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Agricultural Tractor Hitches Analysis of Design Requirements

Published by the American Society of Agricultural and Biological Engineers, St. Joseph, Michigan

Citation:  Agricultural Tractor Hitches Analysis of Design Requirements. ASAE Distinguished Lecture No. 5, pp. 1-28. Winter Meeting of the American Society of Agricultural Engineers, 12 December 1979, New Orleans, Louisiana  903C0879.(doi:)
Authors:   Roy W. Morling
Keywords:   Definition of Agricultural Tractor Hitch, History of Hitches, Implement Pull Forces, Analysis of Several Implement Hitches, Trailing Type Implement Hitch, One Point Mounted Hitches, Three Point Mounted Hitches, Mechanical Force Transfer Mounted Hitches, Advantages of Mounted Implements, Three Point Hitch Standardization, Design Requirements of the Mounted Hitch, Current Types of Three Point Hitches, Kinematic Analysis, Vertical Longitudinal Plane, Horizontal Plane, Vertical Lateral Plane, Force Analysis, Depth Control, Dynamic Load Transfer, Center-ability, Two Point Use of Three Point Hitch, Depth Control and Dynamic Loading, Regulation of Force Sensing Hitches, Hydraulic Systems Used With Force Sensing, Hitch Lift Capability and Stability, Quick Coupler, Trailing Implement Load Transfer, Transport Shock Forces, Design Requirements of Hitch Elements, Lower Links and Upper Link, Lateral Limiters, Lift Links, Lift Arms, Rockshaft & Cylinder, Force Sensing System, Swinging Drawbar, Proposed Future Design Trends

The agricultural tractor hitch has undergone considerable change and development since Mr. Ferguson, introduced his special hydraulic control hitch on the Ford tractor in 1935. This was a draft sensitive automatically controlled three point linkage hitch trademarked the "Ferguson System". Previously the hitch was generally a single pivotal connection between the tractor drawbar and the implement. Many agricultural tractors are now equipped with the three point force controlled hitch patterned after the original "Ferguson System." It converts the implement into a mounted implement or integrally hitched implement. While this linkage system complicates the understanding of the "line of pull" the tractor exerts on the implement, the system has benefit to the two wheel drive tractor and to the implement. The tractor can take maximum advantage of the soil force on the implement and the force of gravity on the mass of the implement to benefit traction. There have been alternatives to the "Ferguson System" of mounting implements developed. Several have been successful, in their own way, of fulfilling the requirements of a mounted implement hitch at the expense of interchangeability. They have given way to the Ferguson-type of three point force control hitch, because of interchangeability, which resulted from standardization of the three point hitch. This analysis is related to the two wheel drive tractor with regard to load transfer.

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