Harnischfeger Corporation

Ram N Rathi

Lembit Vaerk

Ronald E Nelson

David B Gamble

Raymond J Wacht

A mobile crane having a boom and a boom extension connected thereto with a toggle linkage for connecting the boom extension to the boom to allow the boom extension to be offset from the boom by one of a plurality of predetermined angles. A pair of double links is pivotably attached to the boom extension while a pair of single links is pivotably attached to the upper sheave pin in the boom head. Both the single and double links have a hole in the opposite end. Either the single or double links also have a hole in at least one intermediate position. The link having one hole is then pinned to the other link having two holes, the hole selected in the second link determining the angles of offset when tension is applied to the linkage by pivoting the boom extension about the lower sheave pin after removal of the upper boom foot pins. Biasing devices are provided to cause the linkage, which pivots freely at both ends and in the middle, to toggle upward when tension thereon is released. A storage position is provided for storing the double links and the link connector pins so as to prevent interference with the other apparatus and loss of the connector pins when the linkage is not in use.

Crane boom having variable angle offset capability

A mobile crane comprises a multi-section telescopic main boom and a boom extension pivotally connected to the point end of the main boom. The boom extension can be manually swung horizontally between an in-use position extending axially from the point end of the main boom and a stored position parallel to and alongside the main boom. Front and rear boom extension storage mechanisms releasably secure the boom extension in stored position. The front mechanism comprises two vertically spaced-apart storage pins which are slidable in tubular pin guides mounted on one lateral side of the main boom. The storage pins are slidably movable fore and aft by a swingable lever to which they are pivotally connected. The storage pins move into and out of engagement with a pair of vertically spaced-apart aligned pin-engaging holes in a member attached to a confronting side of the boom extension when the latter is in stored position. The lever is not only pivotable but is axially shiftable into and out of latched position and is biased into latched position to prevent unlatching due to 'bounce'. The rear storage mechanism comprises a ramp on the side of the main boom which engages and supports a roller on a member attached to a confronting side of the boom extension and a removable pin secures the member to the ramp.

Boom extension storage means and mechanisms

A pair of hydraulic locking cylinders for a vertically oscillatable wheel axle on the carrier frame of a mobile crane are interconnected and controlled by a hydraulic double-locking valve which is responsive to the centered or off-centered rotary position of the boom-carrying rotatable upper section of the crane. The double-locking valve comprises a pair of normally closed ball-type check valves which are operated by a valve stem comprising independently movable upper and lower sections. The upper valve stem section is positioned by a cam on the crane upper section and the lower valve stem section is positioned by a pneumatic actuator which is controlled by a solenoid valve selectively actuatable by an electric override switch in the crane operator's cab. The upper valve stem is moved to down (valve open-axle unlocked) position by the cam when the crane upper is centered on the carrier frame. The upper valve stem moves to up (valve closed-axle locked) position when the crane upper is rotated off-center. The lower valve stem is selectively movable to up (valve open-axle unlocked) position from its lower (valve closed-axle locked) position by the pneumatic actuator to unlock the axle and allow the crane to be repositioned by the crane operator even while the crane upper section and its boom are off-center.

Override control for axle locking apparatus of mobile crane

Method for extending a jib of a telescopic crane which jib may be stored alongside a base section when not in use. The crane boom comprises at least the base section, a second section with linearly extendable power means, an extension pivotably mounted on the outer end of the second section and stored alongside that section and the base section, and a jib releasably attached to both the base section while in storage and to the extension while in use. To set up the crane for operation, the power means extends the second section forward from the base section, which extends in a forward direction the extension pivotally attached to the second section. This extension places the outer end of the extension in vertical alignment with the inner end of the jib. The extension and jib are then connected along their lengths and the jib is released from its storage position on the base. The inner end of the extension is pivoted around the outer end of the second section and the inner end of the jib is pivoted around the outer end of the extension. Both the extensions and the jib are fixed in an operative position. If the jib is not required, it is left in its attached position on the base, and the base section, second section, and boom extension may be operated independently.

Growing community of inventors

Cedar Rapids, IA, United States of America

Ram N Rathi