Gearbox nomenclature — counting forward ratios A manual transmission that provides four forward speeds and one reverse is commonly described as a:

Introduction / Context:
Transmissions are described by the number of forward gear ratios they provide. This affects drivability, engine speed at cruise, and acceleration. Technicians and drivers should use the standard nomenclature to avoid confusion during service and parts selection.

Given Data / Assumptions:

• Four usable forward ratios plus one reverse ratio.
• Conventional passenger vehicle gearbox.

Concept / Approach:
The industry convention counts only forward ratios for the speed descriptor. Therefore, four forward ratios define a 4-speed transmission regardless of the presence of reverse and occasionally additional special modes.

Step-by-Step Solution:
Identify number of forward gears: 4.Apply convention: name by forward gears only.Conclude: 4-speed gearbox.

Verification / Alternative check:
Owners manuals and parts catalogs list 4-speed, 5-speed, or 6-speed by forward ratios, with reverse specified separately.

Why Other Options Are Wrong:
3-speed and 5-speed describe different counts. 6-speed is not applicable here.

Common Pitfalls:
Confusing overdrive or transfer case ranges as additional speeds in this naming convention.

Final Answer:
4-speed gear box