Chassis, drivetrain and suspension manufacturers remind fleets that following basic rules when servicing components helps keep trucks on the road and out of service bays
Most fleets work closely and successfully with their component suppliers. These suppliers offer excellent training opportunities to help fleet technicians learn basic maintenance procedures. In addition, suppliers offer copious, detailed documents covering every aspect of maintenance and repair on their products. So, that said, please be aware that the comments below are just a snapshot of the kind of maintenance insights and support offered by key suppliers. More detailed information can be accessed at the websites listed at the end of this article.
Suppliers concur
ArvinMeritor Inc. advises fleets to follow a regular preventive maintenance program. This planning not only saves money while operating a vehicle, but also it can pay off when it comes time to trade in or sell that vehicle. Remember, simple visual inspections may prevent costly, time-consuming repairs. Too often, a minor repair can turn into a major overhaul, complete with lengthy downtime.
Fleet operations that don’t have a formal preventive maintenance may consider those offered by maintenance associations –– such as the Technology & Maintenance Council (TMC) of the American Trucking Associations –– that offer members guidelines on maintenance practices. OEM dealers and aftermarket component suppliers also offer technical literature, such as maintenance manuals and technical service bulletins.
The Roadranger organization, which represents Eaton and Dana Corp., agrees and points out that it offers a wealth of information on the basics of troubleshooting and maintaining key drivetrain components. While the information can be easily accessed at its website, experts from the group offer the following basics to ensure consistent, reliable performance across the entire drivetrain of any heavy-duty vehicle.
A starting point
The cornerstone of a good preventive maintenance program is complete, accurate maintenance records on every vehicle. Records are essential, because they provide a quick indication of how axles and other components are holding up, as well as show that the truck owner precisely followed the manufacturer’s maintenance instructions.
The Vehicle Maintenance Recording Standards (VMRS) system, set up by the TMC of the American Trucking Associations, is an excellent and effective method of keeping these records. VMRS provides guidelines and an outline for creating a maintenance program.
Axles
These records need to include information on regularly performed inspections that conform to the manufacturer’s instructions. This is particularly true for axle lubrication specifications that, if not followed, can adversely affect axle life and, in some cases, void the warranty. Lubricants help carry dirt away from moving parts and cool the axle carrier.
In general, truck operators should:
• Use the lube specified by the OEM and axle manufacturer
• Use the proper amount of lubrication
• Follow the lubrication-change interval or schedule for the axle
• Replace the oil filter, if a pump version, when the lubricant in the axle is drained and replaced
Spec’ing an oil or lubrication pump, where available, provides additional protection, particularly against spinouts. The combination of a pump and filter can further increase lubricant efficiency in a vehicle’s operation. ArvinMeritor also recommends regularly performing a visual inspection of the rear axle for signs of oil leaks. Tires should be balanced, tire diameters matched and tire pressure maintained.
Bob Crepas, product specialist for the commercial vehicle systems group of Dana Corp., says, “In the past 10 years, heavy axle lubrication manufacturers have made steady improvements to their additive packages to extend lube change intervals from 100,000 to as much as 500,000 miles. One of the negatives to these higher intervals is some truck owners are putting less emphasis on preventative maintenance. Inspecting the drive axle for leaks and proper lube levels is on the decrease and failures caused by low lube levels are on the rise. Needless to say, proper lube level becomes even more important when the lube is not changed for such an extended length of time. The lower the lube level the more heat created; more heat means the lube is more susceptible to thermal breakdown. Thermal break down equals premature wear.”
Another consideration when using lubricants with extended change intervals is “water ingestion.” Water can enter a drive axle in two ways: by submerging the axle in water (below wheel seals) and condensation that can build up inside the housing. Vehicles running in winter months in regions that see sub-zero temperatures will create condensation due to the heating and cooling of the axles during normal operation. Less than 1% water in the lube will cause premature wear to bearings and gearing.
“Dana recommends that a visual inspection of lube levels and weeps/leaks be performed every 25,000 miles. Lube levels must be at the bottom of the fill hole located in the rear cover of the housing. Vehicles running in northern regions that are susceptible to water ingestion (condensation) should be performing a ‘crackle test’ to identify water in the lube at least once a year.”
For front axles and wheels, ArvinMeritor says regular inspections are important for minimizing potential problems later on. To inspect a vehicle’s wheel-ends and tie rods, you must raise the vehicle off the ground. Carefully check all steering, suspension and frame components, as well as all axles. The following areas should be examined:
1) Linkage – Examine the tie rods and ends for damage, tightness, wear and adequate lubrication. Next, check the steering arms for damage, wear and connecting nut torque. Also look for damage, play, wear and adequate lube in the draglink. Finally, check the Pitman arm for connecting-nut torque and timing position.
