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jack lifted but 700 to 1,100 pounds or higher, according to the size of the car, this one will be required to lift just twice as much every time, namely 1,400 to 2,200 pounds, according to the size and weight of the car.
For this reason, also, it would be well to increase the proportions all over. Devices of this sort have been built and used in many racing contests, in which the smallest fraction of a second was valuable. The device in those cases was built of metal throughout, light weight being of no object. When the signal came for a tire stop on the next round, this was wheeled out into a convenient position, and when the car stopped it was slid under the axle, a couple of men jerked it down, raising the entire axle so wheels stood clear off the ground, and in less time than it takes to tell it, another pair of men were replacing the wheels and tires, or tires alone, as the case might be. These were so made with definite proportions that when fully pressed down the jack would stay down of itself and did not require a man to stand and hold it.
A home-made cradle for bringing in cars having an injured axle or wheel is outlined at Fig. 19, C. It can be constructed by any mechanic of average ability from odds and ends, and as it does not take up much room it can be stored conveniently when not in use, though many uses will be found for it in the garage, even when not employed for the purpose for which it was primarily intended. This consists mostly of a built-up pair of beams forming the two long sides of a very acute triangle, the third side of which is formed by a pair of small metal wheels and an axle, such as might be found on any old farm wagon or other heavy truck. The axle is securely attached above the side beams, which are fastened together at the front. About 18 inches to 2 feet forward of this axle a pair of vertical supports are formed with a notch in the upper surface large enough to take an ordinary rear axle. In the sketch, the side bars are marked B, B, the uprights for the car axle U, the wheels, W, W, the clips holding the axle to the sidebars C, the forward ends E, and the tie bolt holding them together and making a point of attachment TB. The second sketch shows the method of use; the cradle is pushed under the
chassis, so that the uprights catch the rear axle RA, then the front end E and the through bolt TB are fastened to the front axle FA by means of the chain C. This being the case, the rear wheels of the car do not rest on the ground, but the small iron wheels, C, of the cradle do, and the car is pulled home on these and the regular front wheels.
The same outfit can be used for an underslung frame by laying a board across in place of the uprights, and resting the rear axle of the car on this. In doing this, the uprights must be removed, so the board should be made with a pair of extensions and this bolted in place, using the same bolts as with the uprights. A device of this kind has recently been placed upon the market by a western firm, this being finished up very neatly all over, while the sketch simply gives the idea for a more or less rough home-made cradle.
Machinery Equipment for Small Shops.—The amount of machinery used in repair shop equipment will depend entirely upon the size of the shop and the character of the work it caters to. The requirements of the average small shop will be met very well by the use of a 16-inch screw-cutting lathe, a sensitive drill press, an emery grinder or twin wheel stand, and a forge outfit. If all classes of work are to be attempted, a small shaper will be found very useful, as much of the work that can be done on a milling machine can also be accomplished on the shaper, which is a less costly machine tool. In all repair shops, irrespective of size, the lathe is really the most important tool, and one good sized machine of this kind should be included in the equipment of any repair shop worthy of the name, no matter how small. Practically all classes of machine work may be done on a lathe, as very efficient attachments may be obtained on the open market that will enable a machinist to do milling, gear cutting, and grinding on this universal machine tool. Drilling may be done without changing the lathe in any way. About the largest part to be handled in any repair shop would be an engine flywheel, as far as diameter is concerned, and the longest piece would probably be a six-cylinder crankshaft or live axle. It is not necessary to install a lathe capable of swinging 24 inches in order to have a tool available for work that would be unusual, as very effective results may be obtained by using a gap bed lathe which can be purchased at but slight extra cost over that of the regular tools. The adFantages of this type of lathe will be considered in proper sequence. A lathe that will swing 16 or 18 inches will be sufficiently large for most shops, though it can be supplemented by a smaller size adapted for lighter work if the funds permit. In buying lathes, especially for a small shop where the machine tool equipment is necessarily limited, it is well to remember that small work can be handled in a large lathe much easier than large work can be turned in a smaller one, and where it is imperative that but one tool be purchased, it will be the best economy to install a substantial machine. If a drill press is included, one that will swing 24 inches has been found large enough to handle nearly all parts of automobiles. The sensitive drill press is used for drilling small holes, and should have a capacity so that it will handle drills up to a half inch diameter, at least.
Machine Tool Equipment for Complete Repair Shop.-An unusually complete machine tool outfit is shown in the shop plans at Figs. 5 and 6. With an equipment of this nature all kinds of repair work may be accomplished economically and, in fact, the outfits shown are sufficiently complete so competent mechanics will be able to build an automobile without outside assistance. As the lathe is the king of machine tools, the major portion of the equipment consists of these useful machines. Seven lathes are provided, two being ten inch swing, three fourteen inch swing, one eighteen inch swing and one capable of handling work up to twenty-four inches in diameter. A universal milling machine upon which a wide variety of work may be done is a useful adjunct to the lathe. A milling machine can finish flat or irregular surfaces which a lathe cannot do unless fitted with a milling attachment. It will make Woodruff keyways or straight splines, it can cut gears, cams and do a variety of other work that cannot be done on the simple lathe.
A small shaper having about sixteen inches stroke is also useful, because it will do much of the work done on a milling machine and require simpler tools. While a milling machine has a greater range of work and will do it more economically than the shaper, the latter can be used to advantage in many cases where the cost of milling cutters would be much more than that of making the shaper tool and doing the work besides. Both milling machine and shaper should be provided, if possible. Three drilling machines are provided, one a sensitive drill for light work, the intermediate size, a back-geared drill press, and for extremely large work, such as drilling frames, boring cylinders, axle housings, etc., a radial drill is very useful, as it will handle any part of a motor car irrespective of size. A power hack saw, two emery grinders, one used for roughing purposes and the other for tool grinding, and an arbor press, complete the equipment of this machine shop.
Power for the Shop.—Just as electric current is superior for lighting, it also has many advantages as a source of power. The electric motor is an ideal power generator, because it is clean, efficient, economical, easily started and stopped, compact and capable of standing considerable overload. It makes possible individual motor equipment of machine tools in large shops and can be used very effectively for driving the line shafting of the smallest establishment, because it can be suspended out of the way on a platform hung from the ceiling or in the smaller sizes placed on a shelf attached to the wall or some convenient post. Where electric current is not available and where it is not profitable to install a generating plant, the gasoline engine is an economical method of supplying power. The marked advantage of electric current is that it may be employed not only for lighting, but for operating various portable drills, polishing machinery, air compressors, etc., and it also has a great advantage of generating current that can be used for charging storage batteries, which are now included in the equipment of all up-to-date automobiles, as a source of current for the electric self-starter and lighting system. Where electric current is not available from a municipal central station, a garage or repair shop of any size will find it more economical to install a generating plant and make its own electricity for lighting and power than to use a steam or gasoline engine which can only fur
nish power and then depend upon kerosene and acetylene lamps for lighting, which naturally increase the fire risk.
Small Generating Sets.-A typical generating set consisting of a four cylinder gasoline engine driving a direct current dynamo is shown at Fig. 20. The equipment is furnished in various sizes, and an outfit can be purchased that will furnish current econ
Fig. 20.—Isolated Power Plant for Generating Electric Current.
omically for even the smallest shop. The outfits include switchboards and all necessary governing and control appliances, and once the engine is started it requires no further attention, as it will perform the various functions incidental to controlling its speed and power automatically. Instead of using the line shaft, as would be necessary with a gas engine belted direct, it is possible to install individual motor drive on the various machine tools, an example of which is shown at Fig. 21. When one considers that