Minimum profile hoist

In a scissors-type hoist for a dump truck body pivotally mounted on a truck chassis frame, wherein said hoist has an upper frame and a lower frame pivotally connected together at a scissors axis, one end of the lower frame opposite the scissors axis being pivotally attached to the truck chassis frame and one end of the upper frame opposite the scissors axis being pivotally connected to the dump body, and a hydraulic cylinder with a hydraulically extendable and retractable rod for pivoting the upper frame in relation to the lower frame about the scissors axis, the improvement comprising:

• an elongated guide link pivotally attached at one end to the lower frame;
• a lift link pivotally attached at one end to the upper frame such that the distance between the scissors axis and the axis of attachment of the guide link to the lower frame is less than the distance between the scissors axis and the axis of attachment of the lift link to the upper frame, and such that the distance between the axis of attachment of the guide link to the lower frame and the axis of attachment of the lift link to the upper frame when the upper frame and lower frame are at and proximate a closed condition where the truck body is resting on the truck chassis frame is less than the distance between the axis of attachment of the guide link to the lower frame and the axis of attachment of the guide link to the lift link, and wherein the axis of connection of the guide link to the lower frame is lower than the scissors axis when the hoist is in the near the closed condition, the other ends of the guide link and lift link being pivotally connected together, wherein said hydraulic cylinder is pivotally connected at one end to the lower frame and at the other end to the pivotally connected guide and lift links.

In a scissors-type hoist for a dump truck body, which has an upper frame and a lower frame pivotally connected together at a scissors axis, one end of the lower frame opposite the scissors axis being pivotally attached to the truck chassis frame and one end of the upper frame opposite the scissors axis being connected to the dump body, and a hydraulic cylinder with a hydraulically extendable and retractable rod for pivoting the upper frame in relation to the lower frame about the scissors axis, the improvement comprising:

• an elongated guide link pivotally attached at one end to the lower frame;
• a lift link pivotally attached at one end to the upper frame, the other ends of said guide link and said lift link being pivotally connected together, said lift link defining a first line of action which passes through the pivotal connection of said lift link on the upper frame and the pivotal connection connecting said guide and lift links together, and wherein the hydraulic cylinder is pivotally connected at one end to the lower frame and at the other end to said pivotally connected guide and lift links, the hydraulic cylinder defining a second line of action which passes through the pivotal connection of said hydraulic cylinder on said lower frame and the pivotal connection of said hydraulic cylinder on said pivotally connected guide and lift links, said guide link and said lift links being arranged such that the perpendicular distance from the first line of action to the scissors axis is substantially greater than the perpendicular distance from the second line of action to the scissors axis in the closed condition.