Motorised Points 22

 In a previous post Curly alluded to work being done on Motor Point 22 at Toddington.  Here is a bit more detail of what goes on with a motorised set of points.

On the GWR we now exclusively use Alstom HW point machines.  These are a fairly simple and robust machine and were (still are) in wholesale use over the national network.  The photo below shows the machine fitted to Points 22.

The machine sits on two timbers and is bolted through them.  The 'business end' of the machine is bolted through the sole or gauge plate (along with the rail chairs that hold the toes of the point switches) and this ensures that none of those can move relative to the other, thus keeping the toe of the points at the correct gauge and the machine at the same distance from them.  The machine is connected to the points by four bars:  The first and heaviest is the drive bar, this links the drive stretcher of the points to the drive portion of the machine and this is the first part that we set up.  The machine has a throw of about 150mm which is not adjustable, the points would normally have movement of 105mm to 110mm between the two positions.  In order to couple these two movements together we use an item called a basket, which is a block through which the drive bar goes.  On the Drive Bar, either side of the Basket, is a drive nut and lock nut, these are adjusted tight for each position of the points, allowing the drive bar an amount of free movement before picking up the points and moving them.  This is the first job in setting up the machine and is achieved by hand winding the machine between the two positions until the blades have been set correctly.  The second bar connects the Lock Stretcher (a bar which connects the toes of both blades together) to the facing point lock within the machine.  The purpose of this stretcher and bar is to lock the points safely in one or other of the correct positions and this is the next part that we set up.

When the machine is operated from one points position to another a clever set of cranks and gears (unfortunately hidden beneath covers in the photo above) take the machine through three distinct stages: 1: disengage locking bolt, 2: move drive rod, 3: re-engage locking bolt.  The locking bolt is hidden (as is so much in these machines) under the contact block in the above photo.  It is removed and inserted into a slide which is connected to the locking bar from the points locking stretcher and as previously mentioned is the main safety device to hold the points correctly in either position.  This is adjusted to be only just clear when the points are fully over in each direction (there is a go/no go gauge which is slipped between to point blade and stock rail to set the tolerance).  This process is again done by hand winding the machine back and forth until the adjustment is correct.

Finally we have the two detector bars.  These are independently connected to each point blade toe and are a backup check to prove that the blade toes are in the correct positions (should the lock stretcher break or become detached at either end).  These detector rods are connected to two more slides in the machine which are underneath the contact block.  The astute of you will probably guess that the position of the closed blade on a point is very important, with little room for error, whereas there is far more tolerance in the open blade (just needs to be open enough not to foul the backs of the train's wheels) and this is the case with some slots in the slides connected to these bars.  For the position where the bar concerned with the slide has its blade closed there is a very accurate cut out in the slide, and we adjust the bar to position this correctly.  For when the blade associated with that bar is open, there is a big wide cut out which does not need further adjustment.

Having now set up all four bars correctly we come to the clever bit with the contacts.  The contact block has a set of contacts down each side and in the middle a rocking contact mechanism.  This mechanism sits on two sets of rollers, one down each side, and is held down by a strong spring.  When the locking block is correctly inserted and the detector slides are correctly aligned then all the rollers on one side of the contact mechanism are presented with cut outs below them, and the mechanism rocks to one side, thus making those contacts.  These contacts control three main things, motor power, clutch power and detection of position.  The detection contacts operate relays under the signal box, showing the position of the points and releasing signals which may be cleared when the points are set in that direction.  The motor and clutch contacts control the operation of the machine from one position to the other.  Correct detection of the opposite points position causes the contact mechanism to rock to the opposite side and operate the opposite set of contacts.

Once the machine is correctly set up then the winding handle can be removed and the machine operated electrically.  The winding handle inserts through three aligned holes in plates attached to the machine body, the inserting of the handle and aligning of these holes operates a switch which disconnects the power to the motor.  This is a safety mechanism to prevent injury to the operator.  The switch is reset by pressing a release button after the handle has been removed.

I hope the above isn't too wordy and gives a rough idea of how one of these machines work.  We've re-installed three of these post the winter works.

Neil C.

