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.

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.

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...

A Nut Case

Sentinel clearly built their engines to be mounted horizontally. This I found to my expletive cost while examining piston rod steam glands.

What do you think this is for?

Pipe Dream

There's clue in the orientation of the photo.

There's another clue in this photo showing the upper gland tightening nuts removed and not in sight.

Nuts not tight and out of sight

If you have a horizontal engine, the gland space looks like this:

Nuts still not tight and out of sight

In the horizontal engine, if you remove the gland nuts, the nuts fall to the bottom and you can pick them out with your fingers.

In the vertical engine, the nuts tend to fall in behind the lower gland where your fingers really cannot get. A magnet on the end of a telescopic stick also cannot get there; neither can a magnet dangling on the end of a length of wire (because it sticks to everything else before it gets anywhere near the fallen nuts).

So the top photo has the answer. The copper pipe has a cylindrical magnet clamped in the short end that can be fed in behind the lower gland without sticking to the sides. As a result, it can get to the out-of-reach nuts which inevitably hide in the most awkward corners.

Unless you can stop the nuts falling in behind the glands (some hope), this is the tool for any budding gland worker with a vertical Sentinel engine.

Operating Experience (3) Has Beans?

Sentinel 7109 has been back in operation for over a year. At first, it was a matter of getting Joyce working; now I'm becoming aware of oddities that aren't working quite as well as they should.

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)

Looking underneath, there are four copper drain pipes pointing downwards immediately to the rear of the front engine.

Four drain pipes

In the photo above, the left end one drains leaks from the front engine's water pump; the second and fourth ones are drains for the four automatic cylinder drain cocks; the third one drains the two piston rod glands. This third one has been getting hot at its tip whereas the others just look a bit oily.

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.

Beans!

Look closely at the dead centre of the photo. Instead of old packing, I found what looked like a bunch of dark grey baked beans! These I removed for examination.

Beans, Beans

The beans looked to be rolled graphite, the remains of the original packing. It is possible to write with them, hence graphite.

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)

I found it very difficult to measure the distance between the piston rod and the surface of the packing space, known as a stuffing box. However, there is a gland bush which holds the packing in place. This is a close fit in the stuffing box so I measured the thickness of the bush instead.

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)

I screwed the clamping nuts tight to push the packing home and then slackened them off a turn or so to leave the packing uncompressed. As the piston rod surface is pitted, over-tightening the packing will just lead to it being abraded and failing.

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

Working on the packing is not easy physically with everything in situ. However, erecting a seat did make things a little easier.

'In sit you'

Only three more steam glands to go, the right front one could still be guilty...

Being a Dipstick

In an August 2013 article, I was left with a mystery. Why did the rear engine require so much less crankcase oil than the front engine to reach the dipstick half-full mark?

At the time, I'd assumed there was something lodged in the rear crankcase but didn't investigate further. Some three years or so later, while preparing to clean out the rear engine's oil sump, the actual reason has become apparent.

Take a look at the following photo with the two dipstick heads highlighted.

A new slant on dipsticks

Although the photo is taken from slightly above the level of the dipstick heads, it is clear that the far one is not only at an angle but considerably lower than the nearer one, about 3" in fact. I'd not taken any notice of this before and assumed that the dipsticks told the truth. When I checked the two dipsticks together, I found they were identical in length and markings. Thus the lower one dipped 3" further into its oil bath registering full rather in advance of actual fullness!

This answers the mystery of the differing oil requirements for each engine. What worries me is how long has it been like this and why are the two engines different?

Of course, the rear engine will have been running with two fewer gallons of crankcase oil than the front one. Hmm...

At some time in the future, the rear dipstick will need fixing. In the meantime, yet another mystery has also been solved.

In this photo, there is a drain cock to let water out of the sump and another highlighted in the top right.

Extra drain cock, top right

I'd wondered what this extra drain cock was for but now I know. Examining the front engine's dipstick for where the oil level would actually be in the sump, it is clear that this drain cock would let out any oil above the full dipstick level. Thus it is an alternative way of checking for sufficient oil without a dipstick.

The rear engine had a blanking plug instead of a drain cock so I swapped the two. The rear engine oil level can now be checked using the drain cock while the front engine's dipstick can still be relied upon.

The mystery has been solved but why the two engines are not identical remains an unknown.

Front Engine Sludge

Vertical Sentinel locomotive engines were designed to allow for water to accumulate in the crankcase sump, the lowest part of the engine itself.

The water comes from condensation and leakage in the boiler feed pump piston glands. It's dealt with by using special 'Crank case oil' which is formulated to enable water to separate out from the oil quickly and sink to the bottom below the oil itself. A drain valve is provided to enable the water to be let out periodically.

Front engine sump cover in place showing the water drain valve

I'd noticed when draining the water that it seemed to drain out intermittently as if there was something not quite right in the front engine's crank case. Additionally, the dipstick did not seem to register whenever I added some more oil.

The only way to find what was happening was to remove the crank case cover and have a look. It wasn't a difficult job but required the oil to be drained first (about 11 gallons of it!).

