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Giáo trình chế tạo ôtô - Phần 24

Tham khảo tài liệu 'giáo trình chế tạo ôtô - phần 24', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | CONTENTS c H A p T E R 24 Clutches 1. Introduction. 2. Types of Clutches. 3. Positive Clutches. 4. Friction Clutches. 5. Material for Friction Surfaces. 6. Considerations in Designing a Friction Clutch. 7. Types of Friction Clutches. 8. Single Disc or Plate Clutch. 9. Design of a Disc or Plate Clutch. 10. Multiple Disc Clutch. 11. Cone Clutch. 12. Design of a Cone Clutch. 13. Centrifugal Clutch. 14. Design of a Centrifugal Clutch. 24.1 Introduction A clutch is a machine member used to connect a driving shaft to a driven shaft so that the driven shaft may be started or stopped at will without stopping the driving shaft. The use of a clutch is mostly found in automobiles. A little consideration will show that in order to change gears or to stop the vehicle it is required that the driven shaft should stop but the engine should continue to run. It is therefore necessary that the driven shaft should be disengaged from the driving shaft. The engagement and disengagement of the shafts is obtained by means of a clutch which is operated by a lever. 24.2 Types of Clutches Following are the two main types of clutches commonly used in engineering practice 1. Positive clutches and 2. Friction clutches. 885 CONTENTS 886 A Textbook of Machine Design We shall now discuss these clutches in the following pages. 24.3 Positive Clutches The positive clutches are used when a positive drive is required. The simplest type of a positive clutch is a jaw or claw clutch. The jaw clutch permits one shaft to drive another through a direct contact of interlocking jaws. It consists of two halves one of which is permanently fastened to the Fixed Moving a Square jaw clutch. Spiral jaw clutch. Fig. 24.1. Jaw clutches. driving shaft by a sunk key. The other half of the clutch is movable and it is free to slide axially on the driven shaft but it is prevented from turning relatively to its shaft by means of feather key. The jaws of the clutch may be of square type as shown in Fig. 24.1 a or of spiral