Excavators think for themselves
Some manufacturers have taken a turn away from work modes in recent years. Instead, they are taking the decision-making process out of the hands of the operators and allowing the excavators to do the thinking.
John Deere’s C-Series excavators are equipped with the Powerwize II engine/hydraulic management system. This system has only one work mode and four engine speed, or “power”, modes.
“Most operators want maximum productivity, fast cycle times and maximum hydraulic flow,” says Mark Wall, product marketing manager for excavators, John Deere Construction and Forestry Division. “The one work mode in the Deere Powerwize II allows the operator to perform at maximum productivity in a variety of applications. Operators can perform truck loading, trenching, backfilling, lifting and fine grading without having to touch a switch. With the one work mode, operators do not have to worry about selecting the ‘best’ mode for the job.”
The operator can fine tune the engine speed using the power modes without changing the way the hydraulic flow is directed. The modes include “power”, which is used in most applications; “high power”, which increases the engine speed by 100 rpm when the arm-in or boom-up function reaches a preset pressure setting; “economy”, which allows the excavator to operate at a reduced rpm for light applications; and “auto accel”, which varies the engine rpm according to system pressure. “In light load applications, auto accel mode can save the owner approximately 10% in fuel, reducing owning and operating costs,” Wall says.
Caterpillar’s engine and hydraulic system designs take a further step down the road of “thinking” machines. Caterpillar has done away with its work mode and power mode switches completely and replaced them with automatic boom and swing priority, which selects the best work mode based on joystick movement.
“The operator input — the extent to which they move the lever, which lever they’re moving and how much they move it — tells the machine what kind of work the operator is expecting out of it,” says Jason Kern, hydraulic excavator marketing supervisor for Caterpillar. “If you pull the lever a little, you get a little; if you pull the lever a lot, you get a lot. There are electronics and hydraulics behind it, but simply put the machine senses the demand from the operator.”
Caterpillar began eliminating the work modes with its C-Series excavators in 2000. The transition on all excavators is expected to be completed in early 2005.
The company chose to make this switch based on what it was hearing from users in the field. “The feedback we were getting from our customers, and what we observed going out on jobsites, is that the modes weren’t being used at all or were being used improperly. So customers weren’t getting the full capability we designed into the machine,” Kern says. “When we went to our next generation, one of our design goals was to get the modes out of there and build them inherently into the machine so you wouldn’t have to choose what mode you wanted to be in.”
The result is fuel savings, quicker hydraulics and ease of training employees, says John Hepp, owner of John Hepp Excavating, Inc., Watertown, WI. His fleet includes a 2003 Caterpillar 320LC Utility model. “There is an advantage to putting new people on the CAT excavators without the mode system because everything changes automatically,” he says. “The machine can sense what the operator wants to do and it adjusts accordingly.”
The choice between multiple operating modes or a more automated design ultimately comes down to what you want to accomplish with the excavator. Assess the kind of work you expect out of the machine, and the degree of control you want your operators to have, to determine which design will be most productive and cost effective for your fleet.