Abstract: A system for automatically controlling the position of a tractor-trailer rearview mirror to maintain unobstructed vision in the mirror during turns employs a pair of ultrasonic transducers mounted on the external rear wall of the tractor on opposite sides of the centerline thereof so as to project ultrasonic sound beams onto the forward wall of the trailer. A control circuit determines the difference in the two path lengths, indicating the degree of turning of the vehicle, to generate control signals to a mirror rotating motor. A third transducer may be mounted for rotation with the mirror and directs an ultrasonic beam along the zone immediately beside the trailer for detecting persons or objects within the zone and actuating an alarm in the event of such detection.

Abstract: In order to prevent the edge of a floating pool cover from rolling downwardly into the water, as would occur if a child fell or stepped onto the cover, upwardly open channels, the outer walls of which are notched at spaced intervals, are affixed to the pool walls immediately above the water level and extend along substantially the entire periphery of the pool, and anchors are attached to the edges of the cover at the same intervals as the notches, each anchor projecting laterally from the cover and having a shank terminating in a bulbous end which may be dropped into the channel.

Abstract: The splash or landing pool of a water slide has an entry zone of substantially increased depth relative to conventional splash pools and a shallow exit zone leading from the entry zone. The entry zone is provided with a false floor at a depth such that a child can walk thereacross, the false floor being a close mesh net which can safely decelerate an adult who has improperly entered the pool from the slide.

Abstract: In order to provide protection for workers moving on the exterior of an air-supported fabric roof structure, safety ropes extend across the roof and are connected at intervals to the roof, safety lines are adjustably attached between adjacent ones of the ropes and safety harnesses are adjustably attached to the safety lines.

Abstract: A rigging system for retrieving a worker in the event of the collapse or tearing of a peripheral panel of an air-supported fabric roof employs one or more endless cables each entrained over pulleys located at the edge of the roof and inwardly therefrom. The worker is connected to one run of the cable by a safety line and harness. In the event of an accident, the cables are driven, for example by a detachable motor rotating one of the pulleys, to move the worker to the vicinity of the peripheral wall.

Abstract: In order to indicate whether a straight or extension ladder is positioned safely for use, a first label is provided on the side rail of the ladder and includes a level for indicating when the ladder is properly angled and a second label and a cooperating pointer are provided at the foot of the ladder to indicate if the base of the ladder is at a safe angle relative to the support surface.

Abstract: A controller for sequentially energizing a plurality of lights, such as commercial display lighting or Christmas tree light strings, includes a plurality of outlet receptacles into which the lights or light strings may be connected, a Triac for each receptacle to control the energization thereof, a timing circuit and a programmable gating circuit responsive to the timing circuit and generating gating signals for the Triacs according to any of several predetermined sequential combinations.

Abstract: In a circular power saw blade mounting arrangement of the kickback clutch type, the blade clamping washer, spring washer and blade screw are retained as a permanent subassembly to eliminate the possibility of substituting an incorrect part. Markings on the exposed face of the clamping washer and the spring washer provide visual indication as to whether the spring washer is properly tensioned.

Abstract: A fence which provides an effective barrier to the attempts of children to climb and which is of durable and attractive appearance is formed of molded or stamped panels connected to support posts and a fence cap interlocking with the upper ends of the panels. Openings to reduce wind loading on the fence are provided in the panels and are configured so as not to provide hand or foot holds for children. A self-closing gate with a child-resistant latch is also provided.