Clock Repair Archive - -     Seth Thomas 115d:

The Seth Thomas 115d is a ships strike round mechanism. It uses a non - imported balance wheel unit. It uses a cam on the idler gear connected to the minute wheel to make the odd count ; it lifts the lever that catches the hammer causing the "odd" count on the half hour. The rack uses a counter weight with a return spring to facilitate it's operation. The return spring on the rack is .010 inches in diameter. The rack has a spring loaded index end that will release if the mechanism is allowed to run down , in case the hands are moved before the rack has cleared the snail. The spring for this is .021 inches in diameter (brass). The strike trip lever return spring is .013 in. diameter brass wire with a .010 wire inside the plate also. The hammer return spring is .016 in. diameter brass wire. Be sure there is at least 180 degrees of rotation on the warning wheel after the warning pin is caught (when the mechanism "loads" the strike gear train prior to releae) before the hammer is picked up or the odd hour strikes will be erratic because the hammer catch won't always hook.

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