Mini-Project........

Further improvements to my two Flangeway independent snowploughs in support of a twin DRS Class 37 motive power version of the snowtrain.

 

Introduction:

I came across the photo below on the Network Rail website.... and it prompted me to consider a few updates to my ploughs (and maybe also the 37s) to achieve a more reliable and more interesting snowtrain for the loft layout.

 

A real twin DRS Class 37 Snowtrain pausing between snow clearance activities. (Evocative downloadable image from the Network Rail website.)

 

The Problems:

The Flangeway ploughs have a few minor inaccuracies, but in general are a good representation of the independent ploughs positioned strategically around the country, ready for action in case of heavy snowfall.

I added some working lights in an attempt to make the original snowtrain look more impressive. However not all aspects of the original lighting worked well! The attempt at a rotary flashing beacon was a bit of a disaster and the wheel contact continuity is ..... shall we say .... "variable", particularly on the lead plough.

Also, the ploughs are not my most reliable of rolling stock. In particular, the lead plough is prone to derailment when running over the curved track on some of my turn-outs, even at fairly slow speed.

 

Independent snow plough parked next to the Network Rail Depot at York Railway Station

 

Possible improvement opportunities to be investigated:

1) The de-railing risk & poor wheel contact reliability may both be at least partly due to inadequate weight over the front plough wheels. Opportunities to remedy this are high on the priority hit list & a bottle of "liquid gravity" is on the way!

2) If the new weighting arrangements don't dramatically reduce light flicker due to improved wheel pick-up performance, but do increase the available internal space, I'll first try adding stay alive capacitance as an anti-flicker technique. Plan B is to add electrical links to the class 37 wheel contact wiring via sub-miniature connectors. 

3) The lack of a tension lock coupler on the lead Class 37 opens up the opportunity to remove the lead plough tension lock and to somehow close couple the lead plough to the lead 37. (Perhaps using the wheel contact connectors?)

4) The rotary flashing beacons will be replaced by a pair of amber double strobe LEDs placed below and just behind the leading edge of the icicle cutter on the plough roof. The headlights mounted high on the prow of the ploughs are also completely imaginary, but are brighter and less prone to snow coverage than the real battery powered lamps like the one visible in the photo above. Such imaginary headlight assemblies could also incorporate snow wipers and a low light TV camera with monitor in the lead loco cab?

5) The second plough needs to receive Network Rail labelling and both ploughs need reprogramming to simplify their inclusion in the snowtrain consist, plus their addition to the PC software locomotive listings for the same reason.

6) Finally, it would be good to add some scale snow to the front of the ploughs and if it can be effectively removed, a touch on the locos would add extra realism!      

 

Improving weight distribution:

The moulded plastic weight fills the upper body of the plough. Appropriate application of the much denser "liquid gravity" ballast technique should free up a lot of volume in the upper body.

Substituting carefully positioned liquid gravity ballast weight in place of the original moulded

22gm plastic weight, may free-up sufficient room to fit  stay-alive capacitor(s). A weight bay will also

be created at the front of the underframe to increase the loading on the front wheels

 

40 gm substitute liquid gravity weight leaves room above for a 1000uF 25V capacitor.

 

More liquid gravity positioned under the plough front.

 

Anti-flicker circuit:

A 1000uF 25V will fit, but I doubt that this is enough to keep the entire FL4 circuit powered up for around a second, so instead, the stay alive capacitor will support a constant current source driving only the headlight, under FL4 control. (The rear light and strobe lights operate in a flash sequence, which should not be so obviously disturbed by occasional brown outs.)

 

Headlight only anti-flicker circuit.

Well,  the anti-flicker headlight circuit works pretty well! Its running a little over 5mA into the LED which stays fairly steady from 14V down to around 5V. Which takes around 2 seconds after removing the power.

 

Programming the FL4:

Description CV Value
Temporary addresses (different for lead & rear ploughs to allow independent simultaneous movements of each plough) 1 8 lead, 9 rear
Green wire - continuous, [forward only lead plough; reverse only rear plough] 51 0 lead; 16 rear
Purple wire - continuous, [reverse only lead plough; forward only rear plough] 52 16 lead; 0 rear
Brown wire - double strobe, both directions 53 37
     
Green wire - button assignment       F0 35 1
Green wire - button assignment       F0 37 0
     
Purple wire button assignment       F0 36 2
Purple wire button assignment       F0 38 0
     
Brown wire button assignment       F2 39 8
Brown wire button assignment       F2 41 0
     
Strobe timing:    
on duration                              (0-255) 147 default
short off duration                     (0-255) 148 default
long off duration                      (0-255) 146 default

All working! ....... rear plough detail now also provided)

 

Testing the updated plough:

1) Stability on the track:

This is improved significantly! With around 30gm of extra weight and better distribution, including new dedicated weight at the front of the plough, the vehicle can be pushed or pulled at speed around the test track with no sign of any derailment tendencies.

