An average car wash in Germany cleans more than 110,000 cars every year. In terms of
the drive components in the wash bars and heads, the application is equivalent to an
endurance test with water and cleaning agent spray. The bearings in the rotary unions of
the wash heads undergo the same treatment, and in this case, they were not up to the task.
Personnel at the car wash company had to replace the deep groove ball bearings of the
rotary unions several times a year. Therefore, the company contacted NSK to ask for
advice on how to lengthen the service life of the bearings. Analysis of the defective
bearings quickly revealed corrosion and the absence of grease, which had washed off. The
cause: the non-abrasive seals were unable to prevent wash water from penetrating the
bearings, thus rinsing away the grease.
NSK suggested replacing the bearings with Molded-Oil deep groove ball bearings featuring
DU seals on both sides. In this bearing, a carrier material incorporates the lubricant,
releasing it steadily over a long period. As a result, the service life of these bearings (which
are available in ball, spherical roller and tapered roller variants) is more than twice that of
bearings with grease lubrication, particularly in environments exposed to water and dust. In
addition, maintenance intervals are significantly longer because Molded-Oil technology
ensures permanent lubrication. And because the bearing runs grease-free without any need
for replenishment, the operating environment remains clean.
Molded-Oil bearings are available with various seals. For example, the rotary unions at the
car wash use bearings with abrasive DU seals on both sides (DDU), reliably preventing
water and moisture from entering even when this is a constant feature of the operating
environment.
After replacing the bearings, the rotating unions at the car wash ran perfectly. In the first
year alone, the company saved more than €11,900 in maintenance costs. The previous
costs of over €12,000 for bearings and a very low estimate of labour costs are now set
against a one-time investment of €618 for the Molded-Oil deep groove ball bearings.
Recouping this investment took less than three weeks.
