They are basically the same technology as tramway controllers but lack a
reversing/lock drum, as what they powered only ever turned in the same
direction. The Ball Head coal loader basically used a cable haulage system
which circulated wagons on a 20" narrow gauge track between the loading
ganty on the jetty and the coal bins, through a tunnel under the bins.

Trolley Wire, December 1975 describes it this way....

*"The heart of the system is located in the 26 ft x 21ft winding house
which stands near the shore end of the jetty under the elevated section of
the railway. Within this house stands a large 125 hp 450 volt D.C. electric
motor which drives the winding gear at 600 rpm. The motor is a General
Electric of Schenectady, U.S.A. product (Type RG—39, No. 1157990, 213 amp -
compound) and the winding gear train reduces the speed in the ratio of
40:1. In more recent years the motor has been arranged to work at 660 rpm,
thus speeding the cable winding drums from 15 rpm to 16.5 rpm. This
produces a traction cable speed of 3 mph which means that each wagon can
traverse the 0.6 mile round trip 5 times each hour."*

On Monday, 20 March 2023 at 21:42:43 UTC+11bblun...@... wrote:

> I went on a tour through the former Balls Head Coal Loader in Sydney last

> weekend.

>

> Some remnants of the former electric "railway" in the tunnels have been

> preserved.

>

> Think some people here might be interested in the controllers.

>

> Brian

>