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Construction of a 5" Merchant Navy '35006'

Part 6 of an Article by Kevin Neate 

Locomotive Lubrication

There are several aspects to this stage of the build.

                                     
1).  Outside motion

The bogie, bissel truck and tender – are all accessible with an oilcan.  The oil boxes are dummies, so a squirt of oil where necessary on the outside motion. 

2). Inside con rod and eccentric bearings

– these are totally inaccessible for an oil can! 

What I did was to fit brass oilcups into the rear sandbox tubes, with 2.5 mm copper pipes coming out of the bottom, which are directed over the oil holes on the con rod and eccentric.  I punched timing marks on the LH centre wheel, so these can be lined up, and the bearings oiled when correctly aligned.  I threaded the lids 3/8" x 32 on the rear sand boxes fillers.  When the loco is stripped down for painting I will enlarge the oil holes, or perhaps fit oil cups.  The front sandbox lids are loctited in place. 

The adjacent photo shows the pipes leading to the bearings – ignore the paint peeling off.

                                     
3).  Inside motion.

There is actually access under the boiler casing to see the inside slide bar, valve crosshead etc. (using a torch), and I will add oilcups and pipes as needed to the various components when the loco is stripped down for painting. 

4).  Axle boxes.

The full size locos have three oil boxes each side, at varying heights and spacing along the platforms.  These can be bought as 5” gauge castings for about £10 each.

When I made the cylinders, I made 8 of these as a stick on a piece of brass bar and then cut off – 2 for the cylinders, and 6 for fitting on the platforms, and it was quite easy to do.  The lids fit to the boxes using 1 mm wire. 

I soldered 2.5 mm copper tube to each oil box, and then ran a copper tube to each axle box held in place with P clips.  Each axlebox is cross drilled 1/16” dia to lubricate the horns.  The oilboxes are attached to the platforms with M 1.2 (14 BA) hex screws that are difficult to fit.  In order to easily remove the platforms I have used 2.5 mm bore rubber tube to connect between the tubes.

This photo shows the oil boxes scattered along the platforms, hopefully in the right place, and the pipes leading to the axleboxes.  However! - during subsequent work I had to take the platform sections on and off many times, and connecting up the rubber tubes each time was a real pain.  I can leave as is or use the other sand box fillers to run fixed pipes to the axleboxes at the next strip down.  Watch this space.

5). Cylinders.                                     

There are two options, fit a lubricator at the front below the smokebox as suggested by KW, or fit pumps into the platform mounted lubricator boxes.  Neither are easy to do. 

After much deliberation, I made a large lubricator tank and lid with three pumps, similar to the one I made for my King Class.  The three pumps are the usual arrangement of a small piston rod pushing cylinder oil down a hole via a one way valve, to a banjo connection leading to each cylinder.  The pumps are driven by 3 eccentrics at 120 degrees fitted to a 5/32” silver steel cross rod.  The eccentrics connect to scotch cranks with the piston pins below.

The lubricator tank assembly fits under the smokebox on a sub plate, and part of the saddle needed to be cut away.  The drive uses a one-way clutch with a rocker arm, which includes an adjuster to vary the stroke.

The rocker arm is pushed forward by linkage made from 4mm rod, taken from the inside crosshead and runs through a copper tube on a plate fitted to the bogie stretcher; a return spring brings the rocker arm back. 

To prime the lubricator there is a hole in the rocker arm so that a rod can be attached.  Pipes run from the lubricator to each cylinder via secondary one-way valves. 

The lubricator tank/pump is a single unit and can be removed very easily.  All of this is hidden by the front battery box assembly that is quickly removed to give access for priming and filling with oil.  All appears to work well if the loco is pushed along, but don't ask how long it took to make.

The alternative is to fit a pump into three of the four platform lubricators.  These are quite small, so there is not a lot of space to fit pumps inside, but I know other builders of these locos have done this.  I have sourced a set of four very detailed platform lubricators (very expensive), and these will feature in a later article.

 

6). Suspension link.

In full size the cover over the top of this has two hinged flaps to access the bearings.  The cover is described in another article.



Click here for Part 1 of Kevin's article.
   


Click here to go back to Part 5.