Speedy refurbishment puts RMAS Salmaid back to sea

Wyko Electro Mechanical Services worked against the clock to overhaul a vital 5t winch generator and motor assembly, enabling RMAS Salmaid to carry out its service with the minimum of layover time.

Wyko Electro Mechanical Services (WEMS) has worked against the clock to overhaul a vital 5t winch generator and motor assembly, enabling the RMAS Salmaid to carry out its service with the minimum of layover time.

The engineering team took one week to remove and repair the complete unit, in an operation that required metalworkers to cut through the ship's bulkhead, the installation of a 25t hydraulic ram, two dockside cranes and a fleet of vehicles to take the unit to and from the WEMS workshop in Grimsby.

The Royal Maritime Auxiliary Service vessel RMAS Salmaid was due to depart for Newcastle from Grimsby when the motor/generator supplying the ship's main winch began to fail.

Excessive vibration and noise was coming from the unit, which consists of a 124kW DC generator, a 124kW AC drive motor and 24/13.5kW DC generator.

Without this system being operational, a large buoy could not be lowered and raised from the sea, making the vessel unfit to carry out its service without immediate repairs.

An order to overhaul the unit was sent from the Ministry of Defence through to WEMS Plymouth which then took advantage of the UK-wide network of Wyko branches and contacted the Grimsby division.

That same day, a team of engineers arrived at the nearby East Royal Docks and found the 124kW DC generator unit to be emitting bearing noise along with movement in the coupling element.

They then set to work replacing the bearings and coupling rubbers in-situ, but once the split flange had been removed, it became obvious that the damage was worse than previously thought.

As a result, Friday saw the removal of the complete AC rotor core pack and the detachment of the drive end-coupling unit with the DC generator still attached to the AC drive.

The end shield also had to be removed to access and replace the drive end bearing assembly, a process that required a 25ft hydraulic ram to pull free the inner race and revealed extensive shaft wear.

Due to the extent of the tapering on the shaft, the complete generator set had to be removed for repairs and testing at the nearby WEMS workshop in Grimsby.

However, with a combined weight of 5t, a hole had to be cut in of the side of the vessel and a mobile crane set up on the dockside to lift the large components out through the bulkhead.

Once the generator unit arrived at WEMS, the AC/DC unit was completely dismantled and the wear damage assessed and measured.

The results showed that the armature-bearing seat needed to be machined and sleeved back to size.

Over the weekend, the fan coupling and keyway were machined along with the worn bearing grease plate.

The commutators on both armatures were also skimmed, new roller bearings sourced and fitted to the shaft before the unit was reassembled ready for testing.

By Monday morning the complete generator set had been run tested for one hour and favourable vibration levels and spike energy levels recorded.

The single DC generator was then split from the unit ready for dispatch to the ship and both items were returned and refitted to their bed the following day.

To check that the final assembly was done precisely, running tests were carried out onboard, with vibration and spike energy levels retaken and checked against previous reading obtained from the no-load test in the workshop.

Once the repair was considered satisfactory Wyko staff returned to the vessel and cleared the site from loose welding debris and repainted the bulkhead, ensuring that the generator repair was completed well within the tight deadline set.

WEMS is BS EN ISO9002 accredited to carry out all motor, generator, alternator, transformer and pump repairs while also providing condition monitoring services.

Such tasks are co-ordinated by Wyko's Marine Division that specialises in providing vessels of all sizes with guaranteed repairs at their intended destination, rather than having to make unscheduled voyage deviations or incurring excessive layover periods.

The services available include mechanical engineering, electrical work in addition to a worldwide product supply network.

Wyko is also a member of the ISES association (International Ship Electrical and Engineering Services Association), guaranteeing quality workmanship.

Work is carried out by teams of qualified engineers who are supported by a nationwide network of over 140 distribution centres, 35 workshops and a fleet of on-site mobile stores units.

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