12 engineering information - University of （12个工程信息大学）.pdf

ENGINEERING INFORMATION SECTION CONTENTS SPUR GEARS NOMENCLATURE 136 – 137 INVOLUTE138 DIAMETRAL PITCH / PRESSURE ANGLE / TOOTH DIMENSIONS 139 BACKLASH / UNDERCUT / FORMULAS140 LEWIS FORMULA141 HELICAL GEARS NOMENCLATURE / HELIX ANGLE142 FORMULAS143 THRUST LOADS144 MITER BEVEL GEARS NOMENCLATURE 145 MOUNTING DISTANCE146 TOOTH STRENGTH / THRUST147 WORMS WORM GEARS HAND / EFFICIENCY / THRUST LOADS148 FORMULAS / SELF-LOCKING 149 COUPLING / UNIVERSAL JOINTS150 GENERAL INFORMATION MOUNTINGS / ALTERATIONS / LUBRICATION 151 MATERIALS / STYLES / KEYWAYS SETSCREWS152 HOW TO FIGURE HORSEPOWER TORQUE153 APPLICATION CLASSIFICATIONS154 – 155 TERMS AND CONDITIONS156 – 157 INDEX TO CATALOG NUMBERS 158 – 160 Gear Catalog 135 ENGINEERING INFORMATION SPUR GEARS GEAR NOMENCLATURE ADDENDUM (a) is the height by which a tooth projects GEAR is a machine part with gear teeth. When two gears beyond the pitch circle or pitch line. run together, the one with the larger number of teeth is called the gear. BASE DIAMETER (Db) is the diameter of the base cylinder from which the involute portion of a tooth profile is generated. HUB DIAMETER is outside diameter of a gear, sprocket or coupling hub. BACKLASH (B) is the amount by which the width of a tooth space exceeds the thickness of the engaging tooth on the HUB PROJECTION is the distance the hub extends beyond