There was at least 1/2" of thick sludge in the sump.

Nice! Gungy viscous mess about 1/2" deep or more

I drained the sludge and put the crank case cover through the parts washer to produces something a little more serviceable.

Even nicer!

The crank case cover is sealed by a gasket containing a perforated metal coarse filter.

Coarse filter as found

I tried to remove the filter but it did not want to come off easily. I also didn't want to break the filter in case I couldn't get another. I took the easy way out by blowing compressed air through it to remove the remaining oil and any potential blockages.

Coarse filter after (it's not from a beehive!)

The cover is now back in place awaiting the oil to be replaced, hopefully without any gasket leakage!

Camshaft Surface Finish (2)

In a May 2013 article, I was concerned about how best to remove some corrosion from the surface of one of Sentinel 7109's rear engine camshafts. Holding a file to the surface while turning the engine and camshaft using compressed air seemed a good idea at the time but it became no longer practical after the steam feed pipework had been reconnected.

So I decided, that a strip of emery paper pulled back and forth around the camshaft would have to do.

This is the before picture:

Before abrading

This is the after picture:

After abrading

And with a good slopping of crankcase oil:

Ready to go

Meanwhile, I discovered a strange phenomenon in the front engine's cam-finger chamber.

Strange glow or what?

It took me a while to figure out that the lurid green-ness was the new oil dribbling through from the cam-shift shaft oil chamber into the old oil.

Clearly visible is the word 'STEAM' stamped on the end of the camshaft. This differentiates it from the exhaust camshaft on the other side of the engine. It also looks as if there may be a manufacturing date of some time in April 1946. I had previously not been aware that the camshafts had ever been replaced.

Engines (2) Cylinders

Before looking into the cylinder tops, a brief digression. I've occasionally been asked about the four 'pips' on top of 7109's engine cowling; some enquirers had assumed these were a peculiar type of chimney where the smoke would rise from.

7109's four 'pips'

However, this is far from the case. In fact they are merely an adjunct to the cylinder covers to allow space for the top-of-cylinder automatic drain cocks. One wonders whether the 'pips' were an after-thought on the designer's part rather than a feature. Oddly enough, later designs did not have them!

Beneath each of the two covers is a pair of engine cylinders.

Rear engine's cylinders showing auto-drain cocks

When a lid is removed, inside it looks like this:...

Front engine RHS cylinder lid

... and inside the cylinder, it looks like this:

Front engine RHS cylinder

The muck is well stuck on and must have been there a long time. I've cleaned out some of it but it's hard to dislodge and will have to stay put.

The cylinder wall looks like this (the others are similar):

Front engine RHS cylinder wall

Some years ago, in my ignorance, I cleaned the cylinder walls with light machine oil. The variation in colour shows where I washed away the brown cylinder oil which probably would have been better left as it was.

On this occasion, however, I drenched the cylinder in new cylinder oil in preparation for running.

Guess who took the photo!

I did the same for all four cylinders, The piston is right at the bottom in the photo below.

Rear engine LHS cylinder

Finally, I got a bit arty and captured the picture below.

It was a fine day!

Then I put the cylinder lids back on as in the second picture from the top. Job done.

The rectangular holes in the cylinder walls are the steam inlet and outlet ports.

Engines (1) Oil Change

In a previous article, I'd begun to describe the engine oil change (but got distracted on to other oily activities!). Mid-July 2013, I did the oil change on both front and rear engines. The front engine had been topped-up with used (not too clean) crankcase oil (a rather unsuccessful attempt to fling it about by rotating the engine on compressed air. All I'd achieved was to introduce a load of sludge into the works!). The rear engine I'd drained off partly in 2009. I hate to imagine when the last oil change had taken place!

Oil filler 'cap'

Like on most internal combustion engines, there is an oil filler 'cap'. I'd read that each engine needed 10 gallons of crankcase oil so enough had been bought earlier back in 2010 (when I thought it might take less than a year to get 7109 back to life - How wrong I was!).

The crankcase oil is Hallett's Sentinel Crankcase Oil SCC680. It is a viscous oil (ISO 680) and has the specific property of enabling water to separate from it and readily sink to the bottom where there is a drain valve to let it out. This water separation property is important with a Sentinel steam engine which inevitably encounters condensation in the crankcase. (Morris Lubricants also make an equivalent crankcase oil for Sentinels).

Expecting to use 10 gallons per engine, I decided I would log the amount added against the level indicated on the dipstick.

I filled the front engine first with these results:

1 gallon: Not on dipstick.
2 gallons: 1/4 on dipstick.
3 gallons: almost 1/2 on dipstick.

I added a couple of extra litres to make it 1/2 full. (I like to mix imperial and metric units!).

Then the rear engine:

1 gallon: 1/2 on dipstick!

Oddly, I didn't expect this as none had been added since emptying.

So why did the rear engine need 1 gallon and the front 3 gallons to be half full? Simply, I don't know! However, I have to conclude that there must be something that isn't oil also in the rear engine (which was the one without the sludge added!).

