1.Maximum speed that a drive belt can safely handle:
Pulley rim speed is the limiting factor, rather than the belt. This limiting speed depends on the
pulley material and design.
For gray iron casting and statically balanced, pulley rim speeds up to 6,500 fpm is normally satisfactory. A pulley running at more than 6,500 fpm may cause vibration, noise, poor bearing life, and high fatigue stresses. Therefore, pulleys that exceed 6,500 fpm should be dynamically balanced.
2.Causes of vibrations in belt-drive and corrective measures.
Drive belts experience both vertical and lateral vibrations when their natural frequencies coincide with excitation frequency of connected equipment.Belt tension can affect the amplitude of this vibration. Therefore, to correct the problem, first check for proper tension.
If this does not work, consider changing other drive parameters to reduce the amplitude of vibration or alter its frequency. Such parameters include span length, belt type, misalignment, inertia of driving or driven machinery,pulley diameter and weight (inertia), speed, and the number of belts. In some cases (where original unit was oversized), it may be possible to downsize the drive by reducing the number of belts or belt width, and increasing the static tension to alter the belt’s natural frequency so it doesn’t coincide with the excitation frequency of the machinery. When it can be done safely, it is preferable to reduce the static tension to keep the operating belt tension below the belt’s natural frequency range.
To reduce lateral vibration, increase flexural rigidity in the lateral direction. This can be accomplished by using joined belts.
What causes a squealing belt?
A V-belt squealing is usually caused by belt slip, often due to under tensioning. When a new belt replaces one belt in a multi belt drive, the new belt may be tensioned properly, but all of the old ones are undertensioned. To avoid this problem, replace all belts in a multibelt drive at the same time, and with belts of the same construction from the same manufacturer.
Replace worn sheaves, which can lead to noise and belt rollover, as well as worn or damaged belts.
Sudden, high startup torques or peak loads also cause belt slip. Usually, this condition lasts only a few seconds.But, it can lead to heat build-up which reduces belt life. If belt slip and heat build-up is suspected, turn off the drive and place a gloved hand on the belt to feel if the belt is too hot.
Grit, oil, or grease cause belts to slip. Therefore, keep the drive components clean. And don’t use belt dressing.
This only masks the real problem of inadequate tension.
Large pitch, wide synchronous drives may generate noise at high speeds. This can be caused by too-high or too low belt tension, or misalignment, which prevents the belt teeth from smoothly entering or leaving the sprocket grooves. Because of this, alignment requirements are tighter for synchronous belts than standard V-belts.
Note:: when inspecting a problem drive, review all components. Noise can be caused by nonbelt sources,
such as bearings, guard vibration, and loose mounts.
Pulley rim speed is the limiting factor, rather than the belt. This limiting speed depends on the
pulley material and design.
For gray iron casting and statically balanced, pulley rim speeds up to 6,500 fpm is normally satisfactory. A pulley running at more than 6,500 fpm may cause vibration, noise, poor bearing life, and high fatigue stresses. Therefore, pulleys that exceed 6,500 fpm should be dynamically balanced.
2.Causes of vibrations in belt-drive and corrective measures.
Drive belts experience both vertical and lateral vibrations when their natural frequencies coincide with excitation frequency of connected equipment.Belt tension can affect the amplitude of this vibration. Therefore, to correct the problem, first check for proper tension.
If this does not work, consider changing other drive parameters to reduce the amplitude of vibration or alter its frequency. Such parameters include span length, belt type, misalignment, inertia of driving or driven machinery,pulley diameter and weight (inertia), speed, and the number of belts. In some cases (where original unit was oversized), it may be possible to downsize the drive by reducing the number of belts or belt width, and increasing the static tension to alter the belt’s natural frequency so it doesn’t coincide with the excitation frequency of the machinery. When it can be done safely, it is preferable to reduce the static tension to keep the operating belt tension below the belt’s natural frequency range.
To reduce lateral vibration, increase flexural rigidity in the lateral direction. This can be accomplished by using joined belts.
What causes a squealing belt?
A V-belt squealing is usually caused by belt slip, often due to under tensioning. When a new belt replaces one belt in a multi belt drive, the new belt may be tensioned properly, but all of the old ones are undertensioned. To avoid this problem, replace all belts in a multibelt drive at the same time, and with belts of the same construction from the same manufacturer.
Replace worn sheaves, which can lead to noise and belt rollover, as well as worn or damaged belts.
Sudden, high startup torques or peak loads also cause belt slip. Usually, this condition lasts only a few seconds.But, it can lead to heat build-up which reduces belt life. If belt slip and heat build-up is suspected, turn off the drive and place a gloved hand on the belt to feel if the belt is too hot.
Grit, oil, or grease cause belts to slip. Therefore, keep the drive components clean. And don’t use belt dressing.
This only masks the real problem of inadequate tension.
Large pitch, wide synchronous drives may generate noise at high speeds. This can be caused by too-high or too low belt tension, or misalignment, which prevents the belt teeth from smoothly entering or leaving the sprocket grooves. Because of this, alignment requirements are tighter for synchronous belts than standard V-belts.
Note:: when inspecting a problem drive, review all components. Noise can be caused by nonbelt sources,
such as bearings, guard vibration, and loose mounts.
Your post is a convenient and easy preference for those who would want to enhance the performance of their cars. All hail to belt drives! :)
ReplyDeleteThis post is applicable for all belts drives.Not limited to automobile industry.Belts drives are widely used in process plants also.
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