Hydrostatic bearing Servobear®
Guiding system cover
The guiding system in the cover hydrostatic piston rod bearing Servobear® is especially suitable for highly dynamic movements and oscillations with high dynamic side loads.
Hydrostatic piston rod guides allow realizing extremely low friction forces with very high shearing loads on the piston rod.
Depending on the series, the sealing materials and the sealing system, this system is suitable for:
| Piston speeds | up to 4 m/s |
| Temperature range | from -30 °C to +100 °C |
Function
In hydrostatic bearings, the non-contact piston rod guide and the gap seal are realized in the same element. The rod is „floating“ on an oil film created by the bearing pockets around the perimeter. Depending on the rod diameter, 4- or 6-pocket bearings are used.
The contact (functional oil) sealing system and the wiper ring are not under pressure, which makes for very low residual friction that is constant in the entire pressure area.
| L | Collective functional oil port G1/4 or G1/2 |
| E1 | Ventilation head-side G1/4 |
| E2 | Ventilation cap-side G1/4 |
| E3 | Ventilation protection tube G1/4 (optional) |
| Ms1-Ms4 | Measurement port hydrostatic pocket 1 to 4 head-side |
| Ms1-Mk4 | Measurement port hydrostatic pocket 1 to 4 cap-side |
The pressure supply for the hydrostatic bearing is realized internally via the system pressure through channels in the cylinder. The supply pressure corresponds to the system pressure in front of the servo valve, pmin = 140 bar, pmax = 320 bar.
The functional oil shall be discharged into the tank through the functional oil connection without pressure, suction by vacuum is not permissible.
Pre-stressing the functional oil line is admissible up to 5 bar.
Serie 320:
Ports for functional oil are internally connected for alternative connection.
The amount of functional oil depends, among several other factors, on the viscosity of the fluid used, the temperature and particularly on the pressure conditions inside the cylinder.
The amounts of funktional oil indicated here have been determined for a fluid ISO VG 46 at 55 °C. However, these can only be used as guide values for the hydraulic calculation; an exact determination of the functional oil flow is only possible by measuring it on the device itself.
| Functional oil flow Servobear® with hydrostatic piston rod guidem |
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| Rod diameter [mm] |
Functional oil min.* [l/min] |
Functional oil max.* [l/min] |
| 25 | 1.0 | 1.9 |
| 30 | 1.0 | 2.0 |
| 40 | 1.0 | 2.2 |
| 50 | 1.0 | 2.4 |
| 63 | 1.0 | 2.6 |
| 80 | 1.4 | 3.0 |
| 100 | 1.6 | 3.5 |
| 125 | 2.0 | 3.7 |
| 160 | 3.0 | 4.5 |
| 200 | 3.2 | 4.7 |
The functional oil indications for Servobear® apply for a supply pressure of 280 bar (system pressure) for one chamber.