More Machine Runs on Less Fuel

Sept. 28, 2010

While we don't think that the "E" in the new Case 821E's model designation stands for "efficient," the word nonetheless seems appropriate for summing up this new wheel loader's overall design and performance, both of which CE editors had the chance to investigate first hand when spending a day in the dirt with this new machine. That day was in mid-April, when we worked with Case to run the 821E head-to-head with its predecessor, the 821C, in a comparative study of production capacity and fuel efficiency.

As we quickly discovered, the 821E is a significantly different machine than its predecessor. Checking off just the major items, we noted a new Tier-3-compliant Case Family IV diesel engine, new hydraulic system, innovative new cooling package, redesigned loader linkage, redesigned bucket, and all-new cab. But also not to be overlooked are such items as the new model's auto-idle system, temperature-controlled fan, cushioned steering cylinders and enhanced serviceability (lubed-for-life drive shafts, for example).

Case's expansive Arizona proving ground (near Phoenix) was the site for the 821C/821E evaluation. Our 821E test unit was virtually brand new, supplied by Sandpiper Rentals, a division of Falcon Power, a Case dealer in Phoenix. Sandpiper's rental account manager, James Bagshaw, also supplied a low-hour 821C for the evaluation.

The 821C was fitted with a 4.0-cubic-yard (heaped) general-purpose bucket, the largest bucket available for this model. The 821E used a 4.25-cubic-yard general-purpose bucket, which Case considers the standard bucket for the new model. Both buckets were fitted with teeth and segments.

Talking with Case prior to the evaluation about bucket sizes for testing, we concurred that the 821E's ability to handle larger buckets than its predecessor (up to 4.5 cubic yards) is an integral aspect of its enhanced design, and that using the larger bucket on the new model was justified. Both machines used 23.5–25 L2 tires — bias-ply for the 821C and radial for the 821E.

David Boone, project superintendent for Mountainside Materials in Tempe, Ariz., and Michael Tennant, Case's western-region product specialist — both proficient wheel-loader operators — ran the machines during the evaluation. Also on site for the evaluation were Case's Dave Wolf, marketing manager for heavy-range products; Dave Natzke, program manager and platform engineer for wheel loaders; and Trever Bayer, test engineer. Proving-ground supervisor, Carl Fowler, loaned us Quincy Walker, 2nd-shift leadman, and Mike Stacy, test operator, to maintain the stockpiles during the production studies.

The machines worked from stockpiles of heavy desert soil (estimated at 3,000 pounds per cubic yard). The material contained a high percentage of fines mixed with rock that ranged from 2 inches to more than 12 inches in diameter. The production testing simulated a short-cycle truck-loading application and a hopper-charging application — "simulated," because the machines dumped over barriers that represented the truck and hopper.

Both machines were fitted with an auxiliary fuel tank, which was refilled after each test run with fuel weighed across an electronic scale. But tanks were not refilled until temperatures were determined for fuel remaining in the tank (after a test run) and for replacement fuel. Temperature measurements provided the data to adjust replacement-fuel volume (if required) to compensate for hot-fuel expansion.

You'll find the results for the evaluation summarized in an accompanying sidebar. The thumbnail version here, however, is that the new 821E demonstrated an impressive fuel-efficiency advantage (material produced on a gallon of fuel) over its predecessor. Reducing fuel consumption was among the crucial design goals for the new E-Series loaders, and meeting that objective, say Wolf and Natzke, required careful engineering analysis to lessen parasitic loads and to build efficiency into the 821E's overall design.

Power choices, efficient cooling

Among the most innovative aspects of the 821E's design is its fully electronic, multi-horsepower engine, which, with a 6.7-liter displacement, is nearly 25 percent smaller than the 8.3-liter engine used in the 821C. The new six-cylinder diesel, which employs a common-rail fuel system and charge-air cooling, is a product of the CNH Engine Group, involving Case and Cummins (the original joint-venture partners in the Consolidated Diesel Co.), and now Iveco. The 821C's engine had a single net horsepower rating (186) and a single net peak-torque rating (671 pounds-feet). The engine in the 821E, however, has three net-horsepower ratings (181, 198 and 213) and three corresponding net-peak-torque ratings (693, 701 and 712 pounds-feet).

Using the monitor in the cab, the operator can select one of the engine's three horsepower curves — maximum, standard or economy — to suit the application. For instance, handling pipe might be done in the economy mode, loading loose material might best be done in standard, and digging in a dense stockpile might be a job for the max mode. Or, if the application involves a mix of chores, then the operator might opt for the automatic mode, which allows the engine to switch between the max and standard modes as sensors in the control system report turbine torque from the transmission and load on the implement hydraulics.

