How Technology is Simplifying Wheel Loader Operation
By Curt Bennink
With skilled operators harder to find, new technologies can help fill the void by easing the burden for both novice and skilled operators alike.
“I have trained a lot of people over the years,” recalls John Chesterman, product marketing manager for production class wheel loaders, Deere & Company. “Probably the most common mistake is they are not entering the pile with the bucket level. Almost every wheel loader has a return-to-dig. If it is properly set, it is a feature that can at least get the bucket level to the plane of the tires to go into the pile.”
Automating bucket functions reduces the operator’s workload. “There have been several technologies integrated with hydraulic controls which simplify operation and help less experienced operators be more productive, such as Automatic Bucket Leveling, which allows the operator to self-level the bucket without having to manually manipulate the bucket position,” says Chris Connolly, product manager, GPE products, Volvo Construction Equipment. “Another feature is the Boom Kick-Out, which is beneficial to operators if they are loading a truck to one height all day long. The operator just performs one stroke of the lever rather than having to hold the lever.
“To assist with returning the bucket to a set level with one stroke, we have… Return-to-Dig, which moves the boom down to a preset height with a push of the lever,” he adds. “These features are excellent for making operation smoother and helping to reduce cycle times.”
“Controlling the lift arm and the attachment precisely is a challenge for novices,” notes Martin Koller, Liebherr. “Having the bucket in the right position is vital for entering into the material effectively. With the help of the new electrohydraulic (EH) system, lift arm and bucket positions can be programmed.”
EH controls offer enhanced precision. “The Liebherr control lever, which is built into the operator’s seat as standard, allows all working and maneuvering operations to be performed with a high degree of precision and sensitivity,” says Koller. “The proportional control of the hydraulic attachment is carried out by the Liebherr control lever with mini joystick. The hydraulic joystick can be controlled with great sensitivity and very ergonomically. The tipping speed for tilting back and dumping can be regulated individually and quickly via the touch screen display.”
Better Control Through Electronics
EH controls are the building blocks of many time-saving technologies. “Electric-over-hydraulic controls allow the operator to have less fatigue in operation, more consistent operation with their hand controls and the increased performance of their machine based on operator input,” says Brad Stemper, product manager, Case Construction Equipment.
EH controls are coupled with proximity sensors to control automatic bucket functions, such as return-to-dig. “Now an operator can position the loader arms or bucket in the right position and press and hold the activate switch for those functions, much like you would preset a radio station,” says Stemper. “When it beeps, it tells you that position is now saved. The next time you activate it, the loader is going to return to that height or bucket orientation automatically when you use the detent function within the joystick control.”
EH controls have also simplified setup of auxiliary controls for novice operators. “Auxiliary hydraulic flow can be adjusted from inside the cab using the 8-in. touch screen display panel on the Case G Series,” says Stemper. “The touch screen also allows a certain level of customization where operators can make adjustment to idle speed, automatic idle shutdown and reversing fan settings.”
The ability to automatically control flow electronically results in a more efficient system. “In the old pilot systems or mechanical controls, when you grab that joystick and move it, there was immediate response to the spools,” Stemper notes. “You were asking the hydraulics to immediately turn on.”
With the flow not yet moving, this created a lot of wasted effort. “There was a lot of friction and heat loss,” says Stemper. “With the EH control, you can watch and monitor joystick movements. There is a ramp-up process that the controls actually have built into them.” This increases the efficiency as it allows momentum to build up before applying more pressure. “There is better management of hydraulic flow in the application.”
Learning New Technologies
“Certainly, with having more advancements on the machines, that’s often going to mean there is a learning curve and a larger degree of awareness required on the operator’s part,” says Connolly, “and it can sometimes be more involved to run the machine. However, once the operator is familiar with the machine and all its features, having electronic controls ultimately helps to eliminate operator fatigue and makes operation of the machine more efficient and increases productivity.”
One example is the payload management system. “Volvo launched Load Assist on the Volvo Co-Pilot in-cab display. A real-time payload management system, Load Assist provides a visual representation in real time for operators to see how much material is in the bucket, which increases accuracy of each load,” says Connolly. “This is beneficial to new and experienced operators, making every operator more productive.”
