Fixed occupancy seat means a bench seat equipped with Type 2 seat belts that has a permanent configuration regarding the number of seating positions on the seat. The number of seating positions on the bench seat cannot be increased or decreased.
Flexible occupancy seat means a bench seat equipped with Type 2 seat belts that can be reconfigured so that the number of seating positions on the seat can change. The seat has a minimum occupancy configuration and maximum occupancy configuration, and the number of passengers capable of being carried in the minimum occupancy configuration must differ from the number of passengers capable of being carried in the maximum occupancy configuration.
Maximum occupancy configuration means, on a bench seat equipped with Type 2 seat belts, an arrangement whereby the lap belt portion of the Type 2 seat belts is such that the maximum number of occupants can be belted.
Minimum occupancy configuration means, on a bench seat equipped with Type 2 seat belts, an arrangement whereby the lap belt portion of the Type 2 seat belts is such that the minimum number of occupants can be belted.
School bus passenger seat means a seat in a school bus, other than the driver's seat.
Seat bench width means the maximum transverse width of the bench seat cushion.
Small occupant seating position means the center seating position on a flexible occupancy seat in a maximum occupancy configuration, if the torso belt portion of the Type 2 seat belt is intended to restrain occupants whose dimensions range from those of a 50th percentile 6 year-old child only to those of a 50th percentile 10 year-old child and the torso belt anchor point cannot achieve a minimum height of 520 mm above the seating reference point, as specified by S4.1.3.2(a) of 49 CFR 571.210 .
Wheelchair means a wheeled seat frame for the support and conveyance of a physically disabled person, comprised of at least a frame, seat, and wheels.
Wheelchair occupant restraint anchorage means the provision for transferring wheelchair occupant restraint system loads to the vehicle structure.
Wheelchair securement anchorage means the provision for transferring wheelchair securement device loads to the vehicle structure.
Wheelchair securement device means a strap, webbing or other device used for securing a wheelchair to the school bus, including all necessary buckles and other fasteners.
Table 1-Number of Seating Positions as a Function of Seat Bench Width
Seating configuration | Seat bench width (mm) | ||||
380-659 | 660-759 | 760-989 | 990-1139 | 1140-1319 | |
Minimum or Fixed Occupancy | 1 | 1 | 2 | 2 | 3 |
Maximum Occupancy | 1 | 2 | 2 | 3 | 3 |
Table 2-Torso Belt Anchor Point Displacement Limit
Gross vehicle weight rating | Displacement limit in millimeters |
More than 4,536 kg (10,000 pounds) | (AH + 100) (tan[PHI] + 0.242/cos[PHI]) |
Less than or equal to 4,536 kg (10,000 pounds) | (AH + 100) (tan[PHI] + 0.356/cos[PHI]) |
Table 3-Seat Back Point Displacement Limit
Gross vehicle weight rating | Displacement limit in millimeters |
More than 4,536 kg (10,000 pounds) | (AH + 100) (tan[PHI] + 0.174/cos[PHI]) |
Less than or equal to 4,536 kg (10,000 pounds) | (AH + 100) (tan[PHI] + 0.259/cos[PHI]) |
Table 4-Torso Body Block Forces for Fixed Occupancy Seats
Gross vehicle weight rating | True expression | Applied force |
More than 4,536 kg (10,000 pounds) | ((seat bench width in mm)-(380Y)) [LESS THAN EQUAL TO]25 mm (1 inch) | 3,300 N (742 pounds). |
More than 4,536 kg (10,000 pounds) | ((seat bench width in mm)-(380Y)) [GREATER THAN]25 mm (1 inch) | 5,000 N (1,124 pounds). |
Less than or equal to 4,536 kg (10,000 pounds) | ((seat bench width in mm)-(380Y)) [LESS THAN EQUAL TO]25 mm (1 inch) | 5,000 N (1,124 pounds). |
Less than or equal to 4,536 kg (10,000 pounds) | ((seat bench width in mm)-(380Y)) [GREATER THAN]25 mm (1 inch) | 7,500 N (1,686 pounds). |
Table 5-Torso Body Block Forces in Maximum Occupancy Configuration
Gross vehicle weight rating | Applied force |
More than 4,536 kg (10,000 pounds) | 3,300 N (742 pounds). |
Less than or equal to 4,536 kg (10,000 pounds) | 5,000 N (1,124 pounds). |
shall not exceed 1,000 where "a" is the axial acceleration expressed as a multiple of "g" (the acceleration due to gravity), and "t1" and "t2" are any two points in time during the impact.
49 C.F.R. §571.222
For FEDERAL REGISTER citations affecting § 571.222, see the List of CFR Sections Affected, which appears in the Finding Aids section of the printed volume and at www.govinfo.gov.