Wheel loaders ranging from approximately 19,500- to 40,000-lb. operating weight and roughly 2- to 3.5-cu.-yd. bucket capacities often find diverse applications on today’s jobsites. Recent advancements in electronics and hydraulic systems enhance the versatility of these utility-sized machines.
“You have a lot of computers today to fulfill all of the [emissions] requirements,” says Stefan Salomonsson, product specialist, Volvo Construction Equipment. “Electronics have made a huge difference in controlling an engine. You can control the injections so much more than you could before. You can really get delivery of power when you need it, and exactly how much you need and no more. With the transmission, you have much better comfort because you can have more precise gear shifting.”
“We could not achieve the extremely accurate fuel delivery, engine/driveline control and system intelligence without the advanced electronic technology we have today,” says Brien Pleinis, manager, engineering section, Kawasaki-KCM wheel loaders. “Today’s electronic technology has allowed extremely accurate monitoring of all wheel loader systems.”
Electronics have paved the way for many features, such as selectable work modes, return-to-dig, return-to-travel, ride control — all of which can be set inside the cab. “Today’s wheel loaders are also built with a variety of electronic modules and control functions throughout the machine,” says Andrew Dargatz, brand marketing manager, Case Construction Equipment. “The engine and transmission are in sync at all times vs. working as independent systems.”
This ability to more closely match the engine and transmission is due to recent systems integration. “In the past, there were separate controllers available for managing those systems,” says Aaron Kleingartner, Doosan. “But now with the advanced engines and the requirement of electronics on the engine, we are more easily able to optimize the engine output to the transmission input requirements.”
Components essentially talk to each other. “Transmissions are computer controlled and take into consideration a large array of sensor inputs from not only the transmission but the engine and hydraulic system sensors, as well,” says Rob Burke, powertrain and development specialist, Kawasaki-KCM. “This allows the transmission and torque converter to operate at optimum efficiency under all conditions.”
This size wheel loader is not a true production machine, so purchase price becomes a key consideration. “It seems like manufacturers offering machines in this size class are trying to make a machine at lower cost as an answer to the large amount of competition,” says Salomonsson. “The bad thing about this is not many people demo them. People buy on specs and the specs on a lot of machines look the same. But if you really test the different machines, you feel the difference.”
Many machines in this size class are offered with both Z-bar and parallel lift arm configurations. “The standard Z-bar configuration is preferred by most operators who perform dirt work where they are loading and moving a lot of material,” says Kleingartner.
The parallel lift, or tool carrier, versions are more typically used when there is a lot of pallet fork work. In addition to keeping the attachment level through the lift cycle, they generally provide better visibility. But that doesn’t mean the loader can’t be efficient in digging applications. “Just because a machine is a tool carrier and would work better with material handling, it is still a very capable digging machine,” says Kleingartner.
Today’s utility-size loaders can often adapt capabilities to match the application. This includes selectable work modes and various options that can be selected from electronic keypads or touchscreen monitors in the cab.
“The Case G Series offers four selectable working modes to help operators get the maximum out of their machine with less fuel and less wear and tear on the engine,” says Dargatz. “There are advantages to these systems as long as operators are properly trained. We’ve seen operators working in a regular working/loading cycle with the machine set in Maximum that could just as quickly be finished in ECO mode while burning less fuel.”
The application modes make dialing in the wheel loader to the application much easier. “The Auto mode is ideal for the beginning operator,” says Dargatz. “And advanced yet simple to set functions such as return-to-dig and return-to-travel automate some of the operational functions that make it easier to operate and further drive efficiency.”
Kawasaki-KCM loaders offer a Normal mode and a Power mode. “In either mode, the electronics of the machine and the engine work together and go into an Economy or ECO function for maximum fuel savings,” says Wayne Powell, senior manager, product support, Kawasaki-KCM Wheel Loaders. “For instance, even when the Power mode is selected, if the machine is descending a hill, the machine and engine controls recognize that minimal power is required and the ECO symbol will appear indicating a very low power state has been reached, or maximum efficiency.”
Hyundai Construction Equipment offers enhanced control from the cab that allow users to tailor the loaders to the task. “The HL900 Series loaders feature a full-color, 7-in. touchscreen monitor with integrated buttons,” notes Corey Rogers, marketing manager. “An operator can quickly access many settings from the main screen of the monitor. Switching attachments is just as easy as using the integrated coupler lock button on the monitor. Four individual user settings can also be saved within the monitor to customize machine operation for different operators or tasks.”
There are even settings to assist novice operators. “For the novice operator, we offer a quick startup guide with some general operation settings applicable to most jobsites,” says Rogers. “The 7-in. touchscreen monitor is intuitive and easy to use. Also, the four individual user settings can be programmed and quickly accessed within the monitor for new operators.”
To help aid productivity, an onboard weighing system has been added that is accurate to +/- 1%. “The system has automatic and manual settings for monitoring individual and cumulative bucket load weights,” says Rogers. “System measurements are displayed on the multi-function screen in the cab, providing load weight monitoring reliable enough to support production management.”
Case has implemented a membrane keypad that replaces many of the rocker switches that control important machine functions. This simplifies how the operator engages with functions such as Ride Control, detent adjustments, cooling fan reversal and coupler engagement. “This membrane keypad makes it very easy for the operator to understand which features are active or inactive,” says Dargatz.