2) Steering sector – Check for play at the steering wheel that is outside of the manufacturer’s recommendations. Adjust the bearing preload, if necessary. Also check the steering gear for box-to-frame mounting bolt torque.
3) Steering shaft – Make sure the steering driveline, universal joint and steering linkage are adequately lubricated. Check for damage and wear in the moving parts and also check the driveline timing mark alignment.
4) Steering knuckle – Check for worn or damaged kingpin seals, bushings and bearings, and lube parts that need it.
5) Steer angle – Adjust the steer angle if necessary.
Remember, the key to an axle’s lifespan is about much more than which materials and techniques were used to create it –– no matter how advanced they are. It is also about how the components are spec’d and how well they are maintained. The future may be increasingly high-tech, but the basic fundamentals of the past still apply.
Clutches
According to Vince Fuleki, senior representative, customer support for Eaton’s clutch division, the two most often asked questions from technician training sessions are: “What’s the proper clutch adjustment?” and “What are the correct lubrication techniques?”
For the first question, the technician needs to ask, “Where’s the bearing?” Adds Fuleki, “Do not do anything to the clutch before measuring. After you measure, you need to correct the release bearing position, adjust the linkage to achieve clutch brake squeeze and then check the free pedal distance.”
The answer to the lubrication question is: “When greasing the release bearing, apply ample grease until it’s visibly ‘purging’ from the bearing. This will lube the internal bushing in the release sleeve, as well as ensure that the release bearing has adequate fill during servicing of the clutch. Eaton also recommends the use of high-performance lithium-complex grease for the clutch release bearing.
“Properly lubricating the bearing and bushing will help provide normal clutch service life. Bearing and sleeve failures due to improper lubrication cause at least a day of downtime. Pulling a transmission and clutch is typically an eight-hour procedure.
“Service technicians can download Fuller clutch service manuals containing complete details for servicing all Eaton clutch styles at www.roadranger.com,” Fuleki said.
Getting down to basics, the technician trainers at ArvinMeritor advise fleet technicians to inspect the clutch when any of the following occur:
1. As required by the maintenance schedule of the vehicle manufacturer.
2. When any part of the clutch system is serviced.
3. When the clutch pedal free travel is less than 1/2-in. (13mm) or more than 1-1/2-in. (38 mm).
The company goes on to advise fleets to follow four procedures when troubleshooting a clutch:
1. Check to see if the engine is working properly.
2. Check to see if the engine mounts are in good condition.
3. Check to see if the driveline angles of the engine, transmission, driveshaft and rear axle are correct.
4. Make sure the inspection cover is installed on the clutch housing.
Driveshafts/drivelines
Jim Holman, chief engineer for commercial driveshaft products for Dana, says, “All driveshafts, including service-free designs, should be inspected at every vehicle service interval. Each shaft should be visually inspected for U-joint bearing cup rotation in the yokes, U-joint looseness and end-play, dents or gouges in the tube, missing or damaged dust caps and slip seals, or torn boots. The rubber cushion in the carrier bearings should also be inspected for signs of contact with slingers caused by improper shaft length or misalignment of the carrier bearing bracket. Detailed specifications for wear and inspection procedures can be found in the manufacturer’s service manual.
“Following the visual inspection, serviceable driveshaft designs should be completely re-lubricated using high-quality grease that meets the manufacturer’s specifications. Dana recommends Chevron Ultra Duty II or a compatible grease meeting NLGI Grade 2 specifications with an operating temperature rage of –10 to +325 degrees F. When it comes to re-lubricating universal joints, we cannot stress enough the importance of fully purging all four bearings. Grease should be applied to the universal joint until fresh grease purges from all four bearing seals. Each universal joint needs all four bearing assemblies to function properly to move the load down the road, and failing to purge one or more bearing assemblies is equivalent to leaving the grease gun on the shelf. Detailed lubrication procedures can be found at roadranger.com.“
When checking the driveline, ArvinMeritor suggests the following tips for maintaining the system:
1. Check for excess tolerances before lubing application. Lube may mask, or hide excessive play and tolerances.
2. U-joint maximum end play is .006 in.; more than that will result in failure.
3. Slip movement, up and down, maximum allowance is .017 in.; more that will result in failure.
4. Dents, missing weights, dirt and foreign material buildup on the shaft can cause vibration and balance issues, resulting in failure that can also cause damage to transmission and axle.
5. Center bearings: new self-aligning style has gold colored collar, without deflectors. The self-align style became available in 2002 and will allow +/- 5° angle of deflection.