Perhaps inadvisedly, I'm not going to investigate this further for now but monitor it very carefully when initial testing begins.

As yet, I also don't know whether is it is best to fill to the top of the dipstick or not. At least there is some spare oil available!

Oil Out, Rained Off, Oil In

After my last attempt to prevent oil leaking out of the front engine's cam-shift shaft oil chamber, I set out to cure the leak with a gasket of 1.5 mm rubberised cork sheeting.

The offending leak area is shown below in an old photo of the rear engine (which means I probably have a leak on that too!).

Oil Chamber Leak

First a little background: I poked my camera around underneath a Super Sentinel waggon at the 2013 Langport steam rally recently. Sentinel 7109 has very similar engines to the Super Waggon but mounted vertically instead of horizontally beneath the waggon's load platform.

I found the method of moving the camshaft to be quite different on the waggon. Chronologically, the waggon came first so Sentinel 7109's engines are an adaptation of the original approach.

The waggon used the 7109 oil chamber filler location to attach the shaft rotation lever, unlike Sentinel 7109 which has the lever on the end of the shaft.

Waggon shaft rotation technique

This is how it works: (Also on YouTube). Apologies for the background commentary!

Sentinel 7109, instead of having the waggon's rotating sleeve (which did not have to retain oil), has a clamp on sleeve, originally without a gasket.

Clamp on sleeve detached

View to the left...

...and to the right

For my second attempt at sealing the chamber, I painted a 2.75" x 11.75" rubberised cork strip with Heldite and wrapped it around the centre section, secured it in place at the top with gaffer tape and tightened the sleeve over it.

And here's what it looks like:

Attempt No. 2 with rubberised cork gasket

The proof of the pudding is in the filling with oil so that's what I did next but initially with an unexpected surprise.

Not so easy to fill; gasket a bit too effective!

Of course, I hadn't thought that the gasket would also be blocking the filler! Undeterred, I tried the hi-tech solution and jabbed it with a screwdriver.

Hi-tech solution...

...Now holding oil

About half a day later, I took this photo:

No leaks this time (after half a day)

So it looks like I've won this time round!

[Postscript: About a week later there was slight leakage - but not enough to worry about!]

Despite my early difficulties here, Sentinel obviously had faith in the method as they were still using it in post-war locos, the latest I've found it on was built in 1958 (Sentinel 9622).

In 2008, I took this picture of William's engine at Elsecar. (Sentinel 9599 built 1956).

William's Oil Chamber Sleeve

The sleeve is up from and to the right of centre. And guess what? It leaks too (unlike the modified 7109 version, attempt 2)!

Oil Out, Oil In, Oil Out

With the July 2013 heatwave has come the opportunity to do an oil change and refill; the hot weather makes the oil less viscous and hence easier to drain.

Oil Sump Drain Valve

Draining the engines was fairly easy although the drain valves need to be removed completely to get a reasonable flow rate. (The valves are mainly used to drain off condensate that has settled below the oil).

I then began to fill the other oil chambers including the one below which lubricates the shaft used to move the camshafts axially.

Oil Filler (and Emptyer!)

It was easy to get the oil in through the filler hole (with the hex screw-head showing) using a small funnel. Unfortunately, I soon found that there were leaks around where the filler hole support meets the left and right castings.

I loosened the filler hole support and cleaned all the mating surfaces which should provide the seal. I then slapped (technical term!) a load of Heldite on the surfaces and screwed it together again - tightly.

After a while, despite considerable care, I refilled the oil and ... you guessed it, it was no improvement from before and now there is the Heldite in the gap also around where the oil is leaking.

I'm forming the opinion that this was perhaps not one of Sentinel's best designs unless there was originally a gasket present.

Looks like I have an extra task ahead to make an almost cylindrical gasket to wrap around the joint; otherwise, oil consumption will not be a strong point!

Camshaft Surface Finish (1)

In April 2009, I first began investigating Sentinel 7109's engines. The reverser lever was seized so I started tracing the cause (and this is actually why I got so interested in the subject of Sentinels in the first place).

Initially, I found on both engines that the cam followers (the things that actually rub against the camshaft surface and push on the push-rods) were stuck fast as the oil on them had dried over the years and set like varnish.

However, the main problem bothering me was the corrosion at the end of the rear engine's camshaft in the cavity where the cam-selection finger is located.

The following photo shows how it looked in 2009.

Camshaft surface in April 2009

Ironically, I used diesel fuel to remove the corrosion (sad that diesel has to be used to repair steam equipment!).

It now looks a lot tidier as in the photo below.

Camshaft surface in April 2013

The surface was still not very smooth so I made enquiries as to whether this level of roughness was going to be a problem.

I was reassured that, so long as there was nothing standing proud of the surface, then there should be no problem as crankcase oil is so thick that it will be able to protect any pitting from causing trouble.

This was a considerable relief as I had envisaged having to take the whole caboodle apart for re-machining.

To remove anything standing proud of the surface, the easiest way is to turn the engine using compressed air and hold a file (gently!) against the roughness as if using a lathe - a lot easier than taking it all apart!