Fig. 103.—The screw is a spiral inclined plane.
Fig. 104.—The pitch is S.
Fig. 105.—A vise.
Fig. 106.—A jack screw.
Fig. 107.—A micrometer screw.
Fig. 108.—This large worm-wheel is a part of the hoisting mechanism employed for the lock gates of the Sault Ste. Marie Canal.
Important Topics
1. Efficiency of machines.
2. The inclined plane, wedge and screw. Applications.
Exercises
1. A plank 12 ft. long is used to roll a barrel weighing 200 lbs. into a wagon 3 ft. high. Find the force required parallel to the incline.