The last thing that should ever happen to your plant machinery or truck is that it fails through lack of maintenance. Both plant and commercial vehicles have statutory regulations in place for maintenance. For machinery, it’s the Provision and Use of Work Equipment Regulations 1998 (PUWER).
This requires that machinery be ‘maintained in an efficient state, in efficient order and in good repair’. The type of maintenance needed is determined by a risk assessment that considers the manufacturer’s recommendations, amount of use and operating environment, and the experience of the person using it. Where logging the work carried out is required, the document must be kept up to date.
Delegating responsibility
Like trucks, plant machinery has become more sophisticated, so more plant operators are being offered third-party maintenance solutions.
“As excavators become more complex, with greater use of electrics and telematics to monitor how often it’s working and what it’s doing, more companies seek service-on-demand and pre-planned service contracts to maintain equipment,” says James Dodkins, group marketing director of Molson Group, a supplier of Korean- and Japanese-built excavators that employs a fleet of mobile maintenance engineers.
For commercial vehicles, service requirements can be codified in contract. For example, a requirement for tipper operators registering for membership of FORS (Fleet Operator Recognition Scheme) is that the procedure for maintenance of the vehicle, bodywork and ancillary equipment is clearly defined. But where hydraulic equipment is more of a secondary tool, such as a crane mounted on the back of a truck, where exactly theresponsibility lies for maintenance may be more uncertain.
Speaking at the Tip-Ex show in June, Pete Vann, managing director of hydraulic component supplier Binotto (UK), observed: “Today, a lot of operators do not want to get their hands dirty and leave it to a garage, but often they just don’t know if it’s been properly maintained.”
Problems can start even before the customer takes delivery of a vehicle. He pointed to a display vehicle at the show fitted with Binotto front-end lifting gear. A grease point is missing on the cylinder’s lifting bracket. “We send details of how to maintain the equipment when we supply it to the bodybuilder. But what happens to it after that, I don’t know,” he said.
These kinds of misunderstandings are all too common. Also at the show, Carl Hinds, director at tipper bodybuilder Harsh, pointed to a place on a new vehicle where a sticker with the location of an obscure grease point had been painted over. He added: “We had one example of a rear hinge bracket that actually seized; it hadn’t been greased in five years. The answer to that is automatic lubrication, but it’s £2,000, so often customers won’t fit it,” he says.
Inspection and service guidance
For customers who do wish to get their hands dirty, advice is not hard to come by (see also p16 for a checklist for some types of equipment). Peter Smith, sales and marketing director at hydraulic cylinder manufacturer Edbro, argues that while checking components and equipment can be relatively easy, technicians need to know what to look for.
He says: “Around the base of the cylinder is a cavity that requires about a litre of grease. Sometimes a small amount of water makes its way into the cylinder through the cushion ring above, making it bubble and corrode.” He also advises that the air filter be kept clean, so air can get into the tank when in use. If blocked, it can create a vacuum and implode.
The cylinders themselves should be inspected for pitting, corrosion and uneven wear, according to UK hydraulics system supplier Hydraproducts. The first two types of damage could be caused by too much moisture in the fluid, and can damage seals. Uneven wear is often caused by misalignment in the system, and if left uncorrected could damage seals, bearings and the cylinder.
And oil too. “No matter the size or complexity, proper maintenance of both the system and the hydraulic oil is crucial in maximising uptime and reducing repair costs,” contends oil supplier Mobil. It argues that operators should look to achieve four system performance goals to safeguard oil. First, control temperature: overheating burns the oil and could lead to varnish and sludge deposits; while over-cooling could increase moisture content through tank condensation. Second, keep structures clean to prevent contaminants from entering. Third, keep the fluid clean by frequently inspecting fuel filters (pictured). Fourth, implement an oil analysis programme to increase service frequency beyond the recommended annual replacement interval. (For more of its guidance, including a 10-point inspection, see https://is.gd/qanove).
For hydraulics supplier Parker, failure preventions is more about awareness of the risk of contamination than excluding every single speck of dirt.
It says: “The first line of defence in reducing failure of a hydraulic system is to incorporate contamination measurement and control protocols. This is not to suggest that your facility has to be a clean room; the goal is to recognize the sources of contamination and ways to reduce them.”
Despite a measure of realism about contamination, it advocates a hard line on operators’ tolerance of leaks. “Remember, any place that hydraulic fluid can get out, potential contaminants can get in, including particulate and catalytic contaminants that can have a significant impact on the life of a hydraulic system.”
Parker’s list of regular hydraulic system checks is available on https://is.gd/epahax; its free 40-page guide to hydraulic filtering is available on https://is.gd/xocajo.
Turning to one large-scale construction application, tipping trucks, the key areas to check include in-cab controls, air and oil pipes, electrical cables, PTO (power take-off), hydraulic pump, tipper valve, oil tank, oil filter cap, ram nut, ram tube, cover tube and plastic cap, cylinder lifting bracket, cradle bracket (including tank trunnion arm), body hinge bracket and hinge bar, cover sheet and tailgate. It’s also important to ensure that all grease points are fitted.
