The Standard Steam Locomotive Company Ltd has given an update on the progress with the construction of the new Clan Class Pacific steam locomotive No. 72010. Hengist.
The noses of the spring hanger brackets were then checked for equidistance around the centre line, which showed that the trailing spring hanger bracket needed to be moved slightly forward before work could start drilling the bolt holes.
The last of the bogie axlebox guides have been drilled and reamed so that heavy drive bolts can be installed.
All the holes have been fitted, and around 75% of the bolts have been driven in. The remaining bolt holes require oversize bolts, for which quotes have been issued. Before the reaming took place, a 1.5 thousands of an inch feeler gauge was used to check that the axlebox guides were tight up against the bogie frames.
All four outer holes needed to fasten the left-hand trailing spring hanger bracket have been drilled. Because of the difficulty in gaining access, before the inner holes can be drilled, the team has to work out how to drill them as it is necessary to drill upwards. The frames also need to be moved to gain access to the right-hand side bracket.
In order to fasten the dragbox and the hind beam gussets to the rear of the frame extensions at the back of the frames, fitted bolts need to go through all three components.
However, because of the shape of the gussets, two operations are needed to drill and ream the bolt holes to their final size.
First, the dragbox to the frame extensions, and then the gussets. A special drilling jig will be used to drill and ream the holes on each assembly. The drilling jig will use a 26.5 mm Boneham and Turner Drill Bush with a 26.5 mm twist drill to drill the holes, followed by a 27mm reamer in a 27mm bush. The gussets can then be bolted to the frame extensions and dragbox.
Work is also proceeding with the design of Hengist's cylinders and valve gear by developing a 3D model of them. The team intends to adopt the same modification recently installed on 71000 Duke of Gloucester where an extension was cast into the rear cylinder cover to provide a support for the front of the slidebars.
To create the new design, they need to model the existing BR design in which the front of the slidebars are not supported. Information obtained from Bill Harvey's book, who was shedmaster at Norwich when Britannia operated on the Norwich to Liverpool Street main line, shows that there was movement at the end of the slidebars.
Already modelled are the rear cover, swab mop case, and slidebars, and work has started on the piston for the valve cylinder above the main cylinder.
Earlier this month the Main Line Steam Builders Group met to discuss progress on each of the group's projects, in April, an order was placed for Hengist's driving wheels
