Steam clock
From Wikipedia, the free encyclopedia
A steam clock is a clock which is fully or partially powered by a steam engine. Only a few functioning steam clocks exist, most designed and built by Canadian horologist Raymond Saunders for display in urban public spaces. Steam clocks built by Saunders are located in Otaru, Japan; Indianapolis, USA; and the Canadian cities of Vancouver, Whistler and Port Coquitlam. Steam clocks by other makers are installed in Jersey and at the Chelsea Farmers' Market in London, England.
Although they are often styled to appear as 19th-century antiques, steam clocks are a more recent phenomenon inspired by the Gastown steam clock built by Saunders in 1977. One exception is the steam clock built in the 19th century by Birmingham engineer John Inshaw to demonstrate the versatility of steam power.
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[edit] Gastown steam clock
Saunders' first steam clock was built in 1977 as a tourist attraction for the renovated Gastown district of Vancouver. Although the clock is now owned by the City of Vancouver, funding for the project was provided by contributions from local merchants, property owners, and private donors. Incorporating a steam engine and electric motors, the clock displays the time on four faces and announces the quarter hours with a whistle chime that plays the Westminster Quarters.
[edit] How it works
- Engine. The steam engine is a Stuart #4 single expansion double acting 1" piston engine purchased at the Stuart Turner Limited plant at Henley-on-Thames, England. (Engines of this size are typically employed by hobbyists for large model boat propulsion.) It is supplied with low pressure steam — engine inlet pressure is 17 psi — from a centralized steam heating system that serves a portion of downtown Vancouver. The engine, rotating at only a few hundred revolutions per minute, drives a reduction gear train. The steam engine is used to lift ball weights to a top track from which they load onto a drive chain providing the driving force to the clock while the ball weights descend.
- Chain lift. The engine-driven gear train drives the lower sprocket of a vertical link-chain (similar to a bicycle chain), with a lift of about four feet. Chain-mounted pairs of lifting fingers form forks which accept and lift smooth steel balls (about two inches in diameter). The balls are lifted at a rate of one every 4.5 minutes.
- Top transfer. A hammer-like mechanism operates to drive the topmost ball from the lifting fork at the top of the lift. The ball is then received by a transfer chute, whence it is routed to the top of the drive chain. The ball is retained until a descending fork is properly positioned to receive it.
- Clock drive chain. A similar continuous chain receives the lifted balls from the transfer chute at the top of the mechanism. At any time, five or six balls are being carried by this chain. It is the unbalanced weight upon this chain that drives a conventional pendulum clock mechanism through the upper sprocket.
- Ball return. At the bottom of the clock drive chain the balls come to rest upon an inclined blade leading to a chute where they roll to the initial lifting point. Two or three of the balls are in this position, with the foremost awaiting the passage of the lifting fingers.
- Clock movement. The Gastown clock keeps time by a small tower clock movement that was custom-built in Croydon, England by Gillette & Johnston Co, from one of their 1875 designs. This type of tower clock movement was used in many small church tower clocks after 1875.
- Electric motors. The clock uses three electric motors. First, a small gear motor drives the tune playing machine. It rotates a drum with pins that play the Westminster chimes on micro switches which operate the steam whistle solenoid valves. Second, a small fan motor blows out hot air from the roof vent on top of the clock. Third, a small fan motor pulls warm air down to the base to provide air circulation.
- Chiming mechanism. Five steam whistles are mounted atop the clock case. The large central whistle counts off the full hours. The four auxiliary whistles chime the Westminster Quarters four times an hour.
[edit] Indiana State Museum steam clock
The 17–foot–tall Indiana State Museum steam clock is located on the sidewalk on the north side of the museum. It has four 24" diameter dials that are back-lit by neon. The clock’s eight brass whistles play a few notes of "Back Home Again in Indiana" every 15 minutes. A more complete rendition is played at the top of every hour.
[edit] Chelsea Farmers' Market steam clock
The towering and quirky steam clock located at the Chelsea Farmers' Market was constructed in 1984. Although still standing, the clock is no longer in operation.
[edit] Jersey waterfront steamboat clock
The Jersey steam clock is a full-scale replica of the centre section of a paddle steamboat named the Ariadne. The clock was commissioned by the Jersey Waterfront Board in 1996. Although once powered by steam, according to a Jersey government document "the steam workings have been replaced with electrical fittings designed to provide the same functionality including the blowing of ‘steam’ at the appropriate times of the day."
[edit] See also
[edit] External links
- John Inshaw biography
- Indiana State Museum steam clock
- Handheld video of the Gastown steam clock chiming the hour.
- Maintenance report on the Gastown steam clock
- Chelsea Farmers' Market steam clock
- Photos of the Jersey steam clock
- Maintenance report on the Jersey steam clock
- Landmark Clocks
- Photo and sound of the Otaru steam clock
