Equipment World Digital Magazine
Issue link: http://read.dmtmag.com/i/620628
T o meet Tier 4 Final require- ments, many models that had 35- to-40-horsepower engines now have engines of less than 25 horsepower. At the same time, hydraulic systems have become much more efficient. "We're getting more hydraulic horse- power per unit of engine horse- power," says Tom Connor, excavator profit specialist, Bobcat. If there is a drop in engine horsepower it is minimal and in most cases newer models offer better performance than the models they replace. Customers need to be mindful of the relationship between en- gine power and hydraulic power, says Mark Wall, product marketing manager, John Deere. "The impor- tant thing is to have enough engine power and torque to drive the hydraulics," he says. "Any more than that is wasted." Demo the machine in your application with your opera- tors and with any attachments you plan to use. Also check that the machine performs multiple simultaneous functions smoothly at the same time. This requires hydraulics that are not only powerful but sophisticated. Terex uses axial piston, variable displacement hydraulic pumps and motors to provide both load-sensing and load independent flow division (LUDV). "With a load-sensing sys- tem, the pump senses the operator's commands and directs oil flow to that function without stopping the other functions," says Gregg Warfel, compact division sales manager, Terex Construction Americas. Arm length affects performance. A longer arm gives greater dig depth, the ability to move the spoil pile back, and the ability to pull from farther when backfilling, reducing the need to reposition the machine. But a longer arm reduces breakout force and will probably require counterweights. Manufacturers typically list break- out and lift figures using the stan- dard configuration for a machine and usually cite a reference bucket used in obtaining these specs. Connor says customers need to be aware of how these requirements in- fluence specs. A machine that comes standard with a quick-attach may show lower lift capacity because of the added weight. And lift capaci- ties will vary depending on whether a bucket was used in calculating those values. "It's also important to remember that breakout forces are theoretical values derived from mathematics that assume 100 per- cent efficiency. They're helpful for comparison but don't reflect the absolute performance of a machine on a jobsite," Connor says. January 2016 | EquipmentWorld.com 30 machine matters | continued Overall performance Equipped with a Volvo Tier 4 Final engine, the EC60E has 10 percent more swing force and lifting capacity and a 20 percent increase in power, yet has 8 per- cent better fuel efficiency than the model it replaces. Produced in Caterpillar's Athens, Georgia facility, the 305.5E2 compact excavator features a High Definition Hydraulic System with advanced load sensing and flow sharing capabilities. The Terex TC48 has a 4.7-ton operating weight and has several features taken from conventional excavators such as a large operator's platform with two-side entry and an optional air-ride, heated seat.