DEVELOPMENT OF A COMPUTER-CONTROLLED, HYDRAULIC, POWER TAKE-OFF (PTO) SYSTEM

Abstract

Nearly all tractor PTO arrangements used today consist of a rotating mechanical shaft with two or more universaljoints. This arrangement continues to be an entanglement hazard. By driving the attachment with fluid power, this hazardcould be eliminated. This project included the design, development, and testing of an experimental tractor based on a JohnDeere 4040. The entire power train was treated as a single computer-controlled system where both the PTO output and thewheels were driven by fluid power. To support direct laboratory and in-field comparison of hydraulic and mechanicalscenarios, the original transmissions were left intact and functional. Results showed that at low power demand, the hydraulicsystem was more efficient than the mechanical equivalent; however, the mechanical version was more efficient over most ofthe load range and was capable of higher power output. The use of computer control helped to minimize fuel consumptionby matching engine speed to loading conditions while maintaining operating speeds by varying hydraulic pump displacement.The hydraulic PTO system for the JD 4040 has the potential to match or increase fuel efficiency compared to its mechanicalcounterpart for loads up to about 40% of rated mechanical PTO output. Maximum power output in the hydraulic mode hasthe potential to be 75% of that achieved by the mechanical equivalent.