Shaft (machine)

“ This vertical shaft which carries the crushing cone of the machine is loose in its bearings, but the end of this shaft which is eccentric to the axis of the inclosing conical case or cylinder of the machine is carried around in a circle by being placed in an eccentric box in a gear wheel that is revolved on its center, which center is in the axis of the inclosing case or cylinder of the machine. The shaft which carries the crushing cone describes in its movement, when the machine is in operation, a conical orbit around the vertical axis of the inclosing conical cylinder of the machine. ”

“ Fig. 22 shows the machine properly mounted. The belt tension and pull tend to draw B corner of the machine toward the shaft C; and screw B1 is there to resist this pull. Owing to this resistance and the pull along line D, E tends to lift and slew around in E1 direction; screw E2 is, however, in a position to overcome both these tendencies. If the screws are both in front, there is nothing but the machine's weight to keep the back of it from tilting up. The absurdity of placing the screws at F and G, though even this is thoughtlessly done, needs no demonstration. ”

“ In a general sense, the rotation of shafting is greater in proportion as the movements of the machines driven require to run faster.
“This occurs because in proportion as the driving pulleys of the machines require to rotate faster than the line shaft, the diameters of the pulleys on the line shaft must be larger than the diameters of those on the machines; hence a great variation in speed would demand a corresponding increase of diameter of pulley on the line shaft, and the extra weight of this pulley would be so much added to the weight causing friction, as well as so much added to the cost. ”

“ If shoulders are produced by reducing the diameter of the journal bearing of the shaft, the strength of the shafting is reduced to that at the reduced bearing, because the strength of the whole can be no greater than its strength at the weakest part. If collars are placed one on each end of the line of shafting, the difficulty is met that the collars will permit end motion to the shaft whenever the temperature of the shaft is greater than that which obtained at the time at which the collars were adjusted, which occurs on account of the increased expansion of the shaft. ”

“ The shaft to be straightened is rotated by the friction caused by its own weight as it lies between rollers, which saves the trouble of placing the shaft upon centres. Furthermore, the belt that is the prime mover of the gears driving these rollers is driven from the line shaft itself without the aid of any belt pulley. The tension of this driving belt is so adjusted that it will just drive the heaviest shaft the machine will straighten ”

“ The short lengths of shafting that are provided to effect changes of speed, and to enable the machine to be stopped or started at pleasure, are termed countershafts. When there is interposed a countershaft between the motor and the main line of shafting, it is sometimes termed a jack shaft. ”

“ On the same shaft as a is pivoted an arm b having a slot s at one end to receive a pin to which the feed rod e may connect. f is a disk rotated from the driving mechanism of the shaping machine, and having a T-shaped slot g g, in which is secured a pin to actuate the rod e. As f rotates e is vibrated to and fro and the catch c on one stroke falls into the notches or teeth in a and causes it to partly rotate, while on the return stroke of e it lifts over the teeth, leaving a stationary. ”

“ Fig. 1796 represents a flexible shaft for drilling holes inaccessible to a drilling machine, and in situations or under conditions under which a ratchet brace would otherwise require to be used. It consists of a shaft so constructed as to be capable of transmitting rotary motion though the shaft be bent to any curve or angle. A round belt driven from a line shaft rotates the grooved pulley, and the shaft transmits the rotary motion to bevel-wheels contained in a portable drilling frame, the fulcrum for the feed being afforded by a drilling post after the manner employed in ratchet drilling. ”

“ The tool-heads are moved horizontally by the screws H and H1, and the vertical feed for the tool-bars is obtained from the splined shafts V and V1, there being a separate screw and shaft for each head so that the feeding movements are independent. These feed shafts are rotated for the power feed by vertical shafts A and A1 on each side of the machine. ”

“ Dimensions of Keys.
V. SHAFTING.
Shafting is nearly always cylindrical and made of wrought iron or steel. Cast iron is rarely used for shafting.
Axles are shafts which are subjected to bending without twisting.
The parts of a shaft or axle which rest upon the bearings or supports are called journals, pivots, or collars.
In journals the supporting pressure is at right angles to the axis of the shaft, while in pivots and collars the pressure is parallel to that axis.
Shafts may be solid or hollow. Hollow shafts are stronger than solid shafts for the same weight of material. ”

“ For example, the theoretical requirements would demand that the bearings be nearer together on those sections of shafting where most power is delivered from the shaft, while considerations as to the location and desired contiguity of the driven machines may render it impracticable to separate the driving pulleys by the intervention of a hanger at the theoretically required location. ”

“ Thus, if the pressure be applied equally along the length a b, the weaker end b will close most readily, while at a the support afforded by the unsplit section offers a resistance to closure at the ends a of the split, hence the shaft, even though a working fit to the sleeve bore, will be gripped with least force at the end a. If the shaft were simply a close fit, as, say, just movable by hand on the sleeve bore, the form of the coupling bore would, when compressed upon the shaft, be as shown in Fig. ”

“ In order to avoid the great mischief arising sometimes from undue strain upon and the breaking of a shaft, a weak coupling composed of a link is sometimes employed between the shaft and the driven machine, whereby, should the force become suddenly too great, the link of weaker metal is broken, and the connection between the shaft thereby destroyed and the machine stopped. ”

“ 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. ”

“ A very useful and important line of inventions consists in means for forming connections between rotary shafts and their pulleys and mechanisms to be operated thereby, by which such mechanism can be started or stopped at once, or their motion reversed or retarded; or by which an actuating shaft may be automatically stopped. These means are known as clutches.
They are designed often to afford a yielding connection between the shaft and a machine which shall prevent excessive strain and wear upon starting of the shaft. ”

