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Features
Comfortable and Straightforward Cab Design
Roomy cab features ergonomically placed joystick controls, foot pedals, and sealed-switch module. Seat-mounted right-hand joystick includes integrated F-N-R switch. Optional air-ride seat increases the level of operator comfort.
Service and Support Capabilities
All daily service points including fuel refill are conveniently grouped at ground level on the left side of the machine. Sight gauges for transmission and hydraulic fluid levels are easy to read. Hinged doors provide wide-open access to the engine, cooling system, and other components.
Proven and Reliable Components
Designed with reliability in mind, the 644 G-Tier incorporates John Deere's robust PowerTech™ 415-cu in. (6.8-L) engine, tested transmission, and axles. Features such as Auto Idle and Auto Shutdown optimize fuel usage. The build ensures prolonged intervals between services, thus minimizing operating costs.
Specifications
Engine
| Manufacturer | John Deere |
| Model | PowerTech™ 6068H |
| Non-Road Emission Standards | EPA Final Tier 4/EU Stage V |
| Displacement | 6.8 L |
| Displacement | 414 cu in. |
| Net Peak Power | 1700 rpm |
| Net Peak Power At Rated RPM (ISO 9249) | 175 kW |
| Net Peak Power At Rated RPM (ISO 9249) | 235 hp |
| Net Peak Torque | 1400 rpm |
| Net Peak Torque At Rated RPM (ISO 9249) | 1024 Nm |
| Net Peak Torque At Rated RPM (ISO 9249) | 755 lb-ft |
| Fuel System (Electronically Controlled) | High-pressure common rail |
| Lubrication | Full-flow spin-on filter and integral cooler |
| Aspiration | Turbocharged, charge air cooled |
| Air Cleaner | Under-hood, dual-element dry type, restriction indicator in cab monitor for service |
Transmission System
| Type | Countershaft-type PowerShift™ |
| Torque Converter | Single stage, single phase |
| Shift Control | Electronically modulated, adaptive, load and speed dependent |
| Operator Interface | Joystick-mounted F-N-R; Quick-Shift button on hydraulic lever |
| Shift Modes | Manual/auto (1st–D or 2nd–D); Quick-Shift button with 2 selectable modes: kick-down or kick-up/down; and 3 adjustable clutch cutoff settings |
Wheels And Tires
| Tread Width On Standard Tires | 2169 mm |
| Tread Width On Standard Tires | 85.4 in. |
| Width Over Tires On Standard Tires | 2766 mm |
| Width Over Tires On Standard Tires | 108.9 in. |
Axles And Brakes
| Final Drives | Heavy-duty inboard-mounted planetary |
| Optional Differentials Front | Open differential, locking front optional |
| Optional Differentials Rear | Open differential, locking front optional |
| Rear Axle Oscillation, Stop To Stop | 26 degrees |
| Rear Axle Oscillation, Distance Each Direction | 13 degrees |
| Service Brakes (ISO 3450) | Hydraulically actuated, spring retracted, self-adjusting, inboard sun-shaft mounted, oil cooled, single disc |
| Parking Brake (ISO 3450) | Automatic spring applied, hydraulically released, driveline mounted, oil cooled, multi disc |
Serviceability
| Fuel Tank (With Lockable Cap) Refill Capacity | 300.2 L |
| Fuel Tank (With Lockable Cap) Refill Capacity | 79.3 gal. |
| Cooling System Refill Capacity | 30 L |
| Cooling System Refill Capacity | 31.7 qt |
| Engine Oil With Vertical Spin-On Filter Refill Capacity | 21 L |
| Engine Oil With Vertical Spin-On Filter Refill Capacity | 22.2 qt |
| Transmission Reservoir With Vertical Filter Refill Capacity | 25 L |
| Transmission Reservoir With Vertical Filter Refill Capacity | 6.6 gal. |
| Axle Oil Without Coolers (Front And Rear, Each) Refill Capacity | 25 L |
| Axle Oil Without Coolers (Front And Rear, Each) Refill Capacity | 6.6 gal. |
| Hydraulic Reservoir With Filter Refill Capacity | 99.9 L |
| Hydraulic Reservoir With Filter Refill Capacity | 26.4 gal. |
| Parking Brake Oil (Wet Disc) Refill Capacity | 0.65 L |
| Parking Brake Oil (Wet Disc) Refill Capacity | 22 oz. |
Electrical And Lighting
| System Type | 24 volt with 80-amp alternator |
| Battery Voltage | 12 V |
| Battery Capacity Per Each | 950 CCA |
| Standard Alternator Rating | 80 amp |
Hydraulic System And Steering
| Pump Type And System (Loader And Steering) | Variable-displacement, axial-piston pump; closed-center, pressure-compensating system |
| Rated RPM | 2250 rpm |
| System Pressure At Max Rated Flow | 23100 kPa |
| System Pressure At Max Rated Flow | 3350 psi |
| Max Rated Flow At Rated RPM | 329.3 L/min |
| Max Rated Flow At Rated RPM | 87 gpm |
| Loader Controls | 2-function valve; joystick control or fingertip controls (field kit); hydraulic-function enable/disable; optional 3rd-function valve with auxiliary lever |
| Steering Type (ISO 5010) | Power, fully hydraulic |
| Steering Articulation Full Arc Angle | 80 degrees |
| Steering Articulation Angle Each Direction | 40 degrees |
| Turning Radius (Measured To Centerline Of Outside Tire) | 5.56 m |
| Turning Radius (Measured To Centerline Of Outside Tire) | 18.25 ft, in. |
| Hydraulic Raise Cycle Time | 5.2 seconds |
| Hydraulic Dump Cycle Time | 1.5 seconds |
| Hydraulic Lower (Power Down) Cycle Time | 3.2 seconds |
| Hydraulic Total Cycle Time | 9.9 seconds |
Cooling
| Fan Drive Type | Hydraulically driven, proportionally controlled, fan aft of coolers |