One of these is a jet of steam below the front engine when working hard uphill. This indicates steam leaking through a piston rod gland in the front engine.
|Arrowed jet of steam (Photo: Sean Dudden)|
|Four drain pipes|
Having been aware of this leak for some time, I made preparations for repacking the left hand steam gland of the front engine. I needed to order the packing material but did not know the size so I loosened the nuts holding the gland packing in place to enable me to gain access to measure the size of the gap to be filled. I was not prepared for what I found.
Clearly, I couldn't simply put them back to be ready for the next public steaming, six days away.
Sentinel used to produce packing rings with a part number for ordering. This luxury is not available nowadays so I had to find a current substitute. Stuart Gray (Heritage Steam Supplies (HSS)) advised me that the material needed was Pilotpack 4010.
|Empty packing space (rough piston rod surface)|
It measured almost exactly 1/2". Thus 1/2" x 1/2" square section Pilotpack 4010 was what was required. About a yard is required to make the five rings of packing for a 1.35" diameter piston rod.
HSS were out of stock so I had to go directly to the manufacturer, Beldam Crossley, to get it in time. Beldams were more than helpful and sent me eight metres of 4010 next day. Beldams were cheaper than HSS but I had to order eight times as much as was needed immediately. (There are four piston rods in all so it's not that excessive!).
Following instructions provided by HSS, I prepared the required five rings by wrapping and clamping the length of 4010 around a mandrel (piece of plastic pipe the same diameter as the piston rod) then cutting to make each ring using a Stanley knife. The instructions say that each ring should be inserted into the stuffing box so that the ends 'butt' together. Clearly the writer of the instructions has not worked with 4010 as, when cut, the ends splay out like a pony tail. Butting pony tails is not really what is required but for this attempt that is exactly what I had to do.
For the initial attempt at fitting, I could only get four rings into the stuffing box.
|Four rings fitted (they were soaked in SCO1000CTRO+ cylinder oil)|
There is some steam leakage as a result but it is better than the stuffing box being left full of beans again!
After the first day running with the new packing, the four rings had survived but were more compacted than when fitted. A gap was thus left so I could fit the fifth ring. Again, I tightened the nuts to push the packing home and then slackened them off a turn or so. Some tweaking will be needed during the next steaming.
|Five rings fitted|
|'In sit you'|