“Automatic watches are a favorite among collectors. These watches not only offer unmatched convenience and precision compared to manual wind watches.”

But how do automatic watches work? This is a question that many people have asked, and in this post, we aim to answer all your questions.  We will look at the mechanics of three self-winding systems and delve into everything you need to know about how automatic watches work.

So, whether you’re a seasoned collector or a beginner looking to expand your knowledge, this post is for you.”

Beginners Guide to Working On Automatic Watch Systems

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The Bumper Movement

A bumper movement is named after the springs that function as bumpers. The movement works by utilizing a ratchet system. When the bumper weight travels in one direction, it cranks through gears on the oscillator and causes the geared ratchet to move. This movement is driven by a driving pawl that pushes down on a ratchet tooth wheel, causing it to turn.

 The Advantages of this Bumper Movement

One of the key advantages of the bumper movement is that it is amazingly effective. Wearing an automatic watch all day will quickly wind it fully, despite the fact that this system only winds in one direction. This style of automatic movement, which dates back to the 1950s, offers a unique feature of being both automatic and hand-wound, setting it apart from other automatic systems from the early seventies.

Bumper Movement
Bumper Movement

Disassembling the Movement

Before we get into troubleshooting and lubricating the bumper movement, let’s take a look at what it looks like. On the outside, it appears similar to a typical manual wind movement, but you may notice two screws on the crown wheel instead of one. Normally one screw would be a reverse thread screw, but when you see two screws here, they are not.

Crown Wheel with 2 Screws
Crown Wheel with 2 Screws

Lubrication Points

When lubricating the bumper movement, it’s important to know where to apply the lubricant. The oscillator has a pinion that drives the geared rocker and a lower pinion that spins back and forth. To reduce friction, shape the lower tip of the pinion into a cone and apply a small amount of HP 1300 to the pivot. Lubricate the paw winding wheel, consisting of five separate parts, by applying two small dots of lubricant to each side. Also, lubricate the ratchet teeth with a small amount of HP 1300.

Bumper Movement Lubrication Point
Bumper Movement Lubrication Point

 Reassembling the Movement

Once the lubrication is complete, it’s time to reassemble the bumper movement. Start by installing the pawl winding wheel, making sure to insert the pivot into the lower pivot hole and leaving a few teeth open on each side.

Reassembling the Bumper Movement
Reassembling the Bumper Movement

Next, install the bridge for the automatic system, being careful to keep the spring for the second pawl in place. And there you have it, your bumper movement is ready to go!”

Understanding the Seiko Magic Lever Self-Winding System

Introduction

The Seiko Magic Lever is one of the most popular self-winding systems out there. In this section, we’ll take a closer look at this system, its components, and how it works. Specifically, we’ll be looking at one of Seiko’s iconic movements, the 7S26, which is used in a number of vintage watches and is still used today in some of their newer models. This system is a good one to know because it’s relatively inexpensive and is used in many watches, making it a common sight for watchmakers and collectors alike.

The Three Main Components of the Seiko Magic Lever

The self-winding system of the Seiko Magic Lever is made up of four main components: the first reduction wheel, the second reduction wheel, and the pawl lever.

The First Reduction Wheel

The first reduction wheel is made up of two separate parts: the main wheel, which has teeth that interact with the pinion on the rotor, and the center section, which is made up of a pivot, an offset cam, and a groove that accepts the first reduction wheel C clip. The key to the Magic Lever system is that as the wheel turns in a circle, the offset cam moves the pawl lever up and down onto the second reduction wheel. To lubricate the cam, you’ll need to put a small drop of HP 1300 on each side of it, and it’s important to keep an eye out for a failure point in the cam, which can become loose over time and affect the movement’s ability to function.

1st Reduction Wheel
1st Reduction Wheel

The Pawl Lever

The pawl lever has two sides: the left side has a hook that grips the ratchet teeth on the second reduction wheel and pulls it down, while the right side has a notch that pushes up on the teeth. The teeth on the pawl lever can become worn over time due to a lack of lubrication or excessive oils that attract dirt, so it’s important to keep an eye out for this issue and replace the pawl lever if necessary.

Seiko Pawl or Magic Lever
Seiko Pawl or Magic Lever

The Second Reduction Wheel

The second reduction wheel is where the pawl lever interacts with the teeth to wind the movement. When lubricating the ball bearings in the rotor, you will need to put a small drop of 9010 on each side. To lubricate the teeth on the second reduction wheel, you’ll need to put two small drops of HP 1300 on each side and then work the magic lever to distribute the oil evenly.

