Pneumatic torque wrench
The principle is that of a side mounted on a lever arm of the hydraulic cylinder, which when pressure is applied to the lever arm executes a pivoting movement. The lever arm then acts as an open-end or box wrench on a nut or bolt and pulls it tight or solves them. The direction of rotation is achieved by turning the square drive output element or by turning the wrench. According to this principle, a compact construction mechanics are integrated in one housing and thus large screw tightening torques can depend on the lever arm length and hydraulic operating pressure on a very small area to be applied. Modern hydraulic wrench bar can deliver a torque of over 5,000 Newton meters on the screw connection with a total weight of 4 kg and an operating pressure of 700. 3% accuracy very precise - In addition, the hydraulic wrench but operates relatively slowly, but with /. The size of such a 1 " square drive screw driving tool is then comparable to that of a far below in terms of performance and accuracy of the 1/2" air impact wrench.
Hydraulic wrenches are available in two different designs. The cassette wrenches and hydraulic wrenches with square drive.
Hydraulic wrench with square drive usually start at 3/ 4 " output drives and thus at about SW 27 However, they have also readily 1", 1 1/2 " or 2 1 /2" square footage and are therefore for torques up to 100,000 Nm and very large widths across flats in use. The procurement costs start at € 10,000 but may vary according to size but be significantly more. Hydraulic torque wrenches are therefore usually only encountered in industry, eg in power plants, in the assembly of large systems and components. A very typical application is the installation and maintenance of large wind turbines.
Cassette wrenches consist of two basic components. The drive head with the hydraulic connections and the exchange cassette. The interchangeable cartridge defined with the built in their hex output the key length. Usually a separate exchange cassette is used for each key width. To some extent, also worked with Reduzieradaptern or in / out nuts that can extend the range of the cartridge. Advantage of this design is its low profile, the screwdriver, which also allows them to perform in tight spaces.