Handling The Pressure Of Hose Bursts
By Mike Brezonick23 March 2020
Few things are more frightening – and more dangerous – than when a hydraulic hose bursts on a hydraulic excavator. When lifting a heavy bucketload of material, an unexpected spike in pressure or flow can lead a hose to rupture, which usually results in the boom arm dropping uncontrollably, which can be hazardous or even fatal to the operator and anyone else in the vicinity. That’s why today’s equipment safety regulations require the use of lowering control systems that prevent excavator boom or arm drop and ensure a controlled lowering of the load in the event of a hydraulic line failure.
At IFPE, HydraForce, the Lincolnshire, Ill.-headquartered specialist in hydraulic cartridge valves, valve manifolds and electronic controls, unveiled its own solution to the problem of hose bursts in excavators with the EBLV boom lock valve.
In most excavators, the hydraulic system incorporates lowering controls that typically employ a pilot-operated proportional poppet valve to control the hydraulic flow between the boom and the main control valve.
The poppet is controlled through remote pilot pressure that can come from a pilot-operated joystick or an electroportional pressure reducing or pressure relieving valve. That type of system is successful at controlling flow — volume or displacement — but does not address system pressure.
A DIFFERENT APPROACH
With its EBLV boom lock valve, HydraForce takes a different approach by controlling pressure rather than flow. The valve has a poppet seat for low leakage and spool-type metering for improved control. It is internally piloted, HydraForce said, thus eliminating any need for additional pilot lines or sources. The pressure control valve has an integrated housing that also contains a built-in check valve that provides free reverse flow.
The EBLV boom lock valve can be used for a sequence function or a relief function, depending on how it is plumbed, HydraForce said, adding that using it as a sequence valve can help to reduce the effect of backpressure from the main control valve and hydraulic plumbing.
The ELBV boom lock valve has a flow rating of 66 gpm (248 lpm) and can accommodate pressures up to 6091 psi (420 bar).
The valve utilizes a single-piece housing that HydraForce said is more compact and lightweight than typical custom manifolds or valve packages, particularly as it integrates two functions — proportional pressure control and reverse check — in the single valve body. In addition HydraForce said the integrated design results in less chance for leakage, as there are fewer seals and hydraulic lines.
Along with its new EBLV16 boom lock valve, HydraForce displayed a range of additional new electrohydraulic fluid power designs and products for construction and mining equipment at IFPE. This includes a new family of high pressure, low flow SF hydraulic solenoid valves for low leakage blocking and load-holding applications in mobile equipment, as well as several new multi-function valves with various types of feedback devices to provide continuous control of hydraulic systems.
HydraForce also demonstrated its IoT technology for mobile hydraulic equipment which incorporates the new HydraForce ERAU-6200 Remote Access Unit with Globe and Gate powered by Epec.