BOOK_CONTENT
From Manual of Gear Design: Spur and Internal Gears, Volume II

14 Degree Involute System

14 Full Depth Involute System ASA-B6b-1933

20 Full Depth Involute System ASA-B6b-1933

20 Degree Full Depth Involute System

WHEN PINIONS OF SMALL TOOTH NUMBERS ARE REQUIRED FOR SUCH APPLICATIONS AS MOTOR STARTING PINIONS OR LARGER REDUCTION RATIOS IN A SINGLE REDUCTION, UNDERCUT MAY BE MINIMIZED AND AN EFFECTIVE DRIVE OBTAINED BY ENLARGING THE DIAMETER OF THE PINION AND USING IT WITH A GEAR OF STANDARD PROPORTIONS. IN SUCH A CASE, THE CENTER DISTANCE WOULD BE INCREASED TO COMPENSATE FOR THE INCREASE IN THE DIAMETER OF THE PINION.

THE FOLLOWING TABLES GIVE THE TOOTH PROPORTIONS AND THE INCREASE IN CENTER DISTANCE FOR PINIONS OF FROM 5 TO 14 TEETH, BASED UPON THE BASIC RACK OF THE 20 FULL DEPTH INVOLUTE SYSTEM. THE FIRST TABLE GIVES THE RADII FOR 1 DP HOBBED PINIONS. THE SECOND TABLE GIVES THE INCREASE IN CENTER DISTANCE REQUIRED FOR VARIOUS COMBINATIONS. THE THIRD TABLE SHOWS THE CONTACT RATIO FOR THESE COMBINATIONS. THE FOURTH TABLE GIVES THE RADII FOR SHAPED PINIONS OF SEVERAL DIAMETRAL PITCHES. THESE DIMENSIONS MAKE NO ALLOWANCE FOR BACKLASH. TO INTRODUCE THE NECESSARY BACKLASH, THE MATING GEAR SHOULD BE CUT ENOUGH DEEPER TO SECURE IT, WHILE THE PINIONS SHOULD BE CUT AS SPECIFIED IN THE TABLES. THE FORMS OF THESE SMALL PINIONS ARE TOO SENSITIVE TO PERMIT ANY INCREASE IN THE DEPTH OF TOOTH WITHOUT INTRODUCING EXCESSIVE UNDERCUTTING.

Small Pinions (5 to 14 teeth)

Tooth Proportions 1DP Hobbed Pinions

Center Distance for Small Pinions

Increase in Center Distance for 1DP Small...
Copyright Eliot K. Buckingham 1999 under license agreement with Books24x7

Products & Services
Rack and Pinion Drives
Rack and pinion drives use a rotational motor to affect linear motion via a rack and pinion combination. They are used frequently in long-travel applications, such as machine tool table positioning, that require high stiffness and accuracy.
Rack and Pinion Gears
Rack and pinion gears are used to convert rotation into linear motion.
Metric Gears
Metric gears are defined by module, which designates the center-to-center distance between successive teeth. This criteria of gear selection is used in countries which have adopted the metric system and is intended to standardize gear selection.
Gears

Gears are rotating mechanical devices employing 'teeth' in order to transmit torque between separate axes. Two or more cooperating gears are called a transmission and can produce a mechanical advantage by changing speed, torque or rotation direction.

Spur Gears

Spur gears are the simplest type of gear. Transmitting power between parallel axes, the teeth project radially on the disc.


Topics of Interest

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