John Deere's 644K Hybrid wheel loader utilizes two sources of energy, diesel and electric, capturing regenerated energy as it’s being created and using the energy to power the machine.
Read our Field Test evaluation of the Hybrid's performance vs. its conventional sibling.
The unit is equipped with a 229-horsepower John Deere PowerTech 6.8-L Tier 4-Interim engine that runs at an operator-selected constant speed from 900 to 1,800 rpm.
Deere says that the machine’s hybrid technology delivers performance that is equal to or better than the conventional 644K, depending on the application. The engine’s constant operating speed maintains continuous hydraulic flow at all times, which the company says delivers crisp hydraulic responsiveness and reduces cycle times.
Hybrid vs. Conventional
Consumption (gal/hr) Productivity (ton/hr) Fuel efficiency (ton/gal) Truck loading -34% equal +54% Stockpiling -16% +5% +24% Transporting -10% equal +11% Idle -24% n.a. n.a.
“With fuel prices on the rise, the 644K Hybrid can reduce fuel consumption up to 25 percent, helping contractors lower their daily operating costs,” said John Chesterman, global product marketing manager for 4WD loaders, John Deere Construction & Forestry. While Chesterman admitted the new loader would have a "premium" cost above that of the conventional 644K, he said questions on the exact amount should be referred to individual dealers in the company's dealer network.
Deere sees noise reduction on the job site as another benefit of the hybrid design. Since the engine runs at a constant speed instead of increasing and decreasing speed as the machine is worked, the engine noise is continuous and therefore less noticeable to both the operator inside the cab and bystanders outside.
During operation, a PowerShift, countershaft-style transmission maintains smooth shifting whether the operator is stockpiling, truck loading or ramp climbing. The 644K Hybrid has four operating speed ranges, but no reverse gear or clutches, as direction changes are performed by the electric motor.
Four main components pace the 644K’s electric-drive technology: the generator, inverter, motor, and brake resistor.
The generator is brushless and converts the rotational energy from the engine into three-phase alternating current (AC) electrical energy. It can also be driven as a motor to use recycled energy to drive hydraulics and save fuel.
The inverter is a solid-state electronic system designed for reliability, durability, and long life. The water-cooled inverter delivers electrical energy to the motor as demanded by the operator.
The single electric motor is also brushless for added reliability and converts three-phase (AC) back to rotational energy and torque. The motor replaces the job of a torque convertor, but can also work as a generator to recycle energy back into the system.
The water-cooled brake resistor passively consumes energy whenever the power electronics actively control its circuit and is only needed to consume excess recycled energy.
John Deere 644K Hybrid Wheel Loader Specifications
- Net peak horsepower: 229
- Transmission type: hybrid-electric drive
- Operating weight: 40,436 pounds
- Full-turn tipping load: 26,992 pounds