Fixed profile or fixed pad geometry hydrodynamic journal bearings are used in rotating machinery applications such as turbines, pumps, generators etc. These bearings replace rolling element antifriction bearings when the speeds and loads are high. Hydrodynamic bearings are an obvious choice in rotating machinery upwards of 500 kW power. DynoMech offers different types of fixed profile bearings to suit rotordynamic requirements:
- * Plain Cylindrical/Sleeve
- * Elliptical/Two Lobe
- * Offset
- * Sizes ranging from 20 mm to 1000 mm diameter
The fixed profile bearings provide excellent damping. However, at speeds exceeding 3000 rpm in large rotors and 7000 rpm in small rotors, these bearings experience high hydrodynamic instabilities due to oil whirl or oil whip phenomenon, which lead to very high sub-synchronous vibration amplitudes leading to bearing and shaft failures. The oil whirl or oil whip is caused when the cross-coupled stiffness exceeds the direct stiffness. Under these circumstances tilting pad journal bearings are the best.
Today’s rotating machinery industry focuses on high speed machinery, owing to the increasing demand for efficient and high power output. High speed machineries using fixed profile journal bearings undergo hydrodynamic instabilities, causing high sub-synchronous vibration amplitudes (oil whirl or oil whip). To overcome these instabilities, tilting pad journal bearings are used. Dynomech provides design solutions for tilting pad journal bearings:
- * Designs ranging from 4 to 8 pads, based on the specific applications
- * Bearing-designs with both, load on pad and load between pads, with either centre pivoted or offset pivoted pads.
- + For light loads, the preferred choice would be load on pad; and for high loads, load between pads is most suitable.
- + Bearings with offset pivoted pads configuration are suitable for unidirectional rotation only.
- * Size ranges from 25mm to 450mm diameter.
- * Pads made of different materials for cases where bearings experience high temperatures due to high sliding speeds
Dymomech offers both plain faced thrust bearings/washers and taper-land thrust bearings/washers:
- * Plain faced thrust bearings/washers for light axial load applications, with the load limited to 5 bar axial pressure.
- * Taper-land thrust bearings/washers for medium axial load applications of about 16 bar.
These bearings can be combined with radial bearings to suit the requirement of both radial and thrust together.
Tilting pad thrust bearings are most suitable when the axial loads exceed 16 bar pressure
- * Both centre pivot and offset pivot pads configuration are offered based on design requirements. The offset pivoted pads help in reducing the temperature of the pads and thus allow for better bearing performance and load carrying capacity. The offset pivoted pads configuration allows only unidirectional rotation.
- * Under special circumstances the pads can be made of different materials to withstand high temperature and pressure.
- * The sizes range from 50 mm to 1500 mm in diameter and are preferably designed for axial pressure loads in excess of 10 bar pressure and upto a limit of 70 bar pressure.
We offer design solutions for vertical bearing assembly configurations for applications such as vertical turbine pumps, vertical generators, vertical motors, vertical coal crushing machineries, vertical heavy duty rolling mills etc.
- * These bearings can either be vertical thrust alone, or a combination of both thrust and radial/guide bearings.
- * The thrust bearings are of tilting pad type, and the radial guide bearings can be either plain sleeve or tilting pad type.
- * The bearings can be either self-contained, with water or oil cooled type, or can be externally lubricated type.