Dockboard raising mechanism

Claim 2

A dockboard installation including a base part and a dockboard part hinged at its rear end to said base part, and a dockboard raising mechanism connecting said parts and comprising a lever and a link pivotally connected together at their inner ends, the outer end of the lever being pivoted to said dockboard part and the outer end of the link being pivoted to said base part, and further comprising a power cylinder pivotally mounted on said base part and having its piston rod attached to an intermediate pivot on said lever.

Claim 3

A dockboard installation according to claim 1, wherein the dockboard part is hinged to the base part by hinge means comprising an upwardly facing surface fixed to said base part and a co-acting downwardly facing surface fixed to said dockboard part, and means limiting rearwards movement of the dockboard part relative to the base part, and wherein the pivots connecting the link and power cylinder to the base are positioned so as to be at all times in front of the pivot connecting the lever to the dockboard part, whereby the raising mechanism maintains a rearwards force on the dockboard at all times when the mechanism is supporting the dockboard.

Claim 4

A dockboard installation according to claim 2, wherein the said hinge means includes a forwardly projecting horizontal rib attached to the base part and a flange projecting from the rear end of the dockboard part and resting on the top of said rib, the edge of said flange abutting against a shallow step at the rear of said rib.

Claim 5

A dockboard installation according to claim 1 wherein at least a major portion of the piston and cylinder combination lies within an area defined by the four pivots of the lever and link, i.e., by the pivot connecting the lever and link, the pivots at the outer ends of the lever and the link, and by the intermediate pivot of the lever.

Claim 6

A dockboard installation according to claim 1, wherein the pivot attaching the outer end of the link to the base coincides with the pivotal mounting of the power cylinder on the base.

Claim 7

A dockboard installation according to claim 5, wherein the said intermediate pivot on the lever is spaced above a line joining the end pivots of the lever, whereby the lever takes the form of a bell crank.

Claim 8

A dockboard installation according to claim 1, wherein the said lever is constituted by two parallel side plates spaced apart so as to locate one at each side of the cylinder when the dockboard is collapsed.

Claim 9

A dockboard installation according to claim 1 wherein the link and lever are arranged to fold rearwardly of a line joining their outer end pivots.

Claim 10

A dockboard installation including a base part and a dockboard part hinged at its rear end to said base part, and a dockboard raising mechanism connecting said parts and comprising a lever and a link pivotally connected together at their inner ends, the outer end of the lever being pivoted to said dockboard part and the outer end of the link being attached to a link pivot on the base part, and further comprising a piston and power cylinder combination having one end attached to an intermediate pivot on the lever and having the other end attached to a cylinder pivot on the said base part said cylinder pivot being on the same side of the lever as the link pivot and being also positioned to raise the dockboard when the piston and cylinder combination is extended, whereby the link is maintained in tension at all times.

Claim 11

A dockboard installation including a base part and a dockboard part hinged at its rear end to said base part, and a dockboard raising mechanism connecting said parts and comprising a lever and a link pivotally connected together at their inner ends, the outer end of the lever being pivoted to said dockboard part and the outer end of the link being attached to a link pivot on the base part, and further comprising a piston and power cylinder combination having one end attached to an intermediate pivot on the lever and having the other end attached to a cylinder pivot on the said base part said cylinder pivot being on the same side of the lever as the link pivot and being also positioned to raise the dockboard when the piston and cylinder combination is extended, whereby the link is maintained in tension at all times.

Claim 12

A dockboard installation comprising: a base having a raised rear portion and a depressed forward portion; means defining a first hinge portion on the raised rear portion of the base; a dockboard having a rear edge and a forward edge; means defining a second hinge portion on the dockboard adjacent the rear edge thereof; the second hinge portion resting upon and being pivotal about the first hinge Portion, with the dockboard extending forwardly over the depressed forward portion of the base; a normally inextensible lever; first pivot means pivotally securing one end of said lever to the dockboard, forwardly of said hinge portions; a normally inextensible link; second pivot means pivotally securing one end of said link to the base within the depressed forward portion thereof, forwardly of said hinge portions; third pivot means pivotally securing the opposite end of the lever to the opposite end of the link, said third pivot means being disposed closer to said hinge means than are said first and said second pivot means; an extensible/retractable strut; said second pivot means pivotally mounting one end of said extensible/retractable strut; fourth pivot means pivotally securing the opposite end of the extensible/retractable strut to the lever, said fourth pivot means being disposed rearwardly of a plane containing the first pivot means and the second pivot means, whereby said lever functions as a bell crank, and whereby the raising mechanism constituted by all said pivot means, said lever, said link and said extensible/retractable strut maintains a rearward force on the dockboard while the raising mechanism supports the dockboard forwardly of said hinge members.

Claim 13

A dockboard installation comprising: a base having a raised rear portion and a depressed forward portion; means defining a first hinge portion on the raised rear portion of the base; a dockboard having a rear edge and a forward edge; means defining a second hinge portion on the dockboard adjacent the rear edge thereof; the second hinge portion resting upon and being pivotal about the first hinge Portion, with the dockboard extending forwardly over the depressed forward portion of the base; a normally inextensible lever; first pivot means pivotally securing one end of said lever to the dockboard, forwardly of said hinge portions; a normally inextensible link; second pivot means pivotally securing one end of said link to the base within the depressed forward portion thereof, forwardly of said hinge portions; third pivot means pivotally securing the opposite end of the lever to the opposite end of the link, said third pivot means being disposed closer to said hinge means than are said first and said second pivot means; an extensible/retractable strut; said second pivot means pivotally mounting one end of said extensible/retractable strut; fourth pivot means pivotally securing the opposite end of the extensible/retractable strut to the lever, said fourth pivot means being disposed rearwardly of a plane containing the first pivot means and the second pivot means, whereby said lever functions as a bell crank, and whereby the raising mechanism constituted by all said pivot means, said lever, said link and said extensible/retractable strut maintains a rearward force on the dockboard while the raising mechanism supports the dockboard forwardly of said hinge members.