2) Electrical pick-up reliability:

Not such a positive result in this area: Initial results were good, but then contact would be lost and there appeared to be a reluctance for contact to be re-established. (I suspect oxidation problems on the back of the wheels maybe to blame.) After stiffening up the contacts on the front wheels, performance improved dramatically, but occasional brown outs still occur.

3) Lighting behaviour:

The new strobes work well..... with an intensity (in common with the headlight beam) that should be visible in the next county, even through driving snow!!!!  The headlight anti-flicker holds up the beam solidly for around 2 seconds after a power disconnect. The rear light pulses away at the required 2 Hz repetition rate.

 

Next steps:

Electrical pick-up reliability is (I think) still compromised by the poor surface conductivity of the wheel back plates. I have decided to fit a miniature 2 way socket to the front bogie underside of the lead Class 37 locomotive. This will be connected to the right and left front bogie wheel contact conductors. A corresponding flying lead 2 way plug will be attached to the rear of the plough, connected to the corresponding plough wheel contacts. The cable will be arranged so that the length can be fine tuned to close couple plough and locomotive via the tension in the cable.

 

New electro-mechanical coupling arrangements:

Two way TCS miniature socket, glued to the underside of the lead Class 37 front bogie and wired to the wheel contacts.

 

The flying lead of the corresponding plug is attached to the rear of the plough, via an adjustable clamp, to optimise the cable length.

 

Showing the plough coupled to the Lead Class 37:

There is now not even the least hint of flicker from the headlight.

 

With the original tension lock coupler removed and the flying lead providing the required tension during reverse movements, much more realistic close coupling is achieved! I just need to keep the lead short enough to stop it dragging on the track!

 

 

Modifying the second plough:

1) Detail of the main ballast weight construction

The custom shaped ballast weight for the second plough was built as a result of experience gained when making the first weight!  Layered filling ensured that the liquid gravity balls were all securely glued together in one hit this time. The central tunnel ensured that no leakage of the tiny metal balls can occur on the second unit. Finally, a slightly looser fit eased the re-assembly process considerably.

The weight box is constructed using 0.5mm plasticard sheet with central tunnel made from 0.2mm sheet, rolled into a cylinder.

The extended side pieces create a vertical shaft through which the wiring from the capacitor assembly and roof strobes can access the underbody circuit assembly.

 

Liquid gravity balls are added in layers of around 5mm thick and then soaked in Roket card glue. After tamping down, the next layer is added and more glue applied. Until the level reaches a little below the top of the weight box sides. The assembly is then left overnight to dry out thoroughly and finally the top plate is glued in place.

 

The top is bonded in position with liquid poly, and the crack was filled, sealing the box, using Glu n' Glaze.

 

 

Testing the second plough:

It was no surprise to find that occasional wheel contact problems were also apparent on the second plough, mainly when the train stopped. Otherwise, all worked well.

Next steps:

As this unit will be pulled within the snowtrain with only occasional pushing during reverse manoeuvres, I will retain the tension lock coupler. But I will fit another miniature two way connector to the rear bogie of the rear Class 37, which will provide track contact feeds to the plough, without this time also needing to provide mechanical tension. The socket will just fit diagonally on to the bogie underside,  between the end axle housing and the tension lock coupler. The flying lead from the plough passes over the small Class 37 snowplough blade, which hides the plug and socket from view.

 

Need to take a little more length out of the cable & paint the nose weight sidewall on the front of the plough, black !

 

Completely reliable lights now!

 

Adding to the computer:

I finally found the correct way to enter non-motorised rolling stock into the computer listings after initially erroneously entering the ploughs as unpowered locomotives. The warnings that with zero engine power and a weight of several tons, the "loco" could not achieve its specified maximum speed, was a bit of a clue!!!!

However,  I soon discovered that train controller software unpowered rolling stock function control, does NOT include the concept of direction (essential for the plough directional lighting) so I had to revert to the unpowered zero weight locomotive approach after all !

 

Next steps:

I'm generating schedules that initially move 37606 + the rear plough, simultaneously with 37605 + the lead plough, to clear the yard (aka the test track). These two consists then combine to form the full snowtrain, and after a slow pass, the train heads out to deal with the drifts!  .......Youtube video to follow!

 

For the YouTube video, please click here

 

 

Supplier website links:

 

Digitrains    Source of pre-wired chip LEDs used for the new strobe lights.
DCC Supplies    Source of "Liquid gravity" and miniature connectors.
Maplin    Convenient local source for capacitors.

 

 

 

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