a couple of Qs

[cwru32]

hi
i wonder if someone can explain 2 things in a rolex:
first, how does movements of hands are protected from shock and up and downs that watch experiences everyday on ones wrist!

second, when fully wound, there is more force exerted on all wheels and when watch is least wound, there should be less force pushing the wheels. how these extrems are regulated to maintain an accurate watch?
thanks

[shaggy]

good questions
i have no clue but look forward to the answers

[Tools]

Hmmm... two questions that have no relation to each other.. I think..

1) The hands are not protected at all and a sharp blow or knock can rotate a hand slightly on the shaft that it is press fit on.

2) You are correct....when the mainspring is fully wound it does exert more of a pull on the gear-train than when it is not fully wound.. Attempting to get uniform time-keeping (Isochronism) throughout the entire spring torque has been a desire of watchmakers and designers since the beginning..

The first step, is the amount of wind a watch has.. designers have built in a ~50 hour reserve in the watch, not so you can go two days without winding, but so that if it is wound each day, it stays in the upper end of it's torque range.....if you allow the watch to fall into the lower range of torque, then it will be more erratic than a fully wound watch.

The escapement is the key along with the hairspring that oscillates at a known (approximately) frequency. Knowing how many times the pallet fork locks and unlocks the escapement wheel based on the frequency of the hairspring (28,800 beats per hour for a modern Rolex), along with the torque curve of the mainspring, you can calculate and design a gear train that rotates at exactly 24 hours per day (in theory).. Then you tap in extra gears off that main shaft to move the other functions.

But your watch will run differently throughout the optimum designed torque curve, and then more erratically at the bottom of the curve.

This is one of the reasons that Rolex opted to go with automatic movements throughout their main line....A self-wind watch is always adding to the mainspring wind (when worn) and, therefore, keeps the torque more constant and in the upper design range throughout the day, as opposed to a manually wound watch ..

[cody p]

erudite answer Tools.

i wonder if for the first question KIF shock protection might be what the op was asking about? not sure.

for the second question: i think it's kinda neat how the tension on the mainspring works in an opposite way to the speed of the watch. fully wound the watch runs slower than a partial wind when it speeds up. you would think it would be the other way around, but once you understand how the escapement works and get the concept of amplitude then it makes more sense.