Crank

“ In mechanics, a crank is a device by which reciprocating motion is converted into circular motion or vice versa, consisting of a crank-arm, one end of which is fastened rigidly at right angles to the rotating shaft or axis, while the other end bears a crank-pin, projecting from it at right angles and parallel to the shaft. ”

“ Fry then took him out into the labor-yard, which he found perforated with cells about half the size of his hermitage in the corridor. In each of these little quiet grottoes lurked a monster, called a crank. A crank is a machine of this sort—there springs out of a vertical post an iron handle, which the workman, taking it by both hands, works round and round, as in some country places you may have seen the villagers draw a bucket up from a well. ”

“ Fig. 1789 represents a drill crank which receives the drill at a, and is threaded at b to receive a feed screw c, which is pointed at d; at e is a loose tube or sleeve that prevents the crank from rubbing in the operator’s hands when it is revolved. ”

“ An eccentric is the exact equivalent of a crank having the same amount of throw, as may be seen from Fig. 3308, in which the outer dotted circle represents the path of the crank and the inner one the path of the centre of the eccentric. A small crank is marked in, having the same throw as the eccentric has, and the motion given by this small crank is precisely the same as that given by the eccentric whose outer circumference is denoted by the full circle. ”

“ The eccentric is a particular form of crank, being a crank in which the crank-pin is large enough to embrace the crank-shaft. In the eccentric what corresponds to the crank-pin is called the sheave or pulley. The advantage which an eccentric possesses over a crank is that the shaft does not require to be divided at the point where the eccentric is put on. ”

“ The Crank is that part of an engine by which the effect of the steam acting against the piston is converted into work. There are two kinds, Side and Center crank. The term Side crank refers to a disc plate or a crank attached to one end of a shaft and in which is placed the crank-pin. When the shaft extends to the right the engine is called a right hand engine, and when it extends to the left it is called a left hand engine. ”

“ The Starting Crank.—A starting crank may be made of a piece of galvanized wire bent into a crank shape and placed in position through holes punched for it in front of the frame and through an extra piece soldered underneath the frame. ”

“ The eccentric is in principle nothing more than a crank pin so exaggerated as to be larger than the shaft of the crank. Its convenience lies in the fact that it may be mounted at any point on a shaft, whereas a crank can be situated at an end only, if it is not actually a V-shaped bend in the shaft itself—in which case its position is of course permanent. ”

“ 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. ”

“ At one time steam-engine cranks were largely made of cast iron, now they are always made of wrought iron or steel. The crank is either forged in one piece with the shaft, or it is made separately and then keyed to it.
Overhung Crank.—Fig. 37 shows a wrought-iron overhung crank. A is the crank-shaft, B the crank arm, provided at one end with a boss C, which is bored out to fit the shaft; at the other end of the crank arm is a boss D, which is bored out to receive the crank-pin E, which works in one end of the connecting rod. ”

“ Supposing now that the crank is to be shrunk, or contracted on, then the points of consideration are (supposing the crank to fit properly to its seat, whether the same be either parallel or taper) that the hub of the crank opposite to the throw is the weakest and [II-171] is likely to give most in the process of contraction, so that if one part (as f) of the crank be made hotter than another (as g) it will give way more, and this will twist the crank. ”

“ Placing two Cranks on a Shaft so that their Centre Lines shall stand at a Right Angle.—It is obvious that the keyways in both the crank and the shaft must be cut accurately in their proper positions, because it is a tedious operation to file out the sides of the keyways when the cranks are placed upon the shaft. ”

“ An American inventor, Ramsey by name, is working on a motor which is said to possess great possibilities in this line. Its distinctive features include a connecting rod much shorter than usual, and a crank shaft located the length of the crank from the central axis of the cylinder. This has the effect of increasing the piston stroke, and also of increasing the proportion of the crank circle during which effective pressure is applied to the crank. ”

“ Suppose, for instance, that we have moved the driving wheel forward until the crank stands upright at a right angle to the bore of the cylinder, the resistance to motion of the piston and crosshead has caused the crank pin to bed against the half-brass nearest to the cylinder, all the play or lost motion is then between the other half-brass and the crank pin. ”

“ A common method of chucking such a crank is to level the surface of the crank in a planing machine, and to hold that surface to the chuck-plate by bolts and plates, while boring both the holes, merely reversing the crank end for end for the second chucking. ”

“ It was some kind of a machine, and the turning of a crank made it draw together in such a way, that if a person were once within its embrace, the pressure would soon arrest the vital current, and stop the breath of life. ”

“ As the crank revolves from each of those positions where the power of the machine over it is greatest, to where that power is altogether lost, it is continually diminished, so that, in fact, the crank is driven by a varying power, and therefore produces a varying motion. ”

“ This, it will be observed, is a speedy process, and would invariably be adopted if it were not attended with a very serious drawback; it is very hazardous to the solidity of the forging. For it will be easily understood that not above a third of the crank itself can be thus formed, because the iron at the neck n would not carry a greater mass; if the whole mass of the crank, or even the half of it, was formed before the body and neck of the shaft were finished, a proper heat could not be taken on the body and neck for finishing, without the neck giving way or rupturing. ”

“ Suppose a blow is heard at each turn and only when the outside crank is nearly in a straight line with the piston rod looking from the left-hand side of the foot-plate and with the outside cranks on the same center line and on the same side of the axle as the inside crank. ”

