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The New Zealand Railways Magazine, Volume 12, Issue 11 (February 1, 1938)


The model locomotive illustrated below was built by Mr. F. Roberts, of Auckland, to represent, in appearance, the first of the “K” class locomotives built by the New Zealand Government Railways.

The following are the chief particulars of the model.

Scale: ½ inch to foot. Guage: I¾ (or No. I Model gauge). Steam pressure per sq. in.: 75 lbs. Pop safety valve. Cylinder cocks (four) operated from top of cab. Throttle in smoke box operated from top of cab. Chimes whistle under boiler operated from top of cab.

Reverse Lever: Right-hand side of boiler (next air reverse cylinder) fitted with rustless steel handle and sector plat. (Removable for photographic purposes).

Compensated brake gear on engine only (with removable lever for hand operation—at present). Engine wheels, sprung and compensated in pairs only. Front bogie, compensated, sprung, and fitted with swing links. Commonwealth bogie: axle boxes fitted with individual coil springs and frame sprung by laminated spring on the back end of the engine frame. Axle-box lids open for oiling. All axle-boxes have oil ways and engine boxes have swabs underneath.

All of the motion is fitted with oil holes, and the slide bars with oil cups. Cylinder lubrication in sand dome and adjustable feed to each cylinder.

The boiler is of copper—20 gauge—silver soldered. Fire-box: Orthodox type with five ½ in. tubes, but in addition, three ¼ in dia. water tubes from the lower part of the front end of the boiler pass through the flue tubes to the crown of the fire-box for water circulation, and one only from the throat plate to the crown. A vertical flue ⅝ dia. flanged at both ends passes from the crown of the fire-box through the outer shell to the atmosphere, thus facilitating steam raising.
(Rly. Publicity photo.) Model of the “K” class locomotive which forms the subject of the accompanying article.

(Rly. Publicity photo.)
Model of the “K” class locomotive which forms the subject of the accompanying article.

The fire-box stays are of ⅛ in. dia, screwed, soft-soldered and riveted. The water gauge is fitted with automatic ball valve to close if the guage glass bursts.

The water level test cock is on the driver's side—under cover. One 3/16 in. examination plug is fitted in the fire-box leg. The dry pipe is from the dome to the superheater header. The superheater is low temperature, and is fitted in the two flues not occupied by the water tubes. Elements: four in number each 12 in. long are of ⅛ copper tubing. The superheater also supplies the whistle and blower. The regulator valve is in the smoke-box with packing gland accessible from the outside (rotary face joint on spindle renders gland almost superfluous). The boiler check valve is situated inside the sand dome. The boiler feed-water heater consists of 12 ft. of ⅛ in. tubing coiled round outside of smoke-box and lagged. The lagging of the boiler and smoke-box is held in place by brass sheet I/32 in. thick, to which all attachments are fastened.

The boiler feed pump is worked by an eccentric on the intermediate engine wheel axle, through two rocking shafts. The coupling rod between shafts is made in two sections, one sliding within the other, or fixed, at will, thus enabling the pump to be automatic, or cut out. The cotter securing the two sections, when withdrawn, is so made that it can be dropped into a slot provided on the secondary rocker shaft and utilized to operate the pump by hand.

The pump and gear are located inside the left-hand main reservoir, the bottom portion of which provides a tray to collect water leaking from glands, etc., and disposes of such waste water through the left hand dummy injector overflow. The pressure in the pump delivery pipe between discharge valve and boiler check can be released, and discharges also through the left hand injector. The pump valves are easy of access and are hidden from view by a dummy hydraulic jack. Water strainers are fitted between the engine and tender, and are easily removed.

The cab fittings are complete in detail, with throttle lever that operates with the external throttle. The fire-box door opens, and an electrically illuminated fire-box gives realism. The steam gauge is fitted in the roof of the cab, face up, and covered by ventilator plate, when open. The blower is operated from a point near the cab. A nipple under r.h. main reservoir makes provision for attaching a bicycle pump to obtain air pressure for steam raising, if required. Owing to the vertical flue in the fire-box, however, steam can be raised without any such aids.

The bogie wheels of the tender are compensated and sprung individually. The tank is built of copper with lids fitted with spring catches, strainers being also fitted. A float in the strainer tube shows the level of water in tender, when working. A hand feed pump discharges through automatic feed pump and acts as primer, if necessary. A battery, to supply lights for fire-box, cab, and headlamp, is contained in a water-tight box, easily removable. The lights are operated by switches on the tender, and a methylated spirits tank with burners, built rigid, rests on the tender floor, and is free to allow the working movement between engine and tender. A tray of imitation coal covers all controls in the tender, and can remain in position while operating the engine. A tool box on top of the tender contains small tools, larger tools being contained in a tray under the coal.