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J. Johnston & Sons, Invercargill

Geared Steam Locomotives

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Images & Drawings

Johnston & Sons built two main designs of bush locomotives, the small four-wheeler Type A and the much larger 16-wheeler Type D. Together with one Type B 8-wheeler, Johnston's built at least 26 steam locomotives between 1896 and 1930. They originated the concept of the 16-wheeler to replace horse teams on lightweight track. Johnston's also built steam log haulers, boilers, steam winches and other sawmill machinery.

1896 0-4-0 T Type A

J. Johnston & Sons Ltd. built eight of these lokeys starting in 1896 with the last built in 1927. They were 4-wheelers of about 7 tonnes weight. cylinder horizontal engine was mounted between the frames under the smoke box from where it drove a crankshaft near the middle of the loco, thence through herringbone gears onto a central jackshaft below. This gear ratio was 13:30. The jackshaft, located midway between the two sets of driving wheels, then drove through side rods to the wheels. The loco usually towed a 4-wheel tender holding water and fuel but at least four engines operated as tank locos. More & Sons converted their Johnston 'A's to 0-6-0 arrangement fitting a pair of flangeless wheels to the jackshaft thereby increasing adhesion. The average service life of these types was about 37 years. One is now on static display at Riverton, near Invercargill and another resides at McLeans Island.

A Marlborough Timber Co. Johnston A working around 1910 in the Pelorus Sound area. Note the jackshaft and connecting rods. (Marlborough Historical Society)

Dimensions not available

Click for images of More & Sons Johnston 'A's. ( Courtesy of Jim More )

1910 Type D 16-Wheeler

Designed as a replacement for horse teams, the axle loading of 1 tonne per axle was arrived at as being similar to that achieved on log buggies. The loco weighed in at 16.25 tons. A twin-cylinder vertical marine type engine was cab mounted and drove a longitudinal crankshaft that in turn drove an intermediate shaft via spur gears giving two speeds of ratios 1:1 and 1:2. The intermediate shaft then drove another set of spur gears down to the level of the line shaft. The lower, larger gear was 3'6" (1067 mm) in diameter. The line shaft was set just above the truck axles and a bevel gear pair drove from the line shaft to a stub shaft aligned across the truck. A pair of spur gears then transmitted power down to the axle. In all a total of 38 gears were in the transmission. The use of bevels on the stub shaft gave rise to high tooth stress and rapid wear. The wheels were carried on four trucks, the front two trucks being joined by a beam pivoted on the trucks and again at its mid-point where it was attached to the loco frame. The rear trucks were arranged the same. Top speed was about 5 mph (8km/h) and the average service life about 23 years. None exist today.

The above image clearly shows the location of the twin cylinders and the reduction gears to the drive train. The loco worked at the Glenham Sawmilling Co. in 1910. (Southland Museum)

Dimensions not available.

1911 Type B 8-Wheeler

Only two Type B locos were built (and at least one model) giving a similar lokey to the Type D but for use on heavier steel rail. The boiler was offset on the frame, in a similar fashion to the Shay, to allow the two-cylinder engine to be mounted on one side. The transmission was the same as used on the 16-wheeler.

The second lokey, built in 1911, lasted in service at Cape Foulwind until 1927.

Plans and model photo courtesy of Simon Ballantyne

While rummaging around the drawing office of Dispatch Foundry in Greymouth in 1970, Simon Ballantyne came across these drawings which are probably of the Johnston B 8-wheeler.

Additional Johnston Photos

Photo 1 - Johnston 16-wheeler built for the Egmont Box Co. in 1911. (Alan Bellamy col.)

Photo 2 - Johnston 16-wheeler at Hamilton & Co. Papatotara. (Percy Godber)

Photo 3- Johnston 'A' (No.3) at the Ruru mill of Lake Brunner Smg Co. (Alexander Turnbull Library)


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