The logic behind the three horsepower curves, says Natzke, is to promote fuel economy. The electronic control for each mode, he says, uses a programmed matrix that determines the fuel-delivery rate (grams per stroke) for any given throttle position. The three curves are initially identical to ensure sufficient low-end power, says Natzke, but diverge at about 1,200 rpm to provide their own specific power and fuel-usage characteristics. All three curves, however, have the same rpm operating range, he says, which means that hydraulic capability is not compromised in any of the modes.

Adding to the overall design for fuel efficiency in the 821E is the new auto-idle system, which drops the engine's normal low idle of 900 to 600 rpm if the throttle or hydraulic controls are not used for 30 seconds. Also, to assist with fuel-system efficiency, the 821E uses a fuel cooler to maintain consistent fuel density in the common-rail system. (Fuel absorbs heat and expands as the machine works.) Cooler fuel also helps extend fuel-pump life.

The 821E's fuel cooler is but one component in a completely new cooling package (compared to that of the 821C). The 821E employs Case's mid-mount cooling module, first used on its D-Series loaders and consisting of a specially contoured hydraulic tank that is surrounded in cube fashion by the engine radiator on the left, separate transmission and hydraulic coolers on the right, charge-air cooler and air-conditioning condenser on top, and the fuel cooler at one end.

At the other end of the cube is the hydraulically driven fan that pulls ambient air through the coolers and across the tank. Unlike the hydraulically driven fan in the 821C, however, the new model's fan is temperature controlled and can run at speeds proportional to cooling demands, thus conserving considerable fuel and reducing sound levels. (The 821E, by comparison with the 821C, is an extremely quiet machine.) And, while the operator of either machine can reverse the fan to purge the coolers, the 821E also has an "auto-reversing" feature, which allows the fan to automatically send a cleaning blast of reverse air through the coolers at 30-minute intervals.

Because the new cooling module resides just behind the cab in the rear frame, the space at the rear of the machine (usually consumed by a conventional cooling package) can now be used to move the engine rearward, behind the axle, where it serves as a natural counterweight. Plus, the hood can now be sloped more steeply for enhanced rearward visibility.

More efficient loading

Also among the fundamental changes between the 821E and 821C is the design of the new model's hydraulic system. The 821C's open-center system used a tandem, fixed-displacement vane pump to produce a 79-gpm oil flow for the implement and steering systems. The two pump sections (which displaced a constant volume of fluid on every revolution) continually pumped oil, the rate of flow dependent upon engine speed. The excess flow that was inevitably produced (that is, oil pumped, but not needed) was directed back to the hydraulic reservoir through the open center of the main valve.

By contrast, the 821E's system is a closed-center, pressure-compensated, load-sensing type that uses two variable-displacement pumps. While main-relief pressure is 3,600 psi in the 821E's system (up considerably from the 821C's 2,810 psi), maximum oil flow is reduced by approximately 20 percent. Unlike the vane pump in the 821C, the 821E's variable-displacement piston pumps adjust flow to match hydraulic demands. As a result, the pumps produce no excess flow, thus saving engine horsepower and fuel, while generating less heat.

Also, the 821E's system can direct full flow to either the steering or implement systems as needed. And with the new model's 28-percent gain in implement-system pressure, cylinder size can be reduced with no compromise in optimum breakout force.

Complementing the increased power and efficiency of the 821E's hydraulic system is its redesigned loader linkage. Basically, the linkage has been reconfigured to accommodate changes in hydraulic forces, says Natzke, resulting in a geometry that provides added breakout force. But the new linkage also reflects practical refinement. For example, the boom-to-bucket pins are mounted higher on the back of the bucket to keep them cleaner, and split O-rings at all bucket-pivot points help retain lubricant and reduce contaminant infiltration.

Redesigned, too, is the bucket, which incorporates a cutting edge that is longer and less blunt than that of the 821C, allowing it to slice more effectively into the pile. Plus, the floor is now inclined upward at a 5-degree angle toward the back of the bucket, allowing a smoother flow of material. In addition, the new bucket is more stout overall, using heavier reinforcement under the floor, a thicker shell at the top, added gussets and heavier bolt-on heel plates that afford more protection in abrasive materials.

Refined cab, easier service

The 821E's all-new cab has a 15-percent larger floor plate, and floor-to-ceiling front glass enhances the view to the bucket and front tires. The standard loader control is a single joystick with an integral directional-shift switch and a downshift button. Multiple control packages are available, however, and the conventional shift lever on the left of the steering column is still there. A single brake pedal (with adjustable transmission disconnect) is standard, but dual pedals are available for operators who prefer this arrangement.

