Abstract: A device for securing an annular blade retaining plate to a rotor disk includes an annular groove around the disk for receiving an off-set annular flange on the inner end of said blade retaining plate. A split retainer ring extends from a second groove intersecting said first groove to fix the blade retainer ring to the disk. A locking ring is positioned between said split retainer ring and said blade retaining plate to maintain said split retainer ring in its groove.

Abstract: The customary side hand propulsion ring adjacent to each main wheel of a manual wheelchair is mounted through a lost motion connection between the propulsion ring and main wheel so that the propulsion ring can have limited rotational movement relative to the main wheel. A friction brake drum or partial drum fixed to the wheelchair frame inside of the main wheel is engaged by at least one of a plurality of circumferentially spaced over center friction locking devices pivotally held on the main wheel. Each over center friction locking device is moved by a release element to a non-locking position relative to the drum or partial drum in response to reverse movement of the propulsion ring by a chair occupant. Economy and ease of operation are provided for. The wheelchair occupant need not remove his or her hand from the propulsion ring when operating the anti-rollback mechanism.

Abstract: To substantially reduce the physical effort required to slow or stop a manually propelled wheelchair, the customary propulsion ring attached to the outer side of each main chair wheel is mounted on the wheel for limited inward axial movement under manual pressure and is biased outwardly by spring force. A brake ring of similar diameter near the interior side of each wheel in a plane parallel to the plane occupied by the propulsion ring is connected directly with the propulsion ring. An opposing friction brake shoe attached to the chair frame is engaged by the brake ring to slow or stop the chair whenever the chair occupant pushes the propulsion ring axially inwardly.