2nd reduction wheel
2nd reduction wheel

Assembly

When assembling the Seiko Magic Lever, it is important to make sure that the pawl that pulls down on the second reduction wheel is on the right side so that it will be on the left side when you look down on the movement. After lubricating the cam, you will install the pawl lever, then the first reduction wheel, and then the bridge onto the movement. The last piece to go on will be the rotor, and you’ll want to make sure to check the function of everything after assembly to make sure everything is working properly.

Seiko Magic Lever Assembly
Seiko Magic Lever Assembly

Conclusion

The Seiko Magic Lever is a great self-winding system that is widely used in many different watches. By understanding its components and how it works, you’ll be able to troubleshoot and lubricate it properly to keep it functioning smoothly.

Understanding ETA’s Reverser Wheels

We are now examining one of the most classic self-winding systems in the watchmaking industry, the ETA’s Reverser Wheels. The ETA 2783 from around 1970 is one of the most popular examples of this system. The self-winding train in the watch comprises two reverser gears and a reduction gear that drives the ratchet on the mainspring.

Each reverser gear is composed of two wheels with levers sandwiched in between. The top wheel of each reverser gear interacts with the pinion attached to the rotor, causing it to turn in the direction of the rotor. The levers sandwiched between the reverser wheels lock the bottom wheel based on the direction of the rotor.

ETA Reverser Wheel
ETA Reverser Wheel

When the rotor turns clockwise, the bottom wheel of the top reverser wheel spins freely. But when the rotor turns counterclockwise, the bottom wheel locks and provides the driving force to the reduction wheel. The second reverser operates in the opposite way, locking when the rotor turns clockwise and unlocking when it turns counterclockwise.

Stripping Down the System

Let’s take a closer look at the system by stripping it down. The underside of the automatic bridge reveals the two reverser wheels, the reduction wheel, and the driving gear that turns the ratchet wheel on top of the mains.

ETA Reverser Wheel Automatic Works
ETA Reverser Wheel Automatic Works

From the top, you can see the internal levers that control the locking and unlocking of the two wheels based on the direction of the rotor. If any part of the reverser wheel has wear, is broken, or bent, it cannot be repaired and must be replaced.

The reverser wheel closest to the reduction wheel has a pinion that drives the reduction wheel. The automatic bridge is fully jeweled, so the pivots for the reversers and reduction wheel will be lubricated like any other jewel. The only other spot to lubricate is the post from the driving wheel, which requires a small drop of HP 1300.

Lubricating the System

Dip Lubrication is the Optimal Method for Lubricating Reverser Wheels Avoid using a dip oiler and 9010, as it will result in the lubricant getting thrown out, contaminating the parts, and causing failure.

Choose to use a special lubricant called Lubeta V105 for best results. After cleaning the reverser wheels, immerse them in the Lubeta V105 for 10 seconds, then blow off the solvent using a blower until it dissolves. Let the wheels dry under a dust cover for 15 minutes.

Reverser Wheel; Lubricant Lubeta V105
Reverser Wheel; Lubricant Lubeta V105

Reinstall the reverser wheels into the bridge, with the reverser wheel with the pinion closest to the reduction wheel. Then, install the driving wheel and reduction wheel pinion, followed by the bridge held by one screw.

Lubricate the fast-spinning reverser wheels with 9010 and the slower-spinning reduction wheel with HP 1300. Test the bridge to ensure everything is meshing correctly before lubricating the reduction wheel with HP 1300 and the reverser wheels with 9010.

Assemble the movement by first installing the pallet fork and balance bridge. Lubricate the sealed ball bearings in the rotor with the special dip lubricant, Lubeta V106.

Dip the ball bearings in Lubeta V106 in a small mason jar for 10 seconds, then dry off the excess. Allow the lubricant to dry for 15 minutes under a dust cover. Clean up with a clean Q-tip dipped in hexane.

Pro Tip: Making Your Own Reverser Wheel Lubricant

Are you tired of having to buy a special lubricant just for your reverser wheels? Fear not, there is a solution! With items you likely already have, you can make your own dip lubricant that works just as well as the store-bought options.

Ingredients Clean IPA alcohol or hexane Moebius 9010

Instructions Take a small container that is large enough for your tweezers to fit inside. Using a clean syringe, add 33 drops of the solvent (IPA alcohol or hexane) to one drop of 9010 lubricant. Mix.

Bench Made Reverser Wheel Lubricant
Bench Made Reverser Wheel Lubricant

Submerge each reverser wheel into the solution for 10 seconds. Use your blower to remove any excess solvent until it has evaporated. Place the wheel under a dust cover and let it dry for 15 minutes.

The solution will leave a fine film of 9010 on the pawls and levers inside the reverser wheel, mimicking the effect of the V105 lubricant.