Prevention is better than cure when it comes to replacing hoses before they can fail
When the first sign of a component failure is a pool of fluid on the floor, it’s time for any workshop to initiate preventative maintenance, rather than rectification after failure.
Hoses come under the category of being able to generate a major engine or equipment failure just by failing to contain the fluids that travel through them. Prevention of impending failure becomes a matter of scheduling attention at the time of service, usually around the 100,000 km interval, and implementing a replacement programme for the hoses and the attendant clamps at not later than 150,000 km intervals.
It’s unlikely that a workshop manager or mechanic will find reference to hose inspection in OEM service manuals other than mentioned as a possible cursory glance. What should happen is that, unless there’s a glaringly obvious cut or leak displayed on the outside of the hose, at which stage it should already have been replaced, inspection for general condition means removing the clamps and carefully inspecting the hose interior.
As Rahul Palkar, automotive heavy-duty product manager of leading hose manufacturer Gates Australia, explained to PowerTorque:
“Standard service intervals include the requirement to check hoses and clamps, as well as V-belts, drive belts and tensioners at a set distance and with a time-preferred changeover interval. That’s always a good thing in regard to the longevity, as in the case of hoses it enables you to see any examples of electrochemical degradation, and this is only possible if you remove the hose and inspect it internally. When you refit the same hose after examination you should use new clamps, as the old clamp is not going to torque up to match a new replacement.
“The same applies to the checking and replacement of V-belts, pulleys and tensioners. What we have seen over a period of time are well-organised fleets that may change the belt, the tensioner and the pulley at a specific time or distance. This contrasts with a section of the market that doesn’t do regular inspections, and, although they may change a belt, they ignore the tensioner. Even though the tensioner bearings may appear to be okay, they don’t know what pressure the tensioner is applying and it should be changed.
“We actively promote the preventative maintenance programme in relation to the drive system to replace the belt and the pulley and the tensioner, or the hose and the clamp. This produces a much better outcome than replacing just the one component,” said Rahul.
As way of focusing on the importance of hose and belt maintenance, it’s well known that failure of hose assemblies account for up to 47 percent of downtime on equipment such as a drilling rig. For the agricultural sector it’s also known that combine harvesters and tractors fail more from weathering than from usage. It’s for this reason that belts for agricultural applications on farm equipment are built to specifications capable of withstanding harsh ambient temperatures and conditions.
For the transport operator, it’s necessary to look further than the engine and driveline for preventative maintenance options. Hydraulic hoses controlling tippers and other trailer designs such as walking-floor and bulk pressure discharge blowers all need to be controlled by properly scheduled maintenance programmes.
In the past, the typical workshop had to stock a variety of hoses to suit the different applications. Engineers at Gates Australia have worked with their American counterparts to produce a new range of hoses called Multi Master that cover a multi-use application for coolant, fuel, hydraulics and suction hose requirements.
“We have just launched Multi Master into the Australian market and are finding a growing acceptance from end users and our partners. Available in a variety of sizes from ¾ to 6 inches diameter and covering a wide range of applications, this is the first type of hose capable of meeting the needs of coolant, fuel and suction delivery,” said Kent Clark of Gates Australia.
“The Multi Master hoses are generally clamped on but can also be used with crimped ends for those that use a crimped linkage. We can supply Multi Master hoses in bulk lengths of 30.48 metres (100 ft) or as pre-made hose assemblies available direct through our channel partners such as the national support provided 24/7 by 1800 HOSE VAN.
“The mobile 24/7 specialist hose repair vans operated nationally across all major markets by 1800 HOSE VAN provide a national service and repair network for Gates hydraulic and industrial hose and fitting products, for service and breakdown solutions on site or at the scene of an on-highway breakdown. This fleet of mobile units is rapidly expanding and stocks and supplies Gates hoses. 1800 HOSE VAN can be contacted by phoning 1800 467 382 or via the website at www.1800HOSEVAN.com.au
“We see the Multi Master range as potentially becoming the single type of hose stocked in service and parts departments because of its multiple application. Stocking of this hose can reduce the number of product lines usually kept on hand, effectively consolidating three different product lines into one. This simplifies service procedures and reduces parts stock costs.
“Being branded as Multi Master, and with a red strip along its length, it’s easy to identify and its selection comes down to its intended application. The working pressure for the hose at ¾-inch diameter is 350 psi, and as the diameter increases to 6-inches the pressure capability rating reduces to 150 psi. The other advantage of Gates hoses is that each hose has a 1:1 turn ratio. This means that a 2-inch hose has a 2-inch bend radius etc.
“For companies using Gates hoses for specific application, the product availability includes two-ply and four-ply green stripe coolant hoses, plus silicone coolant hoses in three-foot lengths, plus a range of 45 and 90-degree elbows. The four-ply coolant hose provides a superior ability to cope with extremely high ambient temperature usage, such as experienced in stationary engines where airflow may be limited, or on heavy haul mining applications in very high ambient temperatures.
“When replacing standard coolant hoses in linehaul operations we would suggest fitting a four-ply rather than a two-ply hose. The two-ply is recommended by OEMs, but, to prevent leakage, or where the clamps are biting into the hose and you see leakage, we recommend the use of four-ply designs because the hose is thicker.
“We also recommend using a banded clamp rather than a twin-wire clamp, as these provide a more uniform clamping torque across the circumference of the hose. The twin-wire clamps tend to be used because of their lower initial cost, but, while they are acceptable in their functional performance, the banded clamp is superior over time,” added Kent.