It's Hornblock Time Again....

After going slightly astray on its travels between Dudley and Aviemore we found the newly machined LH Driving Hornblock when an Inverness courier phoned Keith Holyland on 12th April and asked if this large pallet-load addressed to the Strathspey Railway Company was urgent.....!

Having got the necessary confirmation it arrived at Aviemore Shed a couple of hours later and there were the old and new hornblocks. So here we go again with a tale of lifting, marking, drilling (and reaming yet to come)....

Arrival at last...Keith Holyland admires the newly arrived hornblock package. Forklift driven by Nathan Lightowler.

With CR828 looking on with interest Dave Green steadies the newly machined hornblock and checks out the excellent finish achieved by Harco Engineering

Shunting by JCB.....Colin Vaughan and Dave Green get the old girl out of the shed in readiness for the first trial fit of the new hornblock. Absence of buffers and any loco brake makes this a somewhat delicate operation - but no problem - the scotches are safely in  position.

A study in wheels.....

Lifting the hornblock under the loco. Forklifts and pallets are wonderful inventions...

Using the pallet as a working platform Dave Green steadies the precisely-cut wooden block that gives the forklift enough height to lift the casting into the correct position..

After a bit of filing on the frame horns the hornblock lifted nicely into position and we clamped it against the frames to allow marking out of the initial four holes for the temporary bolts that would then allow all 22 holes to be marked out..

In the machine shop on the big radial arm drill the hornblock complete with four holes scribed into the marking paint waits on Nathan getting to work..

Nathan clamping the hornblock to the drilling machine table...

The scene a few hours later after refitting the hornblock to the loco with the four temporary bolts and marking out all the bolt holes. Nathan has generated a huge pile of swarf and the casting has its bolt holes...

With the loco back in the shed the hornblock is firmly jacked and bolted into position and all the bolt holes have been formed...next job is to commence reaming the holes truly circular and parallel. This is the view from inside the frames. Once we have reamed all of the holes the hornblock will be taken off again to allow the inner face to be skimmed to provide a true seating for the nuts. We also have to fit the new hornclip to the bottom of the hornblock and check the fit of the axlebox...

The view from outside the frames. Three of the four temporary bolts can be seen

A lovely picture of CR828 during her visit to the Severn Valley Railway a few years ago. She was seen by many people as the star attraction of the 2011 Autumn Gala (Notwithstanding the presence of "Tornado"). The perfect condition of the loco is a great credit to the Strathspey Railway Company "Minders" who stayed with her and made sure the loco was properly looked after and operated correctly. Picture by Mr David Wilcock.

Blue Fingers......

Progress on CR 828 at Aviemore in the last week has been mainly focused on scraping of big end bearings resulting in a set of fingers deeply ingrained with engineers blue...interspersed with some blood when the sharpness of one of the scrapers was proved. ...

Off site Harco Engineering Ltd made great progress with machining the new Hornblock casting and it is due back at Aviemore around April 11th.

Dr HJC (Campbell) Cornwell, former SRC Chairman and former Chairman of the SLPTF (owners of CR 828) and the leading authority on CR locos from the 1880s until the Grouping in 1923 kindly provided copies of the drawings for the eccentrics and straps. This will be very useful when Nathan machines the components and Alan French relines the straps with white metal.

On the table at Harco Engineering - the new LH Driving Hornblock receives the attention of the CNC milling machine

A close shave....

Beautiful finish......it will be a shame to get it dirty...!

The Neilson Reid drawing of the 812 Class Eccentrics and Straps supplied by Campbell Cornwell. The Caley built 812 - 828 themselves at St Rollox and contracted Neilson Reid to build 829 - 848 at the Hyde Park Works in Springburn. The St Rollox drawings may not have survived but fortunately those developed by Neilson Reid have...!

Back half of the LH Big End bearing....one patch was very reluctant to come into contact...and the horridly sharp triangular scraper is hoping for another chance...!

