Hydraulic hose failure costs and prevention

Posted by Brendan Casey on 4/7/2014 to Hydraulic maintenance tips
Hydraulic hose has a finite service life, which can be reduced by a number of factors. From a maintenance perspective, little or no attention is usually paid to the hoses of a hydraulic system until a failure occurs.

Hydraulic hose failures cost more than the replacement hose. Additional costs can include:

Clean up, disposal and replacement of lost hydraulic oil. Collateral damage to other components, e.g. a hose failure on a hydrostatic transmission can result in loss of charge pressure and cavitation damage to the transmission pump and/or motor. Possible damage caused by the ingression of contaminants. Machine downtime.

What causes hydraulic hose failures?

Focus on the following points to extend hydraulic hose life and minimize the costs associated with hydraulic hose failures:

External damage
Hydraulic hose manufacturers estimate that 80% of hose failures are attributable to external physical damage through pulling, kinking, crushing or abrasion of the hose. Abrasion caused by hoses rubbing against each other or surrounding surfaces is the most common type of damage.

To prevent external damage, ensure all clamps are kept secure, pay careful attention to routing whenever a replacement hose is installed and if necessary, apply inexpensive polyethylene spiral wrap to protect hydraulic hoses from abrasion.

Multi-plane bending
Bending a hydraulic hose in more than one plane results in twisting of its wire reinforcement. A twist of five degrees can reduce the service life of a high-pressure hydraulic hose by as much as 70% and a seven degree twist can result in a 90% reduction in service life.

Multi-plane bending is usually the result of poor hose-assembly selection and/or routing but can also occur as a result of inadequate or unsecure clamping where the hose is subjected to machine or actuator movement.

Operating conditions
The operating conditions that a correctly installed hydraulic hose is subjected to will ultimately determine its service life. Extremes in temperature, e.g. high daytime operating temperatures and very cold conditions when the machine is standing at night, accelerate aging of the hose's rubber tube and cover.

Frequent and extreme pressure fluctuations, e.g. rock hammer on a hydraulic excavator, accelerate hose fatigue. In applications where a two-wire braid reinforced hydraulic hose meets the nominal working pressure requirement but high dynamic pressure conditions are expected, the longer service life afforded by a spiral reinforced hydraulic hose will usually more than offset the higher initial cost.

If you enjoyed this article, you'll love Brendan Casey's Inside Hydraulics newsletter. It gives you real-life, how-to-do-it, nuts-and-bolts, hydraulics know-how -- information you can use today.


ABOUT THE AUTHOR: Brendan Casey has more than 25 years experience in the maintenance, repair and overhaul of mobile and industrial hydraulic equipment. For more information on reducing the operating cost and increasing the up-time of your hydraulic equipment, visit his web site: http://www.HydraulicSupermarket.com
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