Key Points
This gear box lid drawing is an example to practice reading GD&T. The part aligns by mating the back surface, hole, and slot to a mating face and two alignment pins. The larger center holes locate bushings and mating gears.
The four clearance holes are for mating screws. A good tolerancing scheme should communicate the function of how the parts fit and identify important features to manufacturing and inspection.
Gear Box Assembly
Example Drawing
