Rod (mechanics)

“ In the first place the rod may be taken by a force at each end and torn asunder by pulling, as a thread may be broken. To do this requires very great power, and the strength of the material with reference to such a mode of destroying it is called its resistance to extension. In the second place, it may be broken by longitudinal pressure at each end, as a pillar may be crushed by the superincumbent weight being too large; the strength that relates to this form of force is called resistance to compression: finally, the rod may be broken by a force applied transversely. ”

“ The most familiar example of the use of a connecting rod is in the steam-engine, where it is used to connect the rotating crank with the reciprocating piston. The rod itself is made of wrought iron or steel, and is generally circular or rectangular in section. ”

“ Although, in general, the divining rod behaves with great gravity and consistency, and looks contemplatively upward, when it comes upon grounds that move it, and then twirls respectably round, as you might twirl your thumbs in a tranquil continuity of rotation, yet there are some—a small proportion only—in whose hands it gibs at starting, and with whom it delights to go in the opposite direction. ”

“ When this rod or shaft has been pushed forward a stage, the lever rises again, until the next notch is reached, when the same thing occurs, and the rod gets a little nearer to the partition, in which, immediately facing the point of the rod, is a circular hole corresponding in circumference to the rod itself, so that ultimately the rod must pass through the hole into a recess between the partition and the end of the box. ”

“ The rod has a chance to turn about on its center from a ball and socket joint, and engages with both wheels in nicely fitted journals, and boxes set in line with the center of the socket joint, so that when one wheel turns, the rod pries the other around by using the rod as a lever and the ball joint for a fulcrum, giving a uniform leverage all the while, with no dead centers. ”

“ When the load comes upon the platform the pull of the vertical rod is transmitted by the nickel bands to the cylinders around which they are wrapped, and causes them to revolve. As they rotate they roll themselves up the pairs of bands which are attached to the top of the casting, and at the same time cause the leaden weights attached to the bottoms of the cylinders to take up a lateral position, where they exercise a leverage opposing the motion of the cylinders, and bringing them up in a definite position corresponding to the pull of the vertical rod. ”

“ When it is intended to reduce the iron to a small rod, the cylinders have such a diameter, that three may be set in the same housing frame. The lower and middle cylinders are employed as roughing rollers, while the upper and middle ones are made to draw out the rod. When a rod or bar is to be drawn with a channel or gutter in its face, the grooves of the rollers are suitably formed.
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To draw out square rods of a very small size, as nail-rods, a system of small rollers is employed, called slitters. ”

“ If a rod or stick of any kind gradually becomes more slender or more flexible, and is bent by any external 271 force, the force will not only increase in effect as the rod becomes weaker, but the rod itself, once bent, will continually yield more willingly, and be more easily bent farther in the same direction, and will thus show a continual increase of curvature from its thickest or most rigid part to its extremity. ”

“ If the bending of a rod to the proper shape is beyond the reader’s capacity, he may build up a crank in the manner shown in Fig. 101. Holes for the shaft are bored near the tops of the supports, and the shaft is put in place. After this has been done, smoke the shaft in a candle flame and solder two small bits of tubing, or bored pieces of brass, to the outside of the supports to increase the length of the bearing. The power-crank boss is a 1-1/2-inch brass disc. ”

“ The axis, M, of the jack, on revolving, carries along a crank, MD, to which is fixed a connecting-rod, A, whose other extremity is attached to the horizontal beam that supports the zincs and counterpoises. If the axle, M, be given a continuous revolution, it will communicate to the rod, A, an upward and downward motion that will be transmitted to the beam and produce an alternate immersion and emersion of the zincs. ”

“ An unequal or an equal degree of valve lead may be given by suitably altering the length of the eccentric rod, but when the lead is equal for the two ports, its amount must be regulated by moving the position of the eccentric upon the crank shaft. ”

