Big Ben and Its Clock Tower

Post Reply
 
franco b
Site Moderator
Posts: 10496
Joined: Wed. Nov. 05, 2008 5:11 pm
Location: Kent CT
Hand Fed Coal Stove: V ermont Castings 2310, Franco Belge 262
Baseburners & Antiques: Glenwood Modern Oak 114
Coal Size/Type: nut and pea

Post by franco b » Sun. Apr. 13, 2014 3:01 pm

Interesting video of the clock in the tower of the House of Parliament.

The design was a breakthrough in design of tower clocks which because of the large hands used that were exposed to weather, any ice or snow buildup, or even strong wind could effect the timekeeping by feeding back to the escape wheel which impulsed the pendulum. This clock eliminates that problem by having the escape wheel indirectly impulse the pendulum by lifting a weighted lever which when released provides the impulse.

http://www.parliament.uk/about/living-heritage/bu ... ower/tour/

 
User avatar
Richard S.
Mayor
Posts: 13537
Joined: Fri. Oct. 01, 2004 8:35 pm
Location: NEPA
Stoker Coal Boiler: Van Wert VA1200
Coal Size/Type: Buckwheat/Anthracite

Post by Richard S. » Sun. Apr. 13, 2014 3:35 pm

I saw a documentary on it once, the thing that was really interesting to me was they keep it in time by adding or removing coins from the weight. Adding one or removing one speeds it up or slows it down.

Advertise on Coalpail.com

 
User avatar
Lightning
Member
Posts: 11906
Joined: Wed. Nov. 16, 2011 9:51 am
Location: Olean, NY
Stoker Coal Boiler: AA 130
Coal Size/Type: Pea Size - Anthracite

Post by Lightning » Sun. Apr. 13, 2014 3:57 pm

I saw that too. My question is how can something be that sensitive yet not be influenced by other conditions like heat and humidity, expansion and contraction of parts..

 
franco b
Site Moderator
Posts: 10496
Joined: Wed. Nov. 05, 2008 5:11 pm
Location: Kent CT
Hand Fed Coal Stove: V ermont Castings 2310, Franco Belge 262
Baseburners & Antiques: Glenwood Modern Oak 114
Coal Size/Type: nut and pea

Post by franco b » Sun. Apr. 13, 2014 4:43 pm

Lightning wrote:I saw that too. My question is how can something be that sensitive yet not be influenced by other conditions like heat and humidity, expansion and contraction of parts..
The pendulum is the timekeeper and is the only part where the influences mentioned will make a difference. To that end the shaft of the pendulum is made of well seasoned and sealed wood which is less effected by temperature than metal. The bob is cylindrical rather than lens shaped and is supported at the bottom. With a rise in temperature the pendulum will get longer, but the bob expands upward to compensate, at least partially. The sealed wood is little effected by humidity.

A one second pendulum makes one vibration in one second and is about 40 inches long. This pendulum is two second and is 13 feet long. It is that long because the arc will depart less from the ideal path which is not circular but cycloidal. If I place a ruler on a piece of paper and then a coin against the ruler I can generate a cycloidal path by holding a pencil against the edge of the coin and rolling the coin along the ruler. The gear teech also have a cycloidal shape at their tips. They roll against each other rather than slide.

Post Reply

Return to “Travel, Adventure & Places of Interest”