Joint Venture

 I took advantage of the nice weather on Monday to fix a wet/noisy cable joint which had been causing problems with the Gotherington internal phone extension.  Nowadays we try to buy and install cables in the correct length to span between cabinets, so that the joints are well above ground, in the dry and only occur where cable access is required.  However, in the old days we often acquired second hand cable in varying lengths and this needed jointing far more frequently.  My predecessor on the S&T electrics side was fond of joining cables in what he called 'Trough Joints' (a crimped joint in a drainpipe inside a length of S&T trough) or a 'Coffin Joint' (a crimped joint in a brick box on the ground with a lid of some sort).  Whilst these joints served a purpose they suffered from rodents nesting in them (and eating the cable grease and insulation) and water ingress.  This inevitably led to cable failures and noisy phone lines.  I have gradually been removing these joints, either by cable replacement or repair.  The cable from Far Stanley Cabinet to Gotherington Box was one of the last he installed and that had a coffin joint just short of Gotherington platform.  The inevitable rodent damage had occurred and the phone line to the Gotherington Box internal phone had gone low impedance to ground, tripping the exchange.  This joint is just a straight joint in a 10 pair grease filled cable, nothing joins or leaves the cable here, so I decided to try an experiment.  I cut the rather moth eaten ends off both cables, cleaned off the grease, remade the joint with new crimps and then 'potted' it in a standard mains resin joint case (see photo).  This joint is now sealed for life and is rodent and moisture proof.  Let's hope it does the job.  The Gotherington phone line is certainly back to normal. 

Now that the joint has set I have dropped it back into the brick coffin and replaced the metal lid.

Neil C.

A Lot of Finishing Off To Do

 Tuesday 8th March

Off once again to Toddington to continue with all the re-connections associated with the new pointwork south of the station.

Firstly the replacement of the signal wire stakes. These are hammered into the ballast and then firmed up with a bit of concrete. Eight of these to do.

Malcolm W spent most of the day re-jointing signal wires - of which there are many - we estimated that about 50 joints are required. He ended up with some fairly rough and sore fingers.

I may have described these joints in a past blog but here is a quick teminder. The wire is threaded through a thimble and cut off leaving about six inches protruding.  Each of the seven strands of wire is then teased out and then sequentially wound round the entry wire. This gives a very reliable joint which will not give . 

Malcolm's knees also taking a pounding, not the best position for doing this!

Because the new pointwork is now in a different position most of the concrete blocks  supporting the angle cranks have to be moved - so some more serious ballast digging to get them in the right position

And for the angle crank across to the points

This will need a bit of  cutting of point rodding to connect up but after a bit of block adjustment this should be OK.

One of the problems with unbolting  these fasteners which have been buried in these blocks for years is that you have to get a spanner inside a limited space  underneath to stop them from turning when you are trying to undo the nut on top. So the four blue nuts you can see holding the two bars here have  a welded strip on the bolt head underneath to prevent it turning.  

And unless you have a large enough clearance round the block,  ballast  keeps falling in to impede  access!

Neil C has been finishing off the wiring of the motor point and associated  connections at the north end of Toddington  station.

No photos I'm afraid but I am reliably informed that the motor point which was removed from Winchcombe adjacent to the embankment works (now completed) has now been put back and re-connected. Just a few more signal wire stakes to replace once the remainder of the contractors  access road adjacent to the track has been levelled. 

So fingers crossed for the weekend!!

Curly

PS  I have recently visited relations in Lancaster and have been made aware of an interesting project that is being launched later this year. This is a major investment planned for Morecambe to build a similar site comparable to the Eden Project in Cornwall called Eden Project North (could be part of the government's levelling agenda??)

Worth a look on www.edenproject.com

Fixing The Pulleys

 Tuesday 22nd Feb

Three of us today at Toddington on concreting duty.  Luckily an electric concrete mixer was available, so that made life much easier. 

We have two sets of six pulley wheels to fix in position. These direct the signal wires under and across the track to the detector and the bracket signal (two for the main arms and two for the call-on arms)

And finally the detector unit is positioned on its plinth. This is secured in the concrete with 4 bolts, the heads of which are sunk in. 

Neil C spent the day fitting and connecting new cables for the track circuits.

A shot of the tamper passing the signal box on its way to the North end of the station while we were having a tea break!

Curly

Mainly Digging

 Tuesday 15th Feb

Five of us off to a very wet Toddington today to continue with the re-fitting of rodding, etc. to the new pointwork south of the station.

Because it was so wet we had to postpone the mixing of concrete for preparing the bases for mounting the detector unit and pulley wheels - just made do with digging holes for the shuttering:

The rest of the day was spent digging in the concrete rodding stools. Quite a strenuous job getting into the fresh ballast and making sure that we kept a good alignment at a constant height relative to the track. 

We managed 7 stools before we decided to call it a day.

All the connections to the FPL have now been made - just needs a small modification to the locking  slots and some adjustment to the throw of the blades and its good to go.

Back in the signal box locking room Neil C has wrestled back into position the electric lock for lever 26 (the one with the mangled pen inside!). Space is extremely limited here and was a bit of a challenge getting it back in and bolted up. Its the one with the grey cover poking out.

Hoping for better weather next week - 

Curly

Toddington Refit

 Tuesday 8th Feb

All hands on deck now to get the new Toddington pointwork reconnected to detectors, signals, rodding, etc. So five of us off there with the diesel railcar trailer loaded for action.

There's quite a lot of work to do here now that the new  pointwork has been re-positioned.

