Mavel Kaplan BULB Turbine
Technical Specification
1.4 Turbine Runner
The turbine runner is the driving element of the turbine, consisting on the runner hub, runner blades,
and regulation mechanism. The runner hub is assembled to the bevel gearbox shaft and holds the four
runner blades with self-lubricated bearings, and the inner regulation mechanism. This mechanism is
composed of a crosshead and lever sets. The linear displacement of the regulating crosshead produces a
rotation of the runner blades. The longitudinal displacement is transmitted to the crosshead by a
straight solid rod, placed along the longitudinal bore of the gearbox shaft. The hydraulic servomotor for
operating the runner blades is located at the end of the gearbox shaft in the turbine bulb and is
accessible through the pillar from the bottom of turbine body without need for de-watering the unit.
The runner blades are sealed both for loss of oil and from water contamination. The runner hub is
covered by a steel cone.
1.5 Runner Chamber
The runner chamber is a cast steel construction. The inner surface of this chamber is spherical and
designed to minimize the distance between the outer extreme of the runner blades and the inner
surface of the chamber. The runner chamber is horizontally split into two parts. The upstream side of
the chamber will be bolted to the distributor, and the downstream side to the steel draft tube cone.
1.6 Guide Bearing
The guide bearing is part of the bevel gearbox and is a roller, oil lubricated bearing.
1.7 Shaft Seal
The shaft seal frictional rings are made of ceramic material with high hardness and high resistance
against wearing. The shaft seal maintenance requires regular cleaning, approximately once a year,
during the regular annual equipment inspection.
1.8 Turbine Draft Tube
The draft tube leads water out of the turbine. The first section is a steel cone bolted to the runner
chamber and is embedded in the concrete. This part of draft tube is assembled to the runner chamber
with an adjustable flange. The second part of draft tube is a transition from the draft tube cone exit
(circle) to rectangular section and the third part of draft tube is a straight diffuser. Mavel will provide
the hydraulic profile of sections two and three of the draft tube.
1.9 Gearbox
The gearbox is placed inside of the turbine bulb. It is composed of a steel casing, bevel gears, bearings
and minor parts. Both the input and the output shafts are placed on anti-friction bearings. The housing
of the gearbox will be steel plate made. Gears will be made out of high quality steel, and the teeth will
be case-hardened. The shafts will be made of high quality steel.
March 2019 ~ KA_Rev04-
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