Читать книгу Harper's Outdoor Book for Boys - Joseph H. Adams - Страница 12

A great deal of fun may be had with a merry-go-round in the rear yard, and while it may not be run by an engine or its motion accompanied by an organ, hand power will turn the table and music can be made with an old accordion or concertina. The only difficult thing about the whole affair is the bevelled gear, the shaft and crank; but if an old reaper can be found at a blacksmith-shop the difficulty is solved, for a pair of bevelled gears are on every reaping-machine. Of course a machine-shop or foundry would contain gearing of various sizes, and a five and twelve inch gear wheel will answer the purpose very well.

In the practical back-yard merry-go-round shown in Fig. 23 the revolving post is four inches square and may be of spruce or white-wood planed on all sides and provided with a ferrule at both ends. These may be taken from old buggy-wheels, and will prevent the wood from splitting when the pins are driven in. The lower cross-beams a a in Fig. 24 are of spruce, eight feet long and two by three inches. The beams b b are six feet and six inches long, and on these four the cross-plates are made fast that hold the top or deck planks. The six cross-timbers are of spruce, one by four inches, and are from two to eight feet in length, according to their location. The beam plan (Fig. 24) shows quite clearly how these supporting beams are arranged. They are held together with steel wire-nails driven down from the upper beams diagonally into the lower ones.

A MERRY-GO-ROUND

The longest beams are securely spiked to the revolving shaft, and in securing them in place take care to see that they are perfectly true, so that the outer edge of the platform will not dip and rise as it revolves. Drive a three-quarter-inch rod in the top of the shaft and another one in the bottom having a bevelled point as shown at Fig. 25. At the lower end of the shaft arrange the larger gear wheel and pin it fast so that it is fixed to the shaft and will not move.

An iron base-plate with an upright arm welded to it will hold the shaft and the smaller gear, which is to be arranged the right height to lock in with the teeth of the large gear. This plate is shown in Fig. 26; and through the four holes at the corners long screws are passed to bolt the plate securely to a wooden base, which last is set in the ground as shown at A in Fig. 27. The shaft B, to the end of which the small gear wheel is made fast, extends out beyond one of the upright posts, and at the outer end a crank and handle C are made fast, so that by hand-power the platform and shaft may be revolved.

Construct an overhead framework of six by two inch spruce beams twelve feet long, and set them in the ground twelve feet apart, bracing the uprights well, braced at both sides with angle beams as shown in Fig. 23. The top bar should be well braced also with one or two angle brackets, to prevent the frame from rocking. If the ground props are not strong enough to properly brace the frame, attach heavy wires to the corners and carry them out in both directions, making the ends fast to stout pieces of joist embedded in the ground.

At the middle of the top cross-bar arrange a plate of wood eighteen inches long with a groove cut in it in which the pin at the top of the square shaft may revolve. This plate should be attached to the bar with lag screws, so that it can be removed when it is necessary to unstep the shaft and platform. The outer line of deck planking is shown in the deck plan (Fig. 28), and inside of these boards as many others can be laid down as desired; or the entire frame may be all decked over, leaving a small space near the middle so as to reach the gear and lower pin in order to grease them. Where the shaft passes one of the uprights of the supporting frame an iron strap will hold it in place against the wood, and this bearing will require lubrication from time to time.

Four stout wire guys must be drawn from the top of the shaft and fastened at the outer edge of the platform to one of the beam ends. The anchorage should be made with very stout, strong screw-eyes, and to make it easier to draw the wires taut four small turn-buckles should be purchased at a hardware store and made fast to the lower ends of the wires, the hook on the buckle being caught in the large screw-eyes.

Seats may be made from boxes and nailed to the deck, and as a safeguard to prevent falling from the turn-table ropes should be attached to the stanchion wires and to the shaft as shown in Fig. 23.

It would be well to paint all the wood-work in order to give it a good appearance, and all the iron parts should be coated with asphaltum varnish to prevent rusting.

If the gears are properly adjusted and there is no friction at the bearings, it will not be a difficult matter to move the table with several children occupying the seats. The bevelled point bearing at the bottom rests in a drilled depression in the plate, and the friction there is reduced to a minimum, while at the top the friction will be slight if the weight is properly distributed on the turn-table.