Advanced electronic controls often imply there is a level of difficulty. “However, many of the functions are engineered to be intuitive, reducing the input from the operator and allowing the loader to run at maximum productivity as it adapts to the environment and application,” notes Sam Shelton, marketing manager, KCMA.
For example, KCMA uses electronic controls to improve loading efficiency. “KCMA has developed a system we call Intellidig that balances the hydraulic power and rimpull so that the loader can dig through materials more effectively,” Shelton indicates. “We also built special logic into the powertrain that avoids upshifting as the operator approaches a truck, or allows the operator to use both boom and bucket functions simultaneously while digging to improve control and performance.
“Advancements in the KCM wheel loaders, like the ‘efficient acceleration’ feature, will make an operator more fuel efficient without requiring operator input,” she continues. “The automatic reversible cooling fan is another feature the operator never has to think about, but it is engineered to improve machine performance.”
Tier 4 engine technologies are another area that may require a learning curve for operators. Depending upon the solution used, operators may require additional training.
The use of diesel particulate filters (DPFs) and regeneration add to the knowledge required by an operator. “As you get novice operators into the machine, they might not have heard of Tier 4,” Stemper comments. “If they have, they might not be fully aware of the different types of systems. With the inclusion of more complex technologies, they could have multiple signals informing them of DPF regeneration, DEF fill and additional maintenance.” In many cases, the operator may have to watch for items such as combustible material buildup on the machine.
Case has addressed this learning curve with an SCR-only solution for Tier 4. “By going that SCR-only route, we have eliminated a great deal of extra needs the operator would need to be aware of,” says Stemper. “The machine is a much simpler machine.”
There is no DPF. “There is no forced regeneration, active or passive. There is no additional concern for combustible materials piling on the machine or coolers,” Stemper points out. “The only thing operators really need to worry about on our full-size Tier 4 Final wheel loaders is they need to have the DEF tank topped off at the beginning of the day.”
There have been many drivetrain advancements that simplify operation for novice operators.
In order to be productive with a traditional torque converter powershift machine, an operator must perform a “dance” coordinating engine speed and hydraulic control, says Chesterman. “A skilled operator is intuitively always adjusting if the material is not a homogenous pile of gravel,” he states. “If you happen to be out in a clay bank with a lot of dirt and construction activity, you must vary your inputs to get that bucket loaded effectively.”
One of the challenges with the conventional torque converter-equipped wheel loader is the torque output and hydraulic speed are tied to the engine speed. “The torque converter machine is a balancing act,” Chesterman asserts.
This can be a challenge for novice operators. “For a wheel loader to do its primary job of loading the bucket, about half of the bucket is filled by the machine simply pushing the bucket into the pile,” says Chesterman. The rest of the bucket fill occurs as the operator lifts the boom just enough to transfer the weight onto the front of the machine for maximum traction, then pushes that bucket into the pile further and curls the bucket. “The operator needs to learn the coordination of pushing enough, getting into the pile and then learning to lift and curl the bucket.”
John Deere currently offers two electric hybrid wheel loaders that can make this task much easier for novice operators. “If you put a below-average operator in our 644 Hybrid or 944 Hybrid, they can be very productive with the machine. The learning curve is very short,” says Chesterman. “Both models use electric motors to drive the wheels. The engine is primarily running a generator and hydraulic pumps. The pushing power of the machines has nothing to do with the engine speed, assuming you are in the operating range and not sitting at idle.”
Also, the hydraulics remain at maximum flow. This eliminates having to rev the engine to make the boom go up faster.
“The 644 Hybrid has an electric drive motor that drives a simplified transmission. But it still has driveshafts that drive a front and a rear axle,” says Chesterman. The 944 features an electric motor driving a planetary gear final drive at each wheel of the machine. “[It is] driving independent wheels, but with that, every machine basically has standard traction control.”
Unlike mechanical-driven machines with open differentials, when a wheel leaves the ground in uneven operations, it cannot “run away.” All wheels constantly turn at the same speed, which reduces the workload for the operators — they no longer have to watch as closely for tire slip and the possibility of a runaway wheel. “The feedback we have on the 944 Hybrid is that it does not spin a tire,” says Chesterman.
