Timing Belt Pulleys Style and Installation Suggestions: General Guide Lines

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

Drives should always be made with ample reserve hp capacity. Use of overload support factors is essential. Belts should be rated at 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 diameter shouldn't be smaller than the width of the belt.

Belts with Fibrex-glass fiber tension members should not be subjected to sharp bends or rough handling, since this could cause breakage of the fibers.

To be able to deliver the rated hp, a belt must have six or more teeth in mesh with the grooves of small pulley. The number of tooth in mesh could be acquired by formula given in SECTION 24 TIMING BELT DRIVE SELECTION PROCEDURE. The shear strength of an individual tooth is a fraction of the belt break power.

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

Belt surface speed should not exceed 5500 feet each and every minute (28 m/s) for bigger pitch belts and 10000 feet per minute (50 m/s) for minipitch belts. For the HTD belts, a speed of 6500 ft per minute (33 m/s) is permitted, whereas for GT2 belts, the maximum permitted acceleration is 7500 feet per minute (38 m/s). The utmost allowable operating quickness for T series is definitely 4000 feet each and every minute (20 m/s).

Belts are, generally, rated to yield a minimum of 3000 hours of useful lifestyle if all instructions are properly followed.

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

Belt drives are usually a source of noise. The rate of recurrence of the noise level boosts proportionally with the belt rate. The higher the original belt stress, the higher the sound level. The belt teeth entering the pulleys at high velocity become a compressor which creates sound. Some noise is the consequence of a belt rubbing against the flange, which could be the result of the shafts not really getting parallel. As shown in Figure 9, the sound level is considerably reduced if the PowerGrip GT2 belt is being used.

If the drive is part 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 some applications, no backlash between the driving and the driven shaft is permitted. For these instances, special profile pulleys can be produced without any clearance between the belt tooth and pulley. This might shorten the belt existence, nonetheless it eliminates backlash. Shape 10 displays the superiority of PowerGrip GT2 profile as far as reduced amount of backlash can be involved.

Synchronous belts are often powered by stepping motors. These drives are put through continuous and huge accelerations and decelerations. If the belt reinforcing dietary fiber, i.e., tension member, as well as the belt materials, have got high tensile strength and no elongation, the belt will not be instrumental in absorbing the shock loads. This will result in sheared belt teeth. Therefore, take this into consideration when how big is the smallest pulley and the materials for the belt and stress member are chosen.

The choice of the pulley materials (metal vs. plastic material) is a matter of price, desired precision, inertia, color, magnetic properties and, above all, personal preference predicated on experiences. Plastic pulleys with metal inserts or metal hubs represent a good Timing Belt Pulleys Style and Installation Suggestions: General Guide Lines timing belt pulleyscompromise.

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

Timing belt installation ought to be a snug in shape, neither too tight 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 as well taut) assures longer life, much less wear and quieter operation. Preloading (often the reason behind Timing Belt Pulleys Style and Installation Suggestions: General Guide Lines teeth bore timing belt pulleypremature failure) isn't required. When torque can be unusually high, a loose belt may “jump teeth” on starting. In such a case, the tension ought to be increased steadily, until satisfactory procedure is attained. A good guideline for installation stress is as proven in Figure 20, and the corresponding tensioning force is demonstrated in Table 9, both proven in SECTION 10 BELT TENSIONING. For widths apart from shown, increase pressure proportionally to the belt width. Instrumentation for calculating belt tension is available. Consult the merchandise section of this catalog.

Make 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 perform against one flange.

On a long center get, it is imperative that the belt sag is not large enough to permit teeth on the slack part to engage one's teeth on the tight side.

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

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

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

As well as the general recommendations enumerated previously, specific operating characteristics of the travel must be taken into account.

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