Object
This test determines the ability of an optical fiber cable to withstand repeated flexing under service conditions. It is primarily intended for specialized cable types, such as elevator cables or other cables subject to continuous movement during operation.

Apparatus
The test shall be conducted using an apparatus configured as shown in Figure 12, or an equivalent arrangement specified in the detail specification.
The pulleys shall feature a semicircular groove for circular cables and a flat groove for flat cables. The restraining clamps (D) shall be positioned so that the applied force is always directed by the weight opposite to the moving carriage. Equivalent systems—such as those described in IEC 60227-2—may also be used.

Procedure
Unless otherwise specified, testing shall be performed under standard atmospheric conditions.
The cable sample shall be routed over the pulleys with each end loaded by a specified weight. The mass of the weights and the pulley diameters (A and B) shall conform to the requirements stated in the detail specification.
The sample shall be flexed for the specified number of cycles, where one cycle is defined as the carriage moving from its initial position to one end of the traverse, then to the opposite end, and back again. The test setup shall ensure that the entire test length of cable passes over the pulleys during each cycle.

The movement speed and traverse duration shall be in accordance with the detail specification, and the acceleration/deceleration of the carriage shall be limited to avoid introducing inertial stresses.

Requirements
Acceptance criteria shall be defined in the applicable detail specification. Typical failure modes include:

• Loss of optical continuity
• Degradation of optical transmittance
• Physical damage to the cable structure