Repair of Pivoting gearbox of Angolan cutter suction dredger

Challenge

Stork Gears & Services was invited by an Angolan dredging company to resolve the root cause of an abnormal sound of the pivoting gearbox, observed by the technical engineers onboard.

Upon arrival of our engineers our customer already removed the hydraulic piping, cooler and oil filter from the gearbox. We decided to remove the upper casing of the gearbox. Damage was observed on the sealing rings mounted on both sides of the 1st intermediate shaft. Also looseness was found on the oil pump gearwheel. The input shaft assembly was removed from the lower gearbox and transported to a local workshop for repair. The clearance of the sealing rings was slightly increased as a precaution for future use. Both bearings of the 1st intermediate shaft and rubber sealing rings were replaced. Also the complete pump assembly was replaced.

Solution

On request of our customer, torque measurements (static and dynamic) were taken under different operational conditions after the gearbox was commissioned. A full bridge of strain gauges was therefore attached on the carbon fiber reinforced gearbox drive shaft, which is located between the clutch and the pivoting gearbox.

Benefits

• Inspection of the gearbox including alignment

• Contact pattern check of the gears and backlash

• Repair of damaged or worn out parts

• Gearbox testrun after repair and re-assembly

• Perform torque (power) measurements on the carbon fiber drive shaft

The whole project was completed within a fixed time line of 24 days, working in continuous shifts. After assembly the gearbox was tested while pumping water only. The dredger was taken to its dredging location where the gearbox was monitored during the first 2.5 hours of operation. No abnormalities were observed and the dredger was back in business.

Location: Luanda, Angola

Market segment: Dredging

Gearbox details: Rated power: 1685 kW, Maximum speed: 1600 rpm, Output speed: 584.7 rpm

Scope of work: 

• Inspection of the gearbox

• Gearbox alignment

• Repair of damaged or worn out parts

• Gearbox testrun after repair and re-assembly

• Perform torque measurements on the shaft