So Why Are They Red? (Injectors)

[Nigel Graham 2Participant @nigelgraham2]

See – I do read the magazine! (ME)

I’d never given it a thought until reading Doug Hewson’s letter in the latest Model Engineer, about injectors on miniature locomotives.

As we all know, it is to his great credit that he and one or two other contributors want the small details like back-head fittings to be as much scale replicas as function allows, as is the overall locomotive.

I wasn’t sure what Mr. Hewson means about the shape of the injector, though for those of his calibre (which I ain’t, guv) it should not be too difficult to make a “simple” injector outwardly reasonably resemble the full-size fitting.

 

More to the point, he appeals to us not to paint it red!

 

Err, that’s how many of them are sold, though I have seen them in bright green and the R.A. Barker blow-down valve on my wagon’s boiler is matt black. (The other fittings from Mr. Barker are unpainted.)

I realised I don’t recall seeing a painted “plumbing” fitting on any full-size steam locomotive or road vehicle. Hand wheels and levers maybe, for better visibility in poor light; but not the devices themselves.

 

So why are many miniature injectors, brightly painted?

[Paul LousickParticipant @paullousick59116]

Injectors on full size engines are not painted at all.

[Speedy Builder5Participant @speedybuilder5]

Reeves 2000 – Matt Black  (2023)

[NealebParticipant @nealeb]

It’s like brake calipers on “performance” cars – makes them go faster!

[JasonBModerator @jasonb]

Because a thick coat of red (or black) hides the rough GM sand castings surface on many a steam fitting. Go for a lost wax or CNC machined fitting and the surface is good enough to leave bare or just a bead blasted matt finish. Like these or these

Some of these second hand full size are painted so must be a full size practice too.

[norm nortonParticipant @normnorton75434]

I recall seeing some red injectors on road engines, that’s fine to copy, but not on standard gauge, main line steam railway locos.

The habit is also sometimes seen as an expression of builder’s preference with red levers and controls on the model railway loco backhead. Prototypical for some regulator handles but little else.

[Chris GunnParticipant @chrisgunn36534]

Because they get hot?

Chris Gunn

[SillyOldDufferModerator @sillyoldduffer]

Many reasons why parts are painted, to:

1. look pretty (very common on steam engines)
2. cover up flaws, (paint and putty is very common on cast-iron castings)
3. prevent corrosion
4. highlight danger, parts likely to move, get hot, high-voltage etc
5. quickly identify parts for assembly, maintenance & diagnostics

Don’t expect consistency unless colour is done to a standard.   For example, most wiring harnesses are multi-coloured because it makes assembly and tracing bugs easier, which makes sense to me.  However, when I was a lad, British military electronics used pink wire for everything.  Until the item was modified that is, after which pink wire was strictly forbidden.  The reason was that using a different colour to show each change makes it much easier to spot alterations, and alterations are always suspicious! As we all know, everyone apart from you and I is a clown, so good news if colour coding shows where the clot has been.   Makes extra sense in the military, where repairs and mods were done on a ship or in the field under trying conditions, with the equipment returned to be refurbished by a fully equipped facility later.

I don’t know if the pink wire system is still used.  May be obsolete because it’s so difficult for ordinary folk to mend multi-layer printed circuit boards packed with SMD, ASICs, FPGA, and microcontrollers.  Easier to swap boards and send the old one back to a specialist or to bin it.

Dave

 

 

[Nigel Graham 2Participant @nigelgraham2]

I have assembled electronics for military equipment, and whilst it’s true many of the wires were pink they were usually identified on their ends by number sleeves, both in the standard 0-9 colours and printed with the digit.

So it was not totally anonymous.

Board-level wiring may be far less common, but it’s probably still normal inside equipment-racks to connect all the board sockets and the outside world.

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Red regulator handles seem quite common, but I suppose there was never much point painting things like injectors which would probably slough the paint off anyway.

I very much doubt anything on a steam locomotive was ever painted to warn anyone it might be hot. All those who had any business being that up close and personal with a locomotive in steam, would know most things with pipes on are likely to be hot; but that was probably one of the least hazards in a busy steam shed.

I recall a friend who’d had some experience on one of the Welsh narrow-gauge railways recounting how he’d been invited to fire on one service. He said the regular crew were impressed that without having been reminded, although he’d turned the injector water on as the locomotive came alongside the platform, he’d not turned the steam on until the footplate was safely by the end ramp. (Not just so he could see the injector overflow easily. It avoided the hazard of splashing people on the platform, with hot water.)

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The transport museum in Glasgow has settled arguments about regulator handle colours simply by removing the levers completely from the three or four locomotives on display! Goodness knows why. I suppose most visitors would not realise there is anything missing, but you and I would spot it immediately. As I did.

 

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