CLOCK REPAIR KITS
Clocks4Classics have developed a kit to repair Smiths and Jaeger car clocks fitted to a wide range of classic cars. The electrical contacts within these clocks frequently fail and until now have been extremely difficult to repair reliably.
The Clocks4Classics kit is a High Tech solution to this problem. The specially developed circuit board fits inside the clock mechanism and replaces the contacts with a solid state infra-red sensor and microprocessor. This provides a long lasting repair but leaves the rest of the mechanism untouched so the repaired clock looks and functions just like the original – the only difference is that it works!
How THE SMITHS CLOCK MOVEMENT Works
The Smiths Pin Clock is a fascinating combination of mechanical and electrical techniques. The clock is based around a traditional clockwork mechanism with a rotating balance wheel and hairspring. The balance wheel rotates backwards and forwards at a fixed rate of five times per second and it is this motion which is used to regulate the timekeeping of the clock.
In order to maintain the oscillation of the balance wheel, the clock has to be provided with energy to overcome the losses in the mechanism. In a traditional clockwork mechanism this energy is provided by a mainspring wound by a key, but in this case the energy is provided electrically. A small solenoid coil consisting of thousands of turns of fine wire is mounted close to the balance wheel. Two shaped metal `pole pieces’ pass through the centre of the coil and are positioned so that their ends are very close to the edge of the balance wheel. When the solenoid coil is energised by an electric current a magnetic field is created and this provides a `kick’ which maintains the oscillation of the balance wheel. For the clock to operate correctly the electric current to the solenoid coil has to switched on for a very brief period at exactly the right point in the movement of the balance wheel. This is achieved by using a tiny set of electrical contacts which brush against a small pin projecting from the underside of the balance wheel – hence the name `Pin Clock’.
What Goes Wrong?
A quick calculation shows that the electrical contacts operate over 3 million times a week – or 157 million times a year! Not surprisingly, these contacts eventually fail leaving the clock in a non-working state. Unfortunately, replacement contacts are not readily available and are very difficult to repair reliably.
The Clocks 4 Classics Solution
Clocks 4 Classics have overcome this problem by using modern electronics to replace the failed contacts. A solid state infra-red sensor is used to sense the position of the balance wheel and a microcontroller chip uses this information to control the current to the solenoid coil. The rest of the mechanism is left untouched so that the clock looks and functions just like the original, retaining that all important tick!.
In order to maintain the oscillation of the balance wheel, the clock has to be provided with energy to overcome the losses in the mechanism. In a traditional clockwork mechanism this energy is provided by a mainspring wound by a key, but in this case the energy is provided electrically. A small solenoid coil consisting of thousands of turns of fine wire is mounted close to the balance wheel. Two shaped metal `pole pieces’ pass through the centre of the coil and are positioned so that their ends are very close to the edge of the balance wheel. When the solenoid coil is energised by an electric current a magnetic field is created and this provides a `kick’ which maintains the oscillation of the balance wheel. For the clock to operate correctly the electric current to the solenoid coil has to switched on for a very brief period at exactly the right point in the movement of the balance wheel. This is achieved by using a tiny set of electrical contacts which brush against a small pin projecting from the underside of the balance wheel – hence the name `Pin Clock’.
What Goes Wrong?
A quick calculation shows that the electrical contacts operate over 3 million times a week – or 157 million times a year! Not surprisingly, these contacts eventually fail leaving the clock in a non-working state. Unfortunately, replacement contacts are not readily available and are very difficult to repair reliably.
The Clocks 4 Classics Solution
Clocks 4 Classics have overcome this problem by using modern electronics to replace the failed contacts. A solid state infra-red sensor is used to sense the position of the balance wheel and a microcontroller chip uses this information to control the current to the solenoid coil. The rest of the mechanism is left untouched so that the clock looks and functions just like the original, retaining that all important tick!.