HOROLOGY

Rolex 3235 · 28,800 vph

The Art
of Time

No battery, no circuit. A coiled spring, a train of wheels and a balance beating 8 times a second — take a mechanical movement apart and watch it keep time.

Explore the MovementHow it works
Or find the movement inside your watch

Find your watch

What beats inside your watch?

Search by brand, model or reference. When its movement is in the library, open it in 3D and watch it work.

Browse every watch in the library

Mechanical watchmaking

A mechanical watch is a small machine that turns stored energy into a steady count. Wound by hand, a spring pushes a train of wheels; a tiny oscillator lets them advance only in measured steps. Everything you see on the dial follows from that rhythm.

HOROLOGY lets you hold such a movement in your hands: turn it over, lift its bridges, slow time down until each tick becomes visible, and follow the energy from the mainspring to the hands.

01Principles

Four organs, one heartbeat.

  1. I

    Energy

    The mainspring

    A long steel spring, coiled inside the barrel by winding, stores energy and releases it as steady torque.

  2. II

    Transmission

    The going train

    A cascade of wheels and pinions carries that torque onward, multiplying speed and dividing force at every mesh.

  3. III

    Distribution

    The escapement

    The pallet fork locks the train and frees it one step at a time — and with each release, passes a small impulse on.

  4. IV

    Regulation

    The balance

    Balance wheel and hairspring swing at a nearly constant frequency. Each swing counts one beat: the true measure of time.

On the dial side, the motion works turns the center wheel’s hourly revolution into minutes and hours for the hands.

02The Collection

Movements, taken apart.

21 calibres modelled in 3D · 234 watches in the library

ETA

5 calibres

  • Manual winding
  • Small seconds 9h

ETA 6497-1

The Unitas pocket-watch calibre: big, hand-wound, small seconds at 9.

Frequency
18,000 vph · 2.5 Hz
Jewels
17
Diameter
36.6 mm
Power reserve
46 h
Seconds
Small seconds at 9 o’clock

Variants

Explore Lesson3 watches →
›A note on accuracy · sources

An approximation of the 6497 layout, not a manufacturer-accurate replica. Frequency (18,000 vph), 17 jewels, 46 h power reserve, Ø 36.6 mm (16½ lignes) and 4.5 mm height are published figures. Tooth counts and the exact shapes of bridges and parts are an approximation drawn from public photographs; the tooth counts are chosen so the fourth wheel turns once a minute, as the small seconds requires. The escapement motion is a kinematic model, not a physics simulation.

  • Automatic
  • Center seconds
  • Date
  • Hacking

ETA 2824-2

The Swiss workhorse: self-winding, 4 Hz, center seconds and date.

Frequency
28,800 vph · 4 Hz
Jewels
25
Diameter
25.6 mm
Power reserve
38 h
Seconds
Center seconds (indirect drive)

Variants

Explore Lesson27 watches →
›A note on accuracy · sources

An approximation of the ETA 2824-2 layout from public drawings and photographs, not a manufacturer-accurate replica. Bidirectional automatic winding, 28,800 vph (4 Hz), 25 jewels, Ø 25.60 mm (11½ lignes), 4.60 mm height, semi-instantaneous date with quick correction and stop-seconds are published ETA figures. Power reserve: 38 h is the figure in ETA’s 2009 technical communication and most specifications; ETA’s product page gives 42 h as typical. Tooth counts, wheel sizes, the barrel position, the outlines of the bridges hidden under the rotor and the seconds drive are an approximation; the tooth counts make the fourth wheel turn once a minute and the escape wheel match 28,800 vph. Parts are drawn larger than life for legibility and the stack is taller than the real 4.60 mm. The escapement motion is a kinematic model, not a physics simulation.

  • Manual winding
  • Small seconds 6h

ETA 7001

The ex-Peseux ultra-thin: hand-wound, 2.50 mm, small seconds at 6.

