John Deere PowerTech™ 6.8-L (415-cu in.) engine
   
   
  Built on over 50 years of experience producing and supporting wheel loaders, the 644 G features a high commonality of components found in other John loaders that are designed and tested to meet John Deere standards including the engine, transmission, and axles.
   
  
   - The John Deere PowerTech 6.8-L (415-cu in.) engine is designed to improve cooling and provide high cylinder and piston ring durability.
 
   - John Deere Teammate V axles contain pressure-lubed input bearings and brake discs that enhance cooling and extend component life, which helps lower total cost of ownership.
 
   - Extended service intervals lower the cost of maintenance over the entire life of the machine.
 
   - Auto Idle and Auto Shutdown reduce engine speed or turn the off completely after a period of inactivity to save fuel and warranty hours.