The most common trait neglected on tipper cylinders is dry joints where grease points have been underused, so checking the hinge in the lifting bracket and the rear hinge is important.
“Hydraulic pumps have seals fitted that separate the hydraulic oil from the gearbox oil. If those seals fail for any reason, hydraulic oil can then flood the gearbox, causing a nasty shock; gearboxes don’t like hydraulic oil. Pumps generally have a tell-tale hole that will drip oil should the seals fail in any way, so that’s another important regular visual check to do,” Smith concludes.”
This article is based on ‘Getting your hands dirty’, Transport EngineerJuly 2018,
Maintenance Guidelines
Typically, a regular inspection of the operational equipment should take place every four to six weeks, with drivers of the carrier vehicle undertaking a daily walk-around vehicle check. Below are suggestions, but OEM instructions should take precedence over these.
TIPPERS
Daily
● The driver’s pre-shift vehicle inspection should include a visual check of the components with an eye on oil leaks and assessing the tank’s oil level, and extent of air leaks and damage. Report if the cylinder’s outer cover is loose, any ram tube is damaged, base ram nut is loose, or if there are signs that the pins are worn in ram trunnion arms or rear hinge brackets
Weekly
● Spend 30 minutes repeating the daily visual check armed with replacement grease points and a grease gun, in case anything is damaged or dry. Confirm that pipes are not kinked, damaged, or rubbing against metal; check they are safely stowed
● Top up hydraulic oil to mesh level, if needed
● Any new PTO/pump mounting bolts should be checked before reaching 1,000 miles
Monthly
● Lubricate all the grease points around the vehicle, including the hinges on the tailgate and locking mechanism, and check the stabiliser frame and tipper hinge bar
● Inspect all hoses and connectors for oil leaks and chafing. Replace any damaged or worn
● Go around each bolt and cover stud and check tightness. Replace damaged or worn parts with like-for-like bolts, or ones of higher quality
● Examine connections on hydraulic pipes and air pipes for leak-tightness
● Clean the air filter on the oil tank
● Check PTO/pump for oil leaks. Also check ram tubes, the tipper valve and ensure gland nuts are tight (visible threads could indicate loosening)
Quarterly
● Use spanners on the PTO, hydraulic pump, tipper valve and brackets to ensure bolts are tight
Annually
● Drain the hydraulic oil and replace it
● Check older cylinders for corrosion on the outer cover tube, especially behind the trunnion ring
● Check pin wear in trunnion arms; if more than 5% of the diameter, the pin needs replacing
TRUCK-MOUNTED CRANES
Daily
● Confirm level of hydraulic oil
● Examine structural fasteners (bolts and/or welding)
● Check hoses and attachments for fitting potential oil leaks
● Examine safety equipment and stowage
Weekly
● Grease pivot points
Monthly
● Verify pressures in the hydraulic system, and integrity of the seals
● Confirm integrity and tightening of tie rods and bolts, hoses, piping and fittings
● Examine fastenings and safety devices, visibility of symbols on remote control, and identification and warning plates are still applied and readable
● Check integrity of hooks, ropes, chain and all the other lifting ancillary equipment
● Inspect structural components for any deformation or cracks
● Measure lean oil levels, including winch-gear and filters
● Check the slewing system and its grease, and replace the grease brush spreader if worn
● Make a working test of the crane, with and without the load, paying attention to possible unusual noises coming from the crane parts
● Grease the hydraulic boom sections
● Examine turntable rotation and bearings, hydraulic motor and pump
● Inspect hydraulic winch, electric motor and brake
● Measure winch-gear oil
● Inspect lift cylinders in boom, extend cylinders, wear pads, sheave
Annually
● Check welding, wire rope and retainer, tower and lift pins, pin for locking mechanism on fly-jib, bucket or lift
EXCAVATORS
Working life is measured in hours. All checks, services and maintenance programmes are set out against the amount of time a machine is used.
Every 10 hours
● Measure engine oil, hydraulic fluid, fuel tank and coolant
● Examine fuel/water separator and pre-fuel filter; check filters; consider replacing
● Check and clean ‘pre-cleaner’ for fuel and air intake systems
Every 50 hours
● Grease pivot points and bearings on boom swing bucket and blade pivot points, front axle pivot points and swing bearing
● Check fuel tank and filter; drain water and sediment
Every 250 hours
● Grease boom, swing cylinder and arm pivot points
Every 500 hours
● Grease front axle steering knuckle and propeller shaft
● Replace engine oil and filter, fuel filter, filters on pilot, air cleaner, air-conditioning
● Clean radiator, oil cooler, intercooler, air-conditioning sensor
Every 1,000 hours
● Lubricate swing gear
● Replace transmission oil and housing oil
● Clean the hydraulic suction filter; replace if needed
● Replace the hydraulic return filter
● Replace filters on air cleaner, fuel cap and air conditioning unit
2,000 hours
● Full service of engine
● Replace the inner and outer filters; replace coolant and hydraulic oil