Case StudiesDB Schenker UK

Overhaul of Mirrlees Blackstone MB 275T


DB Schenker UK



Key Parameters:

Contracted to carry out a number of major workshop overhauls of Mirrlees Blackstone MB 275T Diesel engines, used to power Class 60 Diesel Locomotives.



Project Desciption/Specification:

In 2013 GSE were contracted by DB Schenker UK to carry out a number of major workshop overhauls of Mirrlees Blackstone MB 275T Diesel engines, used to power Class 60 Diesel Locomotives.
The Engines had previously been removed from locomotives and held in storage for several years. Each unit required substantial modification work to critical internal components including Crankshafts, connecting rods and pistons, each engine requiring differing levels of repair.
Following an initial condition Survey on each individual engine, a team of GSE engineers completed the first stage of engine strip removing Cylinder heads, Pistons, Palm rods, Large -end blocks and Liners.
To facilitate removal of the engine Crankshaft, the entablature was positioned beneath a specially built ‘heavy lift’ assembly frame. The sump was removed from the block, along with the bell housing and auxiliary drive casing, flywheel and crankshaft damper. Hydraulically tensioned fastenings were subsequently released using high pressure hydraulic equipment, allowing a safe and controlled removal of the crankshaft.

Following removal the Crankshaft, Palm rods, cylinder Liners, large-end blocks and fuel control equipment were subsequently modified and reconditioned as per current OEM specifications
Each Camshaft assembly were overhauled ‘in-house’ at GSE workshops, replacing worn lobes and renewal of all bearings and thrust plates. The 6.5 Tonne engine block was thoroughly cleaned, examined and measured in-house, prior to rebuild, with all cylinder head studs removed, NDT examined and replaced.

The original Crankshafts were re-fitted to the engine block using OEM bearings, following specialist modification. Main bearing fastenings were re-tensioned, using specialist hydraulic equipment as per original manufacturer’s specification.

Reconditioned Cylinder liners; incorporating machined ‘flame rings’ were re-fitted to the entablature, along with overhauled large end blocks, palm rods and pistons all re-fitted using new bearings and piston rings.

Final stages of the rebuild included assembly of new intermediate timing gears, which had been previously removed from the engines whilst in storage. Each engine was completely retimed, prior to assembly of fuel equipment and cylinder head running gear. On despatch from GSE workshops, the Power unit was re-spayed as original supply.

At key stages during the overhaul of each engine, specific component measurements, clearances and running tolerances were recorded, along with OEM recommended fastening schedules. A comprehensive rebuild report was produced on completion of each overhaul; ensuring procedures detailed by the customer were undertaken and correctly documented.

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