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The Foden 6-ton C type steam estate tractor
PAGE 7
Click on the thumb nails to get enlarged picture
>The pistons and cylinder block plus trunkguides ready for assembly  
     
>   The crankshaft is machined from solid mild steel bar. Here is is marked out awaiting to be rough cut.
     
The roughing out stage of the crankshaft machining. There are a number of stages and at each rough machining stage the crankshaft is left to normalise for a week or so as the stress relieving effect of machining makes it move  
     
  Here a cross head is being machined
     
A view of the crankshaft in its finished state and assembled temporarily in the main bearings.  
     
  The eccentrics are built up roller bearings, here two at the top left are partially assembled to test the fit. Below are the inner and outer with the side shields on the far right. The side shields are riveted in place with 1/16" r/h rivets. At this stage the outers have not had the flat milled on the outer edge to accept the eccentric rods. They are also unhardened.
     
An eccentric temporarily mounted on the crankshaft. They will be held in place by a grub screw into a dimple on the shaft once the valve timing has been verified as being OK. The original design has them keyed. That's very positive ....... and does not allow any adjustment should the timing be out.  
     
  Making the LP piston rings in these series of four photos. The rings are made from close grain cast iron and the process is to make the ring to the exact diameter of the bore and the width of the ring groove minus a thou and as deep as the ring groove minus a couple of thou. The first picture shows the rings grooved to the correct depth and to diameter but the bore is undersize by about 10 thou.
     
  By then boring out to the actual bore size the rings part and drop off onto the boring bar.
     
  The ring is then snapped to make a break, this is done by making a file nick on the inside and then breaking the ring by pressing down over a pin at the point where the nick is just like cutting glass or a ceramic tile. The ring is the expanded by putting a spacer (seen in the middle of the ring bottom left in the picture below) in the break that is equal to 4 x thickness and the rings (in this case done in pairs) heated between clamps to just very dull red and held there for about 15 minutes and then allowed to cool naturally. This puts in place the permanent set in the ring.
     
  Using a holder, seen top right in the picture, each ring is then polished on its sides using very, very fine emery paper greater than 600 grit as a minimum by using a figure of eight motion on a flat surface. The photo shows two completed rings for the LP piston that fitted OK and no breakage's occurred and the fit in the bore was just right.
     

On 25th January 2006 the Foden engine ran successfully on air contiuously.

Air was supplied from a compressor at 90 psi against a closed valve. Running half throttle in compound mode full forward the pressure dropped to 60 psi at the compressor with the compressor running continuously. The throttle valve was smooth and responsive.

A more detailed update to follow.

    
     
     
     
     
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