Home Page T-16 For the sake of completeness, the three additional belt profiles shown in Figure 19j, 19k and 19l are used in Europe and are sometimes found on machinery imported from Europe and Japan. They are not produced in the U.S.A. and are not covered by RMA standards.  The belts are made of polyurethane, and steel is usually used as the tension member. As  described  in  previous  sections,  the  presently  known  most  advantageous  belt  tooth configuration  is  the  Gates  PowerGrip  GT.    This  is  a  result  of  continuous  improvement  of  the previous  HTD  tooth  profile.    The  HTD  profile  is  protected  by  U.S.  Patent  Number  4,337,056, whereas the GT profile is described in U.S. Patent Number 4,515,577. Pulleys for these belt profiles are available only from manufacturers licensed by Gates Rubber Company.  Stock Drive Products is one of the licensees who can supply a full range of these pulleys as standards or specials, per customers' drawings. SECTION 8    PULLEY PITCH AND OUTSIDE DIAMETERS Pulley and belt geometry as indicated in Figure 1 shows reference to a Pitch Circle, which is larger than the pulley itself.  Its size is determined by the relationship: P×N pd = –––––      (8-1)    p where P is the belt tooth spacing (pitch) and  N is the number of teeth on the pulley.  The reinforcing cord centerline will coincide with the pulley pitch diameter while the belt is in contact with the pulley.  At the  same  time,  the  outside  diameter  of  the  pulley  will  be  in  contact  with  the  bottom  of  the  belt  tooth. Hence,  the  distance  “U ”  between  the  reinforcing  cord  centerline  and  the  bottom  of  the  belt  tooth  will determine the outside diameters of pulleys for different pitches.  See Table 4. Distance from Pitch Line to Belt Tooth Bottom “U ” Pulley O.D. O.D. = pd – 2U .010 inches .007 inches .010 inches .015 inches .015 inches .0225 inches .027 inches .010 inches .015 inches .0225 inches 0.3 millimeters 0.5 millimeters 1.0 millimeters Minipitch 0.080" MXL 40 D.P. 1/5" XL 3/8" L 3 mm HTD 5 mm HTD 8 mm HTD 2 mm GT 3 mm GT 5 mm GT T2.5 (2.5 mm) T5 (5 mm) T10 (10 mm) Common Description Due to the particular geometry of the 8 mm HTD belts, some corrections are needed for small-size pulleys only.  Hence, consult pulley specifications tables given later in this text, pertaining to the 8 mm HTD pulley. As  previously  noted,  the  pitch  and  the  number  of  teeth  will  determine  the  pitch  diameter  of  the pulley, whereas its outside diameter will depend on the “U” dimension (distance from tooth bottom to centerline of cord) as shown in Table 4. U U U U Table 4    Basic Belt Dimensions