Cam (mechanism)

“ On the top of the spring bar is an adjusting screw bushing through which the plunger projects. This plunger is [Pg 6] forced against the top of the cam yoke by a spring. As the free end of the cam yoke raises, the spring must be strong enough to hold the pivoted end of the yoke from raising more than enough to give the full stroke of the keyrod. If something prevents the free movement of the escapement, the strain would come to the pivoted end of the yoke, forcing the plunger up, thus releasing the keyrod, cam, or rubber roll of undue strain. ”

“ On the mold turning cam are two adjustable steel shoes for the purpose of taking up the play between the shoes and the square block when in the casting and ejecting position. These shoes are adjusted by screwing in on the bushing screws that extend through the cam and bank against the shoes. Each shoe is held in place by two machine screws that extend through the bushing screw into the shoe. When adjusting the shoes care must be taken to make them parallel. ”

“ It also carries the ejector cam which engages the pawl on the ejector lever and moves it forward, ejecting the slug from the mold.
The tenth cam operates the delivery slide and transfer cam roller arms and causes these two parts to return to normal position after their respective movements. The delivery slide cam roller rotates on the outer surface, while the transfer slide cam roller acts on the inner surface. This cam also retracts the ejector lever after the slug has been ejected. The automatic safety and stopping pawls are attached to this cam. ”

“ A dry cam pivot or a sluggish cam will cause transposition of letters.
To locate the cause of a non-response, first observe if the keyrod is moving. If it is, the trouble will probably be found in the magazine or magazine escapement. If the keyrod does not raise, look for the trouble in the keyboard.
Do not take the keyboard apart every time a few matrices fail to respond correctly. It is much quicker to correct the trouble with the individual parts that may be bothering. Always locate the cause of the trouble before attempting to correct it. ”

“ With the machine in transfer position, the cam lever roller is against the buffer in cam No. 10. The adjusting screw in the automatic safety pawl, being against the inner end of buffer, regulates the distance between the cut in the finger and second elevator bar plate. This adjustment, when properly made, insures the line being moved from the first to the second elevator. Turning the adjusting screw to the right increases the distance between the slide finger and the bar plate. Turning to the left decreases it. ”

“ The instrument consists of two cams, the form of which regulates the components of the curbed signal, one cam being for the dot element and the other for the dash element, which by their sequence give the letter signals; these cams, by means of clutches controlled by the relay, are mechanically rotated by clockwork, the speed of rotation being approximately adjusted to the rate of transmission of a single element, so that the requisite number of consecutive elements is transmitted corresponding to the duration of contact of the relay arm with the side controlling that particular element. ”

“ An end view of the three cams keyed up on the side shaft is given in fig. 40A. In small engines it is convenient to have the air and exhaust cams made in one casting, when one key only will be required. On some engines, instead of employing a movable roller or valve lever, the exhaust cam is fitted on side shaft with a "feather"—i.e., a headless key—and the cam being capable of longitudinal movement, such movement being controlled by a small lever or handle, called the half-compression lever. ”

“ In making models of machinery or toy machines, cams are very often required. A simple way of making these is to lay out the cam plate, or drum, and then bend pieces of brass to the correct shape and solder them in place, whereupon they may be smoothed up with a file or scraper. A cam of this sort on a drum is shown in the sketch at A, and on a faceplate, at B. The method is not quite as accurate as milling, but answers the purpose in most cases.—Contributed by Chas. ”

“ They should be set as close as possible and not rub the plate as they are moved back and forth.
It may be well to explain here that a cam in any machine is a piece of hardened steel of the proper shape and construction to cause some other part of the machine to make the proper movements to perform its functions. In this instance they actuate the needles by coming in contact with the butts.
It will be noted that each one of the needles from e to e, Fig. 16, has a loop in the hook except from the point where they are rising over the cam a-3, and on these the loops rest on the shank. ”

“ The carrying stop and locking detent lever N is provided with a cam-arm or pin N, which was arranged to co-act with the cam disc E (see Fig. 1) , fast to the prime actuating pinion E. The cam surface was short and performed its function during a short lost motion arranged to take place before the ratchet pawl would pick up and move the numeral wheel under key actuation. ”

“ Moreover, if the engine were running at even a slow speed, the motion imparted to lever L would be indefinite; and this, especially if the governor is fitted to the air valve lever, as in fig. 25, is very undesirable. Therefore, to obtain a definite opening we must set out the cam, as shown in fig. 31. In this diagram the roller is shown standing clear of the back of cam by about 1⁄16 in. A line MN is then drawn, forming a tangent to both roller R and circle GHJ at points F and O respectively. ”

“ Figure 21, shows a cylinder or drum cam. A groove is cut in the cylindrical wall of the cam and an arm or lever is provided with a roller which [40] rolls in the groove. When the cam is revolved the lever is constrained to follow all the twists and turns of the groove. A different form of cam is shown in Figure 22. It is formed with an irregular periphery against which the roller is pressed by a spring. ”

“ A main shaft, driven by a band and rigger as usual, brings, as it revolves, a cam into operation upon a lever which carries a double inclined plane or wedge in its front or acting part. This wedge being by the rotatory cam projected forwards between the tails of one of the pairs of hammers, causes the faces of these hammers to approach each other, and to beat or press the redhot iron introduced between them, so as to flatten it upon two opposite sides. The rotatory cam passing round, the wedge lever is relieved, when springs instantly throw back the hammers ”