Frequency
21,600 vph · 3 Hz
Jewels
17
Diameter
23.3 mm
Power reserve
45 h
Seconds
Small seconds at 6 o’clock
Explore Lesson24 watches →
›A note on accuracy · sources

An approximation of the ETA 7001 layout from public drawings and photographs, not a manufacturer-accurate replica. Manual winding, 21,600 vph (3 Hz), 17 jewels, Ø 23.30 mm (10½ lignes), 2.50 mm height, small seconds and the index regulator are published ETA figures; the small seconds at 6, the absence of hacking, Incabloc shock protection and the three-bridge construction come from Caliber Corner, Monochrome and Worn & Wound. Power reserve: 45 h typical per ETA; the press (Worn & Wound, Monochrome, Fratello) gives 42 h. Tooth counts, wheel sizes and the exact shapes and positions of bridges and parts are an approximation from Monochrome’s technical drawing and photographs; the tooth counts make the fourth wheel turn once a minute, as the small seconds requires. The dial-side parts are drawn at the explorer’s common scale, so the model is thicker than the real 2.50 mm, but the bridge-side stack is kept low. The escapement motion is a kinematic model, not a physics simulation.

  • Automatic
  • Center seconds
  • Date
  • Hacking

ETA 2892-A2

ETA’s thin top-range automatic: 3.60 mm, 4 Hz, center seconds and date.

Frequency
28,800 vph · 4 Hz
Jewels
21
Diameter
25.6 mm
Power reserve
42 h
Seconds
Center seconds (indirect drive)
Explore Lesson15 watches →
›A note on accuracy · sources

An approximation of the ETA 2892-A2 layout from public drawings and photographs, not a manufacturer-accurate replica. 28,800 vph (4 Hz), 21 jewels, Ø 25.60 mm (11½ lignes), 3.60 mm height, ball-bearing automatic winding, date with corrector, stop-seconds and the ETACHRON regulator are published ETA figures. The 42 h power reserve, bidirectional winding, 51° lift angle and Incabloc shock protection come from Caliber Corner (no ETA figure was found for them). Tooth counts, wheel sizes, the barrel position, the outlines of the bridges hidden under the rotor and the seconds drive are an approximation; the tooth counts make the fourth wheel turn once a minute and the escape wheel match 28,800 vph. Parts are drawn larger than life for legibility and the stack is much taller than the real 3.60 mm. The escapement motion is a kinematic model, not a physics simulation.

  • Chronograph
  • Automatic
  • Small seconds 9h
  • Day-date
  • Hacking

ETA Valjoux 7750

The cam-operated automatic chronograph: small seconds at 9, counters at 12 and 6, day-date at 3.

Frequency
28,800 vph · 4 Hz
Jewels
25
Diameter
30 mm
Power reserve
54 h
Seconds
Small seconds at 9 o’clock
Explore Lesson5 watches →
›A note on accuracy · sources

An approximation of the Valjoux 7750 layout from public drawings and photographs, not a manufacturer-accurate replica. 28,800 vph (4 Hz), 25 jewels, typical 54 h power reserve (ETA; press figures range from about 42 to 48 h), Ø 30.00 mm (13¼ lignes), 7.90 mm height, unidirectional self-winding, cam-operated chronograph with oscillating pinion, small seconds at 9, 30-minute counter at 12, 12-hour counter at 6, day and date at 3 and stop-seconds are published figures. Tooth counts, wheel sizes, the positions and outlines of the bridges and the chronograph levers, cam, hammer and brake are an approximation (their geometry is not published); the tooth counts make the fourth wheel turn once a minute and the escape wheel match 28,800 vph. Parts are drawn larger than life and the stack is taller than the real 7.90 mm. The escapement and chronograph motions are kinematic models.

Sellita

3 calibres

  • Automatic
  • Center seconds
  • Date
  • Hacking

Sellita SW200-1

Sellita’s 2824-2 clone: self-winding, 4 Hz, 26 jewels.

