To further increase fuel efficiency, Volvo has pursued high-torque, low-rpm engines that produce maximum torque between 1,400 and 1,600 rpm. This requires educating operators on how to properly use the power band. “Operators in the U.S. are under the impression the harder you mash the throttle, the more power you get.” This is not true with these engines.
Volvo responded with the ECO Pedal. There is a step in the throttle pedal. “This stops the operator at the high torque of the engine, about 1,600 rpm,” says Phillips. “It feels like the pedal is down to the floor. That is where we want him to hold it as he loads the bucket. If you add a little more pressure, it breaks through and actually goes to the floor. Then the operator can break through that throttle floor and take off and carry the load.” This lets the operator maximize use of the engine’s torque curve.
Move more per gallon
With the high cost of fuel, efficiency has become a major design criteria.
“Efficiency is measured by calculating the material moved per gallon of fuel burned,” notes Scott Britton, product application specialist for small wheel loaders, Caterpillar. The small wheel loader product line (924K/930K/938K) uses an intelligent power management system. “It governs the hydrostatic drivetrain, engine control and implement system and always monitors operator input and available power to allow for the most efficient operation possible.”
Caterpillar medium wheel loaders feature the Fuel Management System (FMS). When activated, it changes the engine power maps to save fuel. “Historically, we haven’t used economy modes universally because we often find operators not using them or unintentionally activating them and asking for more power,” says Campbell.
He adds, “We prefer to make machine operation intuitive and then do what is necessary behind the scenes to interpret the operators’ desire for more power, less fuel consumption, etc. However, with the dramatic increase in fuel prices globally, customers are looking for all possible ways to save fuel. So we developed FMS for the 950K to 980K.”
Transmissions for the K Series medium-sized wheel loaders have new control strategies. “First, the downshift from second to first is now based upon torque requirements vs. ground speed, which was used on prior generations,” says Campbell. “This enables the operator to select 1-4 automatic mode. If the machine needs extra torque, it will shift down to first gear; otherwise, it will load in second gear. Operating the machine in automatic is akin to driving an automobile.” It is easier for the operator and reduces the average engine rpm, thereby saving fuel.
Then there is the 966K XE with advanced powertrain. “The Caterpillar continuously variable transmission in the 966K XE is more than just a drop-in transmission. Rather, it is an advanced powertrain with deep system integration between the engine, transmission, hydraulics and cooling system,” says Bryan Vogt, engineering manager, Caterpillar Medium Wheel Loader Performance & Controls.
“The ‘magic’ with the Cat 966 XE is in the control strategy,” says Vogt. “This has taken years of research and development to perfect, but the result is fuel savings up to 25% compared to previous models, with some customers claiming even greater fuel efficiency.”
A machine that thinks
The latest Kawasaki loaders feature the IntelliTech Operating System. Found on all Z7 models, it consists of Intellidig, which balances rimpull force and hydraulic digging force to match conditions; Simuload, which allows simultaneous action of lift and tilt while digging; QuickCycle, which speeds loading cycles; FlexShift, which varies the shift points of the transmission to match working conditions; and Efficient Acceleration to prevent over-acceleration, which ultimately wastes fuel.
“The IntelliTech Operating System uses logic and intelligence to adjust the loader operating characteristics,” says Gary Bell, vice president/general manager, KCMA Corporation. “It senses working conditions and adjusts the powertrain and hydraulics to best match application or environmental requirements. Many of the IntelliTech operations are automatic, while others allow the operator to select functions.”