The front panel includes new analog gauges (a request from customer focus groups) and a new digital display that provides real-time operating information (including fuel-consumption rates), allows access to diagnostic data (with user-friendly text messages) and facilitates programming operational modes. A new switch panel in the right console is positioned within easy reach of the operator's fingertips, and a total of 18 diffusers in the cab direct airflow in just about any fashion. A 12-volt outlet and pre-wiring for a radio add to overall convenience, as does a thermal storage compartment.

Enhanced serviceability, another primary objective of the E-Series design, gets a boost from a powered hood, which, when raised, provides easy, ground-level access to all routine service points, including sight gauges for all fluid checks except engine oil. Easily removed inner fenders (just one thumbscrew) allow further access to the engine and cooling module, as do pull-up side sheets forward of the hood.

At the articulation joint, steering cylinders have been moved up to keep them cleaner, and fewer hydraulic hoses pass between the frames. Moving the 821E's engine rearward and extending its wheelbase also open up this area for easy transmission access.

Remote drains for engine oil, coolant and hydraulic fluid make changes tidier, and a sealed glass cover over the fuse panel provides ready access to the electrical system, while protecting against pressure washers. Only the carrier bearing in the driveshaft system needs lubricating (and that's done via a remote zerk), and right-hand steps facilitate window cleaning. A new cab air filter has been relocated, uses a radial seal, and provides longer service life.

"If I can get a technician involved in a machine walk-around," says Wolf, "I have this machine sold."

Case's suggested list price for the standard version of a ready-to-work 821E is $225,335, which compares to the last suggested list for a comparable 821C at $221,017.

Case 821E wheel loader 
The Case 821E is essentially a different machine than its 821C predecessor, in-corporating a new engine, new hydraul
The Case 821E is essentially a different machine than its 821C predecessor, in-corporating a new engine, new hydraulics, new cooling system and new cab.
Fuel measurements included weighing replacement volume, as well as checking temperatures.
The 821C has little in common with its successor, except a similar ZF transmission and similar ZF axles.
During the evaluation, material weights were recorded by an RDS LOADLOG 8000 on-board weighing system, which provided a cycle-by-cycle printout of results.
The 821E's tilt-up hood (electrically raised) provides wide-open access to routine maintenance points. Removable inner fenders below the hood further increase service access, as do pull-up side sheets (forward of the hood) and a tilt-up panel above the cooling module.
821E Shows Fuel-Efficiency Advantage

The 821E/821C evaluation consisted of two production studies — hopper charging and short-cycle truck loading. Each study involved six, separate, 20-minute tests, because each of the two operators ran the 821C, the 821E in its economy mode, and then the 821E in its maximum mode.

In the hopper-charging study, the machines loaded from a stockpile, reversed, then traveled forward up a 30-foot ramp, at the top of which was a bar set at about 10 feet to represent a rock-crusher's grizzly. In the truck-loading study, the machines again loaded from a stockpile, reversed, then traveled forward a short distance and dumped over the top of a barrier representing a large dump truck.

The summary numbers presented here are based on averages calculated from the 12 test runs, which involved a total of 539 loading cycles and four hours working time. The percentages represent the 821E's performance, relative to that of the 821C.

Test SummaryMeasurement821E advantageHourly production: maximum mode10%Hourly production: economy mode-3%Fuel conserved: maximum mode*4%Fuel conserved: economy mode16%Fuel efficiency: maximum mode**14%Fuel efficiency: economy mode12%* "Fuel conserved" — In two hours of running time, working at the same tasks, the 821E consumed 4 percent less fuel in its maximum mode, and 16 percent less fuel in its economy mode, than did the 821C.** "Fuel efficiency" — Material moved per gallon of fuel

In this story:
Operating Specifications
821C 821E
*821C w/4.0-cu.-yd. bucket w/teeth; 821E w/4.25-cu.-yd. bucket w/teeth
As the accompanying table illustrates, the 821E is a larger machine than its predecessor, including a longer wheelbase and wider track. Note, too, that the new model lifts higher(by nearly 7 inches) and lifts stronger to full height (nearly 4,500 pounds more).
Wheelbase (in.) 125.8 131.5
Overall length (in.)* 308.7 314.7
Width, centerline of tread (in.) 82.0 87.5
Height to top of cab (in.) 131.1 135.8
Bucket hinge-pin height (in.) 155.6 162.3
Lift capacity, full height (in.)* 16,221 20,615
Approximate operating weight (lb.) 37,900 37,900