under construction check here often I thought this might help people understand Vostok 2415/2416 movements, self winding function, and reversing wheels or gears. I would like to thank Matt (Matt_Bored_O) for his help, content, input, advice, and photos documenting the parts and their movement. Also, special thanks to Håkan (VWatchie) for his excellent closeup photos of the reversing wheels and the tip on polishing the retainer lock. Also, thanks to Dan (ratfacedgit) for the pics I snatched from his excellent video.
Self Winding Function
When the rotor turns clockwise, or counter clockwise, it turns the first reversing wheel or gear in the opposite direction. The pinions attached to the bottom of both reversing wheels turn a larger gear, called the "first winding wheel", counter clockwise. When the rotor turns counter clockwise, the first reversing wheel and its pinion lock and turn clockwise: this turns the first winding wheel counter clockwise. The first reversing wheel also turns the second reversing wheel counter clockwise, but the second reversing wheel slips, and does not turn the first winding wheel. The reversing wheels only lock in a clockwise direction. When the rotor turns clockwise, the first reversing wheel turns counter clockwise, but does not lock. It spins freely, and does not turn the first winding wheel with its bottom pinion.
When the first reversing wheel is turning counter clockwise, it also turns the second reversing wheel clockwise, locking its pinion, and turning the first winding wheel counter clockwise. The first winding wheel only turns in the counter clockwise direction. When the first winding wheel turns counter clockwise, it turns the second winding wheel and its pinion clockwise. The second winding wheel's pinion turns the third winding wheel and its ratchet wheel counter clockwise, this turns the ratchet gear on top of the main spring's drum clockwise, and winds the mainspring. The mainspring will slip in its drum before it can be over wound by the self wind system. The third winding wheel's ratchet wheel on top spins freely in both directions and only locks if the attached bottom winding wheel turns counter clockwise. This is so that when you wind the watch manually, or if the ratchet gear on the winding drum slips counter clockwise, movement will not be transmitted to the self winding gears. This kind of movement, would turn the gear train at a high speed, and would impart wear and possible damage.
The third winding wheel and ratchet gear have a wire spring loaded lever that is mounted on a pivot to the bottom of the brass winding wheel. The lever under the spring's tension, engages the inner teeth of the ratchet wheel or gear. When the ratchet gear rotates clockwise, the lever is moved against the springs tension and disengages the gears inner teeth, letting the ratchet gear turn freely. When the ratchet gear turns counter clockwise, the spring moves the lever against the inner teeth of the ratchet gear, and locks the gear to the bottom winding wheel. This allows the third winding wheel and its ratchet gear to lock together when turning counter clockwise, but turn freely when you manually wind the watch.
2415 / 2416 Reversing Wheels (Gears)
There are two reversing wheels or gears in the 2415 /2416 movement, which turn in the clockwise and counter clockwise direction. Both reversing wheels only lock in the clockwise direction. In the counter clockwise direction, the reversing wheels slip or spin freely. The top of the reversing wheels have a recess, in which five hill-shaped ramps are in a circular pattern. Between these ramps are five round flat synthetic rubies or jewels, which are allowed to move, but held captive by a retainer cap on top of the wheel. These jewels account for 10 of the 31 jewels in the 2415 movement. At the center of the wheel's recess is a hub, which turns freely in both directions. Under the gear, attached to the hub, is a pinion.
When the reversing wheels are turning in the clockwise direction, the jewels are guided by the ramps to the center, and lock the hub and pinion. When the wheels turn in the counter clockwise direction, the jewels are on the other side of the ramps that are cut to a different angle, and do not guide the jewels to the hub, therefore locking does not take place in the counter clockwise direction. The reversing wheels are located on brass posts.
Common Reversing Wheel (Gear) Problems
Reversing wheels fail by not locking, or by not unlocking. If a reversing wheel will not lock, or will not fully lock, it will cause the rotor to spin freely or slip in one direction, and the watch will not wind, or wind properly, when the rotor is spinning in that direction. If a reversing wheel will not unlock, or fully unlock, it can cause the rotor to drag or not move. More often, there is a failure by one of the reversing wheels to not fully unlock, which will let the rotor turn, but it will be sticky, and not turn properly, this can cause the watch to not self wind enough. Both types of reversing wheel failure, can cause the watch not to self wind fully, have a low reserve, or stop.
Diagnosing a Reversing Wheel (Gear) Problem
Use a wood toothpick or similar tool to rotate the rotor in the counter clockwise direction, while observing the gear train. If the rotor will not turn, do not force it. Check both reversing wheels, first winding wheel, second winding wheel, (which is located under the first winding wheel and not visible with the winding bridge on), third winding wheel and its ratchet wheel, and the ratchet gear on the winding drum, for missing or damaged teeth. The first winding wheel should turn counter clockwise.
Do the same with the rotor in the clockwise direction, the first winding wheel should still turn counter clockwise. Watch the first winding wheel carefully while doing this, It should move whenever the rotor is moving. If it stops at any time the rotor is turning, one of the reversing wheels is slipping. If this happens when the rotor moves in the counter clockwise direction, the slipping wheel is the first reversing wheel. If this happens when the rotor turns clockwise, the slipping wheel is the second reversing wheel. Now gently shake the watch in a circular pattern, in both clockwise and counter clockwise directions, while observing the rotors movement. The rotor should turn easily. If the rotor seems to stick or bind in any one direction but not in the other, you probably have a reversing wheel that is not unlocking. If the rotor is sticking or binding in the clockwise direction, it is the first reversing wheel which is not unlocking. If the rotor binds in the counter clockwise direction, it is the second reversing wheel that is not unlocking. If the rotor spins in either direction very freely and the first winding wheel is not turning or is slipping, one of the reversing wheels is slipping or not locking. If this happens in the counter clockwise direction, it is the first reversing wheel, if this happens in the clockwise direction, it is the second reversing wheel. If the first winding wheel is turning, the watch should be winding.
To confirm a reversing wheel problem, try switching the location of the two reversing wheels. If there was a problem with the rotors movement in one direction, the same problem will now be with the rotors movement in the other direction. To remove the reversing wheels, only the brass retainer lock needs to be removed by taking out the screw. Some prefer to avoid removing the lock and its tiny screw by removing the winding bridge and its three larger screws. A tip here, if you have the ability, is to polish the bottom of the reversing wheel lock. Do not change the shape of the arms or remove material. Just polish the bottom of the arms where they contact the top of the reversing wheels. Make sure you clean the arms and not leave any trace of grit or lapping compound after polishing. Be very careful to avoid bending the arms on the retainer lock! If this happens, just order a new lock when you replace the reversing wheels. If you have to replace a reversing wheel, try to replace both of them with a new set. Just drop them in place. Do not add any oil.
Reversing Wheel Lubrication
The reversing wheels should be cleaned at the same time the watch is serviced. The brass posts should be lubricated lightly. Also, lubricate any one jewel in each reverse wheel. The reason for lubricating any one jewel is so that the proper amount of oil, which is very little, is applied. Do not oil the gear teeth. A good lubricant is Moebius D5 which has been discontinued and replaced by HP-1300.