6. Driveshaft standard slip application has splines that face the power source and end yoke.
7. Driveshaft outboard slip assembly has splines that face toward rear of application.
8. Phasing: mark slip position with paint stripe during disassembly to make sure you reassemble in same position and phasing to avoid timing and vibration issues.
9. Lubrication basic procedures: U-joints: make sure that grease purges at all four seals to ensure that old grease does not contaminate new grease; check for potential chemical incompatibility. Slip splines: 6 to 8 pumps from the grease gun is acceptable.
10. ArvinMeritor maintenance manual MM-96147: has additional information regarding torque specifications and troubleshooting information.
Transmissions
Brian Davis, product service manager, automated products for Eaton Corp., says, “Transmission maintenance can many times be one of the most overlooked items, as it is not the easiest drivetrain component to view during a pre-trip inspection. Yet, obvious problems can be identified with just a glance under the truck. Oil leaks, if ignored long enough will result in catastrophic damage. Leaking PTO gaskets, damaged/loose oil lines, and oil seals are the most common sources of oil leaks. Always check fluid levels and follow the recommended oil change intervals. For optimum performance and more time on the road, always use Roadranger Synthetic Lubricants.
Davis says, “The Eaton AutoShift and UltraShift transmissions are advanced shift-by-wire systems consisting of a Fuller medium- or heavy-duty transmission that communicates with the electronic engine for precise control of the transmission functions. Maintenance of the vehicle’s electrical system will help ensure trouble-free operation of the automated transmissions. Poor battery/chassis grounds, bad batteries, and corroded connectors will all affect performance of the transmission. Lubrication maintenance for automated models follows that of the mechanical transmission.”
ArvinMeritor suggests that oil analysis can help determine the oil change frequency. The company recommends that the oil in the transmission must be changed if it has been analyzed and contamination has occurred.
In addition, the company suggests that when checking for oil leaks when oil has been noted under the vehicle, first make sure that the substance is not coolant, engine oil or another lubricants. Note that under normal conditions, the area around the oil seal, yoke and rear bearing retainer is moist. This moist condition is not a transmission or oil seal leak. To troubleshoot transmission oil leaks, check for: missing or loose fasteners, high oil level, unspecified oil in the transmission, clogged or dirty breather vent, damaged yoke, damaged output shaft seal, worn or damaged sealing tape on electronic speed sensor.
Where to get more information
ArvinMeritor: www.arvinmeritor.com/tech_library
Dana/Eaton: www.roadranger.com
Hendrickson: www.hendrickson-itl.com
SAF-Holland: www.safholland.com
Checking suspension bushing torque
According to SAF-Holland, manufacturers of Neway brand truck and bus suspensions, when dealing with premature bushing wear the culprit is typically a loose connection. The metal core of the bushing will begin to wear first, which will quickly lead to the rubber of the bushing breaking down.
Although many things contribute to deterioration of the bushing’s metal core, improper installation or lack of maintenance is a major cause of bushing connection failures. If proper torque is not maintained on the connection the bushing assembly will fail prematurely.
SAF-Holland recommends that all suspension bushing connections be visually inspected at the initial vehicle pre-operation set-up. New equipment should be inspected after a run-in period of approximately 5,000 miles. If a vehicle pre-op wasn’t performed, an early run-in inspection at 5,000 miles will minimize or eliminate downstream maintenance cost.
After the initial run-in period, inspection intervals are typically scheduled based on the application and in some instances can be scheduled relative to brake wear. For example, an over-the-road highway vehicle traveling from one coast to the other will require infrequent braking as compared to an inner city delivery truck. As a result, undercarriage components such as brake linings and suspension wear components will manage well with extended service intervals. Suspension systems operating in daily heavy vocational off-road conditions will require the most frequent inspection intervals due to extreme environmental and loading conditions.
Field service replacements can generate another set of concerns. Bushings are designed for specific loads and conditions. So it is important when replacing worn bushings to specify the proper bushings to maintain the design intent of the suspension. Use of aftermarket urethane bushings in place of manufacturer-specified rubber bushings should always be avoided.
As bushings start to wear, protruding rubber from the connection will be visible. When you press the old bushing out, you usually will find remnants of the old bushing in the metal sleeve of the suspension component. These remnants need to be cleaned out with a wire brush or other cleaning tool before installing the new bushing. The use of petroleum lubricants to reinstall the bushing MUST be avoided at all cost. Petroleum products like grease and oil greatly decreases bushing installation time but the petroleum lubricants will cause the rubber to deteriorate because it will allow the bushing to rotate within the sleeve leading to premature failure. The outer radius surface of the bushing needs to stay static within the sleeve to functionally absorb the radial movement as it is designed to do.
