Bearing up….

Supervised by Mark Leatherland from Timken, the team at Darlington Locomotive Works pressed the roller bearings on to the crank axle.  The process required the use of an induction heater for the bearings.

Most of Tornado’s roller bearings were fitted by the wheelset assembler at the same time as the wheels were pressed on. For Prince of Wales we have decided to assemble the bearings, axles and axle/cannonboxes ourselves as the plan is to fit the completed axle/axlebox and cannonbox assemblies to the frames before the wheels are pressed on. This makes the setting of the coupled axles much easier as the distance between the axles (which is a critical measurement for a smooth running) can be measured directly – this is not easy when the wheels are on.

The first bearings were fitted on 13th December to the crank axle. Having checked that the dimensions of the axle ends and the various spacer and thrust rings are correct, each component is heated to 110 degrees C using our new SKF bearing heater and slid onto the axle in turn. The axle is typically 0.004″ greater in diameter than holes in the rings and bearings, so as the components cool, they grip the axle. The problem is that if the outside edge of the ring or bearing cools and grips first, the the item will no longer be tight up against its neighbour as it shrinks on cooling. To overcome this we use our 50 tonne jack with various bespoke adapters to press each ring and bearing as it is fitted. The pressure is released once the component has cooled down.

It is a requirement of Railway Group Standards that work on roller bearings is overseen by a qualified bearing specialist which we do not have, so the operation was attended by by Timken Service Engineer Mark Leatherland who will provide suitable paperwork conferring acceptance of our work.

The next stage is to machine the adjustment rings that set the end float of the bearings, after which the axleboxes can be fitted.

    

The roller bearing fitting rig – David Elliott

The induction heater for the bearings – David Elliott

Bill Drumm applies grease – David Elliott

Ian Matthews and Bill Drumm  with their handiwork – David Elliott

The bearings in place, wrapped in cling film to keep them fresh! – David Elliott