“ A saving of time is thus effected, and the looms can be run quicker than with single-lift machines. A crank L on the end of the bottom, or picking, shaft is connected by means of a lifting-rod E to the end of a horizontal arm M, mounted on a shaft G, which constitutes a fulcrum for the arm. On one end of shaft G, at the rear of the machine, there is fixed a toothed quadrant H, which, through the medium of a small wheel, transmits motion to a similar toothed quadrant H′ fixed on the end of a shaft G′ ”

“ Great care is used in its construction, thus making it a very efficient part of the loom, and is driven from the same shaft as the journals and box motion, thus working in harmony with them. The take-up motion is positive, and is very substantial and accurate, consisting of fluted rolls, and operated by the usual train of gearing, while the goods are wound up on a roll below. The let-off is controlled by the tension of the warp over a rocking whip roll, operated by a cam on the bottom shaft, held by a clamp friction, geared to the head of the beam. ”

“ To prevent the metal from running out of the bearing, its ends are closed by means of either clay or putty closely packed against the bearing ends and the shaft, and in pouring in the melted metal it is best to pour it on the top of the shaft, and let it run down its sides into the cavity of the bearing. This heats the shaft equally, and prevents it bending from unequal expansion, as it would do if it met the heated metal on its lower half only, it being obvious that if the shaft bends the bore of the bearing will not be cast in line ”

“ Counter-shaft. Putting up the counter-shaft, when one is employed, is usually the first operation in installing a machine. It is generally placed directly over cone drive machines because of the interference of the driving belt with the upper part of the frame if it is located very far at either side. With constant speed drive machines, it is not necessary to place the counter-shaft directly overhead. ”

“ There are now running in some factories lines of shafting 1,000 feet long each. The power is generally applied to the shaft in the centre of the mill and the line extended each way from this. The head shaft being, say, 5 inches in diameter, the shafts extending each way are made smaller in proportion to the rate of distribution, so that from 5 inches they often taper down to 13⁄4. ”

“ The straining device, including the springs, air pump, guide-ways, cross-head and steel bearing, are all attached to the vertical tubular shaft, which is secured to the heavy cast back support by the box e and eccentric lever f. By raising the lever f, the shaft, being balanced, is free to move up or down to suit any length of saw. ”

“ The set-screws are so adjusted upon the work, that the outside runs quite true from end to end. The jaws of the steady rest are then set to just touch the circumference of the sleeve, care being taken that their pressure does not spring the axial line of the work out of its normal straight line. If the shaft is to be turned from end to end, the cat head should be placed sufficiently to one side of the centre of the length of the work and nearer the live centre, that the lathe tool may turn up the work for a distance of at least half its length, or slightly more than half. ”

“ Third: for any shaft there must be just one drive, or source of torque. A shaft may, however, drive more than one other shaft. Fourth: choose scale factors so that the limits of the machine are not exceeded yet at the same time are well used. For example, the most that an integrator or a function table can move is 1 or 2 feet. Also, the number of full turns made by a shaft in representing its variable should be large, often between 1000 and 10,000. ”

“ The simplest form of shaping machine, or shaper as it is usually termed in the United States, is that in which a tool-carrying slide is reciprocated across the work, the latter moving at the end of each back stroke so that on the next stroke the tool may be fed to its cut on the work. Fig. 1496 represents a shaper of this kind constructed by Messrs. Hewes and Phillips, of Newark, New Jersey, in which p is a cone pulley receiving motion from a countershaft, and driving a pinion which revolves the gear-wheel q, whose shaft has journal bearing in the frame of the machine. ”

“ In the former figure, a b are the screw dies. The rod or bolt to be threaded is placed upon the lower die b, and fed forward while screwing it. The upper die is mounted on a slide c, which is actuated in the downward direction by an eccentric e on the main shaft and the toggle-bar d, the upward motion being obtained by an internal spiral spring f. The lower die b is carried in a slide g, and is adjusted at the proper distance from the upper die by means of wedge h, and the inclined plate i, beneath the slide g. ”

“ The piece or pieces gripping the shaft ends must be capable of concentric and parallel closure along the entire area, enveloping the end of each shaft, and must do this at each end independently of the other, and the piece or pieces exerting the closing or compressing pressure must grip the closing piece or pieces, enveloping the shafting over the entire area. ”

“ In a horizontal bearing d is a shaft at whose end is a weighted lever l, and on the end of this shaft is a crank pin shown engaging a sleeve e which affords journal bearing to the outer end of shaft c, so that operating the weighted lever l operates e, and therefore shaft c with the spur gear receiving motion from the worm. ”

“ Again, if the alignment of the shaft should require readjustment from the warping or sinking of beams, as is a very common occurrence where hangers are fixed to the joists of ceilings, the adjustment is readily and easily effected by means of the plungers, nor need the boxes be fitted to the shaft more than to see that when free from the hangers they bed firmly down until the crowns of their bore have contact with the shaft. ”

“ Besides allowing of the desired adjustment of the machine, the support must be itself adjustable to uneven ground. The bottom of a shaft which is being sunk, or the sides, roof, and floor of a heading which is being driven, present great irregularities of surface, and, as the support must of necessity in most cases be fixed to these, it is obvious that its design and construction must be such as will allow of its ready adjustment to these irregularities. ”