“ Construction of an Enlarging and Reducing Pantograph.—Cut out of 1/8-inch oak, walnut, or beech four rods 5/8 inch wide and 19 inches long. Smooth them well all over, and make marks near the ends of each, exactly 18 inches apart. The graduation of the rods for the adjustment pivot holes is carried out in accordance with the measurements given in Fig. 187. It is advisable to mark out and bore each rod separately if you do not possess a machine which will drill holes quite perpendicularly; if you do, all four rods can be drilled at one operation. ”

“ Figure 1 represents a portion of the pointed rod above mentioned, and Fig. 2 a portion of the tube which forms the casing or lining of the well.
The driving-rod, A, I construct of wood or iron or other metal, or of parts of each, with a sharp point, b, of steel or otherwise, to penetrate the earth, and a slight swell, a, a short distance above the point, to make the hole slightly larger than the general diameter of the rod. This rod I drive, by a falling weight or other power, into the earth until its point passes sufficiently far into the water to procure the desired supply. ”

“ The bearings to the shaft, on which the front roll revolves freely, are eccentric to the roll, and a partial revolution of the shaft moves the front towards the back roll, pinching the board. To an arm which is secured to the front shaft is fastened the upright rod, the upward movement of which opens the rolls, and whose [II-256] downward movement closes the same; the weight of the rod being sufficient to cause the hammer to rise. ”

“ The lowering of the leg of the rod is easy enough, but no efforts of mine to produce a revolution on its axis have as yet succeeded. The muscles which would contract the fingers upon the arms of the stick, pass the shoulder; and it is worthy of remark that one of the medical men who witnessed the experiments made on Bleton the hydroscope, expressly alludes to a slight rising of the shoulders during the rotation of the divining rod. ”

“ Angle coupling for shafts at any angle (shown at angle of 90°) consisting of four crank pins sliding and revolving in holes bored in the shaft ends.
Section 17.—CONNECTING RODS AND LINKS. (See also p. 42.)
1999. Spring connecting rod of steel or wood.
2000. Attachment for connecting rod to a pump ram, with provision for taking up the brasses by a long screw.
2001. Connecting rod end, the back brass being set up by a set screw with coned point, which displaces by penetration a number of steel balls or shot.
2002. Solid rod end, with wedge gib and nut adjustment for brasses ”

“ These must make so good a fit that when slightly lubricated they shall prevent the passage of air between them and yet set up very little friction. If you cannot find a piece of steel rod and brass tubing which fit close enough naturally, the only alternative is to rub down a rod, slightly too big to start with, until it will just move freely in the tube. This is a somewhat tedious business, but emery cloth will do it. The rod should be 3-3/8 inches, the tube 2-1/8 inches, long. I used rod 3/16 inch in diameter; but a smaller rod would do equally well. ”

“ Cast-iron arms, if bulky enough to be safe against external blows, are awkward in shape. The sectional area necessary for any arm depends upon the means provided for preventing a sidewise strain on the lever, due to rotation of piston or friction of its connection to piston rod. The spool or crosshead on the piston rod should be so designed that no sidewise strain can be thus produced on the lever. ”

“ By reeling on a short length of line and reeving it through the guides and then fastening the end to a weight lying upon the floor, a very good idea of the rod's behavior may be gained, since by reeling in the line and putting tension on the rod its elasticity and curve may be seen and felt as well as in actual fishing. ”

“ It is familiar in the titles, showing the colour of their wands of office, of the gentlemen ushers of the three principal British orders of knighthood, the ushers of the Garter and St Patrick being “Ushers of the Black Rod,” and of the Thistle “Green Rod.” The use of a rod as a measuring implement has given rise to the use of the word for a measure of length = 51⁄2 yds. or 1621⁄2 ft.; this length is also named a pole or perch, the origin of the application being the same as in “rod”; as a measure of area, a rod = a square pole or perch, 301⁄4 square yds.= 2721⁄4 square ft., 160 rods = 1 acre. ”