Derived from the ETA 2824-2

Frequency
28,800 vph · 4 Hz
Jewels
26
Diameter
25.6 mm
Power reserve
38 h
Seconds
Center seconds (indirect drive)
Explore Lesson16 watches →
›A note on accuracy · sources

An approximation of the Sellita SW200-1 layout from public drawings and photographs, not a manufacturer-accurate replica. 28,800 vph (4 Hz), 26 jewels, Ø 25.60 mm casing diameter (26.00 mm overall), 4.60 mm height, date with quick corrector and stop-seconds are Sellita’s published figures. Power reserve: Sellita gives 38 h minimum and 41 h typical; older brand specifications usually quote 38 h. As a clone of the ETA 2824-2 it is modelled on the 2824-2 geometry: tooth counts, wheel sizes, the barrel position, the bridge outlines hidden under the rotor and the seconds drive are an approximation, with the fourth wheel turning once a minute and the escape wheel matching 28,800 vph. Parts are drawn larger than life and the stack is taller than the real 4.60 mm. The escapement motion is a kinematic model, not a physics simulation.

  • Automatic
  • Center seconds
  • Date
  • Hacking

Sellita SW300-1

Sellita’s 2892-A2 clone: thin, self-winding, 4 Hz, 25 jewels and up to 56 h.

Derived from the ETA 2892-A2

Frequency
28,800 vph · 4 Hz
Jewels
25
Diameter
25.6 mm
Power reserve
56 h
Seconds
Center seconds (indirect drive)
Explore Lesson12 watches →
›A note on accuracy · sources

An approximation of the Sellita SW300-1 layout from public drawings and photographs, not a manufacturer-accurate replica. 28,800 vph (4 Hz), 25 jewels, Ø 25.60 mm casing diameter (26.20 mm overall), 3.60 mm height, date with quick setting, stop-second, fine timing device, a 51° lift angle and a power reserve of 50 h minimum / 56 h typical are Sellita’s published figures. Older specifications give 42 h; the press dates the longer-running barrel to 2020 (Time+Tide) or 2021 (Monochrome). Bidirectional winding is from Caliber Corner (Sellita does not state the direction). As a clone of the ETA 2892-A2 it is modelled on the 2892-A2 geometry: tooth counts, wheel sizes, the barrel position, the bridge outlines hidden under the rotor and the seconds drive are an approximation, with the fourth wheel turning once a minute and the escape wheel matching 28,800 vph. Parts are drawn larger than life and the stack is much taller than the real 3.60 mm. The escapement motion is a kinematic model, not a physics simulation.

  • Chronograph
  • Automatic
  • Small seconds 9h
  • Day-date
  • Hacking

Sellita SW500

Sellita’s 7750-architecture automatic chronograph: counters at 12 and 6, small seconds at 9.

Derived from the ETA Valjoux 7750

Frequency
28,800 vph · 4 Hz
Jewels
25
Diameter
30 mm
Power reserve
62 h
Seconds
Small seconds at 9 o’clock
Explore LessonNo watches in the catalogue yet
›A note on accuracy · sources

An approximation of the Sellita SW500 layout from public drawings and photographs, not a manufacturer-accurate replica. 28,800 vph (4 Hz), 25 jewels, typical 62 h power reserve, Ø 30.00 mm casing diameter (30.40 mm overall), 7.90 mm height, self-winding on a ball bearing, cam-operated chronograph with two push buttons, small seconds at 9, 30-minute counter at 12, 12-hour counter at 6, day and date with quick setting and stop-seconds are Sellita’s published figures for the SW500 a. Sellita does not state the winding direction or the coupling type: the model reuses the Valjoux 7750 arrangement (oscillating pinion) of which the SW500 is described as an almost direct clone. Tooth counts, wheel sizes and the outlines of bridges and chronograph parts are an approximation. The escapement and chronograph motions are kinematic models.

