Abstract: A multi-engine assembly comprising a plurality of small, light weight and high efficiency type engines, preferably of the two stroke type, connected by a hydraulic power transmission to a common output shaft, and capable of being selectively connected or disconnected to the drive upon demand.

Abstract: A helmet visor to be attached to the front of a crash helmet to protect the user's face and comprising a stiff support comprising a curved transparent plate covered by an antifriction layer and a movable film material extending across the user's field of sight. A supply roll of the movable film is rotationally mounted at one side edge portion of the support and a continuously or intermittently driven take-up roll is mounted at the other side edge portion of the support. When the film section within the user's field of sight has received sight restricting deposits the user actuates the driven take-up roll to draw the dirty film section out of the field of sight and introduce a fresh film section into the field of sight.