The LH Big End bearing in the "secret" 828 cupboard in Aviemore Shed

A place of greater safety....original and new safety valves stand alongside each other dreaming of high pressure steam...

The old girl in the 1990s in her light blue Caley livery. Charging out of Kinchurdy Cutting in the days of ash ballast and wooden sleepers...long since upgraded to stone ballast and concrete sleepers.

Just for fun - a rare double header on the Strathspey Railway. In September 2011we had some Friday evening fun with a special working for Members and Friends. Here we are at Croftnahaven with Outdoor Superintendent G McNair giving directions to the late (and much missed) Driver Graham Elkin on CR 828. Driver John Greig on 46512 EV Cooper Engineer waits patiently with his loco in mid gear.....the photographers take it all in...! Something we could do with repeating....??

The scene we want to see again soon.....CR 828 rolls into Boat of Garten (strangely deserted) on a June day in 2010.

Scraping Through....

Activity on CR828 in the last few days has included a lot of scraping of white metal (thanks Nathan Lightowler and Benny McInnes) ; removal of brake rigging from the tender (thanks Dave Green); blanking off of the boiler safety valves (thanks again Dave Green) and some reflection on the process of white metalling the eccentric straps (thanks to Alan French). The front buffers have been removed to allow renewal of the wooden packing plates that lie beneath them. The C&W Dept is helping with the production of the new plates.

Further afield Harco Engineering have set up the new LH Hornblock casting on their appropriately sized milling / boring machine. They will turn the job round pretty quickly and we should have the component back at Aviemore in a week or so. Then we'll have the fun of fitting it to the frames..!

The new LH Hornblock casting on the table at Harco Engineering. On our machine at Aviemore it looked huge; here it looks a bit diminished...

The wonders of CNC machining.....! Punch in the code and go and have a cup of tea....??

Front buffers removed to allow renewal of wooden packing plates (one of the old ones is on the front buffer beam). But why did the Caley fit packing plates..? Because the dimensions of couplings were altered after 828 was built and the new standard required the buffers to protrude further.

Old friends reunited. Mr Graham King, the man who returned 828 to operation in the early 90s after she had slumbered for 30 years stands beside his former charge. A combined age of 197 years and both still capable of a hard day's work...!

Following some final electrical work on 30/03 by Paul Blount the lathe was returned to operation. Nathan Lightowler machines the bore of the RH Big End bearing (and catches the valuable white metal swarf in a strategically positioned bucket.

Scrapers at the ready to tackle the LH Big End

Scraping underway. It takes a while because of the generous radii at the end of the crankpin. The bearing has to be bedded onto the radii before it comes into contact with the parallel portion of the pin.

The RH Big End fully fitted to its crankpin and temporarily held together by a special clamping tool. Great work by Nathan and Bennie in getting the fit achieved.

The tender minus its brake rigging thanks to Dave Green. Also in the picture is the horrid spring that forms part of the drawbar between loco and tender. A very bad joke perpetuated by JF MacIntosh on the CR fitting staff. If anyone wants to find out why you are welcome to come along and refit it when the tender is recouped to the loco...

Not 828 but a very nice picture from 30/03 by Dave Green showing 46512 doing what we expect 828 to be doing in a couple of months.....

You have to be a bit eccentric...

During the week commencing 21/03 there was quite a bit of activity on CR828. Work continued on the boiler to get it ready for the hydraulic test requested by the Boiler Inspector. All we need now is the pair of large blanks required to blank off the safety valve mountings and we'll be good to go.

The crankaxle has had a lot of attention. Colin Boyd measured up the crankpins for ovality and parallelism. We knew from the previous overhaul that the RH pin is slightly tapered (for reasons unknown) and Colin confirmed that this is still the case. Now that we have the sizes Nathan will be able to machine the big end bearings to size and then we can get them scraped in to the required fit.

