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Posts Categorized: RPI Articles

RPI Published in Recycling Today!

RPI has received the great honor of being published in the Nov 2015 issue of Recycling Today.  Go here to read the article on how properly maintained conveyor belts can help a recycle facility run smoothly.

recycle today cover

Proper Conveyor Belt Maintenance Prevents Downtime

Proper Conveyor Belt Maintenance Prevents Downtime

Construction & Demolition material isn’t the typical material that is run through most conveyor systems, therefore you can’t have a typical system or belt.  It is important to understand how the unique application of C&D affects the conveyor belt and what can be done to mitigate some of the potential issues.  Conveyors by nature are dynamic systems that require constant monitoring, maintenance and cleaning.  In a C&D application, this is especially critical, as the conveyor belt will reflect any symptoms of an unhealthy system with tracking and wear issues.  It is critical to understand conveyor belts and their behaviors when maintaining a conveyor system. 


To read more go to:

As published in the May/June issue of C&D World.


Straight Warp Belt – A problem Solver!

Straight Warp Belt – A problem Solver!

Impact Resistance of Straight Warp Belt Solves problem for C&D Application

We were asked to provide recommendations to an OEM for a crushing application for construction and demolition. The OEM has successful experience with grinding applications for green waste. A standard 3/330 cover x cover belt had worked well in the green waste application; however, instead of processing wood products they would be working with pieces of concrete, rebar and steel. The OEM was having problems with the new materials breaking the fabric plies and punching holes in the conveyor belt.

RPI recommended switching to a 1/440 Straight Warp belt due to success in similar applications within the recycling industry. The polyester carcass has straight warp yarn for low stretch and high strength. A binder warp locks the fabric together. In addition, fill yarns above and below the binder yarn makes for a high crimp fabric. The unique design offers a good rip and impact resistance and permits the use of small diameter pulleys. RMA grade 2 covers were recommended for impact and abrasion resistance over grade 1 and over MOR.

RPI has seen excellent results when used in concrete recycling, impact crushers and steel scrap yard belts, due to the high impact and abrasion in these applications. Because vulcanization on small pulleys is not recommended the chosen splice was R 5 or #190 plate fasteners. The single ply also gives good flex around small pulley diameters, with a recommended minimum pulley diameter of 16”.

Due to the success of the 1/440 belt, the OEM has standardized all equipment for C&D applications with high abrasion and impact to the Straight Warp belt. Standard 3/330 belt is standard for applications with less impact and abrasions. The OEM has seen a significant ROI on the Straight Warp belt, with a drastic decrease in warranty claims for the conveyor belts and satisfied customers.

Conveyor Belt Transition Zones

Transition Zones Are Critical To a Well Functioning Conveyor System

Bulk material conveyors with free flowing products commonly use troughed idlers to increase the belt load carrying capacity.  The conveyor transition zone is the area of belt that changes from flat to a wide “U” shape.  The conveyor belt changes from a flat to troughed profile at the tail pulley and a troughed to flat profile at the head pulley.  These transition zones can cause belt damage due to tension and compressive forces.

The transition must occur over sufficient conveyor length in order to avoid excessive tension in the belt edges (splice tearing) and avoid belt compression (center buckling). The conveyor system operating tension has a strong influence on the transition length.  Transition distances are measurements from the centerline of a terminal pulley to the first full angle system idler (LI). One or more belt supporting low angle transition idlers may be between the terminal pulley and the first full angle system idler and should not be included in this measurement. 

The two most common transition profile types are the full trough depth and ½ trough depth. The full trough is typically found at the tail, with the ½ trough typically found at the head. The full trough terminal pulley may be raised slightly to give a ½ trough configuration. 

Transition Error


Cross belt tension is too great at the edges (more than 130%) and less than zero in the middle of the belt,

Splice edge failures and delaminating in the center of the belt Left unchecked an adhesion breakdown in the center of the belt will occur and thus propagate along the entire belt length.

Proper edge tension without adequate transition distance

Insufficient tension present to keep the bottom of the belt in the trough and avoid some buckling. Long term subsequent problems with the belt and the splices will be encountered.

Cross belt tension is poorly averaged, where the belt edges and the belt center are more than 120% rated tension and the idler junction area of the belt is less than zero

Cs the belt moves onto the pulley the tensions must equalize quickly across the belt width and “belt creep” in the low tension areas can occur. The belt creeps around the pulley face in the low tension areas near the idler junction resulting in skidding, wearing a corresponding channel into the rubber lagging.

Transition length is increased to the belt width

Without sufficient transition distance, too much shearing force across the splice width is encountered. Left unchecked an adhesion breakdown in the idler junction areas of the splice will occur and thus propagate along the entire belt length.


Multiplying the belt width (inches) by the table transition distance factor (below) will give the minimum recommended transition distance (inches).

Idler Angle

% Rated Belt Tension

Full Trough

1/2 Trough



















*For  Fabric Belts Only. Remember, Transition distance, as defined by NIBA is the length from the center line of the first fully troughed idler roll to the center of the terminal pulley (either the head or tail pulley).

Hot Vulcanized Sidewall Wins Again

We thought we’d post a few more casualties from the cold-bonded world. Want to see what happens when the sidewalls are not vulcanized on? Ouch!

Cold Bond Sidewall

Another sad belt left out in the cold-bond world to fail.

Cold Bond Sidewall