The Mainspring of an Automatic Winding Watch In the automatic winding watch, the mainspring must be designed to prevent over winding (with continuation of automatic winding) when the spring is fully wound. This is usually accomplished in contemporary watches with a slipping bridle on the outer end of the... Read more
The Regulator, Spring Stud, andAnti-Shock Mechanism   CLICK ON A RED ASTERISK OR A PART LABEL FOR MORE DETAIL The balance cock assembly of a Jaeger LeCoultre caliber 889 is shown in this photograph. (1) The fine rate-adjustment screw. (2) The regulator with index (or curb) pin and boot.... Read more
THE ESCAPEMENTAn Animated Explanation of Function THE ANIMATION LOAD TIME IS APPROXIMATELY 1.9 MINUTES WITH A 56K MODEM OR 3.7 MINUTES WITH A 28K. DURING DOWNLOAD, YOU CAN VIEW THE ANIMATION AT VERY LOW SPEED. In the animation, the escapement is shown moving through two complete beats: a balance... Read more
The Mainspring, Mainspring Barrel, Barrel Arbor, Ratchet and Crown Wheel CLICK ON A PART OR PART LABEL FOR MORE DETAIL CLICK HERE TO SEE THE MAINSPRING OF AN AUTOMATIC WINDING WATCH. BACK TO THE GLOSSARY INDEX   Read more
AUTOMATIC WINDING The Jaeger LeCoultre Caliber 889/2Switching Rocker The illustrated Jaeger LeCoultre caliber 889/2 uses a switching rocker to accomplish bi-directional winding. This is an efficient, simple and elegant engineering solution. Power is transferred from the central rotor (5) to the first transfer wheel (1). Wheels (2) and (3)... Read more
The Regulator, Curb Pin and Boot The regulator is shown inverted in this photograph, the curb pin on the left, the boot on the right. The balance spring passes through the space between the two (arrow), which determines the “effective” length (as opposed to actually total physical length) of... Read more
AUTOMATIC WINDINGBi-Directional Winding The twin click-wheels are each constructed of two parts, an upper and lower section (as shown in the diagram, left). These upper and lower halves are locked or unlocked (with one-way ratchets), depending on the direction of rotation of the upper section. While both upper sections... Read more
THE KEYLESS WORKSWinding CLICK ON A PART OR LABEL FOR MORE DETAIL The positioning of the keyless-works parts for winding is shown in the green numbering. (1) The crown is pushed in, (2) the setting lever swings in, (3) the opposite end of the setting lever swings out allowing... Read more
THE ESCAPEMENT:The Exit Pallet During Impulse As the end of the escape wheel tooth rides along the inclined impulse face of the pallet, the pallet is impelled away (blue arrow) and the pallet lever rocks, forcing the opposite pallet into locking the escape wheel. Click here to see a... Read more
The Balance Wheel in Detail Read more
AUTOMATIC WINDINGThe ETA Caliber 2842 The automatic winding watch converts motion of the wearer’s wrist into power that winds the mainspring of the watch. As show left (in an inverted position), most such watches use a central rotor with a gear (yellow arrow). As the rotor moves around its... Read more
THE KEYLESS WORKSPatek Philippe caliber 240-PS The illustration reveals the beautifully crafted keyless works of the contemporary Patek Philippe caliber 240-PS. It was Antoine Philippe who, in 1841, developed the concept of the keyless works that is still in use today. Before that time, winding and hand-setting were done... Read more
THE ESCAPEMENT:The Exit Pallet During Locking The geometry of the pallets, pallet lever, and escape wheel teeth assure that the pressure of the escape wheel tooth will deepen and maintain the lock of the pallet. The escape wheel pressure is referred to as “draw.” Draw keeps the pallet lever... Read more
The Balance Cock andBalance Assembly CLICK ON A PART OR PART NUMBER FOR MORE DETAIL The entire balance cock and balance assembly is illustrated. (1) The balance cock. (2) The anti-shock unit for the upper balance pivot. (3) The regulator to control rate. (4) The balance spring. (5) The... Read more
THE BOTTOM PLATEThe Dial Side of the Movement CLICK ON A RED ASTERISK OR  PART LABEL FOR MORE DETAIL  BACK TO THE GLOSSARY INDEX Read more
THE KEYLESS WORKSWinding and Hand-Setting      BACK TO THE GLOSSARY INDEX Read more
The Balance WheelThe Adjustable Mass Balance The adjustable-mass (or adjustable-inertia) balance wheel offers several advantages over conventional balance wheels with fixed mass. Used in most contemporary Patek Philippe wristwatches and pocket watches, the adjustable-mass balance has also long been used in marine chronometers. Among the advantages of this design... Read more
The Anti-Shock Mechanism CLICK ON THE ILLUSTRATION FOR A PHOTOGRAPH OF A KIF-BRAND ANTI-SHOCK UNIT Anti-shock assemblies are used to protect the upper and lower balance pivots from damage due to external impact on the watch. In some movements, shock assemblies are also used on the escape wheel. A... Read more
The Cylindrical Pivot and Jewel The cylindrical pivot (1) has the advantage of simplicity, robustness, and low cost. The friction of the cylindrical pivot is relatively high compared to the two-jewel arrangement used with the conical pivot. This friction results from the relatively thick jewel hole (2) and the... Read more
THE ESCAPEMENT:The Pallet Lever Safety Pin The safety pin (illustrated in yellow) allows unlocking of the escape wheel only when the balance wheel is centered (and the impulse jewel is inside the pallet fork). When a physical shock to the watch unlocks a pallet from the escape wheel accidentally,... Read more
The Balance Staff CLICK ON A PART OR PART LABEL FOR MORE DETAIL Read more
THE TOP PLATE The Movement as Seen from the Back of the Watch CLICK ON A RED ASTERISK OR A PART LABEL FOR MORE DETAIL  BACK TO THE GLOSSARY INDEX Read more
Wheels and Pinions CLICK ON A PART OR A PART LABEL FOR MORE DETAIL     BACK TO THE GLOSSARY INDEX Read more
THE ESCAPEMENT:The Pallet Lever Geometry A very precise geometry of the pallet lever (and escape wheel teeth) is required to assure proper locking and impulse of the two pallets on escape wheel teeth. In the 28,800 beats per hour (bph) watch, each pallet executes both operations 14,400 times per... Read more
The Balance Wheel: Amplitude Each clockwise or counterclockwise swing of the balance wheel is called a beat. The number of degrees of rotation of the beat is the amplitude of the balance. In most contemporary wristwatches, the amplitude of the balance in a horizontal position (i.e. dial up or... Read more
ILLUSTRATED GLOSSARYOF WATCH PARTS by Walt Odets THE MOVEMENT TOP PLATE THE MOVEMENT BOTTOM PLATE THE KEYLESS WORKS THE MOTION WORKS THE BALANCE ASSEMBLY THE ESCAPEMENT THE MAINSPRING AND BARREL THE WHEEL TRAIN AND WHEELS SCREWS Read more