For the first time in more than half a century the eccentric sheaves have been removed from the crank axle. This is not a job for the fainthearted but Alan French made up an excellent special tool that allows the square headed clamping screws to be accessed deep inside the eccentric castings. The castings are a beautiful piece of 19th Century workmanship but they are heavy....very heavy..! Once the sheaves were removed it was a matter of cleaning them up and then reassembling them so they can be checked for wear. Three out of the four were found to be surprisingly unworn but the RH forward eccentric is the exception and shows about 0.037" of ovality. So that we give the newly white-metalled eccentric straps the best start in life all of the eccentric sheaves will be mounted on a mandrel in the big lathe and skimmed back to full circularity. There is therefore a lot of lathe work coming up in the next couple of weeks...

Removing the gauge glasses in preparation for the boiler hydraulic test. The regulator handle will need a lot of polishing before 828 goes back into service.....

View looking into the smokebox during replacement of the five washout plugs. JF MacIntosh designed the Dunalastair boiler to generate large volumes of steam (828 has a Dunalastair I boiler and Dunalastair II cylinders and motion) and the number of boiler tubes testifies to this...not much room for water...!

A grubby hand inserts the rearmost fusible plug into the roof of the firebox.....the firebox has two fusible plugs, the purpose of which is to alert the footplate crew to very low water level in the boiler. The plugs are hollow and lined with lead. At normal water levels the lead is kept relatively cool. If the water level gets too low the lead quickly overheats, melts and is blown out of the body of the plug. This is followed by a jet of steam and water blowing out into the firebox. This immediately alerts the crew who should take appropriate action to try and increase the water level as quickly as possible. At the subsequent official enquiry the Driver and Fireman will have a lot of explaining to do.....!!!

Removing the gauge glass fittings requires some special tools......!

Bothe gauge glasses removed and blank flanges fitted for the hydraulic test

Concentrating hard - Colin Boyd is using a large micrometer to record very accurate measurements on the RH Crankpin. JF MacIntosh sized the bearing surfaces very generously on his locomotives. The crankpins on 828 are 8 inches in diameter. It was features like this that made the MacIntosh locomotives perform so satisfactorily and achieve such long lives.

The Caledonian Railway in MacIntosh's days preferred to build their locos with inside cylinders. This gave greater stability and reduced wear and tear on the track (outside cylinder locos have a tendency to sway from side to side under the power impulses from the pistons). The price for this was the requirement for a very complex crank axle. The Caley used a variety of types of crank axle but by 1899 when 828 was built they used fully built up steel axles. Because these were very costly and time consuming to manufacture they were bought-in from outside contractors. Here, on one of 828's RH crankwebs we see the identification number that allowed the Caley (or LMS) to trace the manufacturing records of this particular axle. Note also the highly polished surface of the journal for the axlebox bearing.

Crank axle with the RH Eccentric Sheaves removed. The LH Eccentrics are still in place. The leftmost of the two is the eccentric that gives forward motion; the other one gives backward motion. 

The crankaxle with both sets of eccentric sheaves removed. As a "fully built" axle it consists of nine individual parts pressed and dowelled together. Manufacturing a replacement would be horrifyingly expensive today....!

One half of the LH eccentric sheaves being cleaned in the Shed's parts cleaner - a very useful piece of equipment indeed.

Both sets of eccentric sheaves on the bench at the north end of the shed. It takes three people to lift them when they are assembled. Nathan Lightowler is measuring the diameter at 90 degree intervals so that we can check for wear.

Reaming, Reaming, Reaming.....

This week's work on CR 828 has been mainly about reaming bolt holes and trying to avoid as many steel skelfs as possible... Nathan Lightowler has also been very busy machining fitted bolts for the RH Driving Hornblock. He's also progressed the machining of the new steel casting for the LH Driving Hornblock. We had a bit of a disappointment when it became clear that despite Nathan's very best efforts the Shed milling machine just doesn't have the capacity to handle the new horn block. So rather than struggle on and perhaps get an unsatisfactory result we took the decision to send the casting out to a suitable third party machine shop. The silver lining to this particular cloud is that it frees Nathan to tackle the machining of the big end bearings and the eccentric straps. We plan to crack on with this during week commencing Monday 21st March. Once the machining is complete there will be a lot of hand fitting to get the components bedded properly to their respective crank pins and eccentric sheaves.

