Lubricate and communicate-those two words would appear to be the top two keys to an effective maintenance plan that will help eliminate the vast majority of potential complications along the driveline of a commercial truck.
At least that’s the contention of a group of driveline experts with Roadranger, the marketing organization that supports truck components and systems from Eaton Corporation and Dana Corporation, including transmissions, clutches, drive shaft assemblies, axles, safety systems and related products.
“The benefits of proper lubrication are well documented,” said Bob Langbo, service manager, Roadranger, and director of around 50 Roadranger service specialists throughout North America.
“But as important as lubrication is, it is not a standalone cure-all.” Communication also is vital to properly diagnosing vehicle problems and getting the vehicles back on the road quickly.
The driveline is defined differently, depending on who you ask. Some people define it as the drive shaft and its various components, from the rear of the transmission to the front of the rear axle. Some include the transmission, the axles and the clutch, and others define the engine as part of the driveline.
Regardless of how many definitions exist, one thing is common: All these components must work together for optimum driveline operation.
Roadranger experts defined what they consider the driveline to be, and explained how each component should be treated in order to make the driveline last.
Transmissions
Lon Miller, product service manager, Eaton Corp., said that the use of a high-quality transmission lube will help ensure maximum life expectancy and reliable transmission operation in just about any heavy- or medium-duty application.
“Recently, we introduced a new specification-PS164 REV7-that called for significant performance improvements,” said Miller. “We strongly encourage everyone using our transmissions to stick with one of the qualifying lubricants.”
Next, always be sure to check for and maintain the correct transmission lube level. “You’ll know you have the correct level when a small amount of lube runs out upon removal of the fill plug,” he said.
Transmission fluid also will need to be changed at manufacturer-recommended intervals, Miller added. Make sure that gearboxes equipped with power take-offs (PTO), mounting kits and fastener locks have been supplied by the PTO manufacturer, he said. If they are not, leaks may develop, which would require repairs to be made as quickly as possible.
Clutches
The best way to maximize clutch life is to minimize wear, Miller said. The best way to minimize wear is to maintain optimal adjustment. “Therefore, self-adjusting clutches are your best bet. Short of that, always be sure to adhere to the manufacturer’s specifications,” he said.
For manually adjusting clutches that are used in combination with mechanical linkages, maintain the recommended amount of clutch free pedal and release bearing travel, Miller said.
“We also strongly recommend that manually adjusting clutches not be used in combination with pre-loaded hydraulic linkages, which do not provide clutch free pedal in the cab, eliminating the driver’s best indicator as to when a clutch adjustment is required,” he explained.
Clutches also need lubrication. “Always use an NLGI #2 EP lithium soap grease, and lubricate throw-out bearings and linkage cross shafts as recommended by the maker of the clutch,” Miller said.
While applying grease to the clutch release bearing, the technician visually needs to verify that grease is purged from the bearing housing onto the transmission input shaft. If the clutch bearing lube tube is damaged, the added grease will fall inside the clutch housing and not make it to the bearing.
“Lastly, and to help ensure good lubrication,” Miller explained, “always manually apply extra lube to the transmission side of the clutch brake, transmission input shaft between the brake and bearing and the area of contact between the release fork and release bearing housing.”
Drive Shafts
These workhorse assemblies just might have the toughest assignment on a truck-up and down, back and forth, start and stop-the drive shaft has quite a bit on its plate. Yet, Jim Holman, engineering manager for heavy-duty applications, Dana Corp., said that today’s drive shafts are more than up for the task.
He said that premium drive shaft assemblies with extended-service intervals are widely available for commercial vehicles, however, when servicing is required, that usually means lubrication.
“Lube intervals vary by application, but all drive shafts need properly greased U-joints and slip members,” Holman said. “One longstanding key to success is to completely purge all four bearing assemblies at each U-joint which should maximize life.
“It is also a good idea to always re-lube the U-joints and slip members after pressure washing to flush out dirt and moisture that may have entered the seals. This is especially important for drive shafts with extended lube intervals that otherwise may not require service for thousands of miles,” he explained.
Correct ride heights on air-ride-suspension equipped trucks always should be maintained to keep U-joint angles where they need to be, Holman added. Doing so will help minimize complications associated with torsion-related vibration.
Drive Axles
“In linehaul applications, today’s 40,000-lb. tandem axles virtually are maintenance free. Many issues typically are related to the rear suspension,” said Leo Wenstrup, senior product manager, drive axles, Dana Corp.
“To effectively prevent the vast majority of complications, we recommend periodically inspecting the bushings, the height control valve and the fasteners, while paying special attention to the U-bolts,” he said.
“Worn bushings can affect alignment and tire wear. Loose U-bolts can affect alignment, but more importantly, axle housing fatigue life. The height control valve setting needs to be checked and serviced to maintain proper driveline angles,” Wenstrup explained.
“Most tandem axles are optimized for a specific ride height and deviation from this can result in very high drivetrain torsion-related vibrations, which can damage axles, drivelines and transmission components.”
Lube levels also need to be monitored closely. “Maintaining the proper level of an approved lube is key to trouble-free axle operation. While extended drain lubes may not require changing for 500,000 miles, it still is critical to check the lube level and condition periodically,” he said.
“The lube level should be maintained at the bottom of the fill hole, and the lube should be free of dirt and metallic particles. Milky discoloration indicates water contamination and that the lube needs to be changed. Axle yoke and wheel seals, as well as fill and drain plugs, should be inspected for leakage,” Wenstrup said.
He then explained the importance of wheel-end adjustment. “While modern low-maintenance wheel-end systems, extended-service brakes and outboard-mounted drums have extended the interval between wheel removals, it still is important to check the condition of the wheel end regularly.”
“Wheel seals need to be checked for leakage that could result in a hot wheel end or soaked brake shoes. When you service wheel ends, be sure to use high quality replacement seals and bearings. Cups and cones should be from the same bearing manufacturer, and the wheel end must be adjusted per OEM standards or Technology & Maintenance Council (TMC) recommended practice,” Wenstrup said.
He added it’s vital that you not ignore the axle’s breather, which is a simple device that often is overlooked. “It must be free and clear to ensure there is no pressure or vacuum buildup in the axle, which can blow out seals or cause ingestion of water.”
Communication
“The best maintenance and servicing practices will get you only so far,” Langbo said. “You need to encourage communication throughout your entire company.”
For example, you and your fleet customers should work closely with OEM and component suppliers to make certain that vehicles are properly specified for the intended application, he said.
“Having the proper drivetrain specs will set up the proper expectations for the vehicle by targeting items such as performance or fuel economy, for example. Proper specs and usage also will help ensure that items such as driveline angles and ride height on the vehicle are correct,” Langbo explained.
A comprehensive and well-documented plan is another important key to make certain that maintenance and servicing chores are performed in a timely, correct manner. “Having the plan well documented not only will help regulate service chores, but also will validate good maintenance practices for component suppliers should product issues arise,” he said.
“Finally, the whole effort needs to include everyone involved with the truck,” Langbo said. “The drivers need to be trained on proper operation as well as what do to when he experiences problems with his vehicle. In turn, the operations people need to get the vehicle in for repair when symptoms exist,” he said.
Then it is the technician’s job to repair the vehicle properly and efficiently.
Langbo said that the best place for a commercial vehicle is on the road where it’s making money, “and the best way to keep it there is to communicate and lubricate.”
Editor’s Note: Truck Parts & Service would like to thank Eaton/Dana/Roadranger for the information provided in this article.
