Locking system for extension members on portable lifts

• US 5,667,352 A
• Filed: 04/18/1994
• Issued: 09/16/1997
• Est. Priority Date: 04/18/1994
• Status: Expired due to Fees

• Current Assignee: Genie Industries Incorporated (Terex Corporation)
• Original Assignee: Genie Industries Incorporated (Terex Corporation)
• Inventors: Smith, Paul K., Kraemer, Matthew G., Curtin, Richard M.
• Primary Examiner(s): Keenan, James W.
• Application Number:
  US08/228,798
• Time in Patent Office: 1,247 Days
• Field of Search: 414/427, 414/667, 212/292, 212/302, 212/306, 212/901, 187/232, 187/242, 187/243
• US Class Current: 414/667
• CPC Class Codes: B66F 9/07522 Variable length or width chassis
• CPC Class Codes: Y10S 212/901 Dolley-type cranes

Abstract

A locking system for extension members on portable lifts or the like has a wedge block with a jaw face on one side and a sloped wedge face on the opposite side engaging a complementing fixed sloped face so that when the wedge block is moved upwardly the complementing faces cause the wedge block to also move horizontally into clamping position by way of the jaw face. The wedge block is moved upwardly responsive to turning of a screw threaded into the block.

Claims

1. A locking system on a portable lift comprising:

a base for a mast comprising a generally horizontal elongated socket having an entry end, said base including a chamber exposed to said socket by a side opening adjacent said entry end, said chamber having a downwardly sloping wall facing toward said socket;

an extension member slidably mounted in said socket; and

a locking mechanism for said extension member including;

a wedge block in said chamber having a tapered face complementing and normally engaging said sloping wall, and having a jaw face facing toward said socket, said wedge block being confined against horizontal movement parallel to the length of said socket;

a spacer seated on said base above said chamber; and

an adjustment bolt having an enlarged head engaging said spacer to prevent downward travel of said bolt, said bolt extending downwardly from its said head through an opening in said base into a threaded hole in said block such that turning of said bolt raises or lowers said block and responsively moves said tapered face on said sloping wall so as to responsively move said jaw face toward said socket for selectively engaging and locking said extension member relative to said base, said side opening being large enough to permit movement of said jaw face into locking engagement with said extension member.

2. A locking system according to claim 1 in which said socket and extension member each have a rectangular cross-section arranged such that the extension member presents a flat outer face opposite said chamber to be engaged by said jaw face of the wedge block.

3. A locking system according to claim 2 in which said jaw face is flat.

4. A locking system according to claim 1 in which said spacer comprises a tube through which said bolt extends, said bolt head engaging the top of said tube.

5. A locking system according to claim 1 in which said sloped wall slopes downwardly away from said socket and said wedge block moves upwardly and toward said socket responsive to turning of said bolt in a direction screwing the bolt into the block.