To connect extension devices to a wheel loader, it is necessary to deal with both residual pressure on the side of the machine and dynamic pressure on the side of the extension device. The consequence is a long conversion time due to awkward releasing. For Volvo wheel loaders, an ideal solution to this problem is a new, specialised coupling from Parker Tema. Even hydraulic extension devices can now be changed in seconds.
Volvo wheel loaders are versatile, all-round machines. Their unmistakable, rounded silhouette and elegant appearance harmonise with high practicality. The extensive range of accessories, which replaces a whole arsenal of expensive special machines, allows it to be used as a shovel in the morning, a road sweeper in the afternoon, and a fork loader or any other of around 60 extension devices in the evening.
In the past, connecting extension devices with a hydraulic supply has been problematic. For example, the wheel loader’s road sweeper has a hydraulic motor and even bottom-dump shovel and side-tipping buckets are hydraulically controlled. “If these tools stand in the sun for a long period after uncoupling, then the oil lines can heat up so much that the line pressure can rise to between 80 and 250 bar,” explains Lothar Stefan, key account manager for Parker. This is also the case for wheel loaders – despite regulation unloading when uncoupling – where there is still a residual pressure of up to 10 bar. “The driver has to open a screw on the extension device hose line and let a little oil out to reduce the residual pressure before the work tool can be coupled up,” he explains.
“We wanted to offer our customers a safe, quick, easy and environmentally friendly solution,” explains the manager of special construction for Volvo Compact Equipment, Reinhold Schneider. This subsidiary of Volvo is a world leader in construction machines, producing compact wheel loaders and excavators in Germany. “Each of our products includes efficient workflows that are thought through down to the tiniest detail,” he emphasises.Volvo can now offer wheel loader customers a real solution to the problem of quick and safe coupling of hydraulic extension devices – a mass-produced special coupling developed by Parker Tema in Sweden.
Coupling despite bilateral pressure
The solution is based on a standard coupling from the Tema flat face range, with a norm profile (ISO Norm: 16028/IF range). This is a leak-free coupling that can be operated without loss of oil. On the one hand, both coupling ends are always hermetically sealed before opening. On the other, the smooth flat face profiles ensure that no oil can collect at the front in the plug area. Three other features make the mass-produced Volvo coupling (IF 3810 S01) stand out: an integrated ball valve that keeps the coupling area pressure-free, a splitter control for protection against operator errors and an extremely short structure. The integrated ball valve allows easy coupling, even if the extension device has a residual pressure of around 250 bar, while a residual pressure no greater than 10 bar is backed up in the wheel loader after the mandatory release. “Provided the ball valve closes, there is almost no pressure remaining in the front area where the coupling and plug are pushed together,” Stefan explains. “It is then easy for the driver of the wheel loader to couple up by hand.”
Volvo also places great emphasis on the safety factor. For example, one important guideline in the design process is that coupling must only be allowed when the ball valve is closed, as enormous pressure can otherwise build up in the extension device on the coupling, either from squeezing together while coupling or if the extension device has not been used for a long time. This can be dangerous, for example if a pressurised bottom-dump bucket starts to move immediately after coupling. The patented splitter control offers protection against operator errors. “If the ball valve is not closed, then it is impossible for the excavator operator to uncouple, as the sliding casing is only released for uncoupling once the ball valve has been closed by 90°” Stefan explains.
“The new, special coupling is the solution to any problem which can occur in coupling hydraulic extension devices,” he enthuses, emphasising that the system has also proven to be successful in practice. “More and more customers are deciding not on the standard but on the optional special coupling,” he concludes.
For more information contact Lisa de Beer, Parker Hannifin, +27 (0)11 961 0700, lisa.debeer@parker.com, www.parker.com/za
| Tel: | +27 11 961 0700 |
| Fax: | +27 11 392 7213 |
| Email: | parker.southafrica@parker.com |
| www: | www.parker.com/za |
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