Alternative designs for an ashpan drop pin

[GreensandsParticipant @greensands]

The attached photo shows an image of the ashpan locating pin drawn up by Martin Evans for his 3.5ins gauge Rob Roy locomotive which I would like to take as the basis for another design. Before setting out on making something up I would be interested to know if there are any other possible designs out there which might be considered first. The tricky bit of course is the end section which prevents the pin from dropping out during a run with potentially damaging results to the engine. Any thoughts on alternative methods of securing the pin would be gratefully received.

 

 

 

[bernard towersParticipant @bernardtowers37738]

what about the flick over clevis, that you have to hold straight to be able to take the pin out?

[duncan webster 1Participant @duncanwebster1]

I made one of mine with a bayonet fitting at the handle end, similar to a BC light bulb

[John PurdyParticipant @johnpurdy78347]

The pin on my loco goes through the rear guard irons to retain the ash pan. It is shaped like this. It  is 3/16″ dia. CRS and the dart on the right end is filed flat to go through the slot in the right guard iron,  the handle is just a short length of 1/16″ dia. CRS silver soldered into the end.  In use it is slid through the left guard iron then through the two sides of the ash pan and with the handle on the left horizontal the dart on the right end is put through the slot in the right guard iron and is then given a 90 degree turn so the handle hangs down retaining the pin in. I have never in 30 odd years of running the loco had it move.

John

 

[GreensandsParticipant @greensands]

Hi Duncan – Any chance of a couple of photos of your drop pin?

[Nigel Graham 2Participant @nigelgraham2]

John –

Simple and effective!

My Society used similar on a 5″ g. Maid of Kent it owned.*

The pin went through holes in the frames rather than guard-irons, and rather than a handle indicating the dart orientation, the face of the knob was painted white with a small red arrow.

It worked well, but I would add what makes such an arrangement effective is a tube right across the ash-pan to guide the pin across the chassis.

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Bernard –

Yes, that would work on some locomotives but on other designs you’d need consider if it would be a faff to use in a hurry, or would put your fingers ‘orribly close to hot bits.

An alternative lock is a small swinging-arm that drops into a groove turned in the rod.

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Another configuration, on my club’s Wren, is a steel-strip ramp welded centrally to the underside of the ash-pan. Its step is engaged by a swinging cross-bar that pivots in holes in the frames below the footplate (which I don’t think is fitted!). The action is a little like a single-tooth ratchet relying on the components’ natural springiness, and gravity.

The ash-pan’s front end has two pins that engage something  – I forget exactly what – on the boiler or frames.

To drop the ash-pan and grate, ease the ash-pan up slightly and pull the swing-arm back. The assembly simply falls out, but is fiddly to re-fit.

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While on my Julie (as LBSC himself light-heartedly suggested naming a doubled-up Juliet), nothing departs from the locomotive. The ash-pan stays in place, catching the grate swinging down on pivots at its ahead end. The grate’s rear end simply rests on a single, central fore-and-aft, captive pin sliding through a block fitted to the foundation-ring, and retained in operation by a notched swing-arm engaging a circlip-like groove.

Its drawback is cinders obstructing the front end, hamper lifting the grate back up.

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Obviously anything fastened to the boiler itself needs a plate extended below the foundation-ring, or being built in as original to the boiler.

…..

You could, at cost of added complexity, give finer-scale locomotives of 5″ g. and above proper rocking-grates as on many fully-size locomotives.

The control lever has a safety-collar or latch limiting partial rocking for fire-cleaning, and by its withdrawal, further movement for dropping the fire. The ash-pan needs bottom doors, especially if you intend removing live fires; but this too is prototypical… as are dampers.

I believe Doug Hewson and Peter (Spenlove? – by all means please correct if necessary) have described these in the magazine, developed for their own projects in 5″ g.

……

One point regarding dropping the fire, if necessary in a hurry (usually, excessively low water)

Alternatively, extinguish the fire by stuffing rag down the chimney and turning the blower on hard, with the fire-door kept closed.

I had to use this recently when a feed check valve blew back, losing the water in a preliminary steam-accumulation test, and was surprised how rapidly it works.

 

For normal disposal I prefer to leave the fire to die out naturally, and clean the locomotive when it has cooled, apart from blowing down while there is still some pressure in the boiler.

”””’

*Ours, named Maid of Athens for reasons I know not, mysteriously “disappeared”! That was in the 1970s, and I do hope she is still in service somewhere.

[John PurdyParticipant @johnpurdy78347]

If the pin goes through the frames where there is lots of room then the dart end could be simplified by turning a cone on the end of the pin and putting a cross pin through just behind the cone. The hole in the frame would be the same as in my guard iron except that the central hole would be the dia. of the rod. I couldn’t do that with my loco (5″ga NER 0-4-0 “Gemma”) as the guard iron is only 5/16″ wide.

As Nigel suggests a tube across the ash pan would make installing the pin easier. Mine doesn’t have it, and it is a bit of a fiddle finding the hole on the far side of the ash pan, although not too bad.

John

[Nigel Graham 2Participant @nigelgraham2]

Note that a guide-tube will not allow a pin or other fitting through it.

So, place the locking arrangement on the handle end of the support pin.

The simplest way is to put a keyhole slot in the frame, with the stem part pointing vertically towards the frame top, and one-sided cross-pin in the support-pin. A dart type lock would also work here, with the dart section formed on an extension to the inner end of the operating-knob.

The main point is that the knob and lock are on the same end of the pin, allowing that free passage through a cross-tube and the far frame. A short taper on the far end of the pin will assist insertion.

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One proprietory type of self-retaining pin uses a ball or other projection controlled by a handle and spring in a tubular stem. I would caution against any such here as it could be affected by the hot, mucky operating conditions.

The main problem with the type of pin retained by a small cross-arm pivoted in its slotted end, is that it would need operating from both sides of the locomotive. These also tend to be of fairly large diameter to be robust, needing a larger guide-tube and holes through the frames and ash-pan, than otherwise necessary.

A 1/4″ dia pin should be fine for a 5″ g. loco; 5/16″ or 3/8″ for 7¼” g.

Make the holes and guide-tube of generous clearance, as the ash-pan could distort slightly with use. Especially if anyone quenches it with water after dropping it – not good practice anyway, to be used only where the fire has to be dropped somewhere dangerous, but I have seen this happen many times in ordinary disposal. Quench the embers, not the metalwork.

Basically, the simpler the better!

[bernard towersParticipant @bernardtowers37738]

Nigel the clevis arrangement I mentioned only folds in one direction so if its folded and hanging down twist 1/2 turn and it should align and pull out.

[Greensands]

On Greensands Said:

Hi Duncan – Any chance of a couple of photos of your drop pin?

The loco is in a box under a load of other stuff. The ash pan and pin might be in the workshop, I’ll have a look this evening

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