Harnischfeger Corporation

Dieter C Juergens

Charles L Wadsworth

A large mobile tower crane comprises a vertical multi-section lattice-type tower having its lower end fixedly mounted on the rotatable upper section of a self-propelled vehicle and a load-supporting multi-section lattice-type crane boom having its base end pivotally mounted on the upper end of the tower. A load to be lifted, swung and lowered, is attachable to a load line suspended from a pulley at the point end of the boom. The tower is selectively rotatable to swing the boom and the boom is selectively pivotable vertically to desired boom (luffing) angles. A crane control system employs strain gauge-type electronic sensing devices mounted on opposite lateral sides of the crane boom and on a side of the crane tower to provide electric signals pertaining to applied loads. A transducer provides an electric signal pertaining to boom angle. A programmable electronic computer, which processes these signals to calculate down load and side load moments in the boom and torque loads in the tower, provides output signals related thereto which are usable to operate the crane within safe limits. The output signals are usable to operate visual display devices which inform the crane operator of safe operating limits, or to effect automatic operation (subject to manual override) of certain crane functions (swinging, luffing, lifting) within safe limits. The sensing devices in the boom comprise strain gauges which are embodied in clevis bolts or pins which are located on opposite sides of the boom and which mechanically secure together certain sections of the multi-section boom. The strain gauge signals, which pertain to load magnitude in the boom, are added to determine load weight suspended from the boom, and are substracted to determine side load magnitude and direction.

Crane control means employing load sensing devices

Disclosed is a crane wherein a trailer-like counterweight carrier has a horizontal motion transmitting connection with a platform which is swivelably mounted on a crane base and which supports the boom and the mast of the crane. Guy connections between the counterweight carrier and the top of the mast and between the mast and the boom translate forward tilting force that a lifted load imposes upon the boom into lifting force on the counterweight carrier. A lost motion connection between the counterweight carrier and the platform comprises rigid members. It allows the carrier to be lifted to a predetermined height above the ground and at that point imposes upon the crane chassis further lift force upon the counterweight carrier, so that the crane base cooperates with the counterweight in resisting forward tilting of the boom under heavy loads. The lost motion connection requires no adjustment to adapt it for different loads and different inclinations of the boom and mast.

Crane with outboard counterweight carrier

The upper works of a boom machine such as a crane is supported for rotation about a vertical axis on a lower portion of modular construction. The lower portion comprises a hub-like member having four leg module holders which are equidistant from said axis and spaced around it at uniform intervals and to each of which a leg module is detachably securable. To outer ends of the leg modules can be secured pad modules or extension leg modules that have ground engaging pads at their outer ends; or laterally opposite pairs of leg modules can be detachably connected to crawler modules. The hub-like member also has a pair of body module holders at opposite sides thereof, each laterally intermediate a pair of leg module holders, to which wheeled transporter modules can be detachably secured. Alternatively, with crawler modules installed, a hydraulic power module for energizing them can be secured to one body module holder. When not supporting the machine for transport or as a truck crane, transporter modules can serve as auxiliary counterweight carriages.

Convertible boom machine having modular bottom portion

An auxiliary counterweight arrangement resists lateral as well as forward tipping of a mobile crane that has a platform rotatable about a vertical axis and a boom mounted on the platform to swing in a vertical plane containing said axis. The boom normally projects at a forward and upward inclination from the platform, and its top, from which a load line depends, may be connected with the top of a mast that is behind it, in the same vertical plane. Two surface-supported counterweight carriers are rigidly attached to the platform, spaced equal distances to the rear of it and at equal distances to opposite sides of said vertical plane. Each carries a counterweight. With a mast on the platform, a guy line extends from its top to each counterweight; otherwise, a guy line extends from the top of the boom to each counterweight. Lengthening the arms of the V-shaped rigid connection between platform and counterweight carriers increases resistance to lateral tilting in step with increased resistance to forward tilting.

Growing community of inventors

Bark River, MI, United States of America

Dieter C Juergens