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For many high speed applications, Sartorius multi-lobe (MGF) bearings provide the most cost-effective solution to the problem of oil film instability. Of all slide bearing types, however, Tilting Pad Journal Bearings offer the optimum in rotor stability due to their exceptional stiffness and damping characteristics. For this reason, Tilting Pad Journal Bearings are ideal for use in high speed machinery operating under low to medium loads, eg, turbines, turbocompressors, pumps and high-speed gear boxes.

Tilting pad-journal bearings

Standard Tilting Pad Journal Bearing, floodes lubrication - Application: Turbocompressor

Tilting Pad Journal Bearing with spherical pad-support and directed lubrication

Basic Design
The Sartorius Standard Tilting Pad Journal Bearing consists of a steel (C15) housing and 5 journal pads which are supported/pivoted centrally. This enables shaft rotation in either direction. The pads are manufactured from C15 steel and coated with a high quality white metal lining (TegoStar738).

Lubrication
Standard Sartorius products consist of two product lines, with three types of oil supply

    Flooded lubrication:
    1. Laterally sealed by floating rings with oil flow controlled by outlet holes.
    2. Laterally sealed by throttle rings and a defined seal gap to the shaft. Additional oil flow controlled by inlet holes.

    Directed Lubrication:
    Oil inlet nozzles metering the flow lateral flange seals equipped with large drain holes on the lower side. All standard Sartorius models are offered as split designs, as this has proven to be the easiest way for assembly and maintenance. Each product line (flooded or directed lubrication) comes standard in two bearing width ratios:
    B/d = 0.6, and
    B/d = 0.9
    Bearings with spherical pad support are the only exception to this. Their bore diameter-size D ranges from 30 mm to 315 mm.

    Instrumentation
    All Sartorius Tilting Pad Journal Bearings can be supplied with temperature sensors, thermocouple or Resistant Temperature Detectors (RTDs). RTDs are available as single or double PT100 types. The use of RTDs, temperature sensors or thermocouples guarantees permanent control of oil and bearing temperatures. This enables higher operational safety to be attained.

    Quality control
    To meet todays most stringent quality control requirements and associated certification standards, Sartorius Tilting Pad Journal Bearings have to pass a strict format of control and test procedures. All function measurements are recorded and material certificates provided where required.
    Ultrasonic inspection guarantees a perfect bond between steel and white metal. To detect and avoid cracks, the bearing surfaces are subjected to a dye penetration test. All qualitiy control procedures are reported on individual certificates. On request, bearings can be marked with the relevant customer identification codes.

    Bearing calculation to DIN 31657
    Bearing layout and calculations are carried out in accordance with DIN31657, with the aid of computer-assisted Tilting Pad bearing charts. As a rule, the Sartorius standard is suitable for sliding speeds up to 100m/s. In individual cases, and after consultation with our technical department, higher speeds may be permitted. During design, all operationally췶elevant factors such as load, lubricant film pressure, gap widths, clearance when warm, and shaft displacement have been considered and adjusted to one another. At the same time, the dynamic characteristics required for rotor calculations are determined. All data is documented in a bearing calculation. The calculation reflecting pressure development in the hydrodynamic surface is the result of solving the Reynolds differential equation onthe basis of the following assumptions:

    • The lubricant shows "Newtonian behavior" with respect to its viscosity.
    • The flows in the lubrication gaps are laminar.
    • The lubricant cannot be compressed.
    • All generated heat is dissipated by the lubricant

    Based on Reynolds differential equation together with a subsequent energy equation, a model has been developed that takes account of the blending of freshly added oil and oil leaving the hydrodynamic surfaces. The numeric solutions for the differential equation, reflecting the characteristic values for friction, oil flow, maximum pressure, maximum temperature, oil film thickness, as well as the dynamic characteristics are recorded in tables in our calculation programs. By applying the Newton interpolation all operating data for bearings can be determined highly accurately. The Sommerfeld number is well-suited to describing the operating events of journal bearings. Equivalent Sommerfeld numbers for different bearing sizes and differing operating conditions result in hydrodynamically similar bearings. Bearing calculations are based on the iterative method. The iteration must continue to the point where the thermal energy removed by the lubricantis in equilibrium with the heat generated by friction. The Sartorius calculation program determines all relevant parameters such as power loss, required oil quantity, permissible load, and stiffness and damping coefficients.

    Konstruktionsskizze Kippsegment-RadiallagerDesignsketch for Tilting Pad Journal Bearing, split version with spherical pad-support.

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