The Wheel Train

Watch Glossary October 10, 2002

The Wheel Train CLICK ON A PART OR A PART LABEL FOR MORE DETAIL The power flow through the movement is shown by the blue arrows: the main wheel (integral to the mainspring barrel), center wheel, third wheel, fourth wheel, and escape wheel. Each wheel drives the pinion gear... Read more
THE ESCAPEMENT:The Exit Pallet The escape wheel rotates clockwise, as seen from above in this view. The exit pallet is the last of the two pallets to meet an escape wheel tooth. The locking face of the pallet locks against the escape wheel tooth and the pressure of the... Read more
The Balance Wheel, Balance Springand Balance Cock CLICK ON A PART OR PART LABEL FOR MORE DETAIL The back-and-forth oscillations of a balance wheel are described in terms of amplitude. To understand amplitude, click here. BACK TO THE GLOSSARY INDEX Read more
ScrewsThe Various Screws Used in the Watch CLICK ON PARTS OR PART LABELS FOR MORE DETAIL  BACK TO THE GLOSSARY INDEX Read more
THE ESCAPEMENT:The Entry Pallet The escape wheel rotates clockwise, as seen from above in this view. The entry pallet is the first to meet an escape wheel tooth. As illustrated, the locking face of the pallet locks against the escape wheel tooth and the pressure of the escape wheel... Read more
The Click and Related Parts The click (1), click screw (2), click spring (3), and mainspring barrel arbor (4) of a Fontainemelon caliber 97 are illustrated above. As illustrated below, the end of the click spring acts on a post on the underside of the click (red arrow) to... Read more
The Cannon Pinion, Hour Wheel, Minute Wheel and Wheel Pinions CLICK ON A PART FOR MORE DETAIL The illustration above shows the motion works of a center-seconds watch. (1) The fourth wheel pinion, which carries the seconds hand. (2) The center wheel pinion, which carries the cannon pinion. (3)... Read more
THE ESCAPEMENT:The Banking Pins The banking pins–or solid bankings–limit the maximum travel of the pallet lever and thus assure the proper geometry between the pallets and escape wheel teeth.  BACK TO THE GLOSSARY INDEX   Read more
The Balance SpringCollet and Overcoil CLICK ON A PART FOR MORE DETAIL The collet (green arrow) sits on the balance shaft and attaches the inner end of the balance spring to the balance shaft. In this illustration, the balance spring is an overcoil design, the overcoil indicated in yellow.... Read more
THE MOTION WORKSThe Hour, Minute and Second Hands   RETURN TO THE BOTTOM PLATE   BACK TO THE GLOSSARY INDEX Read more
THE ESCAPEMENT: Escape Wheel,Pallets and Balance Staff CLICK ON A PART OR PART LABEL FOR MORE DETAIL CLICK HERE FOR ANIMATION  BACK TO THE GLOSSARY INDEX Read more
The Balance WheelA Smooth Glucydur Balance In most high-grade contemporary wristwatches, the balance wheel is like that illustrated above: a smooth (without rim screws) Glucydur two or three arm balance. The design is screwless because contemporary balance spring alloys provide temperature correction and make screws on the balance unnecessary... Read more

The Click

Watch Glossary October 10, 2002

The Click CLICK ON A PART FOR MORE DETAIL During winding, the mainspring barrel is stationary and the ratchet wheel winds the inner end of the mainspring counter-clockwise around the arbor in the center of the barrel. When the movement is running, the ratchet wheel is stationary and the... Read more