Truck hoist
OwnerEldon D. Jonesinventor
Life of this patent
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Abstract
A hoist mechanism that more effectively uses its hydraulic capacity is comprised of a first and a second pair of lifting arms connected at a first pivot point, a hydraulic cylinder connected to said lifting arms, and a pivoting stop means that coordinates movement of the two pair of lift arms. During the initial lifting action of the hoist, the mechanism achieves the advantages of a double arm type hoist by causing the first pair of lifting arms to remain stationary while the second pair of lifting arms rotates around the first pivot point. After the second pair of lift arms reach a predetermined angle with the stationary first pair, the stop means are engaged in a way to cause both pair of lift arms to move upon further lifting action of the hoist, thus achieving the advantages of a scissors type hoist from this point on.
Claims20
A hoist mechanism for use in raising and lower a dump bed pivotally connected to a vehicle chassis, said hoist mechanism comprising:
- a first and a second lifting arm connected at a first pivot point, said first lifting arm having a second pivot point at one end thereof, said second lifting arm having an engaging pivoting stop means located on one end thereof for increasing the effective length of said second lift arm when said second lift arm forms a predetermined angle with respect to said first lift arm;
- and
- an extensible and retractable hydraulic cylinder means connected to said second lifting arm;
- said hydraulic cylinder means and said pivoting stop means being so arranged that upon initial extension of said cylinder means, said first lifting arm remains stationary relative to said second pivot point as said second lifting arm rotates around said first pivot point until said second lifting arm reaches said predetermined angle with respect to said first lifting arm,
- said pivoting stop means being so located that when said second lifting arm reaches said predetermined angle said second arm's effective length is increased and thereafter as said angle is exceeded said pivoting stop means causes said first lifting arm to rotate around said second pivot point upon further extension of said hydraulic cylinder means thereby to increase the rate of lifting of the dump bed relative to the amount of cylinder extension.
In the combination of a dump truck comprised of a dump bed pivotally connected to a truck chassis frame and wherein there is a hoist mechanism located between the dump bed and truck chassis frame for pivotally raising and lowering the dump bed with respect to the truck chassis frame, the improvement comprising, as said hoise mechanism, a first and a second lifting arm connected at a first pivot point, said first lifting arm having a second pivot point at one end thereof, said second lifting arm having an engaging pivoting stop means located on one end thereof for increasing the effective length of said second lift arm when said second lift arm forms a predetermined angle with respect to said first lift arm;
- and
- an extensible and retractable hydraulic cylinder means connected to said second lifting arm;
- said hydraulic cylinder means and said pivoting stop means being so arranged that upon initial extension of said cylinder means, said first lifting arm remains stationary relative to said second pivot point as said second lifting arm rotates around said first pivot point until said second lifting arm reaches said predetermined angle with respect to said first lifting arm,
- said pivoting stop means being so located that when said second lifting arm reaches said predetermined angle said second arm's effective length is increased and thereafter as said angle is exceeded said pivoting stop means causes said first lifting arm to rotate around said second pivot point upon further extension of said hydraulic cylinder means thereby to increase the rate of lifting of the dump bed relative to the amount of cylinder extension.
Dependencies are inferred from the claim text.