Cutting your losses

Cutting your losses

Special lubricants ensure increased gear performance

Published in Konstruktionspraxis, 9/2001

Friction reduction means higher machine efficiency - enter, special lubricants.

Power transmission engineering is developing at high speed, the major pacemaker being the call for ever increasing gear performance and efficiency. There is an increasing awareness that the lubricant plays a big part in meeting these requirements. Apart from technical demands, economic and ecological aspects are also taken into consideration to an increasing extent when selecting the lubricant.

Lubricant requirements

Technical requirements are specified by the gear manufacturer, in standards, or determined by special operating conditions. The most important "classical" parameters are nominal viscosity, the viscosity index, pour point, scuffing load capacity and compatibility with certain elastomers used in radial shaft seals.

In spur gears subject to high loads, additional requirements are micro-pitting resistance and good wear protection of the rolling bearings. Machine operators expect the lubricant to reduce operating expenses, which is possible by extending the oil service life, carrying out simple oil changes, ensuring wear-free operation (if possible) as well as optimum efficiency at all lube points.

New gear oil developments

All these factors have been taken into account by a well-known manufacturer of special lubricants when developing a new series of gear oils. Particular importance was attached to the selection of the base oils. Compared to conventional polyalphaolefins, these special new oils show a higher efficiency of up to 0.2 % per gear stage on the FZG test rig. This primarily results in savings owing to reduced current consumption and constitutes an increase in spur gear efficiency. Furthermore, the oil sump temperature drops by at least 5°C which on the one hand extends the oil life and on the other hand reduces the load that all gear components are exposed to.

Select the right additive on the basis of wear behaviour

The selection of suitable additives was based on the anti-wear properties in gear wheels and rolling bearings. The antiwear properties of these oils were determined in the FZG test and achieved a scuffing load stage of > 13 and a specific wear of < 0.2 mg/kWh (A/16.6/90). The oils also show a high micro-pitting resistance according to FVA No. 54.

The wear behavior of the gear oils in rolling bearings was tested on the FE 8 rolling bearing rig using cylindrical roller thrust bearings (DIN 51819-03-D-7-7,5/80-80).



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				Cutting your losses Special lubricants ensure increased gear performance Published in Konstruktionspraxis, 9/2001 Friction reduction means higher machine efficiency - enter, special lubricants. Power transmission engineering is developing at high speed, the major pacemaker being the call for ever increasing gear performance and efficiency. There is an increasing awareness that the lubricant plays a big part in meeting these requirements. Apart from technical demands, economic and ecological aspects are also taken into consideration to an increasing extent when selecting the lubricant. Lubricant requirements Technical requirements are specified by the gear manufacturer, in standards, or determined by special operating conditions. The most important "classical" parameters are nominal viscosity, the viscosity index, pour point, scuffing load capacity and compatibility with certain elastomers used in radial shaft seals. In spur gears subject to high loads, additional requirements are micro-pitting resistance and good wear protection of the rolling bearings. Machine operators expect the lubricant to reduce operating expenses, which is possible by extending the oil service life, carrying out simple oil changes, ensuring wear-free operation (if possible) as well as optimum efficiency at all lube points. New gear oil developments All these factors have been taken into account by a well-known manufacturer of special lubricants when developing a new series of gear oils. Particular importance was attached to the selection of the base oils. Compared to conventional polyalphaolefins, these special new oils show a higher efficiency of up to 0.2 % per gear stage on the FZG test rig. This primarily results in savings owing to reduced current consumption and constitutes an increase in spur gear efficiency. Furthermore, the oil sump temperature drops by at least 5°C which on the one hand extends the oil life and on the other hand reduces the load that all gear components are exposed to. Select the right additive on the basis of wear behaviour The selection of suitable additives was based on the anti-wear properties in gear wheels and rolling bearings. The antiwear properties of these oils were determined in the FZG test and achieved a scuffing load stage of > 13 and a specific wear of < 0.2 mg/kWh (A/16.6/90). The oils also show a high micro-pitting resistance according to FVA No. 54. The wear behavior of the gear oils in rolling bearings was tested on the FE 8 rolling bearing rig using cylindrical roller thrust bearings (DIN 51819-03-D-7-7,5/80-80).

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				The picture shows the bearing after the test with wear on the rolling element of m_w50< 2 mg and a cage wear of m_k50 < 20 mg. We may conclude from these results that this oil series offers excellent wear protection particularly in low-speed rolling bearings located at the power take-off side of gears. Although this paper is only a brief survey of the properties presented of special gear oils, practical experience clearly shows that only such special lubricants can meet the requirements of sophisticated applications in the long term. It may be concluded from the test results that the oil series offers excellent wear protection particularly in low-speed rolling bearings located at the power take-off side of gears. Please contact us for more information: Klüber Lubrication München KG Geisenhausenerstr. 7, 81379 München Tel. 089/78 76-0, Fax 089/78 76-333 eMail: marketing.service@klueber.com