FIELD OF INVENTION
The present invention relates to an improved system of servomotor mounting
and guide apparatus locking for a large Kaplan turbine. More particularly, the
invention relates to a novel method of locking guide apparatus so that design of
guide vane servomotor becomes simple and hence easy to procure from the
market.
BACKGROUND AND PRIOR ART OF THE INVENTION
In a typical large Kaplan turbine the guide apparatus (viz.- water regulating
mechanism) is operated by two large custom built servomotors which are
mounted in a large Cabin type pocket of the pit liner. The servomotor cylinders
are rigidly fixed to a foundation plate. For locking the guide apparatus in the
closed position and open position for maintenance purpose the movement of the
piston rod of servomotor is locked by suitable means. Thus the servomotor
becomes highly custom built.
In the prior art, guide apparatus of a Kaplan turbine was operated by two large
servomotors mounted in the pit liner. Large pockets were provided for mounting
the two servomotors.

In earlier design of large size Kaplan turbines, servomotors are mounted in large
pits which hamper in convenient load transfer of generator and superstructure
loads to the foundation. Due to large servo pit, the height and weight of the
regulating ring on the guide apparatus increases to suit the servomotor centre
line.
Additionally for locking the servomotors in open and closed positions for
maintenance purposes, custom built servomotors are manufactured which are
costly and needs larger cycle time to manufacture.
OBJECTS OF THE INVENTION
Therefore it is an object of the invention to propose an improved system of
servomotor mounting and guide apparatus locking for a large Kaplan turbine
which makes servomotor mounting to occupy minimum possible space.
Another object of the invention is to propose an improved system of servomotor
mounting and guide apparatus locking for a large Kaplan turbine which makes
servomotor design simple for easy availability in the market.
Yet another object of the invention is to propose an improved system of
servomotor mounting and guide apparatus locking for a large Kaplan turbine

which facilitates easy load transfer of generator and superstructure load to
foundation.
A further object of the invention is to propose an improved system of servomotor
mounting and guide apparatus locking for a large Kaplan turbine which reduces
the cost as well as procurement cycle time.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWINGS
Fig-01:- Elevation view of servomotor mounting according to prior art.
Fig-02:- Plan of servomotor mounting and locking of guide apparatus according
to prior art.
Fig-03:- Elevation and plan of guide vane servomotor mounting according to
prior art.
Fig-04:- Details of custom built servomotor according to prior art.
Fig-05:- Plan of G.V. Servomotor according to prior art.
Fig-06:- Elevation view of turbine with novel mounting and locking arrangement
in accordance with the invention.
Fig-07:- Plan view of turbine with novel mounting and locking arrangement in
accordance with the invention.
Fig-08:- Enlarge view of locking arrangement-Elevation View in accordance with
the invention.

Fig-09:- Enlarge view of locking arrangement-Plan View in accordance with the
invention.
Fig-10:- Enlarged view of detailed locking arrangement.
DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE
INVENTION
In the present invention, servo motor design is simplified. Its procurement cycle
time as well as the cost is reduced. This invention relates to a novel arrangement
of locking guide apparatus so that the design of guide vane servo motor
becomes simple. Also with this new design, load transfer of generator and
superstructure to the foundation becomes easier. Here the locking arrangement
is transferred from servomotor to the regulating ring and top cover so that
servomotor design becomes simple,
As in the prior art shown in fig-2 the locks for open and closed positions consist
of arrangements which prevent the piston rod from coming out of the servo-
motors (13&14).
This makes the servomotors bulky and custom built. Also accommodating these
servomotors in limited space hampers the convenient load transfer of generator
as well as the superstructure load.

The present invention has eliminated these disadvantages of prior art. As shown
in fig. 7, four servomotors (9, 10, 11, 12) are used instead of two servomotors
used in earlier design so that servomotor size reduces for easy availability in the
market. These servomotors (9, 10, 11, 12) are mounted on stay ring (16).
With clevis mounting arrangement (15) as shown in fig.6, these servomotors (9,
10, 11, 12) are connected to the regulating ring (3) through piston rod (17) as
shown in fig.7 and 8. The enlarge view of locking arrangement in fig.8, shows a
lock pin(4) which is held by a bracket(l). The lock pin (4) is adapted to lock the
open and close positions of servomotors. The bracket (1) hold the lock pin (4) in
open and closed positions and preventing rotation of lock pin (4) by guide bars
(18) which bears against machined flat on lock pin. The load of the bracket (1) is
transferred to the inner top cover (2) by dowels (6). Four brackets (1) are
suitably mounted on the inner top cover (2) by stud and nut (7, 8). Guide
cylinder (5) guides the lock pin (4) during locking at open and closed positions
and preventing rotation of lock pin (4) by guide bars (18) which bears against
machined flat on lock pin. As shown in fig.9 two locks (4) each are provided for
locking the servomotors (9, 10, 11, 12) in open and closed positions.

WE CLAIM
1) An improved system of servomotor mounting and guide apparatus locking
for a large Kaplan turbine comprising;
- adapting reduced size of servomotors (9, 10, 11, 12);
- mounting the said servomotors on stay ring (16);
- connecting the said servomotors to a regulating ring (3) through piston
rod (17) adapting clevis mounting arrangement(15);
- holding the lock pin (4) by a bracket (1);
- mounting four brackets (1) suitably on inner top cover (2);
- guiding the lock pin(4) by guide cylinder(5) to lock open and closed
position; and
- preventing rotation of lock pin (4) by guide bars (18) which bears against
machined flat on lock pin.
characterized in that the lock pin (4) are adapted to lock the open and close
positions of said servomotors when the load of the bracket (1) is transferred
to the inner top cover (2) by dowels (6) and two locks (4) each are provided
to lock the servomotors (9, 10, 11, 12) at open and closed positions.
2. An improved method as claimed in claim 1, wherein each of the bracket
(1) is fixed to the inner top cover(2) by stud and nut (7,8).

3. An improved method as claimed in claim 1, wherein four servomotors (9,
10, 11, 12) of reduced size are provided to occupy minimum possible space.

An improved system of servomotor mounting and guide apparatus locking for a large Kaplan turbine consists of four reduced size servomotors (9, 10, 11, 12) and mounting them on a stay ring (16) when the said servomotors are
connected to a regulating ring (3) through piston rod (17) adapting clevis mounting arrangement (15). Four brackets (1) each holding a lock pin (4) is mounted suitably on inner top cover (2). The lock pins (4) are guided by the
guide cylinder (5) to lock at open and closed position of servomotors when the load of the bracket (1) is transferred to the inner top cover (2) by dowels (6) and rotation of lock pin (4) are prevented by guide bars (18) which bears against machined flat on lock pin. Two locks each are provided to lock the servomotors
(9, 10, 11, 12) at open and closed positions. The brackets (1) are fixed to inner top cover (2) by studs and nuts (7, 8) with dowels (6)0.