Page:Popular Science Monthly Volume 89.djvu/947

 Popular Science Muntldy

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��Changing a Boy's Handcar into a Mechanically Propelled Sled

THE ordinary handcar sold at almost any toy store, or the car operated by foot pedals, is not of much use when i ft. of snow covers the ground, and it is usually

���If the front wheels are removed from the handcar it can be securely fitted over an ordinary steerable sled with room enough to accommodate the driving wheels

Stored away until milder weather returns. The sled takes its place in outdoor sports, but coasting down hill and sliding across the ponds does not, after all, take the place of a motive power that can be kept up in- definitely on the level, whether on the ice or snow.

The ordinary hand or foot-pedal car can be mounted on runners and different wheels substituted, and an ordinary steerable sled can be fitted to it with little trouble. First remove all four wheels from the handcar, then fit the sled over it and fasten it down firmly with a few bolts. The handcar stripped of its wheels is so much smaller than the average steerable sled that little trouble will be found in fitting them together. It may be necessary to use a few blocks of wood here and there to bring the parts into a snug, firm fit.

The main thing is that sufficient room should be made on either side to accommo- date the rear driving-wheels. These are fitted to the axles of the handcar, and may be made from solid pieces of wood i in. thick. The rim of the wheels when placed on the axles should clear the ice by about 3^ in. when the sled is standing on its runners. By measuring this distance the wheels can be made the right diameter. Find the exact distance from the hub to the ice, and then with a string form a circle* on a board from which the wheel is to be cut.

Cut out the circle with a compass saw, then make ten i-in. notches around the rim at regular intervals. Hard wood only should be used for the wheels or they will not stand the strain. Into the notches,

��made in the rim small galvanized pieces of iron are inserted with their sharp points projecting outward and forward. These points are the buckets which give tractive power to the sled when on the ice. If this method is too elaborate ordinary i-in. screws may be used, inserted half their length into the wheel, and then filed so a point will be formed. Even ordinary- heavy nails can be used, driving them in firmly, and filing off the heads to a point.

The sled is intended to rest on the runners, but the brads of the driving-wheel touch the ice or snow and gi\e trac- tive power. When the hand or foot-pedals are worked, the tractive or dri\ing-wheels revolve, and the brads digging into the snow or ice will give propelling power. If the back wheels are nicely adjusted, three times the speed may be obtained from the motor sled than from the handcar. The reason for this is that there is less friction to ov-ercome. Ice or hard snow may be crossed with ease, and it will even climb small hills.

Everything depends upon the adjustment of the dri\ing-wheels. If the brads project more than }/§ in. below the runners they will impede the progress.

��o

��Removing a Bushing from a Blind Hole

FTEN it is necessary to put a blind bushing in a fixture for gaging pur- poses, the bushing being pressed in as shown at A ; then before the job is complete it may be required to remove the bushing, through some error. The usual method of

��XHISEL MARKS

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����Two effective methods of removing close-fitting bushings in fixtures and jigs

remoA'ing the bushing is shown at B. A very effective way is shown at C. wherein oil is run in the hole and a close-fitting plug or plunger driven in with a hammer. The compress oil forces the bushing out and there is no danger of damage being done to the parts. — A. H. W'adell.

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