Miyota

2 calibres

  • Automatic
  • Center seconds
  • Date
  • Hacking

Miyota 9015

Citizen’s thin 4 Hz automatic: center seconds, date, a ball-bearing rotor.

Frequency
28,800 vph · 4 Hz
Jewels
24
Diameter
26 mm
Power reserve
42 h
Seconds
Center seconds (direct drive)
Explore Lesson15 watches →
›A note on accuracy · sources

An approximation of the Miyota 9015 layout from public drawings and photographs, not a manufacturer-accurate replica. 28,800 vph (4 Hz), 24 jewels, approx. 42 h power reserve, 11½‴, Ø 26.00 mm and 3.90 mm height are Miyota’s published figures (Monochrome gives 25.94 mm and Grail Watch Reference 25.60 mm; Miyota’s 26.00 mm is used). The sources consulted do not name the escapement type: the 3D lever escapement is a generic illustration. Tooth counts, the barrel and train positions and the shapes of the bridges are an approximation; the tooth counts give the published rate and a seconds wheel turning once a minute. The real rotor winds in one direction only; the shared animation winds on both swings. The escapement motion is a kinematic model, not a physics simulation.

  • Automatic
  • Center seconds
  • Date
  • Hacking

Miyota 8215

The 3 Hz Miyota workhorse since 1977: automatic, date, an exposed gilt balance.

Frequency
21,600 vph · 3 Hz
Jewels
21
Diameter
26 mm
Power reserve
42 h
Seconds
Center seconds (indirect drive)
Explore Lesson18 watches →
›A note on accuracy · sources

An approximation of the Miyota 8215 layout from public drawings and photographs, not a manufacturer-accurate replica. 21,600 vph (3 Hz), 21 jewels, a running time of more than 42 h, 11½‴, Ø 26.00 mm and 5.67 mm height are Miyota’s published figures. Stop-seconds (hacking) follows Miyota’s current specification; older production was non-hacking (Time+Tide, Caliber Corner). The sources consulted do not name the escapement type: the 3D lever escapement is a generic illustration. Tooth counts, the barrel and train positions and the shapes of the bridges are an approximation; the tooth counts give the published rate and a seconds wheel turning once a minute. The real rotor winds in one direction only; the shared animation winds on both swings. The escapement motion is a kinematic model, not a physics simulation.

Omega

2 calibres

  • Automatic
  • Center seconds
  • Date
  • Hacking
  • Co-axial

Omega 8800

Co-Axial Master Chronometer in 26 mm: free-sprung silicon balance at 3.5 Hz, 55 hours.

Frequency
25,200 vph · 3.5 Hz
Jewels
35
Diameter
26 mm
Power reserve
55 h
Seconds
Center seconds (indirect drive)
Explore Lesson18 watches →
›A note on accuracy · sources

This is an approximation of the Omega 8800 layout from public drawings and photographs, not a manufacturer-accurate replica. Bidirectional automatic winding, the Co-Axial escapement, the free-sprung balance with a silicon (Si14) hairspring, 25,200 vph (3.5 Hz), 55 hours from a single barrel, the date, resistance to 15,000 gauss and the rhodium-plated finish with Geneva waves in arabesque are published Omega figures; 35 jewels, Ø 26.00 mm and 4.60 mm height come from the press and reference databases (some databases give 29 mm and 5.50 mm, which are the 8900’s figures). Tooth counts, the escape-wheel tooth count, the Co-Axial geometry, the barrel position, the seconds drive and the outlines of the bridges hidden under the rotor are an approximation; the tooth counts make the fourth wheel turn once a minute and the escape wheel match 25,200 vph. Parts are drawn larger than life for legibility and the stack is taller than the real movement. The escapement motion is a kinematic model, not a physics simulation.

  • Chronograph
  • Manual winding
  • Small seconds 9h

Omega 1861

The Moonwatch calibre: hand-wound, cam-operated chronograph with a horizontal clutch.

