XPZ850 Gates Quad Power 4 XPZ-Section Cogged V-Belt (Uniset Match)

Safety First:

For your safety and that of others around you, before commencing work on any drive please be sure to isolate all sources of power to the installation, electrical, engines, mechanical, water power, wind and stored energy sources such that systems with cams or springs may have.
Isolate and lock off the machinery and make sure you clearly label the apparatus you are working on.
Please make sure your work area is clear from debris and clutter before commencing work.
It is advisable to wear gloves when handling pulleys and belts to reduce the risk of injury to your hands, equally important is correct work wear with no loose clothing which may get caught in the equipment.

Understanding correct belt installation

• Loosen the belt tension to facilitate removal of the old belts easily.
• The pulleys should be inspected for wear or damage and replaced as deemed necessary, badly worn pulleys will cause premature failure of the new belts.
• Where possible the alignment of the pulleys should be checked and rectified if required, the permissible industry standard is a maximum of 1mm misalignment.
• Clean any debris from the grooves of the pulley, rubber deposits can be cleared with a wire brush etc.
• The new belts should be placed over the pulleys and not "Run On". Run on is a term used when belts are forced onto pulleys under tension over the grooves, this causes damage to the belts.
  
  The diagram below shows a straight edge along the faces of pulleys to check alignment. No gap greater than 1mm should be noted at the arrow points.
  
  

Correct belt alignment, fitting and tension ensures proper system performance, long belt and bearing life expectancy and reduced energy costs.

Understanding Proper Belt Tension

• The correct tension of a V-belt drive is the lowest tension at which the belt will not slip at peak load conditions.
• For installations without a variable speed drive (direct online or star delta starters), the belt must be tensioned to handle increased motor torque during startup.
• For slow start variable frequency drive applications (inverter drives), the belt must be tensioned to handle the actual brake horsepower of the driving force.
• Engines are classed as variable speed drives because they don't start at full speed or load.
• Under tensioned belts can slip, generating heat that results in belt cracking and eventual failure.
• Over tensioned belts stretch excessively and also generate heat, which reduces belt and bearing life, and increases energy costs as system loads increase.
• After tensioning the belts should be run around several times to relieve any stresses and re-checked before operating.

There are many factors involved in calculating the correct tension for a given belt, the speed it will operate at, the smallest pulley it will run around, the span length of the belt, it's operating temperature etc.
As a general rule of thumb, we should be looking for 1/64 inch deflection per span inch length or 0.0156mm per span mm length.

e.g.: Measured in inches a 32 inch span length = 32 / 1/64 = 1/2 inch
e.g.: Measured in mm a 813mm span length = 813 / 0.0156 = 12.7mm

The following are generic approximations of the required forces to achieve the correct tensions. Please refer to the original manufacturers manual for the actually required belt tension for your equipment.



After the initial installation tensioning, re-checking and re-tensioning is recommended after one to two days. After that, belt tension should be checked periodically - about every three to six months or more frequently, if noise or vibration occurs. Whilst checking of the belt tension, checks should be made for cracks or fraying, as these indicate belt wear.

Notes:

• Belts should be stored flat and not hung up, they are best stored in a cool dry place away from direct sunlight.
• Do not run equipment without adequate guarding.