TRACTOR IMPLEMENT SYSTEMS - ALCOCK RALPH

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Résumé :
Agriculture has benefited considerably from the wide-scale use of tractors and associated implements. Tractors have developed along two, at times contradictory, design paths. The first of these has resulted in functional improvements to the vehicle, making it capable of im? proved performance in the often harsh environmental conditions in which it is required to operate. For example, agricultural tires have improved the versatility of tractors by allowing them to operate at relatively high speeds on a variety of terrains, and hydraulics have provided for flexibility in controlling and operating implements. It can also be seen that these particular functional design improvements have contributed significantly to the second design pathway, that of ergon? omics, and the human-machine interface. Recent stress on the working environment for the tractor operator has led to design improvements relative to tractor cabs, the placement and labeling of controls, etc. This text discusses those factors relevant to the design, selection, and operation of tractor-implement systems. The audience for which it is intended is undergraduate and graduate students of agricultural engineering studying power and machinery. However, the text is suf? ficiently applied to have relevance for those extension personnel in? volved with advising farmers on the selection and operation of tractor? implement combinations. The tractor cannot be regarded in isolation from the implement, nor from the environment in which both the tractor and implement are ix x Preface working.

Sommaire:
1 Fundamental Considerations.- 1.1 Introduction.- 1.2 Systems.- 1.3 Energy and Principles of Dynamics.- 1.4 The Conservation of Energy.- References.- 2 Thermodynamics.- 2.1 The Steady-Flow Energy Equation.- 2.2 The Nonflow Energy Equation.- 2.3 The First Law of Thermodynamics.- 2.4 The Second Law of Thermodynamics.- 2.5 The Thermodynamic Engine.- 2.6 Gas Laws.- 2.7 Specific Heat.- 2.8 Gas Processes.- 2.9 The Carnot Cycle.- References.- 3 Power Measurement.- 3.1 Power.- 3.2 Torque.- 3.3 Indicated Power (IP).- 3.4 Energy Balance.- 3.5 Measurement of Fuel Flow.- 3.6 Measurement of Air Flow.- 3.7 Tractor Performance.- 3.8 Drawbar Pull (FD).- 3.9 Nebraska Tractor Tests.- References.- 4 Traction.- 4.1 Traction in Soils.- 4.2 Shear Strength.- 4.3 Plastic Limit.- 4.4 Coulomb and Micklethwaite Equations.- 4.5 Bekker Theory.- 4.6 Dimensional Analysis.- 4.7 Tractive Efficiency (?D).- 4.8 Mobility Number.- References.- 5 Tires and Ballasting for Agricultural Tractors.- 5.1 Tire Development.- 5.2 Tire Function.- 5.3 Tire Terminology.- 5.4 Ballasting.- 5.5 Tire Selection.- References.- 6 Machinery Management.- 6.1 Fixed Costs.- 6.2 Operating Costs.- 6.3 Reliability.- 6.4 Selection of Machinery Capacity.- 6.5 Replacement Theory.- References.- 7 Vehicle Performance.- 7.1 Drawbar Performance.- 7.2 Engine Torque Requirement.- 7.3 Vehicle Speed.- 7.4 Vehicle Acceleration.- 7.5 Longitudinal Stability.- 7.6 Tractor Dynamics.- 7.7 Tractor-Implement Forces.- 7.8 Tractor-Implement Dynamics.- References.- 8 Connecting Tractor and Implement (Sverker Persson).- 8.1 Pull-Type, Semimounted, or Mounted Implement.- 8.2 Hitch Point.- 8.3 Load Transfer Due to Pull.- 8.4 Effect of Load Transfer.- 8.5 Free-Link Three-Point Hitches.- 8.6 Powered Three-Point Hitch.- 8.7 Motions of Fully Mounted Implement in Three-Point Hitch.- 8.8 Lifting Capacity of the Hydraulic System.- 8.9 Draft-Sensing Hydraulic Systems.- 8.10 Position Control.- 8.11 Hydraulic Systems.- 8.12 Open- or Closed-Center Hydraulics.- 9 Operating the Tractor and the Implement (Sverker Persson).- 9.1 The Tractor as a Workplace.- 9.2 Tractor Controls and Instruments.- 9.3 Operator Environment.- 9.4 Operator Safety.- 9.5 Systems for Hitching the Implement to the Tractor.- References.- 10 Developments in the Tractor Concepts.- 10.1 Introduction.- 10.2 Controlled-Traffic Farming.- 10.3 Battery-Powered Tractor.- 10.4 Systems Tractor.- References.- Appendix: Problems and Problem-Solving.