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

Drives should be designed with ample reserve horsepower capacity. Use of overload provider factors is important. Belts should be rated of them costing only 1/15th of their respective ultimate strength.

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

The pulley size should never be smaller compared to the width of the belt.

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

In order to deliver the rated hp, a belt will need to have six or even more tooth in mesh with the grooves of the smaller pulley. The number of teeth in mesh may be acquired by formula given in SECTION 24 TIMING BELT DRIVE SELECTION PROCEDURE. The shear strength of a single tooth is a fraction of the belt break strength.

Due to a slight side thrust of synchronous belts in motion, at least 1 pulley in the drive should be flanged. When the center distance between your shafts is 8 or even more times the diameter of the smaller pulley, or when the get is operating on vertical shafts, both pulleys should be flanged.

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

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

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

Belt drives are usually a way to obtain noise. The regularity of the sound level boosts proportionally with the belt rate. The higher the initial belt stress, the higher the noise level. The belt tooth entering the pulleys at high quickness act as a compressor which creates sound. Some noise may be the consequence of a belt rubbing against the flange, which could be the result of the shafts not becoming parallel. As shown in Figure 9, the noise level is substantially 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 back surfaces of the belt be ground to make sure absolutely uniform belt thickness.

For a few applications, no backlash between your driving and the driven shaft is permitted. For these situations, special profile pulleys could be produced with no clearance between your belt tooth and pulley. This might shorten the belt existence, nonetheless it eliminates backlash. Physique 10 shows the superiority of PowerGrip GT2 profile so far as reduced amount of backlash is concerned.

Synchronous belts tend to be driven by stepping motors. These drives are put through continuous and large accelerations and decelerations. If the belt reinforcing dietary fiber, i.e., tension member, along with the belt materials, possess high tensile power no elongation, the belt will not be instrumental in absorbing the shock loads. This will lead to sheared belt tooth. Therefore, take this into account when the size of the tiniest pulley and the components for the belt and stress member are selected.

The choice of the pulley materials (metal vs. plastic material) is a matter of price, desired accuracy, inertia, color, magnetic properties and, most importantly, personal preference based on experiences. Plastic pulleys with metal inserts or steel hubs represent an excellent compromise.

PRECAUTIONS
The next precautions ought to be taken when installing all timing belt drives:

Timing belt set up ought to be a snug in shape, neither too restricted nor too loose. The positive grip of the belt eliminates the necessity for high preliminary tension. Therefore, a belt, when set up with a snug suit (that’s, not too taut) assures much longer life, less bearing wear and quieter procedure. Preloading (usually the cause of premature failure) isn’t required. When torque is normally unusually high, a loose belt may “jump tooth” on starting. When this happens, the tension ought to be increased steadily, until satisfactory operation is attained. A good rule of thumb for installation tension is as demonstrated in Figure 20, and the corresponding tensioning force is demonstrated in Table 9, both proven in SECTION 10 BELT TENSIONING. For widths other than shown, increase drive proportionally to the belt width. Instrumentation for calculating belt pressure is available. Consult the merchandise section of this catalog.

Be sure that shafts are parallel and pulleys are in alignment. On a long center travel, it is sometimes recommended to offset the powered pulley to pay for the tendency of the belt to run against one flange.

On an extended center get, it really is imperative that the belt sag is not large enough to permit teeth on the slack side 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 frame causes variation in center distance and resulting belt slackness. This, subsequently, can result in jumping of tooth – especially under beginning load with shaft misalignment.

Although belt tension requires small attention after preliminary installation, provision should be made for some middle distance adjustment for ease in installing and removing belts. Do not drive belt over flange of pulley.

Idlers, either of the within or outside type, are not recommended and really should not be used except for power takeoff or functional make use of. When an idler is necessary, it should be on the slack side of the belt. Inside idlers must be grooved, unless their diameters are higher than an comparative 40-groove pulley. Flat idlers must not be crowned (use advantage flanges). Idler diameters must go beyond the smallest diameter get pulley. Idler arc of contact should be kept to the very least.

In addition to the general guidelines enumerated previously, specific operating features of the drive must be taken into account.