Why install a belt turnover system?


Marc Theriault, Account Manager western Canada at Enduride inc.

To answer the first question that may come to mind, What is a belt turnover system? Simply put, it is a device that allows a conveyor belt to be “flipped” on the return side so that the dirty side of the belt is no longer in contact with the return rollers, and therefore is not allowed to expel any carry-back material.

To answer the first question that may come to mind, What is a belt turnover system? Simply put, it is a device that allows a conveyor belt to be “flipped” on the return side so that the dirty side of the belt is no longer in contact with the return rollers, and therefore is not allowed to expel any carry-back material.

Why Belt Turnover? Although there has been many innovations in belt cleaning technology, none offer a 100% cleaning solution. For example, 0.001% carryback on a conveyor moving 5 million tons a year is 50 tons. Not a negligible amount. That is 50 tons of material resulting in :

Large clean up jobs = expensive man hours

Or premature wear of pulleys and rollers = expensive replacement parts and downtime

There are several types of Turnover systems, from the simple unguided belt turnover over the guided belt turnover to the more complexe Mordstein belt turnover . All are suitable for specific application and have their pros and cons but the cons can be a major deciding factor when using these systems

Unguided belt turnover

Unguided belt turnovers are not very usual and are suited for really small and light duty textile belts used inside buildings. The belt is simply twisted and held with two horizontal pinch rollers at the beginning and at the end of the twisting transition. This type of turnover must be inside a building as the belt is subject to being caught by the wind, potentially causing misalignment and belt damage. 

Guided Turnover with flat contact rollers

 

The idea is to guide the belt all along the twisting transition with flat return rollers. Some systems only use vertical rollers in the center and some systems (as shown here on the right and below) will also add intermediate 45° flat rollers at one third and two third of the twisting transition to maximize the support.

The biggest cons of a flat turnover system is space requirements. Depending on the belt conveyor specifications, these systems require a very long turnover length often 20 to 35 X the belt width. High Stress and Belt sag in the turnover. Belts tend to buckle in the center.

Troughed

As for troughed belt turnovers, there are two types, Supported or also called Mordstein (Figure A) and Guided (Figure B)

Both these types are very efficient at eliminating carry back.                                                                          

Troughed Turnover (Supported or also called Mordstein)

Mordstein belt turnovers are designed for wide steel cable belts (around 72” to 96” wide). The objective of this type of belt turnovers is to support the weight of belt during is twisting transition to minimize sagging and to avoid buckling. The major down sides to the Mordstein method are these systems are highly complicated, difficult installation and require a substantial amount of real estate on the conveyor. As the supporting rollers of the Mordstein belt turnovers are in contact with the dirty side of the belt on the inside of the twisting helix, they tend to wear and ultimately jam, potentially causing substantial damage to the belt.  

The major advantage of this method is the capability to accommodate either textile or steel cord belts, can be used on very wide belts (up to 96 inches) and run at very high speeds 1200 fpm.

Troughed Turnover (Guided)

Guided systems are easy to install, take up minimum space, gentle contact for minimal wear to belt and require little or no maintenance. They are well suited for textile carcass belts running at speed lower than 600 feet per minutes and compatible with belts up to 60 inches of width. However, it is also possible to use this type of belt turnover with some wider steel cord belts under certain conditions and with proper calculation. In this case, a precise evaluation of the application is required to make sure all parameters are controlled to insure the stability of the system. 

 

Usually, a twisting transition for textile carcass belts will be around 10 to 15 times the belt width.

Width steel cord belts, the transition length will increase around 15 to 20 times the belt width and will depend on the application analysis considering multiple parameters such as operating tension, belt PIW, belt top and bottom cover thickness, belt elastic modulus, belt weight per linear feet and more.        

Figure B

The ultimate goal of either of these methods is turning this :

Into This :

Quick easy clean up concentrated in 1 or 2 areas and substantial extended life of rollers and pulleys.

At Enduride we do not believe in just supplying you with parts and service, we strive to bring you the best solutions for whatever challenges you may have with your material handling applications.

To Learn more about Enduride/Brunone`s unique troughed belt turnover system, Visit us today at https://enduride.com/en/product/belt-turnover-system

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