tailieunhanh - Mechanical Movement 4

Tham khảo tài liệu 'mechanical movement 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Mechanical 207. A modification of 195 by means of two worms and worm-wheels. ị i 20S. A pin-wheel and slotted pinion by which three changes of speed can be obtained. There are three circles of pins of 1 equal distance on the face of the pin-wheel and by shifting the slotted pinion along its shaft to bring it in contact with one or the other of the circles of pins a continuous rotary motion of the wheel is made to produce three changes of speed oi the pinion or vice versa. 209. Represents a mode of obtaining motion from rolling contact. The teeth are for making the motion continuous or it would cease at the point of contact shown in the figure. The forked catch is to guide the ị teeth into proper contact. ị ị ị ị 210. By turning the shaft carrying the curved slotted arm a rectilinear motion of variable velocity is given to the vertical bar. Movements. 55 211. A continuous rotary motion of the i large wheel gives an intermittent rotary motion to the pinion-shaft. The part of the pinion shown next the wheel is cut of the 1 same curve as the plain portion of the circumference of the wheel and therefore serves as a lock while the wheel makes a part of a revolution and until the pin upon ị the wheel strikes the guide-piece upon the pinion when the pinion-shaft commences another revolution. 212. What is called the Geneva-stop used in Swiss watches to limit the numbet of revolutions in winding-up the convex curved part a. b of the wheel B serving as the stop. 213. Another kind of stop for the same purpose. 214 and 215. Other modifications of the stop the operations of which will be easily understood by a comparison with 212. 56 Mechanical .