Over the years more and more trucks are fitted with a sealed driveline which is lubed for its lifetime, but there are still some misconceptions about living with Permalube. Meritor explains just how simple looking after a Permalube™ driveline can be.
During the manufacturing process, Meritor permanently lubricates and seals each universal joint on RPL Series Permalube drivelines. The driveline elements are sealed units loaded with enough grease to last for the lifetime of the component.
There are several advantages to the use of these components. The extended U-joint and E-coated steel guard protects against contaminants and damage and the four-bolt design makes for easy installation and servicing.
The secure flange connections can handle the high torques associated with heavy duty applications. The centre bearing is self-aligning and the triple lip seals are excellent protection against contaminants getting into the unit, helping to ensure extended U-joint life. The nylon thrust washers used eliminate metal-to-metal contact to prevent wear and extend U-joint life.
Once fitted, no more lubrication is required, however, periodic inspection is still necessary but it’s a lot less frequent. Before the development of these sealed units, someone would have to get under the truck every few weeks in order to grease the driveline and check everything was OK.
With a permanently lubricated driveline not only are operators saving on the time involved in maintenance, but also saving on the grease itself and helping the environment.
Sufficient Grease
Meritor fills each universal joint with sufficient grease during the assembly process to last the life of the driveline. However it is also normal during vehicle operation that some of this grease may purge out at one or more of the universal joint seals.
While lubrication is not necessary it is still vital to make regular inspections of the driveline to detect abnormal wear or other issues. Loose bolts, missing balance weights, damaged tubing or excessive slip spline wear can all result in imbalance or vibration which can then cause excessive wear. A failed driveline can separate from the vehicle causing serious damage to people or property.
The first inspection of one of the RPL Permalube sealed units needs to be at no more than 3,200km. At this point it is necessary to ensure bolts are correctly torqued. The Universal joint-to-end yoke bolts need to torqued to 115-135 lb-ft (155-183 Nm) and the flange-to-flange bolts to 133-163 lb-ft (180-220 Nm).
After this, it is recommended to inspect an RPL Series driveline every 40,000 km. At that time, it is important to inspect the universal joints. At the inspection it is also important to check for excessive looseness across the ends of the universal joint bearing cup assemblies and trunnions. Technicians also need to inspect the slip yoke spline seal for grease leakage or seal damage. It is also necessary to check for missing balance weights, damaged tubing, or a missing welch plug at the slip yoke.
If during one of these inspections some grease appears to have come out of the assembly, there is nothing to worry about. Under 6 months of service or 80,000km, it is common for some grease to purge out. This is a normal occurrence and DOES NOT indicate that you must replace the universal joint. Eventually the grease will stop purging, and the universal joint seals may have a ‘crusted’ look. The ‘crusted’ appearance is normal and part of the assembly’s life.
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