Technical Bulletin
Page 3 of 8
The procedure below describes how to adjust
the minimum and maximum mechanical
blade pitch regulating range of the fan
impeller, adjustment of the graduated scale at
the external regulating lever, and adjustment
of the torque switch mounted at the regulating
lever.
Check that the maximum allowable working
pressure has been reduced to an opening
pressure at app. 20-35 bar (290-507 psi). The
pressure reduction is required for mechanical
protection of the mechanical regulating parts
inside the hub when adjusting the mechanical
blade pitch range and the torque switch. See
chapter 3.00 in Fan Manuals “Mounting of Oil
Cabinets”
Warning:
When handling
the blades, it is mandatory
to use Howden's hosting
tool for blades. See Figure 4
and Instruction Manual for
VARIAX
®
Blade Lifting Tool
in Fan Manual.
Close the ball valve placed in the pressure
line. Adjust the pressure relief valves at the
control oil pumps in the oil cabinet
downwards to the minimum pressure working
pressure, 20 bar (290 psi). Open the ball
valve and regulate the hub, if the hub does
not regulate, slow increase the pressure relief
valve setting until the hub moves.
Stop the Hydraulics and observe site safety
regulations for working on energized
equipment and fan blades.
1.
Dismount one blade and mount the
blade adjustment tool onto the blade
pivot in the hub. See Figure 6.
(Note the blade pivot number at the
verification document V213351-9).
2.
Start the control oil unit, for supplying
oil to the hydraulic regulating unit.
3.
Verify the blade angle tool position, it
should be at 55
˚. If adjustment is
required adjust the blade angle to 55°
(mid-pitch) on the blade angle tool by
loosening the set screws on the
internal crank and rotating the internal
crank manually. Exercise caution while
moving the blades.
4.
Stop the control oil unit.
5.
Check that the blade angle is 55°. If
necessary, start the control oil unit and
increase or decrease the blade angle
until 55° is reached when the control
oil unit is stopped.
6.
Adjust the push rod length of the pull
fork when the blades are in the middle
position (55
˚
). The rod length should
be adjusted to position the internal
regulating crank arm exactly in the
vertical position.
Figure 4: Blade Lifting Tool
Figure 6: Blade Angle Measuring Tool
Figure 5: Nipple for Hydraulic Hoses
Figure 7: Regulating Unit
Figure 8: Blade “no touch distance”
