Abstract: An interlocking lens structure comprising two opposed lens pieces is disclosed. Each of the lens pieces has a top portion including an edge having a first region formed with a groove and a second region formed with a projection. The first region of each of the lens pieces is adapted to mate with the second region of the other of the lens pieces. Each of the lens pieces further includes a side portion connected to the top portion and having two edges. One of the side portion edges is formed with a groove, while the other of the side portion edges is formed with a projection. The groove of each of the side portion edges is adapted to mate with the projection of the other of the side portion edges. The depth and the length of each of the groove/projection combinations can be varied to determine the amount of color separation between the lens pieces. The grooves and the projections also prevent light from escaping from the interior of the lens structure at the junction of the lens pieces.

Abstract: An aerial lift platform apparatus has a wheeled chassis, a turret on the chassis and a boom pivoted to the turret. The wheels are carried by extendable axles, to provide increased stability. The boom is depressed to raise at least one wheel, to permit its extension and retraction. Preferably, there are four wheels on two axles, and the wheels of each axle are successively raised and then extended or retracted.

Abstract: A protective circuit for an overload sensor of a lifting boom, such as an aerial platform boom. Excess deflection of the boom under load, due to such factors as weight of the load, boom angle and boom extension, is detected by the actuation of an overload sensor switch engaged by the free end of a beam which extends generally parallel to the boom, the other end of the beam being fixed to the boom. The overload sensor switch is in a protective circuit which causes interruption of current to controls which effect movement of the boom in a manner to increase the boom deflection, and which circuit causes the interrupted circuit to remain interrupted independently of the position of the overload sensor switch. The circuit requires positive resetting once there has been such interruption. The protective circuit includes a drop out relay in series with the overload sensor switch, a latching relay with re-set coil, and control circuit switches controlled by the latching relay.

Abstract: A telescopic crane boom is provided in which tubular boom sections include a thicker, flat bottom plate and a thinner channel having the free edges of its walls welded to the bottom plate at the lateral edges of the bottom plate. Wear pads for supporting an outer boom section, e.g., the fly section, are placed on the bottom plate of the adjacent inner section, e.g., the mid-section, closely adjacent to the vertical walls of the inner section, and underlying the walls of the outer section, to provide substantially columnar support for the walls of the outer section, reduced bottom plate bending forces, and reduced boom width and weight.

Abstract: A machine has a movable boom for lifting a load, and an overload sensing device mounted on the boom to sense boom deflection. The overload sensing device includes a rigid beam having one end secured to a vertical side plate of the boom only by anchors spaced widely apart, welded preferably on opposite sides of the centroid or neutral axis of the boom side plate. The beam has a free end, on which an adjustable contact plate is carried, to engage a switch adjustably carried on a mounting plate secured to the beam side plate.

Abstract: An aerial platform apparatus includes a vehicle, an extensible boom mounted on the vehicle for luffing and swinging movement, and a workman's platform carried by the boom. The boom at its outer end carries a support column, which supports a workman's platform and a pin holder. The pipe holder includes a horizontal oscillatable shaft located rearwardly of the platform, and including a pair of forwardly extending arms, each on one side of the platform. The arms are provided at their outer ends, which are generally forwardly of the platform, with material engaging devices, specifically releasable pipe clamps. Preferably, the arms are extensible. A motor controlled by the occupant of the platform oscillates the pipe holder shaft, and other similarly controlled motors actuate the pipe clamps and extend and retract the arms.