Fig. 40. A BENT LEVER
(3) Where the power is applied between the load and the fulcrum as shown at A, Fig. 39; the foot treadle of a jig saw and sugar tongs are levers of this class. See B, Fig. 39. Then there is the bent lever, as shown in Fig. 40, where the power and load do not act parallel with each other, and the compound lever which takes the place of a single long lever as shown in Fig. 41, and which is used in large platform-scales.
Fig. 41. A COMPOUND LEVER
The wheel and axle is really a form of lever and fulcrum. The axle provides a continuous fulcrum as shown in Fig. 42. Trains of wheel work, such as are used in clocks and other mechanical devices, are used to change a slow moving powerful force into a high speed, or velocity, or the other way about. Fig. 43 shows a train of wheel work.
Fig. 42. THE WHEEL AND AXLE IS A MODIFIED LEVER
The power is applied at A, the weight is at B, and the Fulcrum is at C.
Fig. 43. A TRAIN OF WHEELS OR WHEEL WORK