Small Engines Boilers A Manu PDF Download

This historic book may have numerous typos and missing text. Purchasers can usually download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1899 edition. Excerpt: ...direction is lost in another; but erratic motions are caused by the length of the link itself, the length of the eccentric-rods, and the throw of the eccentric. This is only another form of saying that if the radius of the link, its point of suspension, the length of the rods, and the throw of the eccentrics are not properly designed in the first instance, there will be an erratic motion of the link at one or more points in its stroke. Take the radius of the link for example: This is conventionally the distance from the centre of valve-stem connection with valve at mid-stroke to the centre of the shaft; but sometimes if the connections are very short, indeed this gives a very awkward link, of short curve, --so that the link block binds or works hard; then the link is made of longer radius than the centre of the shaft, or of such proportions that the engine will reverse easily. If the engine works at full stroke all the time this doesn't matter, for the valve can be made to work properly at full stroke, regardless of the link radius. If, however, it is intended to work expansively then difficulties arise at once if the link is of an improper radius, for the lead increases or decreases alarmingly with any shift of the link if the rods are straight connected or " open," as it is called. If the rods are crossed then the lead decreases toward mid-gear. It might be supposed that when the rods are of the proper length and the link is of the correct radius then there would be no motion of the valve with the link in mid-gear, but this is not the case, for it will be observed by the diagram that the centres of the eccentric wheels and the centre of the shaft are not coincident; so that in a complete revolution there is an eccentricity of...