (4,700 versus 4,300 psi). The boost in lifting force results from greater hydraulic pressure in the boom-lift circuit (4,700 versus 3,900 psi), geometry changes (lift cylinders to boom cradle) and nearly 2,000 pounds more counterweight in the rear-bumper (basically, weight saved from the missing upper engine).

The Series II swing bearing is sealed, requiring no periodic lubrication, as does the bearing in the 4100.
Swing Torque

Using the same fixture as in the breakout and lift tests, we pulled laterally against the anchor to check swing torque. The Series II bested its predecessor by 23.7 percent. Although hydraulic pressure in the new model's swing circuit is considerably lower (4,200 psi versus the 4100's 5,700 psi), it uses a new swing motor with 28 percent more hydraulic horsepower. Also, the new model's swing bearing is 15 percent larger, yielding a greater mechanical advantage. Increased swing torque results in faster swing acceleration that promoted faster cycle times.

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In 1994, when CE tested a new Gradall XL-5200 against its 880E predecessor, we found the radically redesigned new model, on average, to be 85 percent more productive at basic earthmoving tasks. Reflecting on this spectacular increase in productivity, the resulting article's headline asked: "Is This Really a Gradall?"

Introduced in 1993, XL-Series models were milestone products for Gradall, designed to retain the fine-grading ability that built the company's reputation, while also rivaling the productivity of conventional excavators. Fast-forward nine years to this April, when CE tested a next-generation XL machine against its predecessor. We found ourselves again asking: Is This Really a Gradall?

The next-generation machine we tested, the carrier-mounted XL-4100 Series II, is definitely a Gradall. But it's a far different excavator than the machine it replaces, the XL-4100. The new model, of course, embodies the company's hallmark design features—a tilting telescopic boom and a highway-worthy chassis. It also keeps its predecessor's high-pressure hydraulic system, which accounted for the impressive gains in productivity exhibited by the original XL-Series models. Beyond these basic elements, though, nearly every other design aspect is new for the XL-4100 Series II.

Changes range from big-ticket items—the carrier frame, boom, boom cradle, cabs, hydraulic design and engine layout—to detail items, such as dent-resistant fenders, LED swing lights and "plug-in" convenience for adding work lights, cab-sound systems and air conditioning. The net result is a machine that's best described, we think, as fundamentally more efficient than its predecessor.

The new model is more capable (as you'll see from the comparative-test details), it's more comfortable to operate and it's easier to look after. And, obviously, the square corners and yellow paint of the XL-4100 have given way in the new model to sleeker shapes and a distinctive gray-on-gray color scheme.

People and places

The site for our XL-4100/XL-4100 Series II evaluation was Gradall's hometown in New Philadelphia, Ohio. We worked both at the company's factory engineering facility and also at a nearby property that provided plenty of room for trenching.

Gradall people involved in planning and conducting the test with CE included Michael Norman, manager of market development; Brian Warner, senior project engineer; Chuck Schreiner, project engineer; Chad Thomas, senior test technician -instrumentation; John Moulton and Scott Skinner, test technicians; and Mike Warner, demonstration operator.

Our guest operator was Bob Warner, Mike's dad, who's been running equipment for area contractors for more than 40 years.

One engine versus two

Among the most significant design changes between the XL-4100 Series II (we'll call it the "Series II") and the XL-4100 (the "4100") is the new model's use of a single engine, versus the 4100's two engines. The 4100 used a turbo-charged, aftercooled Cummins 6B5.9 in the carrier, and a non-aftercooled version of the same engine in the excavator. Horsepower ratings, respectively, were 200 and 150 (gross). A 245-hp Cummins 6CTA8.3 was an option for the carrier.

Replacing these power plants in the Series II is a single, fully electronic Detroit Diesel/Mercedes Benz 906, rated at 250 horsepower (gross). Positioned in the carrier, the new engine uses air-to-air aftercooling and is emissions-compliant in all 50 states. A three-year warranty replaces the two-year plan for the Cummins engines.

Gradall makes the point that the new Detroit Diesel engine powers hydraulic functions with considerably more muscle than did the upper engine in the 4100, providing 100 additional horsepower and 220 lb.-ft. of added torque. This increased engine capability contributes significantly to the new model's ability to outwork the 4100 in difficult digging—by better than 10 percent, on average, based on the results of our comparative testing.

When propelling the Series II down the Interstate, the new engine's 25-percent horsepower gain and 10-percent torque advantage, compared to the 4100's carrier engine, provides a slightly higher top speed and should give the new model added hill-climbing ability with less downshifting.

The electronic flexibility of the new engine, says Gradall's Chuck Schreiner, allows it to function efficiently both on the highway and at the jobsite. Our test team spent considerable time checking the fuel efficiency of the Series II machine against that of its predecessor in heavy digging, and we found that the new engine gives up nothing in this department.

Gradall also points to reduced engine maintenance as a significant source of cost savings for the Series II user. The single engine in the new model has only one oil sump, one cooling system, one fuel system and one set of belts and hoses. The 4100 multiplies these systems and required services by two. Plus, says Gradall, service intervals are extended, including: 600-hour changes for the engine oil, oil filter and fuel filters (versus 200 hours for the 4100).

Chassis refinement

Series II design changes extend to the machine's very foundation, the carrier frame, which serves both as the chassis backbone and as the platform for the excavator. The frame is an all-new fabrication, using steel that weighs less, yet attains superior strength via sectional properties instead of mass. The frame tapers at its longitudinal midpoint, allowing the excavator to sit lower and to create an overall more-compact package. And, being 6 inches wider than the 4100's frame, the new frame gives the Series II a broader stance (8.5 feet) for increased stability.

