Railway interlocking machine

Made c 1879

This interlocking machine is one of the first in NSW and is typical of the multi-levered mechanical devices used in NSW railway signal boxes and on station platforms from the 1880s. It comprises a collection of levers for operating railway points and signals brought together in one machine. It was designed so that it prevented conflicting signal functions being set up simultaneously which might cause an accident. Before this, points were worked independently of each other, often by pointsmen in ...


Railway interlocking machine and sign, mechanical type, full size, No. 5 pattern, metal/timber, made by McKenzie & Holland, Vulcan Iron Works, Shrub Hill, Worcester, England, c.1879, exhibited at Sydney International Exhibition, 1879-1880, New South Wales, Australia, used at Campbelltown Junction, and Macdonaldtown railway station, New South Wales, Australia, 1883-1913

This is a mechanical interlocking machine fitted with ten levers in a metal frame. An interlocking machine is a frame comprising a row of hand-operated levers for changing railway points and signals. The machine interlocks the point and signal levers so that they must work in harmony. The levers are at the signalman's shoulder height to give a mechanical advantage, while the locking components were set up in a signal box or station below floor level. The locking mechanism was attached to wires and metal bars which extended outside to operate the signals and points. The machine "locked" automatically so that conflicting train routes and movements could not be set inadvertently by the signalman.

This frame was constructed for 14 levers but numbers 5, 6, 10, and 11 are not fitted. A rectangular wooden sign indicates which lever controls which signals and points.


2200 mm
1940 mm
1320 mm


This interlocking machine was manufactured in about 1879 by McKenzie & Holland of Worcester, England, and was known as a No. 5 pattern. McKenzie & Holland were railway engineers and manufacturers of signals and interlocking machines. They were established in 1861 as Mackenzie, Clunes, & Holland, and took over the old Vulcan Iron Works, at Shrub Hill.

The design for this machine was patented (No. 1963) in 1866 by J. McKenzie, T. Clunes and W. Holland. The patent documents described the locking mechanism as being of the cam and soldier type, however in Australia it was normally referred to as the rocker shaft type. McKenzie & Holland interlocking machines are said to have revolutionised the world's railways by allowing for safer rail travel. They were used in Britain, Australia, New Zealand, India and the United States and a factory was established in Melbourne in 1880 for their manufacture. McKenzie & Holland continued to supply NSW with mechanical interlocking machines until about 1907 after which time they were made locally by the NSW Government Railways' Signal Engineers Branch. In 1905 McKenzie & Holland were acquired by the Consolidated Signal Co., and in 1920 became part of Westinghouse. The Worcester works closed in 1921.

Information provided by Bob Taaffe, 1988.
c 1879


Gift of The Signalling Engineer, NSWGR, Sydney, 1914
3 June, 1914

Cite this Object

Railway interlocking machine 2017, Museum of Applied Arts & Sciences, accessed 24 November 2017, <https://ma.as/213815>
{{cite web |url=https://ma.as/213815 |title=Railway interlocking machine |author=Museum of Applied Arts & Sciences |access-date=24 November 2017 |publisher=Museum of Applied Arts & Sciences, Australia}}
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