Engineering in Action! Typical Formula (D-Ring) restraints display high upper torso trajectory during a crash. To reduce this trajectory, the crotch straps have to be routed backwards and to be worn extremely tight. Some drivers complain of reduced blood fl ow in their legs.
In addition, this configuration does not help during a rear impact to keep the buckle and the lap belt in the correct position. In particular in typical open-wheel race car seating positions the driver is not kept fi rmly in his seat but is likely to move up exceeding the roll over protection bar.
The so called T-bar 6-point belt design provides a better restraining function since the anti-sub straps can be routed downward following approximately a chest/crotch tangential. This keeps the buckle in place and provides direct load transfer from the shoulder straps into the anti-sub straps. During a rear impact the anti-sub straps keep the buckle and lap belt in place and restrain the driver much better in the seat. The disadvantage of this type of harness: the T-bar should be wide enough to properly separate the antisub straps but is then likely to stick into the upper thighs.
To increase the comfort, the buckle is often not worn as low as it should for best lap belt positioning. The solution: the revolutionary SCHROTH Hybrid™ Restraint. The crotch straps are not routed through D-rings or attached to a T-Bar but are held directly by the specially developed lap belt latches.
Thanks to the patented SCHROTH RFR™ rotary buckle the load tranfer from the shoulder belts through the buckle 30 into the anti-sub straps and vice versa in case of a rear impact is achieved. This direct load transfer is important for optimal restraining performance.