Abstract: A collapsible boom lift comprised of upper and lower telescoping boom assemblies. The upper boom is pivotally connected to an upright support member which is pivotally connected at its lower end to the lower boom. The upright support member is maintained plumb during raising and lowering of the lower boom, and the operator's platform, carried at the end of the upper boom, is maintained level during raising and lowering the upper boom. The upright support member is always positioned within the perimeter of the chassis of the boom lift.

Abstract: An apparatus for retaining the attitude of a platform on an articulated boom is provided. The apparatus includes master-slave piston cylinders for adjusting the attitude of the platform relative to a reference object. The apparatus further includes a pivot plate defining a triangle having first, second, and third mounting locations with a platform being pivotally mounted to the pivot plates at one mounting location. A piston cylinder is pivotally connected to the pivot plates at a second mounting location and is operatably connected to the platform. A pivot means is pivotally connected to the pivot plate at the third mounting location and, at its other end, is connected to the fixed support about which the articulating boom rotates. Rotation of the articulating boom results in the pivot means pivoting the pivot plate in such a way that the platform is maintained at its preset orientation.

Abstract: A latching system is disclosed for a telescopic boom, and comprises a ladder structure for positionment longitudinally along a side of a smaller boom section, and a latch plate assembly for a pivotal attachment to a large boom section. Bias means is further provided for applying a biasing force tending to move the latch plate into the ladder detent slot, and counter bias means for applying counter bias force to the latch plate. Linkages are adapted to extend between the latch plate and the tensioned chains which actuate the small boom section outward and inward relative to the large boom section, whereby the tension forces within the chains serve to provide counter biasing forces to the latch plate mechanism.