Alexandra's Clock
- Diameter: 11m
- Minute Hand: 5.6m including the counterweight.
- Hour Hand: 4m including the counterweight.
- Weight: Each hand weighs approximately 270kg. The driving mechanism
weighs approximately 760kg.
- Mechanism: Reduction gearboxes powered by one 3/4 hp synchronous motor.
- Lighting: 150 torch bulbs, powered by a reduction transformer.
- Structure: Six vertical steel columns averaging 7.3m in length, supported
on concrete foundations, fastened into the rock face with steel supports.
- Location: On the Knobbies Range to the east of Alexandra.
- Height Above Sea Level: 200m.
The Beginning
The idea of a clock on the hill was first suggested by Alexandra Jaycee
Inc. in June 1966. Many different ideas were investigated. Various firms
throughout New Zealand were approached and asked to submit designs and
prices. Prices obtained for the construction ranged from $2,200 to $12,170.
A Dunedin firm of engineers, which had had no previous experience in clock
making, were finally given the task of designing and supplying the driving
mechanism for the clock. In April 1967 the Jaycees disclosed their plans
to the public of Alexandra. A full size mock-up was placed on the site,
and six weeks allowed to gauge local reaction. Such a large scale project
could not be undertaken without the full support of the people of the town.
As there was much opposition to the original scheme, a poll was held, revealing
that over 90% of the people were in favour of the clock.
Work on the Clock
The clock mechanism was ordered in February 1968. The clock face and
supporting structure were designed by an engineer in the Jaycee Chapter.
All construction work was carried out by members. A total of 1264 man hours
were involved in the construction of the clock, on 42 separate working
occasions. One of the main difficulties was the inaccessibility of the
site. This was overcome by erecting a 30.5m rail line down the face of
the cliff. Most of the steel and concrete used on the site, as well as
the clock mechanism which weighed 760kg, went down this rail before being
winched into position. Most of the work on this project involved the construction
of the clock structure. A wide range of tasks had to be done, including
trench digging for electrical cables, laying concrete for foundations,
welding and painting. This last aspect was very important, as the steel
uprights had to be painted in such a way that they became completely camouflaged
against the rock face. Work began in earnest in June 1968. Within five
months - by the end of November 1968 - the clock was finished. After three
weeks of testing, it was officially started by the Mayor of Alexandra,
Mr K W Blackmore, at noon, 14 December, 1968.
Expenditure
Mechanism and accessories including foundations, steel markers, electrical
connection, painting, sundry, totalled $2,996.
Driving Mechanism
The clock is electrically operated. The hands, which are cantilevered
to withstand gusts of wind up to 130kph, are attached to coaxial shafts.
These are driven continuously through reduction gears by a 3/4HP synchronous
motor. A second motor and clutch provided in the gear train enable the
hands to be altered should any adjustment be necessary because of power
failure.
Lighting
Very early in the planning stages it was decided that the clock was
to be illuminated. None of the firms approached in New Zealand could satisfactorily
provide, and guarantee, effective lighting of the clock. Indirect lighting
in the form of ultra-violet lamps was considered, but was not practical.
Direct lighting with spotlights shining on the face would not work because
of the shadows that were cast. It was left to the initiative and inventiveness
of a member to provide a strikingly effective, simple, and inexpensive
solution to the problem. Ordinary torch bulbs, 150 in all, were used, especially
set into the hands and markers. All the designing, wiring and installation
was arranged and supervised by this member. The end result is so striking
that the clock can be read clearly up to five miles away
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