Dr Jayne O'Shea

In belt conveying, indentation rolling resistance arises due to the viscoelastic contact between the conveyor belt and an idler roll. As a belt travels over an idler, an asymmetric pressure distribution is formed that opposes the direction of movement, therefore resulting in a drag force to the system. For conventional systems, this resistance can account for up to 60% of the total drive power [1]. Idler diameter is known to have a considerable influence on the indentation rolling resistance of belt conveying systems, by reducing the indentation and contact stress. But how big is too big? As handling equipment becomes more developed and readily available on-site to aid in conveying component installation, larger idler diameters are becoming a more viable option to install on long conveying systems due to their energy-saving potential. This paper presents indentation rolling resistance measurements with idler roll diameters of 152.4 mm, 219 mm, 316 mm and 400 mm to evaluate the influence of larger diameter rollers on energy savings and discusses the considerations for using them in long conveyor systems.

With recent advancements in conveying technologies, conveyors are required to achieve greater lifts, longer conveying distances and higher throughputs. As such, drive stations continue to increase in size, with gearless drive stations in excess of 10 MW in existence. A significant amount of research has been conducted into the design and optimization of these systems, however, the use of standard methodologies to quantify drive friction is a known limitation that remains. Currently, design standards use Euler's classical 'rope friction' equation to determine drive limitations, with this method failing to account for a variable friction coefficient around the drive pulley. Due to this, the calculated drive is conservative and reaches the limit of efficacy with high-capacity conveyors, due to the high belt tensions required, and the necessary overdesign in structure. This paper investigates the frictional behaviour between a belt conveyor and pulley lagging materials and presents test results demonstrating how the friction coefficient varies with changing load and slip velocity. This improved understanding of the frictional behaviour between the conveyor and drive pulley lagging will further the design capabilities of high-capacity conveyor systems.

This study investigates the influence of idler roller diameter on indentation rolling resistance and idler rotating resistance in belt conveying systems, crucial for long-distance bulk material transport. It encompasses the impact on grease-lubricated rolling bearings, grease-filled labyrinth seals, and lip seals, with the aim of optimizing energy consumption. Experimental devices were used to refine predictive models, demonstrating that larger idler rollers reduce both resistances, leading to a 40% to 55% efficiency improvement. The study offers a detailed breakdown of friction losses under various operating conditions and provides valuable insights for lubricant selection and system enhancement, highlighting the significance of idler roller diameter in reducing energy costs and enhancing system performance.