Ignition systems – what does the distributor do in a coil-ignition I.C. engine? Select the primary function performed by the distributor in a conventional battery-coil ignition system for multi-cylinder petrol engines.

Introduction / Context:
In coil-ignition systems used on traditional spark-ignition engines, the distributor is a key component that routes high-voltage pulses to the appropriate spark plug at the correct time. Understanding its role clarifies how ignition timing and cylinder sequencing are coordinated.

Given Data / Assumptions:

• Battery-coil ignition with a single ignition coil.
• Mechanical distributor with rotor arm and cap (classic design).
• Engine has multiple cylinders and a defined firing order.

Concept / Approach:
The ignition coil steps up battery voltage to a high-tension (HT) pulse at each primary circuit interruption. The distributor rotor, synchronized with the camshaft, physically directs each HT pulse to the correct cylinder’s spark plug via the cap contacts. Ancillary mechanisms (centrifugal and vacuum advances) adjust timing, but the core task is controlled distribution of the spark.

Step-by-Step Solution:
Coil generates HT pulse → needs routing to one plug at a time.Distributor’s rotor aligns with cap contacts in firing order.Result: each cylinder receives a spark near the end of its compression stroke.Thus, the distributor’s primary function is to distribute the spark to the proper cylinder in sequence.

Verification / Alternative check:
Service manuals depict rotor and cap alignment marks, confirming the distributor’s routing role; timing lights verify correct sequencing and advance.

Why Other Options Are Wrong:

• Mechanical power distribution, sensor current distribution, throttle actuation, and fuel-injection pressure regulation are unrelated to the distributor’s function.

Common Pitfalls:
Confusing the distributor’s routing role with timing adjustment; while it often houses advance mechanisms, the fundamental task is HT distribution.

Final Answer:
to distribute the high-tension spark to the correct plug in firing order