(a) Design Load. The design load of the lift shall be at least 270 kg (595 lb). Working parts, such as cables, pulleys, and shafts, which can be expected to wear and upon which the lift depends for support of the load, shall be designed with a safety factor of at least six. Nonworking parts, such as platform, frame, and attachment hardware which would not be expected to wear, shall be designed with a safety factor of at least three.

(b) Controls. Each control for deploying, lowering, raising, and stowing the lift, and moving the barrier shall be of a momentary contact type requiring continuous manual pressure by the operator and shall not allow unintentional improper lift sequencing when the platform is occupied. The controls shall be designed to be interlocked with the bus brakes and with the accelerator or transmission so the bus cannot move when the lift is not stowed and so the lift cannot deploy without engaging the interlock. As an alternative, on buses equipped with hydraulic brakes, an interlock system which complies with the Americans With Disabilities Act (ADA) requirements in Title 49, Code of Federal Regulations, Section 38.23(b)(2), as published October 1, 1995, will be deemed to comply with the interlock requirements of this section subject to the following conditions:

(c) Manual Operation. The lift assembly shall incorporate a manual method of deploying, lowering to ground level with a wheelchair occupant and raising and stowing the empty lift if the power fails.

(d) Power or Equipment Failure. Platforms stowed in a vertical position shall have a provision to prevent their deploying any faster than twice the maximum rate specified in following subsection (i), in the event of a failure of power, chain, cable, or hydraulic hose. Deployed platforms shall have a provision to prevent their falling, when loaded, any faster than twice their maximum rate in the event of the same type of failure. Failure, while the bus is in motion, of any part of the system powering the wheelchair lift shall not reduce the effectiveness of the braking, steering, or electrical systems of the bus.

(e) Platform Barriers. The lift platform shall be equipped with barriers to prevent any of the wheels of the wheelchair from rolling off the platform. The loading edge of the platform shall have a movable barrier that is not shorter than 92% of the length of that edge of the platform and that, when in its normal raised position, is at least 8 cm (3.1 in.) above the surface of the platform. The movable barrier in its raised position shall withstand a total force of at least 1340 Newton (N) (300 lb) parallel to the platform surface in the unloading direction with the top edge remaining above 8 cm (3.1 in.). The force shall be applied at a height of 7 cm (2.8 in.) above the top surface of the platform with 670 N (150 lb) at each of two points 30 cm (11.8 in.) on each side of the center of the barrier. Other sides of the lift platform shall have fixed or movable barriers at least 25 mm (1.0 in.) high unless other parts of the lift or the body of the bus prevent any of the wheels of the wheelchair from rolling off the platform.

(f) Barrier Operation. The barrier on the outboard side of the lift platform shall automatically lower or open when the platform meets the roadway or sidewalk and shall automatically raise or close when the platform is moved upward. As an alternative, the barrier may be raised, lowered, opened or closed by the lift operator. The barrier, when controlled automatically, shall be in its fully raised or closed position at all times when the bottom edge of the platform is more than 8 cm (3.1 in.) above the roadway or sidewalk. Unless lift controls are designed to be operated by a person standing at ground level adjacent to the lift, barriers shall be interlocked so the lift cannot be raised until the barrier has been raised.

(g) Platform Surface. The platform surface on which the wheelchair rolls shall be free of any protrusions over 6 mm (0.24 in.) high and shall be slip resistant.

(h) Platform Deflection. The lift platform at all operating heights shall not deflect more than 3 degrees in any direction between its unloaded position and its position when uniformly loaded with 170 kg (375 lb). Entrance ramps to the lift platform shall be excluded from this measurement.

(i) Platform Movement. No part of the lift platform shall move at a rate exceeding 30 cm/sec (11.8 in./sec) during deployment, lowering, lifting or stowing. This subsection shall not apply to a manually deployed platform.

(j) Boarding Direction. The lift platform shall permit wheelchairs to board both by rolling forward and by rolling backward.

(k) Protective Covering. Any readily accessible parts of a wheelchair lift that could injure passengers or operators or catch or damage clothing or other objects when the lift is in any position shall be covered with a guard.

(l) Fasteners. All fasteners shall withstand vehicle and lift vibrations without loosening.