. Farm implements, and the principles of their construction and use; an elementary and familiar treatise on mechanics, and on natural philosophy generally, as applied to the ordinary practices of agriculture ... s, that is, not obliquely; and in-stead of scraping, they roll over each other with curves are ascertained by mathematical calcu-lation, which can not be here given; it may be enoughto state that they should be so formed that the pointsin contact shall always work at right angles to eachother. For ordinary practical purposes, however, theyFig. 6i. may be made as is shown in
. Farm implements, and the principles of their construction and use; an elementary and familiar treatise on mechanics, and on natural philosophy generally, as applied to the ordinary practices of agriculture ... s, that is, not obliquely; and in-stead of scraping, they roll over each other with curves are ascertained by mathematical calcu-lation, which can not be here given; it may be enoughto state that they should be so formed that the pointsin contact shall always work at right angles to eachother. For ordinary practical purposes, however, theyFig. 6i. may be made as is shown in the annex-k_ ed figure {Fig. 61),by striking circleswhose diameter shallembrace just threeteeth. The points ofthe teeth thus form-Mode of giving the best/orm to cogs. ed are removed, leav-ing a blunt extremity, according figure. There are a few other rules that should always beobserved in constructing wheel-work, in order that thewheels may run easily together, without jerking orrattling, the most important of which are the follow-ing: 1. The teeth must be of uniform size and distancefrom each other, through the whole circumference ofthe wheel. 2. Any tooth must begin to act at the same instant D2. 82 MECHANICS. that the preceding tooth ceases to touch its correspond-ing tooth on the other wheel. 3. There must be sufficient space between the teethnot only to admit those of the other wheel, but to al-low a certain degree of play, which should be equal toat least one tenth of the thickness of the teeth. 4. The pinions should not be very small, unless thewheels they act on are quite large. In a pinion thathas only eight teeth, each tooth begins to act before itreaches the line of the centres, and it is not disengagedas soon as the next one begins to act. A pinion of tenteeth will not operate perfectly if working in a wheelof less than 72 teeth. Pinions of less than six teethshould never be used. 5. To give strength to the teeth of wheels, make thewheels themselves thicker,
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Keywords: ., bookcentury1800, bookdecade1850, bookpublishernewyo, bookyear1854