The redesigned monitor mirrors much of the advanced functionality seen in the digital displays of today’s personal vehicles. “The operator can easily page between a home dashboard to screens that display machine status, trip information, the optional rear camera and machine settings,” Dargatz notes. “The monitor allows the operator to better control auxiliary hydraulic flow for better control of the attachments, easily adjust power modes based on the activity, easily adjust auto idle timers to improve fuel efficiency and adjust timing of reversing fan intervals to maintain clean coolers.”
Doosan has chosen to use an informational screen in the cab with separate input with buttons. “We find it is easier for the operator to push a button with a pair of gloves on,” says Kleingartner.
The advancements lie in the software behind the screen providing the ability for the operator to make adjustments on selections. “That allows the operator or fleet manager to optimize the machine for the capabilities they need from it or to maximize efficiency or productivity,” Kleingartner says. “For example, you can press a button continually and the software will just rotate though Economy, Standard and Power mode.” An indicator light on the button alerts you which mode is active.
Simple Yet Effective
Volvo Construction Equipment offers a different approach to operator controls. It tries to limit the number of choices.
“We often get complaints that you can do too much,” says Salomonsson. “Many operators and owners don’t want a lot of switches or possibilities to change operation.” Too many options can become overwhelming.
While Volvo offers work modes for the transmission that allow the shift points to change based on engine speed, the loaders also offer a simple solution in the form of an ECO pedal for the accelerator. “You have a power threshold that you don’t have to exceed very often,” says Salomonsson. “That means most often, you don’t need the full power of the engine. The ECO pedal helps ensure you only use that power when it’s needed. That saves a lot of fuel. Most of the time, with this size of machine, you don’t need to be at full throttle.”
As machines get larger, the sophistication and options tend to increase. “On the L110 and up, Volvo offers Co-Pilot, a 10-in. Android-based display unit loaded with applications that deliver real-time intelligence to the operator,” says Salomonsson. “The wheel loader application, Load Assist, was just launched. It provides real-time load information and complete work order management functionality.”
Load-sensing Systems Enhance Control
Electronic advancements have opened the door to load-sensing piston pump hydraulic systems. “Computer-controlled electronic engine controls operating on bidirectional CAN Bus networks have increased fuel economy and engine power output and reduced the amount of engine exhaust emissions,” says Burke. “This same technology has allowed us to reduce the hydraulic loads on the engine when hydraulic functions and needs are low by using computer-controlled variable-displacement piston pumps.”
Gear and vane pumps commonly used in the past proved reliable and inexpensive to purchase and replace. “Piston pumps have been common in excavators for over 30 years but were expensive and required adjustments to ‘tune’ the hydraulic performance,” notes Powell. “They are, however, very efficient. Now the pumps are controlled and can be tuned instantly ‘on-the-fly’ by the machine’s computers. So we have been able to bring the precision and efficiency to wheel loaders.”
Many utility size wheel loaders are moving from simple gear pumps to piston pumps. “From a hydraulics perspective, the use of load-sensing hydraulics and the ability to really manage the output required of the machine with what is required by the operator maximizes efficiency and productivity,” reports Kleingartner.
“The Case G Series features an electrohydraulic, load-sensing system that allows for improved functionality and precise bucket and loader functions that produce less heat, require less fuel and provide speed and control options perfect for most loading applications,” says Dargatz. “Additional hydraulic circuits can also be added for greater performance and flexibility.”
Volvo Construction was among the first companies to utilize load-sensing technology in its wheel loaders. “Now we call it intelligent load sensing — using electronics to make machines and operations more efficient,” says Salomonsson. “On the L110 and up, we can set parameters to change flow and sensitivity.”
Some of the industry’s first load-sensing systems used relatively small pumps. “With those systems, it really didn’t make a difference between load-sensing and the old-style gear or vane pumps,” says Salomonsson. “But now the industry has learned a lot — we’re moving to bigger pumps. This could never happen with a gear pump because you would stall the machine at lower revs.”
Hyundai’s HL900 Series maximizes fuel economy and power on demand through variable-displacement, load-sensing hydraulic pump technology. “With improved precision and ease of operation, the electrohydraulic (EH) control system on the HL955, HL960, HL970 and HL980 models also contributes to increased productivity and reduced operator fatigue,” says Rogers. “The HL940 model will feature similar EH control technology in the near future.”
Volvo Construction uses pilot controls on its smaller wheel loaders and moves to EH controls on the L110 and larger loaders. Capabilities of the EH controls increase since they are run by the computer. “There are a lot of things you can easily change with EH controls. You can do the same with pilot controls, but you have to do it in a more mechanical way,” says Salomonsson.
The move from pilot controls to EH controls allowed Case to increase cab comfort on the G Series. “We no longer have that hot hydraulic oil running through the loader control right next to the operator,” Dargatz points out. “Removing that hot oil makes the cab more comfortable; [it’s] cooler for the operator. Since that hot hydraulic oil isn’t flowing through the loader arm every time it is moved, it helps make the cab quieter.”
EH controls also offer more flexibility. The controls are now mounted to the seat and can be adjusted independently for maximum adjustability.
Hydrostatic transmission options are also gaining a foothold with utility size loaders. Doosan recently introduced a hydrostatic transmission on its DL200.
“That is really beneficial for the general contractor because of its maneuverability on the jobsite,” says Kleingartner. “It is more fuel efficient in that lower engine horsepower range... When you are maneuvering around a jobsite, you don’t have to shift as often. The machine offers two ranges instead of four on a traditional transmission, which gives the operator an easier ability to control the machine on the jobsite.” For attachment utilization, machine speed and attachment flow can now be controlled independently.