The John Deere 644J High-Lift Wheel Loader is a robust construction machine designed for efficient material handling at elevated heights. It features a turbocharged, charge air-cooled 6-cylinder 6068H engine with a displacement of 414 cu in, delivering 185 hp at 2200 rpm and a torque rise of 55% at 1400 rpm. The loader has an operating weight of 40,620 lbs (18,425 kg) and a fuel capacity of 93 gallons (352 liters). Equipped with a 4 cubic yard (3 m³) heaped bucket with a width of 9.8 ft (3 m), it provides a breakout force of 30,574 lbs (13,868 kg). The high-lift boom extends the hinge pin height to 15 ft (5 m) with a dump clearance of 11.1 ft (3 m) at maximum raise, enabling the loader to efficiently dump materials into elevated containers. The reach at max lift and dump is 3.9 ft (1.2 m). The hydraulic system uses a variable axial piston pump with a flow capacity of 68 gallons per minute (257 L/min) and operates at 3600 psi relief valve setting. Cycle times include a dump time of 1.9 seconds, lower time of 2.8 seconds, and raise time of 5.9 seconds. The drivetrain consists of an automatic powershift transmission with 4 forward and 3 reverse gears, providing maximum speeds of 22 mph (35 kph) forward and 15.5 mph (24 kph) reverse. The machine rides on 23.5 R25 tires, with a wheelbase of 10.5 ft (3 m) and a turning radius of 18 ft (5 m). With 24 V electrical system and ample fluid capacities across engine, transmission, axles, and hydraulics, the 644J High-Lift is engineered for rugged reliability and productivity in demanding jobsites.