“ The most important part of the business is a flat steel rod, about seven and a half inches long, and an eighth of an inch in breadth, pierced, at a distance of about five and a half inches from its upper end, by a hole, through which is passed the pivot upon which it is made to oscillate. This rod—answering to the Double-Pendulum already described—is suspended, by means of the pivot, in front of a wooden case, and kept in a perpendicular position by a stout leaden bullet, fixed to its shorter end, which, thus weighted, sinks, of course, when at rest, to the lowest place. ”

“ Very small rods to be made in numbers are usually got out by means of special devices which leave the fitter but little to do; indeed, sometimes the machine work is so accurately and finely fitted and finished as to finish the rod without the aid of the vice hand, save to put it into its place upon the engine or machine. As, however, the dimensions of the rod increase, this method of manipulation is in practice departed from, and the filing, fitting, and adjusting operations increase. ”

“ If, now, we hold the rod vertically, as at C, giving neutrality, and give a few slight blows with a wooden mallet to its upper extremity, we can give just the amount of freedom required for it to produce evident polarity, and we then have equal polarity, no matter which end of the bar is below, the center of its free rotation here being perfect, and the rod perfectly neutral longitudinally when held east and west. ”

“ If the one end of a rod be clamped, we can twist the rod, but not turn it round; so if any part of the contour of a disk is clamped we can impart a twist to the disk, but not turn it round its central plane. In the case of extensible materials a long, thin rod will twist round its axis, even when the axis is curved, as, for instance, in the case of a ring of India rubber. ”

“ Now, to do away with the last vestige of impracticable mechanism, in which the heavinesses of all parts of each long rod are supported on the thread of an ideal screw cut on a vertical shaft of ideal matter, absolutely hard and absolutely frictionless: first, go back a step to our supposition of just one such rod and screw working in a single pit excavated down to the center of the sun, and let us suppose all the rest of the sun's mass to be rigid and absolutely impervious to heat. ”

“ Variable radius lever, operated by a crank motion to give variable angular reciprocating motion to a shaft.
37. Hand or power feed-gear, for a drill, boring-machine, &c.
38. A method of doubling the length of stroke of a piston-rod or the throw of a crank. A pinion revolving on a spindle attached to the connecting-rod is in gear with the fixed lower rack and also with the upper rack, which is carried by a guide-rod above and is free to move backward and forward. ”

“ When the rods have been carefully placed in line, the distance between the end of one rod and the following has to be ascertained, and also, for getting at the actual length of each rod, the difference in the length of the iron and zinc rod in each of the cases. A small space is always left between two rods, which are not made to touch each other, in order to avoid sudden and too sharp contact. ”

“ Now, if the pressure of the balls of the digits be in the least relaxed, the stalk of the rod [Pg 81] will naturally fall. It has been assumed by some, that a restoration of the pressure will bring the stem up again, pointing towards the operator, and a little further pressure will elevate it into a perpendicular position. A relaxation of force will again lower it, and thus the rotation observed in the rod be maintained. ”

“ The displacement z, which necessarily must be small, can be enlarged by aid of a lever OT′. To regulate the displacements y of the points C (fig. 24) each spring is attached to a lever EC, fulcrum E. To this again a long rod FG is fixed by aid of a joint at F. The lower end of this rod rests on another lever GP, fulcrum N, at a changeable distance y ′′ = NG from N. The elongation y of any spring s can thus be produced by a motion of P. If P be raised through a distance y ′, then the displacement y of C will be proportional to y ′y ′′ ”

“ The joints increase the friction considerably, and are of no use whatever, except where the rod is too long to keep itself straight. Where the rod does happen to be in the middle of the room, and there are three or four dials, the two horizontal bevelled wheels at each end of it must be a little larger than all the others both the one in the clock and those of the dial-work ; for otherwise the three or four wheels in the middle will meet each other and stick fast. ”