Application, Design Principle

FAG hydraulic nuts are used for pressing parts with a tapered bore onto tapered seats. They are used primarily where the drive-up force of locknuts and pressure bolts is not sufficient.

Main fields of application:

• Mounting of rolling bearings with a tapered bore. The bearings can be mounted directly on tapered shaft seats or on adapter or withdrawal sleeves. Hydraulic nuts can also be used to dismount sleeve-mounted bearings.
• Mounting of couplings, gearwheels, impellers, ship‘s propellers ...

Design Principle

FAG hydraulic nuts consist of an annular body and a piston, fig. 1. The piston is operated hydraulically. The pressure chamber is sealed by two O-rings of soft PVC. The hydraulic nuts are designed for a maximum oil pressure of 800 bar.

Their stroke is powerful enough that the rolling bearings or other parts can be mounted in a single operation.

The bore d2 in the annular body is available with a metric fine thread, a trapezoidal thread or an inch thread so that suitable FAG hydraulic nuts are available for all currently used sleeve and shaft threads.

Where higher drive-up forces are required FAG also offer hydraulic nuts with a straight bore (reinforced design). FAG hydraulic nuts feature two oilsupply connection holes with a G 1/4 thread. In devices with a threaded bore, one hole each is provided in the face and in the O.D., in the reinforced design both are located in the O.D. If a dial gauge (page 16) is used, an additional connection hole in the face may be required. Threaded-bore hydraulic nuts have handling holes for easier handling. The larger the hydraulic nut, the larger the number of these holes, see table in fig. 2. Larger hydraulic nuts also feature threaded holes for eyebolts to facilitate handling.