The smoothness of the electric drive 644 further benefits novice operators. “With a conventional drive machine, depending upon the engine, sometimes during a reversal in a truck loading operation, the operator lets off the throttle to make a smooth reverse to forward shift,” Chesterman comments. “The engine speed can go way down at the same time the operator wants to accelerate the machine toward the truck and raise the boom to get the bucket up over the truck. As engine speed drops down to 1,000 or 900 rpm, the hydraulics get pretty darn slow.” The available torque also drops at a time when it is needed for acceleration.
“With an electric drive machine in the same instance, they are not dropping to the really low engine speed, so the hydraulics are always fast,” says Chesterman. “And when the loader gets hit with this high load, the engine is already up to speed.” You don’t have to wait for a turbo to spool back up.
“When you talk about the unskilled operator who is not used to coordinating all of this, they can literally perform faster,” Chesterman states. “The expert operator is already performing because he knows all of the tricks on a conventional machine.”
Volvo also offers innovative driveline solutions. “New engine and drivetrain technology have had the greatest impact on the total cost of operation and operator productivity,” says Connolly.
Reverse-by-Braking (RBB) is a feature Volvo introduced to reduce stress on the wheel loader by novice operators. “If an operator shifts from reverse to forward without applying the brakes, it puts stress on the torque converter to decelerate. RBB helps to avoid this problem by reducing the engine’s rpm and automatically applying the service brakes when the operator changes the direction of the machine,” Connolly explains. “Optishift combines RBB with a lockup torque converter that eliminates power losses, reduces wear on the driveline and increases fuel efficiency by about 15%.”
Volvo also automates shifting during loading operations. “When loading the bucket with material, you always want to be in first gear as soon as the bucket penetrates the material,” says Connolly. “For newer operators, it can be a challenge to have the coordination to know the optimal time to shift into first gear. That’s why Volvo has automatic downshift, which will automatically shift the wheel loader into first gear when there is enough resistance. Most experienced operators will manually select so they can have the optimal amount of torque while loading.”
Preventing wheel slip can be beneficial to all operators, particularly novices. “Volvo now has the ECO Pedal, which is a great way to prevent wheel slip,” says Connolly. “When the operator applies pressure to the accelerator pedal and gets up to two-thirds pressure on the pedal, they can actually begin to feel the resistance. There is also a visual status meter that will show the foot’s pressure on the pedal. This is a useful feature for operators because it provides both visual and haptic feedback. The operator can learn the limits of the machine to keep it operating most efficiently, keeping fuel costs down and avoiding unnecessary wear and tear on the machine.”
Traction control innovations increase tire life. “Liebherr wheel loaders offer high levels of tractive force,” says Koller. “The tractive force needs to be controlled by the operator in order to prevent wheel spin, for example, when entering the material. This is why Liebherr offers its continuous tractive force regulation, which works automatically — a true asset for novice wheel loader operators. Together with the automatic self-locking differentials, the continuous tractive force regulation prevents wheel spin and reduces tire wear to a minimum.”
The Operator Environment
“In addition to innovative technologies, the operator needs a comfortable working environment to work productively,” says Koller.
On its XPower wheel loaders, Liebherr strove to ensure the displays, operator elements and driver’s seat form a single ergonomic unit that can be adjusted by the operator to suit their individual needs. “For example, the driver can select one of three adjustment options on the steering column,” says Koller. “The movement-following Liebherr operating lever is integrated into the driver’s seat as a standard feature and allows accurate and intuitive control of the working and driving functions. These investments in the comfort of the driver facilitate fatigue-free and focused work.”
The operator’s environment was also a major focus on Case G Series wheel loaders. “One of the goals with that update was to impact the operator’s experience — whether it be quality of ride or how they can become more proficient within the cab,” says Stemper. “One of the things we tried to do inside the G Series cab is create a simpler working environment with less clutter, less material and more space around the operator, so when they sit down there is much more concentration on what needs to get done than on how to operate. This includes the simplicity to operate things like lights, windshield wipers and cab climate.”