Pumpteq Pty Ltd | Vulcan Sinclair Fluid Drive Coupling Overhaul
2273
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Vulcan Sinclair Fluid Drive Coupling Overhaul

Vulcan Sinclair Fluid Drive Coupling Overhaul

A fault was found with this Valcan-Sinclair fluid coupling whilst in service on a plant in SA. This fluid coupling is sited between a Siemans three-phase motor and a 6”/8” 10 stage boiler feed pump.

The unit was suffering from a large amount of vibration and was unable to adjust its speed.

Project

Once the fluid coupling had been isolated it was removed from its bedplate and oil tank, disconnected from the scoop tube mechanism and all unnecessary pipe work. The fluid coupling was then transported to our workshop in WA.

Once arriving in WA we started the dismantling process, starting with the removal of the couplings and scoop tube assembly, tacking note of all measurements and full photo reports.

The Valcan-Sinclair Fluid Coupling is a scoop trimming type of motor to pump variable speed coupling, it is a scoop trimming type of coupling.

This type of fluid coupling allows the rotational speed of the boiler feed pump in this case to be varied, whilst the motor runs at a constant rotational speed.

The scoop trimming type of coupling operates by oil volume which with maximum oil volume means maximum speed, reducing this oil volume will results in a reduction of speed of the boiler feed pump.

Oil volume control, hence output speed control, is effected by a scoop tube which removes oil from the rotating parts of the fluid coupling. The tip of the adjustable scoop tube is situated in the casing and the scoop trims the oil to the depth determined by the radial position of the scoop tip, which therefore, in turn determines the oil volume and in turn speeds up or slows down the output shaft.

Dismantle, Inspect and Report

  • Overall Axial Float- This check could not be obtained due to a failure.
  • Main locknut on the output shaft has come undone in service, which has caused the entire internal assemblies to shift.
  • Both locknuts will be drilled and tapped to accept two grub screws and a small brass piece to lock onto the thread.
  • The scoop tube damaged, due to the internals shifting.  The internal assemblies have been rubbing on the tube.
  • Due to the assemblies shifting the internal spherical bearing has been taking all the axial thrust which has caused a catastrophic failure of the bearing.
  • Metal particles found throughout the unit due to the bearing failure.
  • Bearing outer race has been spinning in the bore of the internal housing.  Internal housing bore is in poor condition and out of specification.
  • Bearing support ring has severe pick and rubbing marks due to the failed bearing.
  • End of the output shaft has severe pick up marks due to the failed bearing.
  • Many internal bolts were excessively tight and had to be destroyed to remove.
  • Internal dowels were excessively tight.  Extraction holes had to be drilled and tapped into them to remove.
  • Both white metal seals are severely damaged.
  • All white metal bearings have scoring and worn appearance.  White metal bearings are not suitable for service.
  • White metal bearing thrust pads have minor scoring.  Pads are suitable for service to require minor hand polishing.
  • Output shaft end cover is cracked all the way through the flange.
  • Pump drive coupling is missing from the bevel gear box output shaft.
  • Externals of unit are in poor condition. External blasting is required.

Preliminary Inspection Report – Bore Diameters

Bore Dimension OEM Specification
Internal Housing Within Specification OK
Bore Within Specification OK
Bevel Gear Within Specification OK
Housing Bore-A Within Specification OK
Bevel Gear Within Specification OK
Housing Bore-B Within Specification OK
Bevel Gear Within Specification OK
Housing Bore-C Within Specification OK
Bevel Gear Within Specification OK
Housing Bore-D Within Specification OK
Scoop Assembly Within Specification OK
Housing Bore-A Within Specification OK
Scoop Assembly Within Specification OK
Housing Bore-B Within Specification OK

