Tractors And Their Power Units

At the time of the writing of the fourth edirion of this textbook, the agricultural economy in the United States and Canada was depressed. The prices paid to farmers for their grain crops were very low, and consequently most farmers in North America could not afford to buy a new tractor when needed; there fore, the sales of tractors and other farm machines were much below normal. The farmer who was the victim of the depressed economy was forced to "make do." Instead of purchasing a new tractor when the old one needed to be replaced, the farmer usually purchased a used or second-hand tractor or repaired the old one. In a strict sense, tractors usually do not wear out; instead, they become obsolete. The farmer who owns an obsolete tractor would prefer to replace it with one having more power, more speeds, more conveniences, a better hydraulic system, lower operating cost, or all of the above. But farmers in the United States, Canada, and other industrial nations will continue to want to purchase tractors that have all of the features, in cluding microprocessors, found on other vehicles.

The third edition of this book exposes the reader to a wide array of engineering principles and their application to agriculture. It presents an array of more or less independent topics to facilitate daily assessments or quizzes, and aims to enhance the students' problem solving ability. Each chapter contains objectives, worked examples and sample problems are included at the end of each chapter. This book was first published in the late 60's by AVI. It remains relevant for post secondary classes in Agricultural Engineering Technology and Agricultural Mechanics, and secondary agriculture teachers.

This book is for use in introductory courses in colleges of agriculture and in other applications requiring a problematic approach to agriculture. It is intended as a replacement for an Introduction to Agricultural Engineering by Roth, Crow, and Mahoney. Parts of the previous book have been revised and included, but some sections have been removed and new ones has been expanded to include a chapter added. Problem solving on techniques, and suggestions are incorporated throughout the example problems. The topics and treatment were selected for three reasons: (1) to acquaint students with a wide range of applications of engineering principles to agriculture, (2) to present a selection of independent but related, topics, and (3) to develop and enhance the problem solving ability of the students. Each chapter contains educational objectives, introductory material, example problems (where appropriate), and sample problems, with answers, that can be used for self-assessment. Most chapters are self-contained and can be used independently of the others. Those that are sequential are organiZed in a logical order to ensure that the knowledge and skills needed are presented in a previous chapter. As principal author I wish to express my gratitude to Dr. Lawrence O. Roth for his contributions of subject matter and gUidance. I also wish to thank Professor Earl E. Baugher for his expertise as technical editor, and my wife Marsha for her help and patience. HARRY FIELD v 1 Problem Solving OBJECTIVES 1. Be able to define problem solving.