Lights for Independent Snow Ploughs.

 

 

Note that the smaller pictures can be enlarged by clicking on the images.

 

Introduction:

Having recently obtained a pair of Flangeway snow ploughs, to incorporate into a "snow train" powered by a pair of Class 66 locos, the question of appropriate lighting soon came to the fore.

The only hard evidence of modern snow plough train lighting I have found, are U-Tube film clips of fair weather training runs. However, the lights used for this purpose would not be effective when dealing with drifts on an operational snow clearing run, particularly at night. This webpage therefore adds some speculative lighting, intended to provide a powerful headlight on the leading plough, which doubles as a flashing rear light when the train goes into reverse. Additionally, an orange rotary safety light is mounted high on the roof of both ploughs, to provide visual warning if the headlight is unsighted or turned off to avoid dazzling manual snow clearing activities on points etc.

Flangeway Snow Plough before modification

Real World training lights:

I found two films of modern snow plough trains on U-Tube. Both films showed trains on fair weather training runs during daylight. A white portable Dorman headlamp unit was positioned on the lower right hand lamp bracket of the leading plough. A standard white Dorman style red flashing rear lamp was mounted on the lower left hand lamp bracket of the rear plough.

Dorman portable headlight

Dorman Portable flashing rear light

 

Extrapolating the Real World training lights to a speculative operational snow clearing solution:

When clearing snow, any lamps on the lower brackets would be subjected to an avalanche of moving snow whenever the plough hit a drift. A better operational lamp location would be the upper bracket, mounted just above the intersection of the plough blades.

The headlight intensity would need to be very bright, to push a beam through falling snow, so a new lamp assembly, larger than the standard Dorman portable 8W headlight, is proposed, with 9" diameter headlight. This unit also incorporates a flashing LED rear light operating at the standard 2 flashes per second repetition speed. Within my imaginary scenario, a change in the direction of movement of the train automatically switches between headlight and rear light modes dependent on the direction of the train controls. The lamp would be powered via heavy duty cables from the adjacent locomotive as the high headlamp power would preclude battery operation. There will be times when the headlamp becomes a liability e.g. when staff are working close to the front plough on manual snow clearing of points or other delicate track work. To provide visual warning of the train at such times, an additional rotary orange safety lamp is also fitted to the snow plough roof. 

 

 

Converting the new lighting concept into 1/76 scale reality:

A TCS FL4 decoder is fitted to each snowplough. Wheel contacts are added to the ploughs, picking up from the outer wheel sets only. The combined head and rear lights are constructed using tiny pre-wired red/white chip LED pairs, sourced from DCC Concepts via Bromsgrove Models. The rotary lamp is a 3mm diameter orange LED from Maplin. The decoder programming is used to activate the headlight in one direction or the rear light in the opposite direction via controller button zero. The rotary light is activated in either direction via button 1. The TCS "mars light" option is used to power the orange LED, simulating the varying light intensity of a rotary beacon style lamp. The TCS decoder flashing options are too slow for a UK rear light, which flashes at approx 2 times per second. So a hidden flashing 3mm LED, which switches at the correct rate is used in series with the rear light, using a continuous decoder output.

The circuit diagram and CV table below show the concept in more detail below.

 

 

Circuit diagram:

 

 

 

CV Programming Table for TCS FL4 Decoder:

Description

CV Number

Value

Front Plough (P1)

Rear Plough(P2)

Green wire to headlight,  on constantly,  forward only P1 & reverse only P2

51

0

16

Purple wire to rearlight,  on constantly,  reverse only P1 & forward only P2

52

16

0

Brown wire to orange rotary light, “Mars Light”,  both directions

53

34

34

Green wire switched via button zero:  P1 forward, P2 reverse

35

1

2

Purple wire switched via button zero:  P1 reverse, P2 forward

36

2

1

Brown wire switched via button one:  P1 & P2 both directions

39

3

4

 

 

 

Wheel contacts:

The wheel contacts are made using 1mm phosphor bronze strip from Albion Alloys. Two strips are used, mounted via super glue to plastikard blocks fixed to the chassis unit. (See photos below). The chassis unit can be removed from the snow plough by first unscrewing and removing the tension lock coupler. Next, the other two small screws are removed, enabling the chassis unit to be extracted from the plough body shell.  Additional structure is fabricated from plastikard to support the contact strip assembly.

The rear face of the snow plough wheels are covered in some form of non-conducting coating. This needs to be removed from the outside wheel sets by rotating the wheels with their back pressed into a piece of fine abrasion paper.  

