General Guide Lines
There are some general guidelines which are applicable to all timing belts, including miniature and double-sided belts:

Drives should always be made with ample reserve horsepower capacity. Use of overload support factors is essential. Belts ought to be rated at only 1/15th of their respective ultimate strength.

For MXL pitch belts, the tiniest recommended pulley could have 10 teeth. For various other pitches, Table 8, ought to be used.

The pulley diameter shouldn’t be smaller compared to the width of the belt.

Belts with Fibrex-glass fiber stress members shouldn’t be subjected to sharp bends or rough handling, since this may trigger breakage of the fibers.

In order to deliver the rated hp, a belt will need to have six or more tooth in mesh with the grooves of small pulley. The amount of tooth in mesh could be attained by formula given in SECTION 24 TIMING BELT DRIVE SELECTION PROCEDURE. The shear strength of an individual tooth is only a fraction of the belt break strength.

Because of a slight part thrust of synchronous belts in movement, at least a single pulley in the travel must be flanged. When the center distance between the shafts is 8 or even more times the size of small pulley, or when the drive is working on vertical shafts, both pulleys ought to be flanged.

Belt surface quickness shouldn’t exceed 5500 ft each and every minute (28 m/s) for larger pitch belts and 10000 feet per minute (50 m/s) for minipitch belts. For the HTD belts, a swiftness of 6500 foot per minute (33 m/s) is certainly permitted, whereas for GT2 belts, the maximum permitted swiftness is 7500 feet each and every minute (38 m/s). The maximum allowable operating acceleration for T series is certainly 4000 feet each and every minute (20 m/s).

Belts are, generally, rated to yield at the least 3000 hours of useful life if all guidelines are properly followed.

Belt drives are inherently efficient. It could be assumed that the efficiency of a synchronous belt drive is greater than 95%.

Belt drives are often a way to obtain noise. The frequency of the noise level increases proportionally with the belt swiftness. The higher the original belt tension, the greater the sound level. The belt tooth entering the pulleys at high velocity act as a compressor and this creates sound. Some noise may be the consequence of a belt rubbing against the flange, which could be the consequence of the shafts not really getting parallel. As shown in Figure 9, the sound level is considerably decreased if the PowerGrip GT2 belt has been used.

If the drive is component of a sensitive acoustical or consumer electronics sensing or recording device, it is recommended that the trunk surfaces of the belt be ground to assure absolutely uniform belt thickness.

For a few applications, no backlash between your driving and the driven shaft is permitted. For these cases, special profile pulleys could be produced with no clearance between your belt tooth and pulley. This may shorten the belt lifestyle, nonetheless it eliminates backlash. Shape 10 displays the superiority of PowerGrip GT2 profile as far as reduction of backlash can be involved.

Synchronous belts are often powered by stepping motors. These drives are subjected to continuous and huge accelerations and decelerations. If the belt reinforcing fibers, i.e., tension member, and also the belt materials, have got high tensile strength no elongation, the belt will not be instrumental in absorbing the shock loads. This will result in sheared belt teeth. Therefore, take this into account when how big is the tiniest pulley and the components for the belt and tension member are selected.

The decision of the pulley materials (metal vs. plastic material) is usually a matter of price, desired precision, inertia, color, magnetic properties and, above all, personal preference predicated on experiences. Plastic material pulleys with metallic inserts or metal hubs represent a good compromise.

PRECAUTIONS
The following precautions should be taken when installing all timing belt drives:

Timing belt installation ought to be a snug in shape, neither too restricted nor too loose. The positive hold of the belt eliminates the necessity for high preliminary tension. Consequently, a belt, when installed with a snug fit (that’s, not too taut) assures longer life, much less bearing wear and quieter operation. Preloading (usually the cause of premature failure) is not necessary. When torque is usually unusually high, a loose belt may “jump teeth” on starting. In such a case, the tension ought to be increased steadily, until satisfactory operation is attained. An excellent guideline for installation tension is as proven in Figure 20, and the corresponding tensioning force is proven in Table 9, both proven in SECTION 10 BELT TENSIONING. For widths other than shown, increase force proportionally to the belt width. Instrumentation for measuring belt tension is available. Consult the product portion of this catalog.

Be sure that shafts are parallel and pulleys are in alignment. On an extended center get, it really is sometimes recommended to offset the powered pulley to compensate for the inclination of the belt to perform against one flange.

On an extended center drive, it really is imperative that the belt sag isn’t large enough allowing teeth on the slack part to engage one’s teeth on the tight aspect.

It is necessary that the frame supporting the pulleys be rigid at all times. A nonrigid framework causes variation in center range and resulting belt slackness. This, in turn, can lead to jumping of teeth – specifically under starting load with shaft misalignment.

Although belt tension requires little attention after initial installation, provision should be made for some center distance adjustment for ease in installing and removing belts. Usually do not force belt over flange of pulley.

Idlers, either of the within or outdoors type, are not recommended and should not be utilized except for power takeoff or functional use. When an idler is essential, it must be on the slack side of the belt. Inside idlers must be grooved, unless their diameters are greater than an comparative 40-groove pulley. Flat idlers must not be crowned (use advantage flanges). Idler diameters must go beyond the smallest diameter drive pulley. Idler arc of contact should be held to a minimum.

As well as the general guidelines enumerated previously, specific operating characteristics of the get must be considered.