How to Prevent Belt Slippage on Inclined Belt Conveyor Systems

Ever noticed an inclined belt conveyor frustratingly attempting to haul loads up an incline, then seen the belt essentially freeze while the drive pulley continues to spin? That's belt slippage, and it's an operational nightmare. When belts fail to adhere to the drive pulley, materials accumulate around the tail end, halt production, and typically require a labor-intensive cleanup. This scenario is even more complex on inclined belt conveyor systems, as gravity perpetually pulls the load downward. Fortunately, slippage is preventable. With the right solutions, you can eliminate the operational frustrations and keep your system running freely. I'd like to discuss the main causes and effective the solutions that can keep slippage at bay.

Belt Tension Should Be Correct Initially

An insufficient belt tension is one of the most common reasons for slippage. A belt that is too loose cannot grip the drive pulley adequately, especially under heavy load conditions. Imagine a rubber band that is being used with a wheel. It will just spin around without grabbing. Most conveyor belts have a take up device to adjust tension, which can be either a manual screw type or a self-adjusting type that uses gravity. This device is also used with shorter inclined belt conveyor systems. However, if you are using a manual type, be aware that it needs to be checked and tightened regularly. A good rule of thumb to use is to look at the sag of the belt between the returning rollers. If the sag is more than a couple of inches, you may need to tighten it up. Having too much tension is just as bad, which can cause extra strain on the bearings, increase the wear on the belt and cause ducking problems. So look for a good tension, where the belt is not too loose but also not over strained.

Just the Right Amount of Grip

Unless the belt system is specifically designed for steep inclines or heavy materials, tension may not be enough. This answers the question, what is a wrap angle? The wrap angle is the measure of how much of the drive pulley is used by the belt. Typically, the belt is designed to have a standard contact angle of about 180 degrees. For instance, a snub pulley can be used to provide variable contact angles. Snub pulleys are small pulleys mounted to the return side of the belt and positioned next to the drive pulley. The purpose of a snub pulley is to press the belt more firmly against the drive pulley, thereby increasing the wrap angle to 210 degrees or more. From a physics perspective, more the surface area of contact from a belt to a pulley, the more friction and less likely the belt will slip. Snub pulleys do have a detrimental side. Because they are mounted to the return side of the belt, they can be prone to becoming dirty and require maintenance. Because snub pulleys are typically the first from the take-up pulley side, they should have a belt cleaner to remove the debris. Also, adding a smooth rubber lagging to the snub pulley drum protects it from wear. Within a conveyor system, if a snub pulley won't fit, never fear, as there are still alternatives.

Increase Your Lagging Materials to Maximize Pulley Traction

One important component to pulleys lagging materials is lagging pulley rubbers. Lagging rubber is used to help fight the occurrence of belt slippage. Most rubber lagging types are sufficient in dry condtions. But the presence of water and mud drastically reduces the lagging rubber's friction. During these conditions is the time to utilize ceramic lagging. Ceramic lagging is lagging materials with embedded tiles of high grade alumina ceramic in rubber. This creates rubber surfaces that are near the same level as corrugated rubbers and extremely high levels of friction in the presence of water, ice, and mud. One example of this was a quarry that worked in a wet, cloudy, cold mountain environment with an inclined belt conveyor system. They were consistently losing production due to excessive slippage. They made a number of attempts to resolve the slippage, including installing different rubber lagging and increasing the tension in the system. They were finally able to resolve the slippage problem by using ceramic lagging. The result of this was so good, that the conveyor belt lagging behind it had to be replaced in order to keep pace. This is the kind of dramatic improvement that can be expected with the right types of lagging materials.

Installing Protection for Inclines

Belt conveyors move materials in one direction, but some your materials are inclined and need protection from falling back, this is protection from falling back. On inclined belt conveyors, if the motor fails, the fully loaded belt will fall derisively. The belt will move back and countless materials will fall out. This is a dangerous mess. Materials may overspeed the gearbox, etc. Backstops are needed for this reason, backstops are mechanical clutches. Backstops engage in the case of reverse spin, but allow forward spin. Backstops are often on the conveyor head shaft. Backstops are protective from reverse and are secured. Most safety regulations require backstops in this case. Backstops may be unwanted, but are most critical in unfortunate circumstances.

Regular Inspections and Maintenance

With appropriate components and careful installation, belt slippage can still occur if maintenance is neglected. Over time, the belt stretches, the lagging wears, and the pulleys become smooth. Additionally, material build-up on various components can occur. Each of these small changes reduces friction and then, one day, the belt just starts slipping. Addressing these issues is simple. Check your belt tension regularly. Inspect the lagging and belt for material build-up. A misaligned belt is a significant source of slippage, and can tension the system unevenly, and so ensure the belt is tracking properly. A few minutes of inspection can save hours of downtime. Be mindful of your load limits. Overloading an inclined belt conveyor system is a surefire way to cause slippage.

Conclusion

The four-key factors to eliminating slippage of belts on inclined belt conveyor systems are adjusting tension, increasing grip by increasing the wrap angle, upgrading to ceramic lagging when conditions are tough, and installing backstops on inclines to ensure safety. Regular inspections will help identify any potential issues before they become costly. Slippage can be avoided by maintaining the right system. Keeping materials moving up inclines will not result in frustrating interruptions. Your production line will be more efficient.