Power Transmission
conditions and applications for which chain drives would have been the used traditionally, including bottling and textile machines, cylinder changing mechanisms in newspaper printing machines, and even in go-karts (Fig. 2). One feature in particular that helps these belts to handle extreme starting torques, shock loads and highly dynamic loads, is reinforcement of the teeth on the pulley side.
sprockets. To help further in reducing the cost of ownership, the belts do not stretch, do not require retensioning and do not need lubricating.
Quietly efficient
Design engineers seeking low-noise, high-efficiency power transmission belts could consider the Eagle NRG introduced by Goodyear Engineered Products in 2010. The Eagle NRG is described as an innovative upgrade to the Eagle Pd power transmission drive, rated for up to 25 per cent more power, while achieving an impressive efficiency of 98 per cent. Additionally, the new belt design is rated for continuous service at 93°C (200°F) and is also static-conductive.
Fig. 3. With its Heletical Offset Tooth design, the Eagle NRG belts operate up to 19 decibels quieter than straight-toothed synchronous belts, as well as running smoother.
Operating up to 19 decibels quieter than straight-toothed synchronous belts, Eagle NRG’s Heletical Offset Tooth (HOT) design merges belt and sprocket into what is claimed to be the quietest, smoothest and one of the most compact synchronous drive packages available (Fig. 3). The result is a continuous rolling tooth engagement that reduces vibration and improves the overall efficiency of the drive system. Tom Burgett, power transmission products manager for Veyance Technologies, the exclusive manufacturer of Goodyear Engineered Products, states: “Eagle NRG’s 98 per cent energy efficiency rating is at least five per cent higher than typical V-belt drives, which translates to immediate energy savings. Savings really add up when Eagle NRG is applied to high-energy-consuming drives that operate almost continuously year-round.”
Fig. 2. The Contitech heavy-duty Conti Synchrochain timing belts are suitable for tough operating conditions and as replacements for chain drives.
Another company offering a timing belt alternative to chain drives is the Gates Corporation, which introduced its Poly Chain GT Carbon Extended Length Synchronous Belts just over a year ago. These belts are suitable for drives requiring longer centre distances and high load-carrying capacities. Typical applications will be found in food processing, HVAC&R (heating, ventilation, air conditioning and refrigeration), oilfield, pulp and paper, mining and water treatment. According to the company, the belts offer a number of advantages including a life expectancy three times longer than chains, and pulleys that last ten times longer than
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www.engineerlive.com V-belt variants
So far we have focused on developments in synchronous belts but there are also evolutions in V-belts. Enhanced energy efficiency and sustainability are two themes adopted by manufactures of this type of belt as well. One example of this is the Blueconcept label from Contitech, with the Conti-V Pioneer being the first wrapped V-belt so designated. This belt is manufactured using vegetable oils, mineral fillers, chalk and cotton yarn, and completely dispenses with the carbon black (Fig. 4). Nevertheless, the Conti-V Pioneer is still conductive to ISO 1813 (Belt drives - V-ribbed belts, joined V-belts and V-belts including wide section belts and hexagonal belts - Electrical conductivity of antistatic belts: Characteristics
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