Frequency
21,600 vph · 3 Hz
Jewels
18
Diameter
27 mm
Power reserve
48 h
Seconds
Small seconds at 9 o’clock

Variants

  • Omega 3861Yes — seconds stop when the crown is pulled
Explore Lesson16 watches →
›A note on accuracy · sources

An approximation of the Omega 1861 layout from public drawings and photographs, not a manufacturer-accurate replica. Manual winding, 21,600 vph (3 Hz), 48 h power reserve (Omega; WristBuzz gives about 45 h), 18 jewels, Ø 27.00 mm, 6.87 mm height, rhodium-plated finish, a cam-operated chronograph with horizontal clutch and Delrin brake, small seconds at 9, 30-minute recorder at 3 and 12-hour recorder at 6, and no hacking are published figures. Tooth counts, wheel sizes, the bridge outlines and the chronograph levers, cam, hammer and brake are an approximation (no exploded view or service document was found); the tooth counts make the fourth wheel turn once a minute and the escape wheel match 21,600 vph. Parts are drawn larger than life and the stack is taller than the real 6.87 mm. The escapement and chronograph motions are kinematic models.

Rolex

2 calibres

  • Automatic
  • Center seconds
  • Date
  • Hacking

Rolex 3135

Rolex’s date calibre for three decades: free-sprung, bridge-held balance, 4 Hz.

Frequency
28,800 vph · 4 Hz
Jewels
31
Diameter
28.5 mm
Power reserve
48 h
Seconds
Center seconds (indirect drive)
Explore Lesson18 watches →
›A note on accuracy · sources

An approximation of the Rolex 3135 layout from public drawings and photographs, not a manufacturer-accurate replica. 28,800 vph (4 Hz), 31 jewels, Ø 28.50 mm (28.10 mm casing), 6.00 mm height including the automatic and date mechanisms, the free-sprung annular balance with two pairs of Microstella nuts, the Breguet hairspring, the balance bridge adjustable in height by two nuts, the date with rapid corrector and stop-seconds are Rolex technical-sheet figures. Bidirectional winding, the jewelled-axle two-piece rotor, the two red reversing wheels, the Swiss lever escapement and the power reserve come from watch press and reference databases; Rolex’s sheet gives no power reserve, and sources split between about 48 h (used here) and 50 h. The orientation follows Rolex’s caseback render (balance at about 6, crown at 3: medium confidence). Tooth counts, wheel sizes, the barrel position, the train layout, the bridge outlines hidden under the automatic bridge and rotor, the seconds drive and the dial side are an approximation; the bridges are shown grained because no source names a decoration. Parts are drawn larger than life for legibility. The escapement motion is a kinematic model, not a physics simulation.

  • Automatic
  • Center seconds
  • Date
  • Hacking
  • Chronergy

Rolex 3235

Rolex’s current date calibre: Chronergy escapement, blue Parachrom, about 70 hours.

Frequency
28,800 vph · 4 Hz
Jewels
31
Diameter
28.5 mm
Power reserve
70 h
Seconds
Center seconds (indirect drive)
Explore Lesson14 watches →
›A note on accuracy · sources

An approximation of the Rolex 3235 layout from public drawings and photographs, not a manufacturer-accurate replica. Bidirectional winding by a monobloc rotor on a ball bearing held by a single screw, red reversing wheels, 28,800 vph (Rolex: eight beats a second), about 70 h power reserve, the Chronergy escapement (cut-out nickel-phosphorus escape wheel and fork, thinner pallet stones, offset pivots), the variable-inertia balance with four gold Microstella nuts, the blue Parachrom hairspring, the traversing height-adjustable bridge, Paraflex, the instantaneous date with rapid setting and stop-seconds are Rolex figures. Rolex publishes no jewel count, diameter or height: 31 jewels and Ø 28.50 mm come from Caliber Corner, Grail, Ranfft and Chronospex, and no reliable height was found. The orientation follows Rolex’s caseback render (balance at about 6, crown at 3: medium confidence). Tooth counts, wheel sizes, the barrel position, the train layout, the bridge outlines, the position of the escapement, the number and position of the reversing wheels, the seconds drive and the dial side are an approximation; the bridges are shown grained because no source names a decoration. Parts are drawn larger than life for legibility. The escapement motion is a kinematic model, not a physics simulation.

