ILLUSTRATING SOME OF THE FUNDAMENTAL DEVICES
There are numerous little devices and shop expedients which are desirable, and for which the boy will find uses as he progresses.
We devote this chapter to hints of this kind, all of which are capable of being turned out or utilized at various stages.
LACING BELTS.--To properly lace a belt is quite an art, as many who have tried it know. If a belt runs off the pulley it is attributable to one of three causes: either the pulleys are out of line or the shafts are not parallel or the belt is laced so it makes the belt longer at one margin than the other.
In Fig. 58 the lacing should commence at the center hole (A) of one belt end and lace outwardly, terminating at the hole (B) in the center of the other belt end, as shown in Fig. 58.
In Fig. 59 the lacing commences at A, and terminates at the hole (B) at the edge. This will be ample for all but the widest belts.
Fig. 60 is adapted for a narrow belt. The lacing commences at one margin hole (A), and terminates at the other margin hole (Z).
Fig. 62. GEARS.--This is something every boy ought to know about. Fig. 62 shows a pair of intermeshing bevel gears. This is the correct term for a pair when both are of the same diameter.
[Illustration: _Inside Fig. 58. Belt Lacing_ _Outside Fig. 58. Belt Lacing_ _Fig. 59. Belt Lacing_ _Fig. 60. Belt Lacing_ _Fig. 61. Belt Lacing_]
MITER GEARS.--In Fig. 63 we have a pair of miter gears, one being larger than the other. Remember this distinction.
Fig. 64. CROWN WHEEL.--This is a simple manner of transmitting motion from one shaft to another, when the shafts are at right angles, or nearly so, without using bevel or miter gears.
Fig. 65. GROOVED FRICTION GEARING.--Two grooved pulleys, which fit each other accurately, will transmit power without losing too much by friction. The deeper the grooves the greater is the loss by friction.
Fig. 66. A VALVE WHICH CLOSES BY THE WATER PRESSURE.--The bibb has therein a movable valve on a horizontal stem, the valve being on the inside of the seat. The stem of the handle has at its lower end a crank bend, which engages with the outer end of the valve stem. When the handle is turned in either direction the valve is unseated. On releasing the handle the pressure of the water against the valve seats it.