A welcome sight..! The RH Driving Hornblock now fully bolted to the frames. The new bolts were made a slight interference fit and then driven into the holes using a seven pound long handled hammer. Hopefully it will be a long time until they are next removed...!

With the RH Hornblock refitted it was time to make a start on truing-up the holes in the LH Driving Horn where we had to make a weld repair to a crack that ran through several bolt holes. The Welder did a great job in trying to preserve the holes during the repair and it was possible to ease them back into a circular section with some filing and then the trusty reamer. There will be no need to anything more here until the horn block casting is lifted into position.

All the holes in the leading edge of the horn are now reamed circular and to the same size...

This object is the horn clip that bolts onto the underside of the RH Driving horn. It has two main functions. 1) It ties the open ends of the horn block together to give the structural rigidity necessary to resist the powerful thrusts of 828's 18 1/2" pistons. 2) It transmits the weight of the locomotive to the suspension springs on the crankaxle. In total the crankaxle carries about 18 tons of the loco's weight so the horn clips on either side of the loco carry about 9 tons each. The circular holes in the clip are for the spring hanger pins that connect to the axlebox. In this view we are looking at the top surface of the clip. The square holes at each end are for the studs that carry the large nuts that clamp the clip to the hornblock. 

This view shows the side and the bottom of the clip. The seatings for the springs are the two large circular recesses. The clip weighs about 35kg and is made of cast steel. It looks a strange colour because it had just been removed from the Shed sandblaster. We decided that it would be a good idea to get two new clips made and these will be produced in the next week or so by Blantyre Castings who manufactured the new horn block a few weeks ago.  

  

The weather in Strathspey was very sunny and warm during the week and here is our old friend enjoying a view of the Spring sunshine......hopefully it won't be too long till she'll be back out enjoying it....

Let's get these bolts fitted...

Quite a lot of progress with 828 in the last few days. Most of the attention has been on the RH Driving Hornblock where we need to true up the bolt holes in the frame and the horn block casting. One disadvantage of inside cylinder locos is that the piston thrusts are transmitted through the axleboxes and the hornblocks. On a loco like 828 each piston thrust may be as much as 12 tons so the bolts need to be a tight fit. Because the bolt holes have been progressively opened out at different times in the long life of the loco it's important that we remove as little metal as possible when truing up the holes. This meant that it's better to do it with an expandable (adjustable) reamer driven by hand. It is excellent exercise....then having reamed the holes truly circular and parallel we need to make up bolts that are a very precise fit in the holes. The bolts need to be slightly bigger than the holes and driven into place using a heavy hammer. In our case the bolts, properly known as fitted bolts, are manufactured in the shed machine shop by Mr Nathan Lightowler who can turn them up from hexagonal bar stock in a very short time - and every one is a perfect fit...!

John Greig has carried on white-metalling the remaining eccentric straps and these are now all ready for machining in the lathe and then hand-fitting them to their respective eccentrics. The eccentrics themselves will need to be dressed and polished to ensure there are no rough surfaces to tear the white metal.

Starting to ream out the bolt holes with an expandable reamer and a big tap wrench...

eight holes reamed circular and parallel ready for the fitted bolts.

Nathan Lightowler machining the first of the fitted bolts......only 43 to go after this one, Nathan...!

The first fitted bolt alongside my calibrated lunchtime orange...

The first eight bolts driven home.....

The hammer that drove the bolts home.....they are a tight fit...!

View of the bolts from inside the frames...

Crankaxle moved down to the machine shop awaiting fitting of the big end bearings and the eccentric straps - all newly white-metalled by John Greig

General view from the new mezzanine floor...828 crankaxle, 5025 bogie and main springs plus No.17 "Braeriach" just crying out to be converted into the 0-6-2T that Eric Cooper had always intended....!!!!!