Shift it yourself, or let the car shift — watch the gears either way.

One simulator, two real ways to change gear. In Manual mode you operate a clutch and an H-pattern lever to select fixed gear pairs. In Automatic mode a torque converter and a planetary gearset change ratio for you while you just steer the throttle. The engine, gearbox and wheels are physically coupled (engine RPM, ratio, wheel speed and road speed all agree), and every mechanism is drawn in a semi-3D cutaway. Scroll down for the manual vs automatic comparison, pros and cons.

Gear lever (H-pattern)

Clutch pedal

Hold Space (or C) = clutch in. You must be off the clutch to drive, and in to change gear.

Manual driving tips

1) Clutch in → 2) pick 1 → 3) some throttle → 4) release clutch smoothly. Shift up as the needle climbs; clutch in first or you'll grind.

Engine & load

Throttle15%

Playback

Sim time scale1.00×

Ready. Follow the mode tips on the left.

Manual cutaway — clutch → selected gear pair driver presses the clutch to break the engine–wheels link, moves the lever, releases.

gear 1 · 3.55:1

engine → clutch → gearbox → final drive → wheels

Engine speed900 rpm idle 900 · redline 7000

GearNneutral — engine free

Gearbox ratio—input turns : output 1

Engine linkclutch openpress the pedal to break the link

Gearbox output—

Wheel speed—driveshaft ÷ final 3.90

Vehicle speed0 km/h

R = N_driven/N_driver ·ω_out = ω_in/R ·τ_out = τ_in·R ·v = ω_wheel·r_tyre ·planetary: ω_sun + k·ω_ring = (1+k)ω_carrier, k = N_ring/N_sun

How the model works ▼

Engine. Throttle sets engine torque (peak ~205 N·m near 3 600 rpm); with the throttle closed above idle the engine brakes the car instead of driving it (engine braking). Idle ≈ 900 rpm, redline 7000 rpm.
Manual coupling. Clutch in → engine and gearbox are separate (engine free-spins, car coasts). Clutch released in gear → they are locked: wheel speed = engine RPM ÷ (gear ratio × final drive). Dumping the clutch at very low rpm with little throttle stalls the engine.
Manual ratios (typical). 1st 3.55, 2nd 2.10, 3rd 1.40, 4th 1.00, 5th 0.77 overdrive, reverse 3.50 (direction reversed through an idler); final drive 3.90.
Automatic coupling. The torque converter lets the engine spin faster than the gearbox input when pulling away — that speed difference is slip, and at stall it multiplies torque (~1.9×). Near matching speeds the converter stops multiplying and the gearbox input runs almost at engine speed.
Planetary set. One sun, one ring and planets on a carrier obey ω_s + k·ω_r = (1+k)·ω_c. Lock one member and the other two give a ratio (3.50 / 1.40 / 0.714) or reverse. Direct 3rd locks the set together. Simplification: real 4-speed automatics use two coupled planetary sets (Simpson/Ravigneaux) — this page shows one conceptual set so each ratio's logic is visible.
Shift schedule (auto). Upshifts at ≈ 22 / 42 / 66 km/h, downshifts at ≈ 10 / 26 / 44 km/h (hysteresis stops gear hunting). Typical values, not a specific car's.

Educational simulation. Plain HTML, CSS & JavaScript — no libraries, works offline. Numbers marked "typical" are illustrative; verify a real car's specs online.

Manual vs automatic — what is actually different?

Both change the ratio between engine speed and wheel speed. They differ in who changes it, how the engine is temporarily uncoupled from the wheels, and in cost, effort, efficiency and driving feel.