Seiko

1 calibre

  • Automatic
  • Center seconds
  • Date
  • Hacking

Seiko NH35A

The 3 Hz automatic from SII: Magic Lever winding, hacking, hand-winding, date at 3.

Frequency
21,600 vph · 3 Hz
Jewels
24
Diameter
27.4 mm
Power reserve
41 h
Seconds
Center seconds (direct drive)

Variants

Explore Lesson20 watches →
›A note on accuracy · sources

An approximation of the NH35 layout from public drawings and photographs, not a manufacturer-accurate replica. 21,600 vph (3 Hz), 24 jewels, a power reserve of more than 41 h, Ø 27.40 mm (12‴), 5.32 mm height, bidirectional automatic winding on a ball-bearing rotor, hand winding, hacking and the quick-set date are published figures (TMI specification sheet); the Magic Lever is named by Unimatic and Caliber Corner. Tooth counts, the seconds drive and the exact shapes and positions of parts are an approximation from the TMI drawings; the tooth counts make the seconds wheel turn once a minute and the escapement beat 21,600 times an hour. No source checked names the escapement type: the lever escapement shown is a generic illustration, and its motion is a kinematic model, not a physics simulation.

Tudor

1 calibre

  • Automatic
  • Center seconds
  • Hacking

Tudor MT5602

Tudor’s Manufacture Calibre: 70 hours, silicon hairspring, balance held at both ends.

Frequency
28,800 vph · 4 Hz
Jewels
25
Diameter
31.8 mm
Power reserve
70 h
Seconds
Center seconds (indirect drive)
Explore Lesson13 watches →
›A note on accuracy · sources

This is an approximation of the Tudor MT5602 layout from public drawings and photographs, not a manufacturer-accurate replica. The bidirectional rotor system with an openworked monobloc tungsten rotor, 28,800 vph (4 Hz), 25 jewels, about 70 hours, Ø 31.8 mm, 6.5 mm height, stop-seconds, the variable-inertia balance with a silicon hairspring, the traversing balance bridge with two-point fixing and COSC certification are published Tudor figures. Tudor calls it an in-house Manufacture Calibre; Caliber Corner and watch-winder.app say it is made by Kenissi, in which Tudor holds a stake. Tudor does not name the escapement type, so none is claimed; the builder draws a generic escape wheel and pallet fork. Tooth counts, the barrel position, the train layout, the seconds drive and the bridge outlines are an approximation; the tooth counts make the fourth wheel turn once a minute and the escape wheel match 28,800 vph. Parts are drawn larger than life for legibility. The escapement motion is a kinematic model, not a physics simulation.

HOROLOGY teaching calibre

1 calibre

  • Manual winding

Demonstration Calibre H-01

A hand-wound movement, built to be taken apart.

Frequency
18,000 vph · 2.5 Hz
Jewels
17
Diameter
36 mm
Seconds
No seconds hand
Explore LessonNo watches in the catalogue yet
›A note on accuracy

A procedural teaching model, not a replica of a production caliber. Tooth counts and the 18,000 vph rate are realistic and drive every animated ratio; wheel sizes, bridge shapes and the plan layout are simplified for clarity. The escapement motion is a kinematic model (timed release and impulse), not a physics simulation.

03How it works

How does a mechanical watch work?

A guided lesson in 5 steps. The movement lights up the parts that matter, turns to face you and sets its own pace — from 0.05× in slow motion to 60× real time.

Begin the lesson
  1. IThe Perpetual rotor
  2. IIThe going train
  3. IIIChronergy
  4. IVParachrom under a full bridge
  5. VCenter seconds and the instant date