THE WORLD OF TIMING BELTS - MAELabs UCSD

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13.5 Size Recommendations Inside idler pulleys can be used in the minimum recommended size for each particular belt pitch. Inside flat idlers can be used on the tooth side of synchronous belts as long as they are of a diameter equivalent to the pitch diameter of a 40-groove pulley in the same pitch. Drives with inside flat idlers should be tested, as noise and belt wear may occur. Flat backside idlers should be used with diameters at least 30% larger than the minimum recommended inside pulley size. Table 18 summarizes our idler size recommendations. Table 18 Idler Size Recommendations Belt Type Minimum Inside Idler Minimum Backside Idler O.D. inch mm Minimum Inside Flat Idler O.D. inch mm MXL 12 grooves 0.50 12.7 1.00 25.4 XL 12 grooves 1.00 25.4 2.50 63.5 3 mm HTD 12 grooves 0.75 19.1 1.50 38.1 5 mm HTD 14 grooves 1.25 31.8 2.50 63.5 2 mm GT 12 grooves 0.50 12.7 1.00 25.4 3 mm GT 12 grooves 0.75 19.1 1.50 38.1 5 mm GT 14 grooves 1.25 31.8 2.50 63.5 13.6 Specifying Shaft Locations In Multipoint Drive Layouts When collecting geometrical layout data for multiple pulley drive layouts, it is important to use a standard approach that is readily understood and usable for drive design calculations. This is of particular importance when the data will be provided to our Application Engineering Department for analysis. 2-Point Drive When working with a simple 2-point drive (driver/driven only) it is sufficient to specify the desired distance between shaft centers for belt length calculations. 3-Point Drive When working with a 3-point drive (driver/driven/idler), X-Y coordinates are desirable. It is sufficient, however, to specify desired center distances between each of the three shaft centers to form a triangle. In either case, pulley/idler movement details for belt tensioning and take up are also necessary. Multi-Point Drive When working with a drive system having more than 3 shafts, the geometrical layout data must be collected in terms of X-Y coordinates for analysis. For those unfamiliar with X-Y coordinates, the X-Y Cartesian coordinate system is commonly used in mathematical and engineering calculations and utilizes a horizontal and vertical axis as illustrated in Figure 27. The axes cross at the zero point, or origin. Along the horizontal, or "X" axis, all values to the right of the zero point are positive, and all values to the left of the zero point are negative. Along the vertical, or "Y" axis, all values above the zero point are positive, and all values below the zero point are negative. This is also illustrated in Figure 27. Fig. 27 Cartesian Coordinate System T-54
When identifying a shaft center location, each X-Y coordinate is specified with a measurement in the "X" as well as the "Y" direction. This requires a horizontal and vertical measurement for each shaft center in order to establish a complete coordinate. Either English or Metric units of measurement may be used. A complete coordinate is specified as follows: (X, Y) (13-1) where: X = measurement along X-axis (horizontal) Y = measurement along Y-axis (vertical) In specifying X and Y coordinates for each shaft center, the origin (zero point) must first be chosen as a reference. The driver shaft most often serves this purpose, but any shaft center can be used. Measurements for all remaining shaft centers must be taken from this origin or reference point. The origin is specified as (0, 0). An example layout of a 5-point drive system is illustrated in Figure 28. Here, each of the five shaft centers are located and identified on the X-Y coordinate grid. When specifying parameters for the movable or adjustable shaft (for belt installation and tensioning), the following approaches are generally used: Fixed Location: Specify the nominal shaft location coordinate with a movement direction. Slotted Location: Specify a location coordinate for the beginning of the slot, and a location coordinate for the end of the slot along its path of linear movement. Pivoted Location: Specify the initial shaft location coordinate along with a pivot point location coordinate and the pivot radius. Performing belt length and idler movement/positioning calculations by hand can be quite difficult and time consuming. With a complete geometrical drive description, we can make the drive design and layout process quite simple for you. SECTION 14 BELT PULL AND BEARING LOADS Fig. 28 Example of 5-Point Drive System Synchronous belt drives are capable of exerting lower shaft loads than V-belt drives in some circumstances. If pre-tensioned according to SDP/SI recommendations for a fully loaded steady T-55
Page 1 and 2: SECTION 1 INTRODUCTION THE WORLD OF
Page 3 and 4: The main stress line in a trapezoid
Page 5 and 6: Figure 5 shows an illustrative grap
Page 7 and 8: 4.3 Noise The smoother meshing acti
Page 9 and 10: The tension members are embedded in
Page 11 and 12: The "S" twist is obtained if we vis
Page 13 and 14: SECTION 7 BELT TOOTH PROFILES There
Page 15 and 16: In order to provide fast reference,
Page 17 and 18: No. of Pitch Diameter Outside Diame
Page 19 and 20: No. of Pitch Diameter Outside Diame
Page 21 and 22: T-23 7.003 7.066 7.130 7.194 7.257
Page 23 and 24: T-25 13.130 13.250 13.369 13.488 13
Page 25 and 26: T-27 6.015 6.053 6.090 6.128 6.166
Page 27 and 28: T-29 5 mm Pitch HTD ® Pitch Pulley
Page 29 and 30: T-31 8 mm Pitch HTD ® Pulley Dimen
Page 31 and 32: T-33 2 mm Pitch GT ® Pulley Dimens
Page 33 and 34: T-35 Table 13 (Cont.) 3 mm Pitch GT
Page 35 and 36: T-37 5 mm Pitch GT ® Pulley Dimens
Page 37 and 38: SECTION 9 DESIGN AND INSTALLATION S
Page 39 and 40: slip), and because they require min
Page 41 and 42: elts than pure water. Urethane timi
Page 43 and 44: angular shaft alignment, resulting
Page 45 and 46: • Design with large pulleys with
Page 47 and 48: inch (0.4 mm per 25 mm) of span len
Page 49 and 50: overloaded which may cause an edge
Page 51: 4. Pulleys for fixed center systems
Page 55 and 56: procedures can be used for finding
Page 57 and 58: In measuring the length of a synchr
Page 59 and 60: Tolerancing/Inspection Procedure: A
Page 61 and 62: Table 31 ISO Pulley O.D. Tolerances
Page 63 and 64: Belt Type MXL XL 2 mm GT 3 mm GT &
Page 65 and 66: Drive selection procedures for driv
Page 67 and 68: Fig. 39 Belt Nomenclature The use o
Page 69 and 70: T-71 1.000 1.042 1.053 1.056 1.059
Page 71 and 72: T-73 2.000 2.083 2.100 2.105 2.118
Page 73 and 74: SECTION 22 CENTER DISTANCE FORMULAS
Page 75 and 76: 22.6 Determination Of Belt Size For
Page 77 and 78: pm of Faster Shaft 14,000 12,000 10
Page 79 and 80: 20,000 10,000 8,000 6,000 5,000 4,0
Page 81 and 82: The number of teeth in mesh on the
Page 83 and 84: Table 40 (Cont.) Rated Torque (N⋅
Page 89 and 90: Table 43 (Cont.) Rated Kilowatts fo
Page 93 and 94: Table 45 Rated Torque (N⋅m) for S
Page 95: Table 47 Rated Torque (lb⋅in) for

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