 

Chassis removal

Extra plastikard decking & blocks fitted

(top view)

Wheel contacts glued to plastikard blocks

(underside view)

 

Head/Rear Light:

The new light assembly is made from three laminations of 1mm white plastikard, each with a 3mm diameter hole in the centre plus a thin white plastikard back piece (no hole). The DCC Concepts white/red "nanolights" are two back to back chip LEDs, pre wired with 3 extremely thin enamelled copper wires (common positive). The LEDs are mounted with the wires sandwiched between the front two plastikard laminations, with the white LED beaming forward and the red LED facing the back of the cavity, which reflects the red light back in an annular ring around the LED assembly. The assembly is glued together and painted satin black, then a clear lens is deposited across the front aperture, using "Glue 'n Glaze".

 

New Light parts on the cutting board, before assembly

Assembled lamp painted satin black

 

Modifications to the upper body shell parts:

To access the underside of the roof, the plough body shell is disassembled into upper and lower parts by removing the two larger screws on the underside. The solid plastic block must then be extracted from the upper body shell (don't loose the rear window which is held in by the plastic block). A 3mm hole can then be drilled in the required position through the ridge of the roof for the orange LED. The top of the plastic block is drilled out to leave space for the underside of the orange LED and its wires.  Wiring holes are also drilled through the upper and lower halves of the body shell to enable the LED wiring to pass through to the underside of the unit.

 

Upper body shell halves dismantled

Solid plastic block removed

Holes drilled for wiring and orange LED

 

Fitting the lights:

The lamp bracket spike on the top front of the body shell is cut off and after feeding the wires through the hole at the base of the bracket, the head/rear light is super-glued to the bracket base (facing forward). The orange LED leads are extended and insulated. This LED is then pushed up through the 3mm hole in the roof and super-glued in position.

The wires are then routed through the appropriate holes as the upper body shell is re-assembled, to emerge ready for connection to the remaining circuitry on the underside of the unit.

 

Accommodating the circuitry:

The circuit components are fixed with super glue to a 20x31mm piece of 1mm plastikard and soldered together as per the circuit diagram above.  The circuit board is fitted with plastikard stand-off feet to leave room for the orange LED wires to emerge under the board. Check for clearance of the chassis unit before the assembly is glued to the underside of the lower body shell. The lighting cables are soldered to the appropriate components on the circuit board. Finally, the chassis unit is screwed back into place and the decoder wheel contact wires (black and red) are soldered to the chassis wheel contact strips.

 

Circuit Board (before flashing LED was painted over)

Circuit Board wired in and chassis refitted

 

Testing the lights:

The modified snow plough is programmed with the CVs shown in the table above and checked on the test track.  Both snow ploughs are programmed with the same address and re-tested as a pair of back to back units. An additional coat of satin black paint on the headlamp / rearlamp, was found to be required to prevent unwanted light leakage.

 

headlight and orange rotary light on

rearlight and orange LED active

 

Some minor cosmetic improvements:

The blue moulded icicle guard is painted satin black.

A small triangle of plastikard is added to the prow of the snowplough and painted yellow.

The side lamp brackets are painted white.

A black top cap is painted on to the rotary beacon lights.

 

The leading plough

 

 

Adding the snow plough pair to a consist of two locomotives:

The required light settings are applied to each of the locomotives participating in the snow train (normally this will be "lights off"). A "consist" is then formed, including the two locomotives. The direction of the snow ploughs is set to correspond to that of the locomotive pair. The required light settings are selected for the snow ploughs and they are also added to the snow train consist.

The consist direction now defines the switching of the headlights and rear lights of the snow ploughs.

 

 

 

 

 

 

 

 

 

A few shots of the DBS Snow Train in action

 

Problems:

The biggest problem encountered was poor wheel contact reliability on the two snowploughs. The contact wheel sets were removed and the rear surfaces were more thoroughly cleaned. The contact spring pressure was increased and the units re-assembled. This solved the problem.

 

 

Supplier  website links:

 

Flangeway Source for the UK independent snow plough models
Trains 4 U (Peterborough) A good (almost local) source of Bachmann and Dapol product. (My source for the phosphor bronze wheel contact strip.)
Bromsgrove Models Good source of DCC decoders and specialist LED devices for this type of project.
TCS (Train Control Systems) A U.S. company. My preferred DCC decoder family with good programming data and advice on their website.
Maplin A convenient local source for electronic components such as resistors and transistors

 The photos of the models were taken on the kitchen worktop at 100 ISO, using a tripod and fill-in flash.    

 

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