“ As the magneto is grounded when it is placed on the engine, and as the movable electrode of the igniter is also grounded on the engine, a circuit for the current is provided only when a movable electrode is in contact with a stationary electrode. The construction of the cam shaft is such that only one igniter at a time makes contact, which occurs during the compression stroke, so that the rupturing of the circuit will occur at the point in the compression stroke when the spark is required for ignition. ”

“ The system is controlled by a switch located on the dash. The contact breaker shown in Fig. 67 consists of an exceedingly light steel contact arm. One end rests on a hardened steel cam which rotates one-half as fast as the crank shaft. [127] This cam has as many sides as the engine has cylinders. When the contact points are opened by the movement of the cam the primary circuit is broken and produces a discharge of secondary high tension current at one of the spark plug gaps.
Fig. 66. Atwater Kent Circuit Diagram—Type CC
Fig. ”

“ New main bearings in a motor should always be scraped to secure a perfect fit. A loose piston or connecting rod bearing will produce a sharp knock which can easily be determined from the dull thud produced by a loose main bearing. (Fig. 9.) The cam shaft revolves on bearings and is usually located at the base of the cylinders on the left hand side looking toward the radiator and carries a set of cams for each cylinder. The cam pushes the valve open, and holds it in this position, [19] while the piston travels the required number of degrees of the cycle or stroke. ”

“ It appears, then, that the larger the roller the quicker the forward motion and the slower the return one, which is advantageous, because the object is to move the roller out quickly and close it slowly, so that under a quick speed the cam shall not run away from the roller as it is apt to do in the absence of a return or backing cam, which consists of a separate cam for moving the roller on its return stroke, thus dispensing with the use of springs or weights to keep the roller upon the cam and making the motion positive. ”

“ Fig. 40a
Having once thoroughly grasped the important part the cams play in the working of the engine, it will be an easy matter to adjust the valve settings, and to keep them adjusted correctly. The effect of a wrong setting will then be strikingly apparent. On small engines a separate cam to operate the gas valve is not a necessity; and the practice of fitting [Pg 73] the gas valve spindle (or the pecker, the effect would be the same) with a device for increasing or diminishing its length, is also unnecessary and unsound. ”

“ The cases which receive these cams are engine lathe turned and bored and so true and smooth that the cams when in operation create almost a perfect vacuum and will “pick up” water for a long distance and hold it efficiently. The cams are carefully and accurately planed to mesh into each other to fit their case.
It is a point worth noting that if a little good oil be put into the case of these pumps before and after using at first, or simply to pump air with the oil a few times, the cams become as hard upon the surface as tempered steel, and are almost unaffected by long use afterwards. ”

“ Cam movements, and others of like character, producing simultaneous operations according to the needs of the case, such as opening valves in a steam-engine as the piston ascends and descends, and a thousand other things, are in such common use, that it requires but very little invention to adapt them to a particular case, like the one under consideration. ”

“ The cam shafts are generally driven by a gear meshing with a smaller one attached to the front end of the crank shaft of the motor, which forms one of the forward train of gears that are enclosed in an aluminum case. ”

“ MOTIVE POWER FOR AERIAL CAMERAS As long as circumstances permit, hand operation still remains the most reliable and satisfactory method of driving a camera. It is always available, can be applied to just the amount desired, and at the time and place needed. For instance, in a magazine of the Gaumont type (Fig. 40) , what is needed is the periodic application of a very considerable force rather quickly, and while this can be done quite simply by hand, no mechanism has even been attempted to go through this same operation automatically. ”

“ A A A A is a cam, sloping as in the drawing, which, it must be understood, represents the circular construction opened out and laid flat. As the barrels, carrier and locks revolve the slope of the cam forces the locks forward and backward alternately. At position I. the cartridge has just fallen into the carrier, the lock and bolt are completely withdrawn. At positions II., III., IV., the cam is forcing them forward, so that the bolt pushes the cartridge into the barrel. ”

“ When the carriage reached the left end of the machine this cam would be moved down in alignment with cams w and r, so would be in the position that would not make any change in the position of the jacks.
In making some kinds of work it is desirable to put all the back jacks in and out of operation at certain times. ”

“ In making a cam of this form, the body of the cam is covered by a sleeve. The groove is cut through the sleeve and into the body, and is made wider than the diameter of the roller. When the rollers are in place on the spindle or journal, the sleeve is pushed forward, or rather endways, and fastened by a set-screw. This gives the desired bearing on both sides of the groove, while each roller touches one side only of the groove. ”

“ The advantage of cams of this kind is that they waste as little force as possible in the lift, and keep the lever acting upon them as a tangent at its point the whole way ; and the cams themselves may be of any length according 1 to the angle through which you want the lever to move ,
Most people however prefer dealing with circles, when they can instead of epicycloids ”

“ The object of using a cam instead of an eccentric is to enable the opening of the valves abruptly at the beginning of the piston stroke, maintaining a uniform steam-port opening during nearly the entire length of stroke, and as abruptly closing the valves at the termination of the stroke. ”

“ The action of the cams is to give the needles their up-and-down motion in loop formation, they move round to work on the needle butts in succession, pushing them up so that the hooks receive the thread from the carrier, and drawing them down again so as to discharge and knock over the loops. ”

“ The principle on which this improvement is effected is by the introduction of a revolving cam wheel aeneath each lever, which, continually turning, raises the lever the moment the hammer has struck the bell, so that the latter is at once brought into position again for striking, and the action of the pins on the barrel, instead of being a lifting and letting-off action, is merely a letting-off, the whole of the lifting being done by the cam wheels. As in many other mechanical inventions, the simplicity of action which characterises the new carillon machinery was not attained at once. ”