Machines — Terminology Check A non-reversible machine (no motion of the load when the effort is removed) is also called a self-locking machine. Is this statement correct?

Introduction / Context:
In the study of machines like screw jacks, hoists, and geared blocks, reversibility indicates whether a load can drive the machine in reverse when the effort is removed. This property determines safety and back-driving behavior.

Given Data / Assumptions:

• Machine exhibits sufficient friction or geometry to prevent back-driving.
• Effort is removed after raising the load.
• Terminology per standard machine theory.

Concept / Approach:
A reversible machine allows the load to drive the effort side when the applied effort is removed (e.g., runs backward). A non-reversible machine does not back-drive; if it holds the load by itself due to friction or geometry, it is termed self-locking.

Step-by-Step Reasoning:

Verification / Alternative check:
For screw mechanisms, a < φ (helix angle less than friction angle) ensures self-locking; under this, the load cannot descend on its own, confirming non-reversibility equals self-locking in standard usage.

Why Other Options Are Wrong:
Disagreeing would contradict conventional definitions in machine theory and safety literature.

Common Pitfalls:
Confusing self-sustaining (holding momentarily) with self-locking (cannot back-drive at all); assuming all irreversible machines are efficient—they usually have higher friction losses.

Final Answer:
Agree — a non-reversible machine is called self-locking.