“ When this is done, the man turns the crank, which successively moves the screw, the wheel and the roller, on which, as the cable winds up, the tree must gradually yield, until, at length, it is precipitated by the weight of its top. ”

“ The piston H is attached to the connecting rod I, which is coupled to the crank, as shown. The crank shaft has a small gear J, which meshes with two gears of double size on opposite sides of the crank shaft, one of the gears K, being designed to carry the cam L for actuating the stem L ́, which opens the valve M in the port that admits the carbureted air. ”

“ When the crank is turned end for end on the chuck-plate and again bolted with its plain surface against the surface of the chuck, the second hole bored will again not stand at a true right angle to the planed surface, and furthermore the error in one hole will be in a directly opposite direction to that of the other hole, so that the error in the crank will be double the amount that it is on the chuck surface. ”

“ Turning the crank now sets the central band in continuous motion, whilst the margins of the field remain really at rest, but after a while appear moving in the contrary way. Stopping the crank results in an illusory appearance of motion in reverse directions all over the field.
A disk with an Archimedean spiral drawn upon it, whirled round on an ordinary rotating machine, produces still more startling effects. ”

“ One End of this Crank at Y is placed close abutting to the End of the Axle-tree X, where they are at those Ends six Inches Diameter, each having a Slit in the Ends, where an Iron Wedge is put, one half into the End X, the other half into Y, by Means of which the Axis X turns about the Crank Z Z.
The four Necks of the Crank have each an Iron Spear, or Rod, fixed at their upper Ends to the respective Libra, or Lever, a 1, 2, 3, 4, within three Foot of the End. These Levers are 24 Feet long, moving on Centers in the Frame b b b b ”

“ No crank can see his crankiness at the time of crankling, though sometimes he sees it afterwards. The crank is a person who holds views which to us seem ridiculous. The man who first objected to cannibalism was a crank. The man who first thought lunatics should not be chained to walls or left naked on unsavoury beds of straw was a crank. Galileo was an intellectual crank of the shameless type. Shelley is the beautiful crank of all times, champion of forlorn causes, the inspired rebel of the spirit. ”

“ A small force-pump, worked by a crank, with the assistance of a fly-wheel, draws the carbonic acid from the gas-holder, and forces it into the water. The combination260 of the gas and water is facilitated by an agitator, the axle of which projects through a stuffing box, and it is worked either by hand, or is turned by means of a small cog-wheel, that works into the teeth of a larger one fixed to the crank axle, so as to produce rapid rotation. ”

“ As shown in Figure 1-f, the crank throw consists of a flat piece of steel, 3⁄32′′ thick, 3⁄8′′ in length by 1⁄4′′ in width. At each end of the crank throw a hole 3⁄16′′ in diameter should be drilled, the holes to be one-half inch apart. Into one hole a piece of steel drill rod 3⁄32′′ in diameter by 1⁄4′′ long is soldered, to which the connecting rods are mounted, as shown in Figure 1-f. ”

“ The ends of crank pins are often riveted after being shrunk in, in which case it is best to recess the end, which makes the riveting easier, and causes the water poured upon its face to be thrown outward, thus keeping it from running down the crank face and causing the crank to crack or split. ”

“ To secure noiseless running, the crank pin should be turned with great exactness, and should be set exactly parallel with the direction of the shaft. When the pressure on the pin or any bearing is over 800 pounds per square inch, oil is no longer able to lubricate it properly. ”

“ 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. ”

“ The crank arms stand at angles to each other, so that the crank shafts are turned in opposite directions, and the position of the link is such that it can be readily changed by the reversing lever to simultaneously reverse the motion of the crank shafts. ”

“ ENGINE PARTS The sudden and powerful outward movements of the piston under the pressure from the combustion are transmitted to a crank shaft, which must be of great strength in order to resist the heavy strains under which it operates. ”

“ If ignition occurred with the crank inclined ever so little toward the right, the pressure of the piston would force the crank downwards in a right handed direction. If the crank were inclined to the left, the tendency would be for left handed rotation. ”

“ A six-crank engine may be arranged in this 'way to secure an extremely close approximation to per feet balance, and the same state of balance can be secured when the number of cranks is reduced to five. ”

“ Cranking must stop when the lack of movement of the wire shows the piston to be at top dead center, and then the crank shaft must be turned backward by means of the flywheel until the piston has moved down one half inch. ”

“ A fruit jar usually takes the place of a churn and the work is exceedingly hard, the jar being shaken so the cream will beat against the ends in the process of butter-making. The accompanying sketch shows clearly how one boy rigged up a device having a driving wheel which is turned with a crank, and a driven wheel attached to an axle having a crank on the inner end. This crank is connected to a swinging cradle with a wire pitman of such a size as to slightly bend or spring at each end of the stroke. ”

“ The balance weights are to be separately calculated for each system, the one set being added to the crank shaft as revolving weights, and the second set being included with the reciprocating weights and operated by a properly placed crank on the crank shaft. ”

“ Adjustable Index Crank. The index crank of the spiral head is adjustable circumferentially. This is shown in Fig. 6. Many times it is desired to make a delicate ajustment of the work, or to bring the index pin to the nearest hole without disturbing the setting of the work. ”

“ Then, Harry, as we have a pretty tough job before us, I suggest that you make two capstans, something like those you saw on shipboard, around which the two raising ropes can he wound, each to have a crank, and a means for holding the crank at any position. ”