Exhibit Codex
Inline-four Engine
Run an inline-four engine slowly, scrub the crank angle and follow intake, compression, power and exhaust. Inspect the synchronized pistons, rods, crankshaft, valves and supporting assemblies.
Open interactive exhibit ↗About this exhibit
Casting, motion & control
Reference and coverage
Original interactive inline-four teaching mechanism. Fixed-length connecting rods, paired piston motion and valve events follow a four-stroke cycle. Dimensions, idealized lift, gas colors and clearances are educational, not manufacturing data.
Available layers
- Housing
- Moving assembly
- Cylinder head
- Cycle visualization
Structure index
Named structures in this reference. Open the interactive Codex for additional study views and selectable records.
Cutaway cylinder block
Housing
Cutaway casting exposes four cylinder bores and the crankcase. The open side is a teaching section through the housing.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Crankshaft and counterweights
Moving assembly
Four crank throws convert piston travel into shaft rotation. Cylinders 1 and 4 move together, opposite cylinders 2 and 3.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Flywheel and starter ring
Moving assembly
The flywheel stores rotational energy between firing events. The teeth engage the starter during cranking.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Sectioned cylinder head
Cylinder head
The cylinder head closes the combustion chambers and supports valves, spark plugs and camshafts. This teaching cutaway leaves the front of each chamber visible.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Twin camshafts and lobes
Cylinder head
The camshafts rotate once for every two crankshaft revolutions. Idealized valve lift illustrates the four-stroke sequence; real engines use overlap and different profiles.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Cylinder 1 · cutaway liner
Housing
The cylindrical liner guides the piston and supports its sealing rings. Half of the liner is removed for inspection.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Piston 1 and compression rings
Moving assembly
The crown receives gas pressure. Compression rings seal the bore, while the wrist pin connects the piston to its rod.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Connecting rod 1
Moving assembly
A rigid rod of fixed length links the wrist pin to a rotating crank pin. Its angular swing produces the non-sinusoidal piston travel.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Intake valve 1
Cylinder head
Opens during the intake stroke to admit fresh charge. The animation uses a simple sinusoidal lift profile.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Intake valve spring 1
Cylinder head
The helical spring returns the valve toward its seat when the cam releases it.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Exhaust valve 1
Cylinder head
Opens during the exhaust stroke to discharge spent gas. Valve overlap is omitted from this teaching cycle.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Exhaust valve spring 1
Cylinder head
The helical spring returns the valve toward its seat when the cam releases it.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Spark plug 1
Cylinder head
The plug initiates combustion near the compression-to-power transition in this spark-ignition engine.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Cylinder 1 · working gas
Cycle visualization
Color indicates intake, compression, power and exhaust. The volume follows piston motion; temperature and pressure are not numerically simulated.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Cylinder 2 · cutaway liner
Housing
The cylindrical liner guides the piston and supports its sealing rings. Half of the liner is removed for inspection.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Piston 2 and compression rings
Moving assembly
The crown receives gas pressure. Compression rings seal the bore, while the wrist pin connects the piston to its rod.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Connecting rod 2
Moving assembly
A rigid rod of fixed length links the wrist pin to a rotating crank pin. Its angular swing produces the non-sinusoidal piston travel.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Intake valve 2
Cylinder head
Opens during the intake stroke to admit fresh charge. The animation uses a simple sinusoidal lift profile.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Intake valve spring 2
Cylinder head
The helical spring returns the valve toward its seat when the cam releases it.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Exhaust valve 2
Cylinder head
Opens during the exhaust stroke to discharge spent gas. Valve overlap is omitted from this teaching cycle.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Exhaust valve spring 2
Cylinder head
The helical spring returns the valve toward its seat when the cam releases it.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Spark plug 2
Cylinder head
The plug initiates combustion near the compression-to-power transition in this spark-ignition engine.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Cylinder 2 · working gas
Cycle visualization
Color indicates intake, compression, power and exhaust. The volume follows piston motion; temperature and pressure are not numerically simulated.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Cylinder 3 · cutaway liner
Housing
The cylindrical liner guides the piston and supports its sealing rings. Half of the liner is removed for inspection.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Piston 3 and compression rings
Moving assembly
The crown receives gas pressure. Compression rings seal the bore, while the wrist pin connects the piston to its rod.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Connecting rod 3
Moving assembly
A rigid rod of fixed length links the wrist pin to a rotating crank pin. Its angular swing produces the non-sinusoidal piston travel.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Intake valve 3
Cylinder head
Opens during the intake stroke to admit fresh charge. The animation uses a simple sinusoidal lift profile.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Intake valve spring 3
Cylinder head
The helical spring returns the valve toward its seat when the cam releases it.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Exhaust valve 3
Cylinder head
Opens during the exhaust stroke to discharge spent gas. Valve overlap is omitted from this teaching cycle.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Exhaust valve spring 3
Cylinder head
The helical spring returns the valve toward its seat when the cam releases it.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Spark plug 3
Cylinder head
The plug initiates combustion near the compression-to-power transition in this spark-ignition engine.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Cylinder 3 · working gas
Cycle visualization
Color indicates intake, compression, power and exhaust. The volume follows piston motion; temperature and pressure are not numerically simulated.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Cylinder 4 · cutaway liner
Housing
The cylindrical liner guides the piston and supports its sealing rings. Half of the liner is removed for inspection.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Piston 4 and compression rings
Moving assembly
The crown receives gas pressure. Compression rings seal the bore, while the wrist pin connects the piston to its rod.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Connecting rod 4
Moving assembly
A rigid rod of fixed length links the wrist pin to a rotating crank pin. Its angular swing produces the non-sinusoidal piston travel.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Intake valve 4
Cylinder head
Opens during the intake stroke to admit fresh charge. The animation uses a simple sinusoidal lift profile.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Intake valve spring 4
Cylinder head
The helical spring returns the valve toward its seat when the cam releases it.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Exhaust valve 4
Cylinder head
Opens during the exhaust stroke to discharge spent gas. Valve overlap is omitted from this teaching cycle.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Exhaust valve spring 4
Cylinder head
The helical spring returns the valve toward its seat when the cam releases it.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Spark plug 4
Cylinder head
The plug initiates combustion near the compression-to-power transition in this spark-ignition engine.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Cylinder 4 · working gas
Cycle visualization
Color indicates intake, compression, power and exhaust. The volume follows piston motion; temperature and pressure are not numerically simulated.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Intake plenum and runners
Housing
The plenum distributes intake flow to individual cylinder ports. Displayed runner lengths are illustrative.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Four-into-one exhaust manifold
Housing
Separate runners collect exhaust from each cylinder into a common outlet.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Sectioned oil sump
Housing
The sump collects lubricating oil below the crankshaft. The near side is opened for visibility.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Cylinder-head fasteners
Cylinder head
Fasteners clamp the cylinder head and gasket to the block. The displayed spacing is explanatory rather than a bolt-torque specification.
Original museum mechanism. Slider-crank geometry and a 1–3–4–2 four-stroke sequence are synchronized; dimensions, valve lift profiles and combustion coloring are illustrative.
Read the detailed records
Open the full exhibit Codex for individual structure records and time-specific information. The Credits page lists source creators, licenses and adaptations.