TowHaul Corporation has every intention of staying the world’s no. 1 manufacturer of customised lowboys and towhooks for the mining industry. That is why it opted for the Sauer-Danfoss PVG 100 – the valve choice for mines on the move.
Some of the world's biggest open pit mines in Australia, South Africa, Russia and the Americas have come to count on the post-compensated PVG 100 valve from Sauer-Danfoss. Discretely placed, the PVG 100 is a key hydraulic component on all the TowHaul lowboys designed for efficient mobility around the mine.
TowHaul Corporation was among the first OEMs to start using the high-performing directional control valve following its launch in 2005. "As soon as we started using them, we were pretty tickled with their function. They work so well in our application, that we use them on all our units," says Matt Crawford, systems design manager at TowHaul in Bozeman, Montana, USA.
Mike Henson, field sales manager at Berendsen Fluid Power, a key Sauer-Danfoss distributor in North America, introduced the PVG 100 to TowHaul in response to a request for an electrically actuated valve. The aim was to replace the existing mechanically actuated valve on its patented hook unit, the TowHaul Removable Gooseneck. Supplied with TowHaul lowboys and suitable for use on all other TowHaul mine vehicles, the heavy-duty gooseneck enables fast and reliable hook-up of loads ranging from 120 to 1500 tonne.
"For TowHaul, speed is not of the essence - controllability is. The PVG 100 is the valve they will go forward with in the future," says Henson.
Multifunctional capability
The PVG 100 supplies flow for all the gooseneck functions, each requiring some 210 to 230 litres/minute. Electrical actuation of the valve fits well with the modern mining industry's move towards more electronic functions.
"The electric actuator makes the valve much cleaner, less cumbersome and easier to install than our previous mechanically actuated valve. The DIN electric connectors are really handy as wires can be quickly reconnected if they are damaged in the mine," says Crawford.
"We also like the mechanical stroke limiters. Even though we do not use the full load-sensing ability of the valve but only the on-off function, the limiters make it possible to reduce the amount of flow so it matches the application's requirements."
TowHaul employs the flexible PVG 100 as a three to six-function valve, depending on whether the gooseneck is a non-towing or towing unit.
For non-towing purposes, the unit serves as a hitch assembly that connects a truck up to a lowboy. The three valve functions here include the apron, responsible for up and down positioning of the hitch; the grab hook mechanism, which positions the hitch on the lowboy pickup shaft; and the toe that raises the lowboy for transport.
On towing units, a fourth function is necessary to slide the hitch into a rigid position for connection to a disabled haul truck that can then be safely towed to the repair workshop.
Optional valve functions are also available, such as the auxiliary dump circuit that hooks into the hydraulic system of the disabled vehicle so its load can be shed prior to towing. Another option is a more recent development - a patent-pending park brake release mechanism that allows the tow truck operator to release the brakes of the disabled haul truck. With the help of the PVG 100 valve, the system is able to maintain a constant oil pressure, preventing the brakes from reapplying while towing is underway.
"The PVG 100 helps us stay ahead of the game," says Crawford.
New prototype
More new developments are on the way. At present, TowHaul is collaborating with Berendsen Fluid Power on a valve design for a 600-ton unit with four cylinders. To accommodate the extremely high flow needs, a hybrid valve is currently being tested, comprising a PVG 100 valve bolted onto a hydraulic integrated circuit block - yet another display of versatility.
TowHaul is one of a growing number of companies that have discovered the high flow potential of the PVG 100. With production now underway at Sauer-Danfoss sites in Europe as well as the USA, the valve's flexibility is complemented by its accessibility on global markets. Heavy-duty hydraulic systems with multiple functions have everything to gain.
For more information contact Ron Sheehan, Sauer-Danfoss, +27 (0)11 803 8390, [email protected], www.sauer-danfoss.com
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