HydraulicMaintenance

& Safety

Tips to prevent downtime and save you money.Presented by Gates Corporation

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Why Preventive Maintenance? . . . . . . . . . . . . 3

Choosing the Right Hose . . . 5

Periodic Inspections . . . . . . . 8

Hose Troubleshooting . . . . 10

Hose Routing . . . . . . . . . . . 11

Hose Cleanliness. . . . . . . . . 12

Assembly Installation. . . . . 13

Safe Hydraulics . . . . . . . . . . 15

Table of Contents

ydraulic preven-tive maintenance

and safety is important for anyone whooperates hydraulically powered equipment. Improperlymaintained hydraulic assembliescan cause premature assemblyfailure and blowouts, resulting inequipment downtime, possibleequipment damage, personalinjury and even death.

At Gates we believe followingproper preventive maintenanceprocedures is time well spent.Shown at the right are some ofthe numerous benefits providedby preventive maintenance.

Let’s take a look at some preven-tive maintenance and safety procedures. They’ll put you onthe right track to safe and long-lasting hydraulic assemblies.

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Benefits� Reduce downtime.� Improve production.� More efficient use of

maintenance personnel.� Better control of spare-

parts inventory.� Decrease safety

hazards and accidents.� Extend equipment

service life.� Reduce capital

outlays for new equipment.

Why Preventive Maintenance?

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Choosing the RightComponents

Safe, long-lasting hydraulic assem-blies begin by choosing the rightcomponents. The “right” compo-nents are couplings and hosesdesigned to work together. Mostmanufacturers offer safe, high-quality components. But mixingand matching couplings from onemanufacturer with hoses fromanother manufacturer can lead to premature assembly failure.

That’s because hoses, couplings,assembly equipment and crimp-ing tolerances vary from onemanufacturer to another and are not interchangeable. Whencomponents from different manufacturers are mixed, couplingretention can be adversely affect-ed. Mixing components can notonly cause unnecessary down-time, it can result in personalinjury as well. In addition, thethread or flange ends of couplings

must be properly matched to theirmating components to createleak-proof connections.

Gates offers a complete line ofcouplings, hoses and relatedequipment, all designed to worktogether as a system. Gates components meet stringent testrequirements and are engineeredto provide the highest quality andlongest service life. Your Gates dis-tributor is specially trained tomake sure you get the couplingsand hoses that specifically meetyour needs.

Choosing the Right Hose

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hoosing the righthose is the first

step to long and safeassembly service life. But beforewe look into how to select theproper hose for the job, let’s firsttake a look at the benefits ofusing rubber hose in fluid powerapplications. Unlike rigid tubing,rubber hose offers the followingadvantages:

� Less susceptible to vibration and movement.

� No brazing or specialized bending required.

� Easier to obtain inthe aftermarket.

� Easier to route aroundobstacles.

� Sound absorption.� Dampens pressure surges.

Given its easy availability androuting advantages, many mainte-nance personnel actually preferrubber hose to metal tubing. In

fact, it’s not uncommon for main-tenance technicians to replacetubing with a hose assembly.

Hose Construction

Hydraulic hoses have three parts:the cover, tube and reinforce-ment. The cover protects the tubeand reinforcing material fromenvironmental conditions such asthe weather, ozone, abrasion,

heat, chemicals, etc. Choose ahose with a cover that can meetthe demands of your system,especially in abrasive situations or ifthe hose will be exposed to chemi-cals or extreme temperatures.

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Cover

Tube

Reinforcement

The tube is the part of the hosethat comes in contact with thehydraulic fluid. Reinforcementallows the hose to withstandinternal pressures, or in the caseof suction/vacuum hose, externalpressures. Hoses generally havebraided, spiraled or helical rein-forcement. The type of reinforce-ment depends on the intendeduse of the hose.

When choosing a hose, itis crucial that the cover,tube and reinforcementare all compatible withthe type of fluid used in the system. This is an important point to remember, becausemany hoses are notcompatible with all ofthe common fluids onthe market today, includ-ing petroleum-based,phosphate esters, water-based and diester fluids.

