The one and only surviving Davidson lokey is on display at Mawhera Reserve alongside
State Highway 7 about 20 kilometres east of Greymouth. The loco has been there for
many years but has recently been rebuilt and given a coat of black preserving paint.
It is set on a short length of track. While not completely authentic, the rebuild has been carried out well and
it nevertheless is a fine example of a Davidson engine.
Built in 1913 for the Kotuku Sawmilling Company, it saw service there until 1920
when it was sold to Westland Sawmilling at Camerons, just south of Greymouth. After
four years there it spent the next six years at Redjacks Sawmilling Company in the
same area where it now rests.
The loco is of 0-4-4-0 wheel arrangement and there is an additional bogie resting
at the rear of the loco. When Davidson's built these engines, they did not lag the
boiler, but usually the customer did by laying timber horizontally along the boiler
and retaining this in place with steel bands.
A three-quarter front view of the Davidson showing the cylinders in more detail,
together with the reversing lever and flywheels. A large sprocket can be seen beneath the drive crank.
The extra bogie can also be seen. It was common practice to place the third bogie under the loco's
tender or to support the end of the first load. By extending the drive chain
arrangement, this extra bogie would provide additional traction.
Here is a close up photo of the wheel assembly showing part of the patented chain
sprockets. Devised by George Davidson and patented, the chain was so made
that all loadings were not carried on the pivot pins, but by shoulders machined
into the links. In the original chain, sprocket wheels used were of the flat or
single disc type with teeth at every link (i.e. on a pitch of 4"). It was necessary
to adapt the chain for use on the bush lokeys so that misalignment could be accepted,
so the sprocket wheels were a double-flanged
type with the chain run between them and the teeth protruding from the bottom of
the groove into every second link (i.e. on a pitch of 8").
This view illustrates the main crankshaft and herringbone gears (before rebuild) which carried the flywheel/crank discs
on the outer ends and, between the frames the eccentrics for the Stephenson link
motion and the two herringbone gear wheels, one for forward motion, the other for
reverse. Part of the drive chain is also visible.
Finally we have a view of the crankshaft flywheel/crank disc depicting the driving gears and chains.