| Guest Editorial |
By G. Allan Hagelthorn, P.E., President, Rather Engineering, P.C.
Some actions can be anticipated
From personal observations while working in For safety, it is my recommendation that • Preload adjustment of tapered roller bear-
the engineering world, I have found that it is not attempts to adjust tapered roller bearings ings will provide improved performance.
unusual for engineers to explain complex technical with preload not be made unless the manu- • Maintenance can be simpliﬁed with
requirements in ways that are not easily understood. facturer involved issues speciﬁc instructions improved practices.
Service technicians have often developed their for that purpose. With the results of this survey in mind, the
expertise logically without adequate instructions • At the present time, the Recommended following actions can be anticipated:
from the engineers, and this has led to difﬁculties. Practices (RPs) published by the Technology • Manufacturers of axle nut systems will
Problems can occur if engineers fail to realize and Maintenance Council (TMC) do not develop and publish simple installation
that deviations of maintenance procedures might describe how “controlled preload” can be instructions to include identiﬁcation of “an
occur in a manner they did not anticipate. installed by service technicians. Rather, the acceptable range of preload adjustment”
It remains for all engineers to be constantly RPs state that the component manufactur- and the description of how the process
aware that the instructions they develop might ers of axles, bearings, oil seals and axle nuts should be accomplished.
either be improperly presented or misunderstood. should be requested to provide appropriate • Personnel involved in maintenance of
It is also a primary responsibility for all engi- instructions. wheel-end assemblies will be advised
neers to monitor product deﬁciencies and to • There has not been any deﬁnitive infor- of when and how often periodic wheel-
provide worthy assistance to maintenance provid- mation published to inform those involved end inspections should be performed.
ers whenever necessary. in commercial vehicle maintenance how (This recommendation was offered by the
None of us are perfect and mistakes will some- wheel-ends should be inspected. Nor have National Transportation Safety Board in a
times happen. So, when unforeseen problems do those who are responsible for preventa- 1995 special investigation report, Medium/
occur, it is necessary that everyone communicate tive maintenance been instructed on how Heavy Truck Wheel Separations.)
effectively to resolve the issue. often the wheel-end components should be • This year, there will be action on the part
Having designed wheel-end systems for high- disassembled and visibly inspected. of some trailer component manufacturers
way trailers, and being exposed to numerous wheel to introduce improved versions of precisely
separation accidents over the past 25 years, I am adjustable wheel-end fasteners.
aware that it is a very complex situation. • There will be efforts by some component
Because there are some obvious problems that Newly manufacturers to provide the improved
remain unattended, I feel compelled to make maintenance instructions needed by
recommendations to reduce the frequency of developed mechanics involved in trailer maintenance
problems associated with inappropriate adjust- to accurately install a minimum of end play
ment of tapered roller bearings. concepts and within the wheel-end assemblies.
Within the engineering community dealing with