THE WORLD OF TIMING BELTS - MAELabs UCSD

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Step 5 Check belt speed Belt speeds up to 6,500 fpm (33.02 m/s) do not require special pulleys. Speeds higher than these require special pulley materials and dynamic balancing. Speed is computed using the following equations: V(fpm) = 0.262 x pulley PD (in) x pulley rpm (24-5) V(m/s) = 0.0000524 x pulley PD (mm) x pulley rpm (24-6) where: m/s = 0.00508 x fpm (24-7) Step 6 Determine belt length The design layout may govern the determination of the belt length. Since the pulley sizes are known, use of Center Distance Factor Tables shown in SECTION 23 (starting on page T-77) will yield NB – the number of teeth of the belt. If a fractional number is obtained, the closest integer number should be chosen, and the calculation must be repeated to obtain the new center distance for the design. It is worthwhile to check if a belt with the chosen number of teeth is available in this Handbook. If it is not available, the closest fitting belt size must be chosen, and the calculation must be repeated to establish the center distance to which the layout must be corrected to accommodate the available choice of belt. Step 7 Determine the belt width The number of grooves of the small pulley as well as the rpm of the faster shaft on which this pulley is located are known. Tables 40 through 47 show the torque and/or horsepower or kilowatt ratings for the base width of particular belt pitches. For the HTD and GT drives, the torque ratings shown in these tables must be multiplied by the length correction factor. This factor is a number smaller than 1 for shorter length and higher for longer belts. This reflects the fact that a longer belt will be less prone to wear and tear as opposed to a shorter belt. When the given torque from the table is multiplied by the length correction factor, this figure may be smaller or larger than the previously computed peak torque Tpeak. If it is smaller, a belt narrower than the base width can be used. Alternatively, if Tpeak is larger, a wider belt must be specified. In order to finalize the belt width, the width multiplier given on the particular table itself must be used. Also, consult the appropriate belt product page for availability of standard widths. We are able to supply nonstandard width belts as well as nonstandard width pulleys, if desired. In any event, the torque ratings given in the table multiplied by the length factor and by the width multiplier must yield a torque greater than the Tpeak computed previously. The torque or horsepower ratings are based on 6 or more teeth in mesh for the smaller pulley. Step 8 Check the number of teeth in mesh The arc of contact on the smaller pulley in degrees can be found as follows: 60 (PD – pd ) Arc of Contact = 180 – (––––––––––––) (degrees) (24-8) C where: PD = Large pitch diameter, inches pd = Small pitch diameter, inches C = Drive center distance, inches T-146
The number of teeth in mesh on the smaller pulley can be found as follows: (Arc) (n) Teeth in Mesh = –––––––– (24-9) 360 where: Arc = Arc of contact; small pulley, degrees n = number of grooves, small pulley Drop any fractional part and use only the whole number as any tooth not fully engaged cannot be considered a working tooth. If the teeth in mesh is less than 6, correct the belt torque rating with the following multiplication factors: 5 teeth in mesh .............. multiply by 0.8 4 teeth in mesh .............. multiply by 0.6 3 teeth in mesh .............. multiply by 0.4 2 teeth in mesh .............. suggest redesign 1 tooth in mesh .............. suggest redesign Step 9 Determine proper belt installation tension Procedure to calculate proper belt installation tension for specific applications are included in SECTION 10, on page T47. Step 10 Check availability of all components For the specified parts, both pulleys and belt, obtain part numbers from the Handbook or CD- ROM. In case special sizes or alterations are needed, contact SDP/SI Application Engineering Department. Free CD-ROM companion disk This CD-ROM, which will run on any IBM or compatible PC, will contain the programs to compute center distances, belt lengths, number of teeth in mesh, etc., as well as give the appropriate selection of our catalog parts based on the parameters supplied by the designer. To obtain your copy see page 1-0. Tel: 516-328-3300 Fax: 516-326-8827 See our Catalogs online at: http://www.sdp-si.com T-147
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 and 52: 4. Pulleys for fixed center systems
Page 53 and 54: When identifying a shaft center loc
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: 20,000 10,000 8,000 6,000 5,000 4,0
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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