Hydraulic hoses are literally the life lines of most construction equipment. Nothing can grind productivity to a halt faster than a ruptured hose. A little time invested up front to monitor the condition of the hydraulic hoses and fittings can dramatically reduce expensive failures in the field.
“The potential cost of hose failure in terms of lost production, environmental impacts and possible injury to operators and others argues strongly in favor of replacing hoses on a time-based schedule, periodic visual inspection or some combination of the two,” says Douglas Jahnke, marketing manager, Eaton’s Hydraulics Group. “Hose replacement while equipment is already ‘out of service’ as part of a planned preventive maintenance schedule can prevent critical downtime and expense.”
“As a general rule, hoses should be replaced as part of a preventive maintenance (PM) program, especially in critical applications,” agrees Tim Deans, Gates Global Hydraulic Systems engineer. “Consider that hose shelf life is similar to automobile tires. After four to six years, the rubber begins to break down and you can expect to see visual cracking and weeping around the couplings.”
Monitor for Signs of Failure
A preventive maintenance program for hydraulic hoses and fittings should begin with a thorough inspection.
“If there are no signs of leaking, abrasion wear, cracks or twisting, then there is no reason to proactively replace the hose assembly,” says Ronald Gruber, Caterpillar. “However, other considerations — including the remoteness of the jobsite or cost of the machine being down — may prompt some customers to replace hose assemblies at a scheduled overhaul, especially if the customer has developed experience with hose life in specific applications.”
A visual inspection can catch many potential hose failures. “In many (but not all) cases, there are indications of an impending failure,” says Gruber. “Wetness or leaks, cracked rubber, loss of flexibility or worn rubber are all signs of a potential problem. There is really no reliable way to tell how long a hose assembly will last once these symptoms are noticed.”
Joseph Skovrinski, Gates Condition Monitoring Engineer, agrees, noting, “In most cases, hydraulic hoses will provide clues that indicate a pending failure. That’s why it’s important to conduct a daily visual inspection before operating hydraulic equipment. But never conduct an inspection by running your hand over the hose while the system is pressurized. Hot materials and chemicals can cause serious bodily harm, or even death.”
No hose assembly will last forever. “All hydraulic hose assemblies ultimately will fail and they often generate consistent indicators of impending failure,” says Jahnke. “Until recently, however, there has been no practical way to detect those indicators and proactively replace the hose. The good news is that the technology now exists to monitor those indicators and provide a warning of impeding failure.”
For example, Eaton LifeSense hose delivers this capability. “As the technology becomes more widespread, the need to throw away perfectly good hose on a time-based schedule will disappear,” says Jahnke.
Gates also offers advanced hose monitoring technology. “For highly critical applications, it pays to install a hose monitoring and diagnostic system, such as Gates Sentry IQ,” says Skovrinski. It monitors what goes on inside a working hydraulic hose. “It measures pressure spikes and correlates them to the temperature inside the hose when the spike occurs. This correlation between the temperature and the pressure estimates the end-of-life for hydraulic hose assemblies.”
While many types of hose may look similar and even have the same physical dimensions, there are key differences you must understand. “The important thing to remember is the replacement hose must meet or exceed the specifications of the old or original hose assembly,” says Gruber.