The Series II swing bearing, the connection between the chassis and the excavator, is larger in diameter and uses an "internal-tooth" design, which means that the gear on the swing motor engages the bearing's drive gear on its inner diameter. (The 4100 used an "external-tooth" design). The new design allows sealing the bearing and makes it maintenance-free.

Also, a new hydraulic swivel/electric slip ring combination is positioned within the bearing. This device passes hydraulic oil and electricity across the swing bearing, from the stationary carrier to the rotating excavator. The new "swivel" is simpler in design than that used in the 4100, because the latter also had to channel compressed air across the bearing to activate the carrier's brakes from the excavator cab. The new model handles this task hydraulically.

Boom and cradle

Park the Series II and the 4100 side-by-side, and you'll note a big change in the new model's boom and supporting cradle. First, the stationary section of the Series II boom uses contoured gussets from about its midpoint forward to accommodate higher digging and lifting forces. Complementing the main boom's added strength is a stronger telescopic section. A new hose-handling design also simplifies telescopic plumbing, says Gradall, and the telescopic cylinder is now cushioned at both ends, not just on the extend stroke, as is the 4100.

The 4100's boom cradle, which supports the boom and allows it to tilt (rotate), enclosed nearly the rear third of the stationary boom section. The 4100 used a hydraulically powered worm-gear-type drive (located at the rear of the cradle) to tilt the boom, and a system of rollers at the cradle front to support it.

The Series II, however, replaces the 4100's massive boom-cradle arrangement with a much smaller, mid-mounted cradle. The new cradle uses a swing-bearing-type rotation mechanism, which is powered via a hydraulically driven planetary gear set. The new tilt mechanism requires no support rollers (eliminating periodic adjustment), is lubricated for life and incorporates a new integral brake.

Cabs—excavator And carrier

Also on the list of redesigned major structures for the Series II are the cabs—both excavator and carrier—which are, respectively, 5 and 7 inches wider than the 4100's cabs. The new cabs, now supplied by an outside vendor, Angus-Palm, have more glass for considerably improved visibility and are finished by Gradall with entirely new interiors and instrumentation.

Also, the carrier and excavator cabs are now the same basic weldment, with the door on the left side. This means the excavator cab now can be positioned on the left side of the boom, similar to a conventional excavator. Standard seats are a suspension type in the excavator and an air-ride in the carrier. Both cabs are wired for "plug-in" installation of a radio, CD player and additional lights.

The excavator cab also includes an air-conditioner evaporator as a standard part of its climate-control hardware. The air-conditioning system can be completed with a condenser and hydraulically driven compressor, which are assembled as a compact package that mounts neatly (with four bolts) in the excavator's left fender. For cold-weather operation, a closed hydraulic circuit routes hot oil through the excavator cab, making for an effective, 20,000 Btu/hour heater.

Hydraulic refinement

As we've noted, a key design point for the original 1993 XL-Series models was a high-pressure hydraulic system. Series II models refine the system, however, through simplification.

For instance, the 4100 used three big hydraulic pumps—two mains and a swing—driven by the excavator engine and producing 76 gpm. By contrast, the Series II uses only one pump, an axial-piston, load-sensing type that is rated at 77 gpm and driven from the carrier transmission. Pump simplification allows the Series II to get by with only one main control valve, not two as with the 4100. And, the new mono-block valve, says Gradall, eliminates the potential leakage points between the sections of the 4100's stacked valves, and also easily accommodates an auxiliary section—to operate mowers and hammers, for example.

Both machines, of course, can be driven remotely from the upper cab. The remote-drive system in the Series II uses two hydraulic motors that "back drive" into the carrier transmission through two small power-take offs (PTOs). The 4100 used only one motor that powered the transmission through a single PTO. Dual motors, says Gradall, provide more balanced torque loads into the transmission.

The new system also provides two-speed operation, which the operator activates from the excavator cab. Changing remote speeds in the 4100 required leaving the excavator cab, shifting the transmission to a higher gear in the carrier cab, then returning to the excavator cab. Remote operation is further streamlined by electro-hydraulic (versus mechanical) actuation of the system's steering pedals.

A substantial reduction in hydraulic-oil volume for the Series II (55 gallons, compared to the 4100's 95 gallons) further simplifies design (and maintenance expense). The hydraulic oil cooler is now neatly tucked away (with a hydraulically driven, thermostatically controlled fan) in the excavator's right fender. This arrangement simplifies the chassis cooling package, which in the 4100 had the oil cooler stacked with the radiator.

And for modifying the excavator's control pattern, color-coded, quick-disconnect lines are readily accessible at a central panel.

Series II in perspective

Until the early 1990s, Gradall's niche as king of the grading and ditching market was unrivalled, and its machines were in such demand that design updates were infrequent. But as competition increased, and as buyers demanded more versatility from their equipment, the company made up for lost time with its XL-Series models.

Since then, product development has been a key focus at Gradall, evidenced most recently by the new XL-4100 Series II. Based on CE's testing history with Gradall excavators, the new Series II model is the most technically advanced Gradall we've seen yet.

Test Set• New ModelXL-4100 Series II• TypeExcavator• Weight Class20-Metric-Ton• ReplacesXL-4100• AvailableMid-2003