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NTN Corporation (NTN) has developed a sealed deep groove ball bearing featuring an 80% rotational torque reduction for automotive transmissions, where higher efficiency is required to respond to CO2 emission reductions and soaring crude oil prices.
To address the demands for fuel-efficient cars, lower torque transmission bearings are required. Until now, non-sealed bearings focusing on rotational torque and sealed bearings focusing on the prevention of ingress of foreign matter have been used for transmissions. With non-sealed bearings, the rotational torque is low because no seal lips are used, but special material and heat treatment were necessary to maximize bearing life due to the potential risk of ingress of foreign matter. On the other hand, with a fully sealed bearing, the considerably higher torque due to sealing lips compared with the non-sealed bearing was an issue. Accordingly, bearings with features of both sealed and non-sealed bearings have been in demand.
With this newly developed product, seal material composition and lip configuration were reviewed and the seal sliding condition with inner ring was optimized. The light contact seal lip wears at an early stage of operation and the seal becomes a non-contact type ensuring a minimum clearance with inner ring. As a result of this, approximately 30 times the lubrication oil penetrates into the bearing through the seal compared to that of a conventional sealed bearing, and rotational torque equivalent to a non-sealed bearing is realized. In addition, reduction of rotational torque by 80% compared with a conventional
| Product Model | Inside Diameter | Outside Diameter | Thickness |
| K42X47X30ZW bearing | 42 | 47 | 30 |
| K39X44X26ZW bearing | 39 | 44 | 26 |