Repair of a propulsion gearbox after cracked casing
Stork gears & services was approached by a maritime customer to discuss the options for a complete repair of a highly damaged gearbox based on a new casted casing.
The customer gave us green light to do the reparation so that they could minimize the downtime of the ship.
The problem of the Lohmann & Stolterfoht gearbox was major: the propeller of the ship caught a fishing net which was wound up between its hub and the ship’s hull. This caused such extreme forces that the stern shaft was pulled out, causing the gearbox casing to crack. Due to the size of the crack it was not possible to repair the casing and we were asked to let the ship sail again by repairing the gearbox to its original dimensions.
To repair the gearbox using the best methods to minimize the downtime we followed several steps:
- Dismantling, cleaning and inspection of the gearbox
- Revers engineering of the casing and discuss engineering parameters with classification company
- Manufacture a new middle section casing
- Grind gear teeth of bull gear
- Manufacture Both input pinion shafts
- Re-metal sliding- and thrust bearings
- Renew roller bearings and seals
- Assembly of gearbox onsite
- Test run
- Installation of gearbox onsite
- Commissioning and sea trials
With the reparation the customer can sail in as little as 9 weeks from reception in our workshop. The original equipment manufacturer offered a delivery of 12 months for the casing. Stork Gears & Services minimized the downtimes so that they could save a large amount of money.
Gearbox specification: Manufacturer: Lohmann & Stolterfoht; Type: GVA 1250;
Imput speed: M1 = 825 rpm; Power: 2x 2590 kW
Scope of work: Dismantling, cleaning and inspection of the gearbox; Revers engineering of the casing and discuss engineering parameters with classification company; Manufacture a new middle section casing; Grind gear teeth of bull gear; Manufacture Both input pinion shafts; Re-metal sliding- and thrust bearings; Renew roller bearings and seals; Assembly of gearbox onsite; Test run; Installation of gearbox onsite and Commissioning and sea trials