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Rexnord's Chains Help Harness Hydro Power
Rexnord's triple stranded 48 B-3 and 28 B-3 chains have been used in a hydroelectric water mill on the river Ems in northern Germany.
Harnessing the power of water to generate power is one of the greenest ways of producing electricity. And the more efficient, simpler and reliable the power transmission package between the motive force and the generator the better. A privately owned water mill on the river Ems in northern Germany has been adapted by its owner to produce hydropower electricity using its two paddle wheels to drive a generator.
The driving energy of the paddle wheels is transferred to the generator via a chain and sprocket arrangement.Particular attractions of this design are its high efficiency, easy installation, robustness in short-term overload conditions, and easy maintenance.Further, this solution was adopted because only 500N were required to start producing electricity (much less than the alternative gear drive considered).
It also offered the advantage of being able to span the large shaft centre distances involved whilst the simple chain/sprocket configuration delivers maximum power (74kW) from the water wheel shafts to the drive chains.
The chain types selected for the two stage drive mechanism are Rexnord's triple stranded 48 B-3 and 28 B-3.These chain sizes, together with centre distances and number of sprocket teeth, were specified to ensure maximum power transmission plus optimised service life.Also considered were the clearances between the inner and outer links to ensure effective lubrication penetration to prevent possible fretting corrosion and cold welding.
Rexnord's triple stranded chains were selected in order to distribute drive loads.This chain type also offers high tensile strength.Considered in conjunction with the chain's properties were the sprocket dimensions and tooth size and number; the first with regard to wear properties and the latter to minimise the risk of vibration arising from the effect of polygonal action.Different transmission ratios are employed on the two drive stages.This is to reduce the impact of centrifugal forces and thereby minimise lubrication requirements.Ultimately, power is delivered to the generator via a spur gear when input speed reaches 90rev/min.After more than a year in usage the Rexnord roller chains are not exhibiting any signs of significant wear.
| Product Model | Inside Diameter | Outside Diameter | Thickness |
| GAKMR6 bearing | 6 | 20 | 9 |
| GAKMR5 bearing | 5 | 18 | 8 |