Howden VARIAX B Technical Bulletin

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Technical Bulletin:
Calibration of the Regulating Unit
on VARIAX
Howden has seen difficulties with the previous erection procedure for regulating
units on VARIAX
operating in parallel – that the regulating units are mounted and calibrated correctly.
This procedure is implemented in all new erection and maintenance manuals edited after December 2013. The
procedure is valid for fans with Howden B- and C-hubs.
Verification Document V213351-9 (see pages 7/8/9).
3.20

Blade Pitch Actuator

The movement of the actuator lever is
transmitted to the external regulating arm of
the fan through a connecting rod. From the
external regulating arm the regulating
movements are transmitted to the hydraulic
regulating unit (hydraulic cylinder) through a
regulating shaft and a pull fork.
The position of the actuator in relation to the
regulating arm is designed so that the angular
motion of the actuator and the air volume are
almost linear.
1.
The pedestal for the actuator on the
side of the diffuser has been mounted
according to the drawing in chapter
10.00 of the Fan Manuals "Actuator
Arrangement". Verify the location of
the bracket is correct in verification
document V213351-9.
Notice: All dimensions and angle given in this instruction are for reference only and the relevant project drawings must be
used when calibrating the regulating drive assembly.
Issue 3 – March 2014
®
B & C Hub Fans
®
B & C Hub Fans. It is very important – especially for fans
Figure 1: Bracket on outer regulating arm
Internal and external
regulating parts –
schematic view
Page 1 of 8

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Summary of Contents for Howden VARIAX B

  • Page 1 B & C Hub Fans Internal and external regulating parts – schematic view Howden has seen difficulties with the previous erection procedure for regulating ® units on VARIAX B & C Hub Fans. It is very important – especially for fans operating in parallel –...
  • Page 2 (Figure 2) according to the above mentioned drawings – correct if necessary. If tolerances are greater than ± 3 mm (0.12”) contact Howden for new calculation of “L3”. Mount the rod ends on the external regulating arm and adjust the connecting rod length “L3 (Figure 2)
  • Page 3 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.
  • Page 4 Technical Bulletin Start the control oil unit and check that 13. To avoid mechanical contact between Close the blades carefully to minimum the blade angle is 55°. If necessary, the blades the current minimum blade e.g. 31° and tighten the “closed the pull fork push rod length may be angle must be adjusted to a distance mechanical stop bolt”...
  • Page 5 Technical Bulletin Regulating Drive – Complete 3.22 Readjustment of Maximum 3.23 Balancing the Counterweight Balance procedure: Working Pressure at the Internal Regulating Disconnect the external regulating Crank Arm arm linkage. Stop the control oil unit. Start the control oil unit. All position numbers refer to drawing “Regulating Drive –...
  • Page 6 Technical Bulletin Howden Verification document V213351-9: Page 1 Page 6 of 8...
  • Page 7 Technical Bulletin Howden Verification document V213351-9: Page 2 Page 7 of 8...
  • Page 8 Technical Bulletin Howden Verification document V213351-9: Page 3 For more information please contact your local Howden office. This bulletin has been released by: Howden Denmark ApS, Industrivej 23, DK-4700, Næstved, Denmark Tel: +45 55 77 62 62 Web: www.howden.com Email: variax@howden.com...

This manual is also suitable for:

Variax c

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