There are five components to a turbine;
the Spindle, Chuck, Impeller, Bearings (two), and
O-Rings (two).
The spindle is a stainless steel
shaft on which the other components are mounted. It
requires no maintenance but can be damaged if the
handpiece is dropped with a bur installed. The result
can be a bent spindle.
The chuck is located inside the
spindle and it holds the bur. There are two types of
chucks; the manual and the automatic chuck. A manual
chuck, which requires a bur-wrench, should be taken out
periodically and cleaned. It is easily replaced when
needed. In some cases the back cap or turbine must be
removed to perform this replacement. Most automatic
chucks are not designed for removal and cleaning as they
are one-piece assemblies and provide no access for this
type of maintenance.
The impeller is the paddle-wheel
shaped part that is driven by air. It is usually made of
aluminum or brass. It is the “motor” of the turbine. The
impeller requires no routine maintenance, but corrosion
and residue build-up from poor quality lubricants can
cause vibration and loss of torque. This vibration will
cause premature failure of the bearings.
The two bearings are attached to
the spindle allowing it to spin freely. Bearing failures
are the most common failure. The bearing assemblies
consist of three components; the race, stainless steel
or ceramic balls, and the cage. The race is the inner
and outer track on which the balls travel. They are made
of stainless steel and are not usually the cause of a
failure or breakdown. The balls function like wheels to
allow the bearings to roll effortlessly. Even after
extensive use the balls usually only have minor surface
scratches indicating the balls are rarely the cause of a
turbine failure. The cage is a plastic retainer that
holds the balls in their proper alignment and is the
most fragile part of the bearing assembly.
The two O-rings surround the
bearings and act as shock absorbers. This allows for
some vibration and lateral flex when the bur is cutting.
