Hyundai Construction Equipment continues to refine its wheel-loader line with the recent introduction of the model HL780-3A and its high-lift counterpart, the HL780XTD-3A, which are powered by the Cummins QSM11-Tier II engine. Maximum bucket capacity is 6.7 cubic yards (heaped) for both machines, but the high-lift model provides an added 13 inches of clearance under the bucket pin (16 feet 1 inch versus 15 feet) with 29.5–25 tires. Operating weight for both machines is 65,000 pounds.
The new Cummins diesel in these latest Hyundai wheel-loader models is electronically controlled and, according to Hyundai, improves transient response and reduces fuel consumption, compared to predecessor models. The new 11-liter engine delivers 320 net horsepower @ 2,100 rpm in this application, and generates 1,400 lb.-ft. of torque at 1,400 rpm.
The engine drives through a single-stage, single-phase torque converter with a 3:1 stall ratio, and into a powershift transmission equipped with Hyundai's Ergopower control system. Proportional valves control the engagement of the transmission's clutches, and the system monitors the engagement process and adjusts shift pressure to suit operating parameters. The control system, says Hyundai, delivers exceedingly smooth shifts, even under load, with no interruption of traction. The transmission is equipped with an auto-shift feature, but it can be switched off at the operator's discretion.
Axles under these new Hyundai loaders feature wet-disc brakes (at each wheel) and limited-slip differentials. An external cooler controls brake temperature.
The implement hydraulic system is an open-center type with pilot-operated controls. The system's vane pump delivers 125 gpm at governed speed and operates at 2,990 psi. Bucket breakout force for the standard model is 54,720 pounds, and the high-lift version is rated at just 1,000 pounds less. The pilot-operated hydraulic control system features a single-lever joystick with an integral transmission-kick-down button.
A test bank for measuring pressures in the implement-hydraulic, steering and brake systems simplifies diagnostic checks, says Hyundai, as does the electronic engine-diagnostic system, which displays error codes and signals maintenance. The electronic transmission display indicates speed and driving direction, as well as provides diagnostic error codes. Wiring harnesses for the new loaders are fitted with waterproof connectors, and remote drains for engine oil and coolant are environmentally friendly.