Stauff will present a new QRC-FG series of threaded flat-face couplings at Bauma, the world’s leading trade fair for construction machinery, building material machines, mining machines, construction vehicles, and construction equipment.
Stauff’s new series is the consistent further development of their existing QRC-FT coupling series, which has proven itself in the market for more than 10 years. The new couplings of the QRC-FG series include additional customer requirements and can be coupled under residual pressure on both sides. With these couplings, the flow rate is higher, and the coupling forces are lower.
Flat-face hydraulic screw couplings for demolition machinery
Threaded flat-face couplings are mainly used in large demolition excavators. The booms of the excavators are multi-part and reduced in size piece-by-piece as demolition progresses. Coupling and uncoupling the hydraulic lines must therefore be uncomplicated and safe for the user.
Flat-face screw couplings also have advantages in other heavy-duty construction and agricultural machinery.
1. In case of strong shocks, vibrations, and pressure peaks: screwing instead of pushing
Connections need to be highly resistant to shocks and vibrations. Screw couplings are the method of choice because they have a larger contact surface between the male tip and the female half of the coupling.
The components of screw couplings are less subject to wear than push-to-connect couplings. With push-to-connect couplings, “Brinelling” can occur due to recurring vibrations and pressure peaks. In addition, especially with larger nominal diameters, screw couplings require less force. Such force can be reduced to a minimum, which is not possible with push-to-connect couplings.
2. Coupling under residual pressure
While the predecessor series could only be coupled on the plug side at up to 250 bar, the sleeve can now be easily coupled by hand under residual pressure. Stauff’s designers developed a particularly reliable second valve for this purpose.
There are also design features inside the sleeve that enable the QRC-FG series to be coupled under pressure on the female side. For this purpose, the pressurized surface of the valve is as small as possible to press the valve open against a low force during the coupling process.
3. No hydraulic fluid contamination
Demolition excavators and other heavy-duty construction and agricultural machines are naturally exposed to high contamination levels. Neither solid particles nor air may get into the hydraulic system when coupling. Solids and air cause hydraulic oil to age more quickly and must be replaced more frequently. In addition, humidity condenses and corrodes or changes the consistency of the oil, and dirt particles promote abrasion on the components used. Therefore, the flat-face screw couplings minimize drip quantities and prevent the entry of dirt particles and air into the hydraulic system.
At Bauma, Stauff will first present sizes DN 10 to DN 25 of the new QRC-FG series, and sizes with higher nominal diameters will follow.