Input Shaft and Mating Components

Input Shaft and Mating Components
Journal Dimension OEM Specification
A-Support Bearing Within Specification OK
Journal Within Specification OK
B-White Metal Within Specification OK
Bearing Journal Within Specification OK
B-White Metal Within Specification OK
Bearing Bore Within Specification OK
C-Thrust Collar Within Specification OK
Bearing Journal Within Specification OK
C-Thrust Collar Within Specification OK
Bearing Bore Within Specification OK
D-White Metal Within Specification OK
Seal Journal Within Specification OK
D-White Metal White metal destroyed
Seal Bore White metal destroyed

Output Shaft and Mating Components

Output Shaft and Mating Components
Journal Dimension OEM Specification
A-White metal Within Specification OK
Seal Journal Within Specification OK
A-White Metal White metal destroyed
Seal Bore White metal destroyed
B-Pump Drive Within Specification OK
Gear Journal Within Specification OK
B-Pump Drive Within Specification OK
Gear Bore Within Specification OK
C-White Metal Within Specification OK
Bearing Journal Within Specification OK
C-White Metal Within Specification OK
Bearing Bore Within Specification OK

White Metal Support Bearing and Sleeve

White Metal Support Bearing and Sleeve
Journal Dimension OEM Specification
A-White metal Within Specification OK
Seal Journal Within Specification OK
A-White Metal Within Specification OK
Seal Bore Within Specification OK

Bevel Gear Housing Sub Assembly Input Shaft and Mating Components

Bevel Gear Housing Sub Assembly Input Shaft and Mating Components
Journal Dimension OEM Specification
A-Bearing Journal Within Specification OK
B-Gear Journal Within Specification OK
B-Gear Bore Within Specification OK
B-Bearing Journal Within Specification OK
D-Gear Journal Within Specification OK
D-Gear Bore Within Specification OK

Bevel Gear Housing Sub Assembly Output Shaft and Mating Components

Bevel Gear Housing Sub Assembly Output Shaft and Mating Components
Journal Dimension OEM Specification
A-Bearing Journal Within Specification OK
B-Gear Journal Within Specification OK
B-Gear Bore Within Specification OK
C-Bearing Journal Within Specification OK
D-Coupling Journal Within Specification OK
D-Coupling Bore Within Specification OK

Scoop Assembly Control Shaft

Scoop Assembly Control Shaft
Shaft Journal Bore Dimension OEM Specification
A-Bearing Journal Within Specification OK
B-Bearing Journal Within Specification OK
C-Seal Journal Within Specification OK
D-Seal Journal Within Specification OK

Gear Teeth and Bearing Numbers

Gear Position Number of Teeth
Output shaft gear 79
Bevel housing input shaft gear 92
Bevel housing input shaft bevel gear 39
Bevel housing output shaft bevel pinion 34

Assembly Notes

  • Overall Axial Float – 0.35
  • Bevel Set Backlash – 0.16
  • Output shaft was taken from spare parts
  • Bevel set was taken from spare parts
  • Spacer ring from support bearing was taken from spare parts
  • Internal housing was taken from spare parts
  • Output shaft end cover was taken from spare parts
  • Scoop housing was taken from spare parts
  • Scoop tube was taken from spare parts
  • Miscellaneous bolts and dowels were taken from spare parts
  • Support bearing retainer was taken from spare parts
  • Output coupling was taken from spare parts
  • All white metal components were taken from spare parts
  • Runner was weld repaired and crack detected once again
  • Input and output shaft assemblies were balanced to Grade 1 specification
  • All new gaskets were manufactured
  • Externals of housing was blasted to bare metal and primed and pained to required specifications.
Project Conclusion

Once the Valcan-Sinclair fluid coupling had been delivered back to the plant in SA it was set back in its original position, coupled up to the motor and boiler feed pump in the correct way which we believed had not been coupled correctly before, this had meant since its last overhaul the fluid coupling had been pulling the balance face of the boiler feed pump together. The Valcan-Sinclair Fluid Coupling was commissioned and is running well.

PROJECT IMAGERY

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