THE WORLD OF TIMING BELTS - MAELabs UCSD

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Trapezoidal Tension Member Fig. 2 Stress Pattern in Belts Curvilinear • Greater shear strength due to larger tooth cross section. • Lower cost since a narrower belt will handle larger load. • Energy efficient, particularly if replacing a "V" belt drive which incurs energy losses due to slippage. • Installation tension is small, therefore, light bearing loads. In Figure 2, the photoelastic pattern shows the stress distribution within teeth of different geometry. There is a definite stress concentration near the root of the trapezoidal belt tooth, with very low strains elsewhere. For the curvilinear tooth, there is a uniform, nearly constant, strain distribution across the belt. The load is largest in the direction of the tension member to which it is transferred. Because of their superior load carrying capabilities, the curvilinear belts are marketed under the name of Gates' HTD drives. This is an abbreviation of High Torque Drives. As a result of continuous research, a newer version of the curvilinear technology was developed by Gates, which was designated as Gates' PowerGrip GT belt drives. SECTION 2 GATES POWERGRIP ® GT BELT DRIVES The PowerGrip GT Belt Drive System is an advance in product design over the Gates' older, standard HTD system. The PowerGrip GT System, featuring a modified curvilinear belt tooth profile, provides timing and indexing accuracy superior to the conventional PowerGrip Trapezoidal Belt System. Plus, PowerGrip GT Belts have a higher capacity and longer belt life than trapezoidal belts. It's difficult to make a true quantitative comparison between the backlash of a trapezoidal tooth drive and PowerGrip GT drive due to the difference in "pulley to belt tooth" fit (see Figure 3). Trapezoidal belts contact the pulley in the root radius-upper flank area only, while the PowerGrip GT system permits full flank contact. PowerGrip ® GT ® Belt Tooth/Groove Contact PowerGrip ® HTD ® Belt Tooth/Groove Contact Fig. 3 Comparison of Different Tooth Profiles PowerGrip ® Trapezoidal Belt Tooth/Groove Contact T-4
The main stress line in a trapezoidal tooth timing belt is at the base of the teeth. During operation, this stress greatly reduces belt life. The PowerGrip GT system overcomes this condition with its complete tooth flank contact which eliminates the tooth stress line area. This greatly increases belt life and prevents tooth distortion caused by drive torque. In addition, the conventional timing belt has a chordal effect as it wraps small pulleys. This is significantly reduced in the PowerGrip GT system because there is full tooth support along the pulley. Full support improves meshing, reduces vibration and minimizes tooth deformation. On drives using a low installation tension, small pulleys, and light loads, the backlash of the PowerGrip GT system will be slightly better than the trapezoidal timing belt system. However, with increased tension and/or loads and/or pulley sizes, the performance of the PowerGrip GT system becomes significantly better than the trapezoidal timing belt system. The PowerGrip GT system is an extension of the HTD system with greater load-carrying capacity. HTD was developed for high torque drive applications, but is not acceptable for most precision indexing or registration applications. The HTD design requires substantial belt tooth to pulley groove clearance (backlash) to perform. As smaller diameter pulleys are used, the clearance required to operate properly is increased. HTD drive clearance, using small diameter pulleys, is approximately four times greater than an equivalent GT timing belt drive. The PowerGrip GT system's deep tooth design increases the contact area which provides improved resistance to ratcheting. The modified curvilinear teeth enter and exit the pulley grooves cleanly, resulting in reduced vibration. This tooth profile design results in parallel contact with the groove and eliminates stress concentrations and tooth deformation under load. The PowerGrip GT design improves registration characteristics and maintains high torque carrying capability. PowerGrip GT belts are currently available in 2 mm, 3 mm and 5 mm pitches. Specific advantages of the PowerGrip GT system can be summarized as follows: • Longer belt life The strong fiberglass tensile cords wrapped in a durable neoprene body provide the flexibility needed for increased service life. The deep tooth profile provides superior load-carrying strength and greatly reduces ratcheting when used with pulleys provided by a licensed supplier. • Precision registration PowerGrip GT belts provide timing and synchronization accuracy that make for flawless registration, with no loss of torque carrying capacity. • Increased load-carrying capacity Load capacities far exceed HTD and trapezoidal belt capabilities making PowerGrip GT belts the choice for accurate registration, heavy loads and small pulleys. • Quieter operation The PowerGrip GT belt's specially engineered teeth mesh cleanly with pulley grooves to reduce noise and vibration. Clean meshing and reduced belt width result in significant noise reduction when compared to Trapezoidal and HTD belts. • Precise positioning PowerGrip GT belts are specifically designed for applications where precision is critical, such as computer printers and plotters, laboratory equipment and machine tools. Some of the many applications of PowerGrip GT belts are: • data storage equipment • machine tools • hand power tools • postage handling equipment • DC stepper/servo applications • food processors • centrifuges • printers • floor care equipment • money handling equipment • medical diagnostic equipment • sewing machines • automated teller machines • ticket dispensers • plotters • copiers • robotics equipment • vending equipment • vacuum cleaners • office equipment T-5
Page 1: SECTION 1 INTRODUCTION THE WORLD OF
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 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 85 and 86:
Page 87 and 88:
Page 89 and 90:
Table 43 (Cont.) Rated Kilowatts fo
Page 91 and 92:
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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THE WORLD OF TIMING BELTS - MAELabs UCSD

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