Hydraulic systems are the lifeblood of construction equipment like excavators, wheel loaders, forklifts, cranes – the kind of equipment that moves or lifts heavy loads, digs in the ground or breaks things apart. These systems rely heavily on hydraulic hoses to transport fluid under high pressure, enabling the machinery to perform heavy-duty tasks. However, these hoses are not impervious to failure due to the fact they are often outside rain or shine and in wide temperature ranges. Understanding the various ways hydraulic hoses can fail and the implications of such failures is crucial for maintaining safety and efficiency on the job site, and minimising the amount of downtime.
How does hydraulic hose failure happen?
1. Fluid Contamination
Contaminated hydraulic fluid is where dirt, metal particles, or other debris in the fluid can cause internal abrasion, leading to premature wear. Over time, this degradation weakens the hose’s integrity, making it prone to bursting under pressure. Regular fluid checks and filtration help prevent contamination from causing accelerated damage to the hoses. Fluid changes at intervals recommended by the manufacturer will also help prevent hoses from bursting.
2. Old Age and Degradation
Hydraulic hoses, like any other component, have a finite lifespan, and as hoses age, they undergo a natural process of degradation that is exacerbated by exposure to environmental elements like UV rays, chemicals, dust, water, and temperature extremes. Over time, the hose material becomes brittle, loses flexibility, and eventually cracks or bursts, sometimes spectacularly. Regularly replacing hoses based on their recommended service life can prevent unexpected failures.
3. Poor Workmanship
The quality of workmanship during hose assembly plays a significant role in the hose’s longevity; a diligent service technician is a valuable asset to your company. Poorly executed crimping, incorrect assembly, or using the wrong type of fittings can all contribute to hose failure. Using the wrong hose for the machine can put it under undue stress. Hoses must be assembled by qualified personnel who understand the specifications and requirements of the hydraulic system.
4. Trapping or Bending
Hoses can become trapped between moving parts causing sharp bends or kinks that can restrict fluid flow, increase pressure, and cause the hose to fail. Hoses should be installed with proper bend radii to avoid these problems.
5. Operating Conditions
The conditions under which hydraulic equipment operates influence hose longevity. Extremes of temperature and pressure, and continuous operation will accelerate wear and tear. For instance, excavators and wheel loaders often work in harsh environments where exposure to abrasive materials, chemicals, and fluctuating temperatures is common. Ensuring that hoses are rated for the specific conditions they will face is critical for preventing failures.
6. Coupling Issues
Improperly fitted couplings or connections that are too tight or too loose can lead to leaks or hose separation. This not only causes a loss of hydraulic fluid but also increases the risk of catastrophic hose failure. Regular inspections and ensuring that all connections are properly secured can mitigate this risk. Check the service manual for guidelines on what connections to check, and what they should look like.
7. Defective Hose
In some cases, hose failure can be traced back to manufacturing defects. Even though quality control processes are stringent, defects can still occur. These defects might not be immediately apparent, but under pressure, they can cause the hose to rupture. It’s important to use hoses from reputable manufacturers and to inspect new hoses before installation.
8. Twisting
Hydraulic hoses are designed to handle pressure, but they aren’t meant to withstand twisting. Twisting can cause the hose to kink or weaken at specific points, leading to a reduction in its lifespan. Proper installation techniques that avoid twisting, along with the use of swivel fittings, can help prevent this issue.
9. Incompatible Hydraulic Fluid
Using hydraulic fluid that is not compatible with the hose material can cause chemical reactions that weaken the hose structure. Over time, this incompatibility can lead to swelling, cracking, or softening of the hose, ultimately causing failure. Always ensure that the hydraulic fluid used is compatible with the hose material.
10. Abrasion
In construction environments, hydraulic hoses are often exposed to abrasive materials, for example dust created in the construction process. Constant rubbing against rough surfaces can wear down the outer cover of the hose, exposing the reinforcement layers and leading to leaks or bursts. Keeping the machine clean, using protective sleeves or routing hoses away from abrasive surfaces can help reduce the risk of abrasion.
Implications of Hose Failure
The failure of a hydraulic hose on construction equipment can have severe consequences. A sudden loss of hydraulic pressure can render the equipment inoperable, leading to costly downtime and potential project delays. Most modern equipment has protection valves to stop buckets or forks from crashing to the ground if hydraulic pressure is lost. However, hose failure can pose serious safety risks through injection injuries, and exposure to skin and eyes. A burst hose under high pressure can cause hydraulic fluid to be ejected at high speeds, which can injure operators or bystanders; hydraulic fluid under the skin eats away at human tissue, potentially causing catastrophic injuries that require amputation.
How to Check Hydraulic Hoses
Regular inspections are key to preventing hydraulic hose failure. Checking hoses is covered as part of excavator training. Operators should check hoses for signs of wear, such as cracks, abrasions, or leaks. It’s also important to inspect connections for tightness and look for any signs of fluid leakage. If a hose shows any signs of damage, it should be replaced immediately. Routine maintenance should also include checking the condition of the hydraulic fluid to ensure it’s clean and free from contaminants.
Hoses should be replaced according to the manufacturer’s recommended service intervals, even if they don’t show visible signs of wear. Regular replacement helps avoid the risks associated with hose degradation due to old age.
Conclusion
Hydraulic hose failure is a significant risk in construction equipment, but with proper knowledge and preventative measures, it can be minimized. Understanding the common causes of hose failure—such as fluid contamination, poor workmanship, and harsh operating conditions—allows operators to take proactive steps in maintaining their hydraulic systems. Regular inspections and timely replacements are critical to ensuring the safety and efficiency of the equipment, ultimately keeping the job site running smoothly.
Darren is an expert on driving and transport, and is a member of the Institute of Advanced Motorists
