Home Page T-12 Steel Tensile Strength 360,000 lbs/in² Elongation at break 2.5% Modulus (approx.) 15,000,000 lbs/in² Additional characteristics of tension members and their effect on the drive design are shown in tabulated form in Table 1. E E F E P P P P F E F P E Fig. 16    Cord Twist Fig. 15    Belt Cross Section Operate over Small Pulley High Pulley Speed High Intermittent Shock Loading Vibration Absorption High Torque Low Speed Low Belt Stretch Dimensional Stability High Temperature 200° F Low Temperature Good Belt Tracking Rapid Start/Stop Operation Close Center-Distance Tolerance Elasticity Required in Belt G E G G P P P P G G G P G E E G E P P P P G E E P E F F E G F P F P G G G P G P P E F G G G E G F P G P F F E F F F G E E G G F P P P P P E E E E E F P E P P P G P E E E E E P E E P G G F F F G G F G E G G P *  Courtesy of Chemiflex, Inc. Table 1    Comparison of Different Tension Member Materials* E = Excellent G = Good F = Fair P = Poor Belt Requirements Continuously Applied Filament Step of Helix Spirally Applied Filament 6.2  Cord Twist And Its Effect On The Drive There  is  a  specific  reason  for  not applying  the  yarn  directly  in  the  form  of untwisted  filaments  around  the  mold.    If the filament would be applied continuously,  the  top  and  bottom  of  the belt body would be prevented from being properly  joined,  and  separation  could result.  See Figure 15. Two  strands  each  composed  of several filaments are twisted around each other,  thus  forming  a  cord  which  is subsequently  wound  in  a  helical  spiral around the mold creating a space between subsequent layers, which corresponds to the  step  of  the  helix.    The  two  strands, however, can be twisted two ways in order to create an "S" or a "Z" twist construction. See Figure 16.