Other variables, such as elevatedtemperatures, fluid contaminationand fluid concentration, will alsoaffect compatibility. If in doubt,consult your hose distributor orthe hose manufacturer.

The “STAMPED” Method

Studies conducted by fluid powerparts manufacturers indicate that

the three most commoncauses of hydraulic hose failure are abuse,misapplication andimproper plumbing.Equipment operatorsand technicians canreduce, if not eliminate,premature hydraulichose failure by givingmaximum considerationto hose assembly selection and installation.

Yet, with all of the differ-ent types of hoses onthe market, choosing theright one can be difficult.

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SSIZE

TTEMPERATURE

AAPPLICATION

MMATERIAL

PPRESSURE

EENDS/COUPLINGS

DDELIVERY

Gates suggests using the“STAMPED” method to be sureyou get the right hose assemblyfor the job. “STAMPED” stands forSize, Temperature, Application,Material to be conveyed,Pressure, Ends or couplings, andDelivery. Here’s how it works:

Size – Choose a hose with aninside diameter that is adequateto minimize pressure loss and toavoid hose damage caused bythe heat generated by excessivefluid turbulence.

Temperature – The hose mustbe able to withstand the system’sminimum and maximum fluidand ambient temperatures.

Application – Determine whereor how the hose will be used.You’ll need to know the equip-ment type, working and surgepressures, fluid to be used, bendradius, electrical conductivity, etc.

Material to be Conveyed –The hose, including the hosetube and cover, along with thecoupling and O-rings, must becompatible with the type of fluidto be used.

Pressure – Know the systempressure, including pressurespikes. The hose’s publishedworking pressure must be equalto, or greater than, the normalsystem pressure and any pres-sure spikes it will encounter.

Ends or Couplings – Identifythe type of threads the systemuses and select a coupling that iscompatible with that thread type.

Delivery – How many hoseassemblies do you need andwhen do you need them? Yourlocal Gates distributor will workwith you to make sure you getthe assemblies you need whenyou need them.

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eriodic hose assembly inspections

can prevent unwantedand unexpected assembly fail-ures. During normal operations,be aware of how the equipmentsounds, feels, etc. Be sure tocheck out any noticeable abnormalities.

When and how often to inspect a hose assembly can vary by thetype of equipment used. Refer to your equipment manual andalways follow the manufacturer’sinspection recommendations. If the recommendations are not available, use the followingguidelines:

Other factors that influenceinspections include:

� Whether the equipment iscritical to the operation.

� Operating pressures andtemperatures.

� Difficult routing conditions.� Environmental factors such

as extreme temperatures,high or low humidity, abra-sive conditions, exposure tosunlight, etc.

� The type of usage: rugged, abusive, shock, vibration,operating time, etc.

� Accessibility of equipment.

Periodic Inspections

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� Inspect mobile equip-ment every 400 to 600hours or every threemonths, whichevercomes first.

� Inspect stationary equip-ment every three months.

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Inspection Procedures

Here’s a checklist that will helpkeep your equipment in goodrunning order:

First, always turn off theequipment’s power.

Place the equipment andcomponents in a safeand/or neutral position.

Remove access panels andinspect hose and fittingsfor damage or leaks.

Repair or replace assem-blies as needed.

Inspect other hydrauliccomponents.

Reinstall access panels.

Turn power back on.

Remain aware during operation for unusual noises, vibrations, etc.

All of these points are covered in greater detail in the Gates“Safe Hydraulics” workshop. See your local Gates representa-tive to schedule a workshop atyour location.

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he goal of trouble-shooting is to identify

the cause, or causes, ofa hose failure, and then to takethe appropriate corrective action.Here’s a list of some commoncauses of premature hose failureand some everyday solutions tocorrect the problems:

Hose Abrasion

Solution – Reroute the hose tokeep it away from abrasivesources or guard the hose with a protective sleeve.

