Q3-1

With spur gears having twisted teeth (cycloidal), what is the form of the line of contact along the tooth surface? What is the form of pitch surface in spur gears, bevel gears, hypoid gears? What conditions favor the use of each?

Q3-2

What is meant by pressure angle in gears? What are the usual angles in involute gears? What conditions are necessary to make involute gears interchangeable?

Q3-3

A mild-steel spur-gear (15-tooth, 20 , full depth involute) pinion, rotating at 750 rpm, is to transmit 30 hp to a mild-steel gear rotating at 200 rpm. Determine ( a) number of teeth in gear, ( b) diametral pitch of teeth required, ( c) face width of teeth, and ( d) required shaft center-to-center distance.

Q3-4

Find the dimensions of the teeth of a cast spur gear whose cirular pitch is 1.25 in.

Q3-5

Some values dealt with in gear design are the following: ( a) number of teeth, ( b) pitch of teeth, ( c) depth of teeth, ( d) thickness of teeth, ( e) pressure angle, ( f) gear diameters, ( g) face width, ( h) transmitted torque, and ( i) radii of curvature of contacting profiles.

Indicate by letter which of the above-mentioned values are involved in calculating the tooth load in pounds per square inch of face width, assuming all the load to be carried on one pair of teeth.

What additional values are...