Ozone is a naturally occuring gas that is found in the air that we breathe. It consists uniquely of three oxygen molucules bonded together rather than the two of normal oxygen. Ozone is produced during lightening storms and is responsible for the fresh smell of the air afterwards. Electrical arcs from arc-welding or from around the brushes of electrical motors or ultraviolet light all produce ozone gas. It can often be detected by it's very unique chlorine bleach like smell in more concentrated form. Ozone is a powerful oxidant, so is sometimes used in air and water purification systems. To much, though, can have detrimental effects on plants, lung tissues, and organic materials like latex, plastics, and rubber.
The potential for excessive ozone concentrations is low for most environments in which belt drive systems are found. There are industrial environments, though, with higher concentrations of ozone gas making belt performance and durability a concern.
While all belts are designed for resistance to ozone, excessive concentrations can still affect rubber belts in much the same way as high environmental temperatures. Ozone slowly errodes the chemical composition resulting in rubber hardening and cracking. The amount of degradation is a function of the ozone concentration and the time of exposure. To prevent excessive detrimental effects on rubber power transmission belts, the following concentration levels should not be exceeded: (pphm = parts per hundred million)
Non-Conductive Belt Constructions: 100 pphm
Conductive Belt Constructions: 75 pphm
Non Marking Constructions: 20 pphm
Low Temperature Constructions: 20 pphm
The polyurethane material used in Poly Chain GT Carbon belts is considerably more resistant to ozone degradation than conventional rubber materials. Poly Chain GT Carbon drives are an excellent choice for drive applications located in environments with ozone concentrations.
GATES BELTS, HOSES, AND APPLICATIONS
Tuesday, January 24, 2012
Monday, January 16, 2012
Overhung Load
To prevent premature failures, manufacturers typically publish overhung load values for the speed reducers they offer. When designing a belt drive for use on a reducer, it is important to review the maximum published overhung load value to prevent overload of the bearings and shaft.
Along with their overhung load ratings, each speed reducer manufacturer publishes unique overhung load equations and constants. Therefore, it is crucial to obtain the correct overhung load calculation procedure from the reducer manufacture and to use their corresponding ratings.
If the overhung load is too high, the designer may consider increasing the pulley diameters, reducing the belt width, and/or mounting the pulley closer to the bearing. Following design adjustments, the overhung load calculations should be re-run to ensure that the drive is acceptable.
Along with their overhung load ratings, each speed reducer manufacturer publishes unique overhung load equations and constants. Therefore, it is crucial to obtain the correct overhung load calculation procedure from the reducer manufacture and to use their corresponding ratings.
If the overhung load is too high, the designer may consider increasing the pulley diameters, reducing the belt width, and/or mounting the pulley closer to the bearing. Following design adjustments, the overhung load calculations should be re-run to ensure that the drive is acceptable.
Tuesday, January 3, 2012
Right from the Start - Belt Storage
To get the most from a belt drive, its important to properly store a belt -all the proper installation procedures and design practices can be for nothing if a belt is improperly stored or damaged in storage.
A few of the major belt storage guidelines:
1) Belts can be stored up to 6 years if properly stored at temperatures less than 85 degrees F, and less than 70% relative humidty.
2) Make sure the belts are not bent to diameters smaller than the minimum recommended diameter for that cross section.
3) V-belts can be stored by hanging on a wall rack if they are hung on a saddle or diameter at least as large as the minimum diameter recommended for the cross section. Don't hang from a pin or nail!
4) Don't store in direct sunlight.
5) Don't store near heating devices.
6) Don't store near ozone generating devices such as transformers or electric motors.
7) Don't store belts where they are or could be exposed to solvents or chemicals.
8) Don't store on the floor unless in a proctive container.
9) Don't crimp belts, either in storage or handling.
Complete guidelines can be found in the Gates Belt Drive Preventive Maintenance & Safety Manual.
A few of the major belt storage guidelines:
1) Belts can be stored up to 6 years if properly stored at temperatures less than 85 degrees F, and less than 70% relative humidty.
2) Make sure the belts are not bent to diameters smaller than the minimum recommended diameter for that cross section.
3) V-belts can be stored by hanging on a wall rack if they are hung on a saddle or diameter at least as large as the minimum diameter recommended for the cross section. Don't hang from a pin or nail!
4) Don't store in direct sunlight.
5) Don't store near heating devices.
6) Don't store near ozone generating devices such as transformers or electric motors.
7) Don't store belts where they are or could be exposed to solvents or chemicals.
8) Don't store on the floor unless in a proctive container.
9) Don't crimp belts, either in storage or handling.
Complete guidelines can be found in the Gates Belt Drive Preventive Maintenance & Safety Manual.
