## American Machinist Gear Book: Simplified Tables and Formulas for Designing, and Practical Points in Cutting All Commercial Types of Gears |

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accurate action addendum angle base bevel gears carried cast cent Chart circular pitch coefficient of friction combination curve cutter depth developed diametral pitch direction distance divided driving effect efficiency employed equal example face feet fiber follower formula gear teeth give given greater hardness helical herringbone inches increase internal gear involute iron lead length less limit load machine material measured metal method milling minute motion necessary normal number of teeth obtained operation pair pinion pitch diameter pitch line position pounds practice pressure proportion rack radius ratio reduced rolling safe shaft shown side slip space speed spiral spur gears standard steel strength surface tests thickness thread tool tooth transmitted true turn velocity wear wheel width worm

### Popular passages

Page 228 - The pitch surfaces of the bevel pinion are frusta of a figure generated by the revolution of a straight line about an axis to which it is not parallel, a "hyperboloid of revolution.

Page 4 - The cycloidal system cannot compete with the involute, because its cutters are formed with greater difficulty and less accuracy, and a further expense is entailed by the necessity for more accurate center distances. Cycloidal teeth must not only be accurately spaced and shaped but their wheel centers must be fixed with equal care to obtain satisfactory results. Cut gears are not only more expensive in this system, but also when patterns are made for castings the double curved faces require far more...

Page 133 - The number of teeth for which the cutter should be selected is equal to the number of teeth in the gear or pinion divided by the cosine of its center angle.

Page 172 - ... regulating the opening of the recoil-valve so as to throttle the water in its passage from the cylinder into the air-vessel. At first sight it might be assumed that, saving friction of the mechanism, the air-pressure which would suffice to check the fall of the gun would be sufficient to raise it again ; but a little consideration will show that this is not the case. To allow the gun to fall in the short space of time during which recoil takes place, the pressure of the air must be less than...

Page 198 - When a pinion of less than 20 teeth is used with a standard gear, the center distance must be slightly increased to suit the enlargement of the pinion. If it is desired to keep the center distance to the standard dimensions, the gear diameter may be reduced by the amount of the enlargement given to the pinion. For example, if a pinion of 10 teeth, 5...

Page 268 - A friction drive, as the term is here employed, consists of a fibrous or somewhat yielding driving wheel working in rolling contact with a metallic driven wheel. Such a drive may consist of a pair of plain cylindered wheels mounted upon parallel shafts, or a pair of beveled wheels, or of any other arrangement which will serve in the transmission of motion by rolling contact. The use of such drives has steadily increased in recent years, with the result that the socalled paper wheels have been improved...

Page 281 - Having now determined a safe working pressure of contact and a representative value for the coefficient of friction, it is possible to formulate equations expressing the horse-power which may be transmitted by each combination of wheels tested. Thus, calling d the diameter of the friction wheel in inches, W the width of its face in inches, and N the number of revolutions per minute, the equations become, for combinations of...

Page 88 - The effect of power transmission from pinion to gear is to put these axis-lines out of position, moving them in opposite directions and resulting in end contact of teeth and concentrated load instead of evenly distributing the load along the whole length of tooth. In this particular the question of maintaining bevel gears is decidedly more of a problem than that of spur gears. In this latter case small end motions of carrying shafts produce no effect, while the wearing of bearings is only the shifting...

Page 155 - T. The throat diameter of a worm gear or wheel corresponds to the outside diameter of a spur gear of the same. number of teeth and the same pitch. D. The extreme outside diameter of a worm-wheel can be found by the formula given, but ordinarily the measurement of a carefully drawn sketch is sufficiently accurate. Insufficient stock for a sharp tooth edge, depicted FIG.

Page 36 - Module is the pitch diameter in millimeters divided by the number of teeth in the gear. Pitch diameter in millimeters is the Module multiplied by the number of teeth in the gear. M = Module. D' = The pitch diameter of gear in millimeters. D = The whole diameter of gear in millimeters. N = The number of teeth in gear. D" = The working depth of teeth.