Is there such a thing as a quiet week?!  Another busy one with lots of activity, a sample of which is presented here, along with a sequence of photographs showing the work on 114’s two bearings which have been re-metalled.

RHEC Updates

Below: The living van is now on the home straight, with top coats of paint being applied to the body panels, the roof canvas finished and given its first coats of paint and the new mudguards delivered to enable the body panels to be made to fit them.

Below: The belly-boxes are being configured to suit our Fairground operation, with new drawers being made to contain items such as coconut balls, coconuts and other sundries.  An electrical consumer unit is also fitted in this area.  This view shows the new drawer runners and strengthened belly-box structure.

Below: A test fitting for one of the new drawers.

Below: A view of the rear belly box, which is all new, as well as showing the rave surrounding the mudguard.  Already this has hugely changed the appearance of the van and given an impression of depth to the body.  Tony is creating mouldings for the corners and to give a transition between the body and belly panels.

Samson

Below: Dave has been working hard on the axleboxes for Samson.  These are now all fitted so that they sit snuggly into their hornguides.  It is now thought that it will be prudent to line-bore these to ensure they are both parallel and true, to each other sideways and across the frame.  We will have to contract this out however as the whole frame will need mounting on the borer’s bed for the work to be done.

Below: An overall view showing the front pair of axleboxes, with keeps in place and temporary wedges to set them in their lowest position (the frames being upside down here).  Final boring will be to accept the reduced journal on a 3inch axle.  Once the boring is completed, further machining of the axlebox underkeep will enable it to be offered up to an axle (and removed!) once the bore is true.

Newcastle 114 repairs

Below: 114 has already made news this week with the announcement of its trip to Derbyshire in September. Needless to say, therefore, this ever-reliable tram has tempted fate and failed this week with evidence of white metal in the oil space of one axlebox being observed during a routine exam.  Some background may be useful.  Two of the four journals (the machined face of an axle that engages with a bearing) are white metalled, and two are plain bronze bearings.  White metal is used to create a bearing surface for some wheelsets, and is tinned to and applied directly onto the bearing (usually bronze).  It can then be machined and scraped to an accurate fit and oil-ways cut to enable lubrication.

In this view the axlebox cover is removed and the weight of the tram supported on jacks, to enable the bearing ‘brass’ (as they are usually know) to be removed.  The axle end is prominent here, with a machined grove into which a thrust plate is slotted, retaining the wheel within the axlebox (you can see the corresponding slot in the casting).  This limits the side-to-side movement.  114 is fitted with a Brill 21E type truck – almost a universal design at one time and one common in preservation today (196 is similarly fitted).  This truck was shortened to suit 114, originally originating from Oporto.

Below: This is the ‘brass’, a bronze casting, seen here inverted.  The white metal skin can be seen clearly, and also where it has been easily picked away from the metal below – a result of improper preparation and lack of sufficient tinning when last applied.  White metal is an alloy, usually copper, antimony and tin with other constituents if required.  It produces a hard and impact resistant metal (Beyer Peacock referred to it as ‘wear resistant metal’ on their drawings), easily worked and often familiar to modellers as it has excellent casting properties, especially in a centrifuge. Anyone using a soldering iron in the vicinity of white metal will be aware of its relatively low melting point however!

Below: Here Matt is heating the brass, in doing so causing the white metal to melt and flow into the saucepan.  it also burns off oil, which seeps into the pores of the ‘brass’ (bronze!) and enables better tinning when re-applied.

Below: Making new ingots for use in the re-metalling process.

Below: With the brass clean, Tom then machined a series of corrugations into the surface.  This improves the keying of the white metal to the surface.  Our bearing had not failed due to heat (overheating can cause the metal to melt altogether and run out of the axlebox in extreme circumstances) but because it was brittle as a result of not adhering properly to the parent casting.  Work and impact wear further exacerbated this.

Below: Here the white metal (seen being recovered earlier and supplemented by material from old bearings we had in store as donors of such material) is seen being puddled onto the brass.

Below: With the metal cooled, the rough result can be seen, awaiting machining.

Below: The milling machine is set up to bore the white metal, seen here.  The first cuts have been made, which will be incrementally increased to give a depth equivalent to the journal.

Below: The finished bearing, after a test run up and down the yard to check for high-spots and potential problems.  All well here.

Below: The machined bearing refitted to 114 in readiness for running in to check its integrity. Note the tapers at each side to prevent the oil being scraped of the journal by the bearing (the lubrication being from the oil well beneath the axle and transfer via cotton pads just visible here).

Below: After running-in, normal service will resume!  Hopefully this sequence of photos is a useful illustration of what is often referred to in a few words such as ‘the bearings were re-metalled’.  Obviously these are quite small bearings, but the process is broadly similar whatever the size, though an alternative method of metalling is to create a mould and pour the white metal – see a very early post on this blog regarding the construction of the Steam Mule for more on this…