Hose Burst Away from Hose Ends

Solution – Inspect system operating pressure and select ahose that meets or exceeds thesystem’s maximum pressure. Try rerouting the hose to preventexcessive flexing and/or to keepthe hose from exceeding its mini-mum bend radius.

Hose Burst at Coupling

Solution – Increase the hoseassembly’s length to accommo-date contraction under pressure;increase the hose bend radius or install bend restrictors; orreplace the hose assembly with a properly crimped assembly.

Hose Troubleshooting

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any assemblies failbecause of improper

routing. To minimizedamage caused by excessive flex-ing or whipping, restrain, protector guide (using clamps) allreplacement hoses. Protectivearmor, spring guards or sheathsmade of abrasion-, temperature-or chemical-resistant material willhelp protect hose from cuts, abra-sions, corrosives or hot compo-nents. Here are some hose rout-ing tips that will prevent unneces-sary assembly failures:

Hose Routing

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When hose installation is straight,allow enough slack in hose line toprovide for length changes that willoccur when pressure is applied.

Length Change

To allow for length changes when thehose is pressurized, do not clamp atbends so that curves will absorbchanges. Do not clamp high and lowpressure lines together.

Length Change

Adequate hose length is necessary todistribute movement on flexing appli-cations and to avoid abrasion.

Movement/Flexing

When radius is below the requiredminimum, use an angle adapter toavoid sharp bends.

Tight Bend

ontaminants in the system can

decrease equipmentlife and cause expensive failures.Therefore, it’s important to useclean components and assem-blies. Cleaning methods varybased on shop capabilities, thecleanliness level required and thecritical nature of the equipment.

Perhaps the easiest cleaningmethod is to blow shop airthrough the hose assembly afterit is completed. However, thisoffers minimal cleaning and is theleast effective method. A moresophisticated method is to use acombination of shop air, waterand a small sponge soaked withisopropyl alcohol. Push thesponge through the hose withshop air until the hose meetscleanliness levels.

A fluid flushing apparatus provides the most effective cleaning method. With this technique, cleaning fluid isflushed at a high velocity through the hose until the hose meets cleanliness levels.Your Gates representative canprovide you with more informa-tion on hose cleanliness andcleaning methods.

Hose Cleanliness

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e sure to followthese seven steps

when installing ahydraulic assembly:

Clean the surrounding areawhere the connection willbe made. Do not let dirt orcontaminants get into thehydraulic opening.

If adapters are used, installthem now.

Lay the hose assembly intothe routing position to verifylength and correct routing.

Thread one end of theassembly onto the port oradapter. Install angled fit-ting first to ensure properpositioning.

Assembly Installation

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continued on page 13

Now, thread the other endof the assembly, takingcare not to twist the hose.Use a wrench on the fit-ting’s backup hex whiletightening.

Properly torque both ends.

Run the hydraulic systemunder low pressure andinspect for leaks and poten-tially damaging contacts.

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here you have it—anoverview of hydraulic

safety and preventivemaintenance. If you are lookingfor more information on thistopic, Gates offers a specialhydraulic preventive maintenancetraining program called “SafeHydraulics.” The class providesyou with everything you need toknow to properly maintain yourequipment for safe operation.

In addition to the training pro-gram, refer to the Gates Guide to Preventative Maintenance &Safety for Hydraulic Hose &Couplings for detailed informationon the following topics:

� Fitting orientation� Coupling identification� Agency specifications� Hydraulic fluids� Hose storage life� Proper installation

torque values

� Crimper preventive maintenance

� Troubleshooting and hoseassemblies

For more information, contactyour local Gates hydraulic distributor, call Gates at 1-800-777-6363 or visit usonline at www.gates.com/safehydraulics.

Safe Hydraulics

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Seminar

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Tips to pre

The World’s Most Trusted Name in Belts, Hose and Hydraulics.

Gates CorporationP.O. Box 5887

Denver, CO 80217-5887

www.gates.com

39595-P 04/05