Aspect	Manual shift	Automatic shift
Who picks the gear	The driver — a lever (H-pattern) and clutch pedal	The transmission — a shift schedule in the control unit (valve body / TCU), or driver via a mode/selector
Engine–gearbox coupling	Friction clutch (driver-controlled, with a pedal) + synchromesh collars	Torque converter (fluid coupling) or, in newer boxes, clutches; the coupling is automatic
Mechanism	Parallel shafts with fixed gear pairs; a selector fork slides a collar to lock one pair to the output shaft	Planetary gear sets whose members are locked by clutches and bands (or dog clutches / dual clutches in DCTs)
Pedals / hands	Three pedals; left foot busy with the clutch	Two pedals; both feet rarely needed while driving
Shifting action	Engine torque is interrupted each shift (clutch in), then re-applied	Shifts happen under power (or with a small torque-converter / clutch hand-over), usually seamless
Learning curve	Steep: clutch control, hill starts, rev matching, stalling	Shallow: select D and go
Efficiency	Mechanically direct, historically better on fuel; but depends heavily on the driver	Modern 8–10 speed units and lock-up converters often match or beat manuals; older units lose a little in the converter
Control & engine braking	Exact control of ratio, gears hold on descents, predictable engine braking	Good, but the box may upshift or hunt on hills; many cars offer manual paddle/gear overrides
Weight / cost / maintenance	Lighter, cheaper to buy and repair; clutch wears with use (esp. bad technique and stop-start traffic)	Heavier and more complex; periodic ATF service; repairs can be expensive
Feel & engagement	Direct, involving, "connected to the road" — many enthusiasts' choice	Effortless, smooth, convenient in traffic and for new drivers

🚘 Manual transmission

Pros
PRO Full driver control of gear and engine speed at all times.
PRO Usually lighter, cheaper to buy, cheaper to repair.
PRO Direct mechanical link — very predictable engine braking and response.
PRO Can be push-started; harder to steal (for most people!).
PRO Many drivers find it more involving and fun.

Cons
CON Takes practice — stalls, hill starts and clutch slip are beginner traps.
CON More effort and fatigue in heavy traffic.
CON Clutch wears faster with poor technique or constant stop-and-go.
CON Bad shifting hurts fuel economy and driveline life.
CON Vanishing availability — few new cars, weaker resale market.

🚗 Automatic transmission

Pros
PRO Easiest to drive — no clutch, no stalling, no gear choice.
PRO Smooth, quick shifts; modern units shift faster than most drivers.
PRO Very convenient in traffic and on hills (creep, hill-hold, no roll-back).
PRO TCU always shifts near the engine's sweet spot — often best real-world economy.
PRO Easier for new drivers, accessibility, remote start, towing modes.

Cons
CON Less direct control; gear choice can feel delayed or "hunt" on hills.
CON Heavier, more complex, more expensive to repair.
CON Torque-converter slip wastes a little energy (mitigated by lock-up).
CON Older units can feel sluggish and need periodic fluid service.
CON Less engaging for drivers who enjoy controlling the car themselves.

Mini glossary

Ratio R: How many times the input shaft turns for one turn of the output (3.55:1 first gear = torque multiplied, speed divided).
Final drive: The last fixed reduction (differential) between gearbox and wheels — here 3.90:1.
Synchromesh: Friction cones inside the collar that match shaft and gear speeds before the teeth engage, so shifts are quiet.
Torque converter: Fluid coupling (impeller → turbine, plus a stator) that lets the engine idle while the car is stopped and multiplies torque when pulling away.
Planetary gearset: Sun gear, ring gear and carrier-mounted planets; lock different members to get different ratios from one compact set.
Overdrive: A ratio below 1:1 (e.g. 5th 0.77) — engine turns slower than the wheels for economical cruising.
Shift schedule: The speed/load table an automatic uses to decide upshifts and downshifts.
DCT / CVT: Automatics with two clutches (dual-clutch) or a continuously variable ratio — different mechanisms, out of scope here.

🔍 Check the numbers online (the author flagged these as "look it up")

Real gear ratios, converter curves and shift points differ from car to car. Try these searches to replace the typical values above with a real vehicle's data:

" manual transmission gear ratios final drive" — e.g. a MX-5 or Civic 6-speed; compare with the table above.
planetary gearset Willis equation derivation sun ring carrier — to check the formula sign convention and the ratio cases.
4 speed automatic transmission clutch band application chart Simpson gearset — see why real 4-speeds need two planetary sets.
torque converter stall speed torque ratio curve lockup clutch — converter behavior, stall ratio and lock-up speeds.
manual vs automatic pros cons fuel economy maintenance — current independent comparisons and economy tests.
how does synchromesh work and automatic transmission valve body shift schedule explained — the parts this sim simplifies.

Educational simulation. Plain HTML, CSS & JavaScript — no libraries, works offline.