Gears and Cams Questions

• ANSI/AGMA publishes detailed standards for gear design and drawings.
• In working drawings for worm gears, gear teeth are omitted and the gear blank is represented conventionally.
• When laying out a gear, the number of spaces should be twice the number of teeth.
• Worm wheels are similar to helical gears cut to conform to the shape of the worm.
• Proportions and shapes of gear teeth are not standardized.
• In working drawings with teeth cut to a standard shape, individual teeth typically are not shown.
• Bevel gear teeth have the same involute shape as teeth on spur gears but are tapered toward the cone apex.
• On detail drawings, the worm and gear are usually drawn in the same detail drawing.
• Gears are used to transmit power and rotating or reciprocating motion from one machine part to another.
• Cams are used to produce regular repeating motions.
• The motion of the follower as it rises or falls depends on the shape of the curves in the displacement diagram.
• Teeth are spaced by laying out equal angles.
• A worm is a screw with a thread shaped like a rack tooth.
• Working drawings for bevel gears give both the dimensions of the gear blank and the data necessary for cutting the teeth.
• When the follower movement is in a plane parallel to the cam shaft, an irregular cam must be employed.