John P and Neil C concentrated on refitting the FPL (lever 11) , stretchers and angle cranks , all of which needed a fair amount of drilling- some through steel and some through sleepers. 

We had taken the precaution of bringing the portable generator with us but we didn't need to use it as there  was , luckily, a mains connection in the adjacent pit and we had a nice long lead to oblige!

Note the multicoloured environment with the brand new yellow  stretchers! Note the insulated joints for track circuiting.

Meanwhile on the platform 2 side there was Malcolm W, John B  and myself dealing with the metal plates for mounting angle cranks onto concrete blocks which have been roughly positioned and need fine tuning to get everything in the right position .

Then followed the problem of getting the point rodding stools (most of which had been removed) back in perfect alignment relative to the track. So, forward with our hightec  equipment -- a large plank (remember the film with Eric Sykes and Tommy Cooper) with attached locating devices! This was very effective.

Getting the alignment of this angle crank to match up in both directions is proving a bit tricky with the mounting plate perilously close to a drain cover.

 

Most of the  concrete rodding stools that were removed to facilitate the track replacement have to be repositioned with freshly dug  holes in the ballast.

Work will continue with more of our colleagues tomorrow and Thursday . More serious shovelling to look forward to!

Curly

Unlocking the Lock

 Monday 7th Feb

The following is a detailed description of the resolution of a problem with an electric lock from Toddington signal box courtesy of Neil Carr.

For a while now the lever lock on lever 23 at Toddington controlling the point machine for the North siding has been intermittently sticking requiring the cover to be removed, and a brief bit of S & T assistance to the lock mechanism. Often the lock appeared stuck, but then freed when pulled manually  and worked happily once again.

Since the box is currently closed , whilst much point replacement work is happening, the chance was taken to unwire and remove the lock - a Tyers large lock with contract drum. That in itself isn't a five minute job, as there are many connections,  and the lock is well hidden behind the locking trays. These locks have more travel than a standard lock,  having several locking positions   and are driven directly from the lever via an actuating arm  clamped to the lever shaft; therefore they are usually found behind the normal locking and among the signal wires.

The lock was then brought back to the  S & T Coach to be stripped, cleaned and reassembled. 

Given that the lock intermittently jammed up, and then worked for a period once freed  I was expecting to find some dirt or swarf in the mechanism 

 What I actually found  amazed me. At some point in the last few years a signalman must have dropped a plastic pen down through one of the lever slots in the frame; against all odds this had bounced into the back of the lock mechanism and had been comprehensively chewed up by the locking bar moving up and down as the lever was operated. Now and then bits of plastic must have jammed in the lock bolt mechanism  preventing the solenoid from being able to pull the bolt from the lock. 

Whilst the lock was apart the entire mechanism was cleaned of old oil and rubbish ( and pen) the contacts on the contact drum were stripped and cleaned and the lock was set up correctly with the contacts all operating in the correct positions. It was then reassembled clean and dry of oil and grease

This photo gives a good idea of the physical size of these locks, the locking bar is just over a metre long.

Looking right to left we start with the top of the locking bar (they are mounted vertically) where the actuating arm from the lever attaches. Next we have the coli and lock closed connections, then the lock bolt itself , followed by the solenoid coil with the lock actuating arm above it. Energising the coil pulls the iron block at the left hand end of the coil tight to the coil, and via the arm withdrawsthe lock bolt from the locking bar. This locking bar has three positions; as shown it is locked in "Normal"   where the lever is normal in the frame and the points would lie in their normal position.  Underneath the coil you will see a very long slot cut in the bar, when the lock is energized, and the lever moved away from normal the bar is drawn towards the right ((in this picture , in reality it is lifted upeards) until the lock bolt drops into that long slot. The bar then continues its travel until the lefthand end of that long slot hits the lock bolt. The lever is then in the 'Reverse Check' position, and the contact for operating the points reverse is made.

Once the points have moved and been detected in reverse the lock will again energise (automatically via the ele trial locking) and allow the lever to be moved fully reverse  where it will again be locked

Moving from reverse to normal is the same procedure as above , only going the other way. 

The large casting on the left hand end of the lock body is the contact drum. This has a series of pairs of contacts over rotary contact rings, rotated via a gear wheel and a long angled slot in the locking bar. These contacr boxes can have many contact rings and many different lengths and positions of rings - allowing contacts to be made at various positions of the locking bar and for varying durations of its travel. 

An in-depth description of the varying contact combinations is probably touch detail for here, however, suffice it to say.that this contact drum is configured with four contact rings; providing contacts for the Normal, Normal Check, Reverse Check and Reverse lever positions.

The astute of you will however notice that this drum has eight sets of contacts, although only four are used. These locks can have drums which are much longer and can carryall least twice as many contact rings

I hope you found this Informative!

Curly ( on behalf of Neil Carr - S & T Electrical Engineer)