Tuesday, 14 August 2018

Glandular Fervour

I haven't use the word 'fervour' in the heading lightly. It means 'intense and passionate feeling' or 'intense heat'. Getting these piston rod glands right has been a learning curve and a half for me and fraught with continual failures for months.

Bearing in mind that Joyce has four cylinders, and hence four steamy piston rod glands, I had done my ninth packing replacement by April 2018. With snow and freezing conditions abounding at the start of March, these repairs had not been a lot of fun and hugely frustrating.

When Joyce ran in May, I thought I had got things sorted. I had found a way to get the packing compressed 'just the right amount'. So, with a feeling of achievement, we did 8 runs on the 6/7th May expecting no further problems.
Frayed remains of 20 layers
As the photo shows, after two days running, the five layers of packing in each cylinder were reduced to a pile of shredded fibres, two layers at best per gland.

At this stage, I was feeling pretty low. Whilst I acknowledge that Joyce's piston rod surfaces are not as smooth as they really should be, they don't feel abrasive.
As such, I can only conclude that the advice I was given to use Beldam's Pilotpack 4010 was ill-founded. Bearing in mind the authoritative source, I felt I had to persist; however, I feel badly let down, have wasted over £400, had to cancel a S&D steaming weekend and had nine months of worry. Not pleased.

Pilotpack 4010 ticks all the boxes for temperature and pressure specifications. What it is incapable of doing is holding together its fibrous construction in this reciprocating situation despite my considerable efforts to adhere to the manufacturer's (flawed) instructions.

I am making progress with another form of solid packing which is behaving much better (so far) - I'd be foolish to say I am completely confident after this bad experience but keep your fingers crossed.

My advice, based on this experience, is that Pilotpack 4010 is not suited to this application. Click here for an illustration.

Wednesday, 21 February 2018

Exploring New Territory

1st Steam Loco on this part of the S&D in over 50 years.
My apologies for being quiet for so long; it's been a very busy time hauling Christmas specials in December and doing annual repairs, maintenance and some enhancements this year. Rest assured that there will be more to follow.

In the meantime, here's a video clip of Joyce exploring some new territory at Midsomer Norton after passing her annual boiler inspection on February 20th.

Wednesday, 11 October 2017

Not Butting Pony Tails

Following on from my brief R&D activity to prevent Gland packing turning into a pony tail, I bought a 35mm diameter wooden dowel from B&Q. The gods must have been on my side - how often can you go to a DIY store and actually buy what you want in exactly the right size? 35mm is the same diameter as Sentinel 7109's piston rod.

Wood is a good material for winding the packing around as it grips the packing surface just the right amount without abrasion. I first drew a line along the dowel so I could see the angle of rotation. Then I pinned the end of the packing to the dowel.

I rotated the dowel to pull the packing rope around the dowel and pinned each turn either side of the line to allow me to cut one ring at a time without the remaining packing unwinding.

One end of the dowel was held in a vice to make it easier to hammer in the pins.
Packing rolled on to the dowel
Along the line drawn on the dowel, I painted some Heldite around the outer surface and sides of the packing (but not the inside surface).
Packing pinned in place
I took the dowel and its turns of packing to site for fitting into Joyce's rear left piston rod stuffing box. By taking it on the dowel, I was able to cut one packing ring at a time and fit it straight away (soaked in warm cylinder oil). This minimised the time the packing might have to become a pair of pony tail ends and it proved very effective.

Next task is to light the fire and blow out the two old right hand piston gland packings and run-in this one.

Sunday, 1 October 2017

Butting Pony Tails

Recently, I wrote about Sentinel 7109's piston rod gland packing challenges but didn't have a photo to illustrate. Also I've now found a way to reduce the challenge to a reasonable level.

The photo below shows an experimental sample of the Pilotpack 4010 1/2" square section material.
Pilotpack 4010
To the right is the 'pony tail' created by cutting the 4010 without any means of holding the fibres together. (It is not quite this bad in practice but it does emphasise what happens if the end is left to its own devices). Butting this against another such end is not easy!

At the left hand end, I'd painted some Heldite around the outer surface and sides of the of the 4010 at the cutting point. To avoid any risking of the 4010 sticking to the rod, I left the inside rubbing surface clean.

I considered Heldite as opposed to Evo-stik because it is good at withstanding high temperatures and oil (used to assist pushing it home in the stuffing box). Although it takes a while to dry, it soaks into the 4010 like a glue and holds the fibres together.

As the photo shows, at the left end where the 4010 has been cut, the Heldite seems have held the fibres together effectively. Now to do it for real...
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