ROLL-OFF FRAME HAVING ADJUSTABLE HEAD AND TAIL PORTIONS ACTUATED BY SINGLE ACTUATION STROKE

A hoisting frame apparatus for loading and unloading containers onto and off of a roll-off vehicle includes adjustable head and tail portions that are cooperatively actuated by a single actuation stroke to move relative to a main portion of the hoisting frame apparatus. The hoisting frame apparatus includes a linkage connecting the tail portion to the head portion such that displacement of the head portion by a hoist actuator relative to the main portion causes displacement of the tail portion relative to the main portion. The total longitudinal displacement of the tail portion may be shorter than the total longitudinal displacement of the head portion, and the linkage may be configured to release the connection between the head and tail portions when the tail portion reaches a travel limit to allow independent further longitudinal displacement of the head portion.

FIELD OF THE INVENTION

The present invention relates generally to roll-off transport vehicles equipped to load a large container onto the vehicle and to unload the container from the vehicle. The large container is typically a waste container.

BACKGROUND OF THE INVENTION

Roll-off vehicles are known to include a top frame mounted on the vehicle for supporting the container. The top frame is pivotally mounted to be tilted away from a horizontal home position such that the top frame is inclined toward a rear of the vehicle to assist in loading and unloading the container. The top frame may be tilted by one or more lift actuators, for example hydraulically powered linear actuators, arranged between the top frame and a subframe fixed to the vehicle. The top frame may incorporate a cable hoist mechanism having a set of sheaves and a cable wound around the sheaves. Some of the sheaves may be mounted on one or more movable shoe members that are displaceable along the top frame to take up an end of the cable coupled to the container to pull the container onto the top frame during loading. Sheave displacement may be reversed to unload the container. A locking mechanism may be provided at the front of the frame for engaging a front roller or grip bar of the container to secure the container on the frame during transport.

Roll-off frames of the type described above may include an extendable and retractable tail portion designed to extend from a main portion of the frame when the frame is tilted to meet the ground proximate to the rear of the vehicle. For example, U.S. Pat. No. 6,641,353 describes a roll-off frame10that has an extendable tail portion18operated by a hydraulic actuator44. As another example, U.S. Pat. No. 8,708,635 discloses a roll-off frame wherein a hydraulic cylinder410extends a tail portion402relative to a main portion404of the frame to reach the ground. As a further example, U.S. Pat. No. 8,746,804 describes a tiltable frame104having a sliding tail portion108moved by actuators160.

It is also known to provide a roll-off frame with an extendable and retractable head portion for adjustably accommodating containers of various lengths. U.S. Pat. No. 7,112,030 discloses a roll-off frame having a main portion14and an extendable head portion26moved by a pair of hydraulic actuators50.

In the prior art roll-off frames summarized above, there is either an extendable and retractable tail portion, or an extendable and retractable head portion, but not both. The actuators used to move the tail or head portion are dedicated to that function, and are not used for any other function.

U.S. Pat. No. 4,840,532 describes a roll-off frame having both a tail portion72and a head portion75respectively extendable and retractable relative to a main frame portion. The tail portion72is operated by a dedicated actuator74; the head portion75is operated independently by a separate dedicated actuator81. The use of separate and independently operable actuators for driving the tail and head portions adds weight and expense. Moreover, where the actuators are hydraulic actuators, the hydraulic system becomes more complex.

SUMMARY OF THE INVENTION

The invention provides a hoisting frame apparatus for loading and unloading containers onto and off of a roll-off vehicle. The invention addresses shortcomings of the prior art by providing adjustable head and tail portions that are cooperatively actuated by a single actuation stroke.

The apparatus comprises a top frame including a main portion, a head portion movably connected to the main portion for longitudinally directed displacement relative to the main portion between a rearward retracted position and forward extended position, and a tail portion movably connected to the main portion for longitudinally directed displacement relative to the main portion between a rearward extended position and forward retracted position. The apparatus also comprises a plurality of sheaves including a rear sheave mounted to the main portion and a front sheave mounted to the head portion, and a cable having a fixed end coupled to the head portion and a free end configured for coupling to a container, wherein the cable extends from the fixed end to the free end by way of the sheaves. The apparatus further comprises a hoist actuator operable to longitudinally displace the head portion of the top frame relative to the main portion of the top frame between the rearward retracted position and the forward extended position, and a linkage connecting the tail portion of the top frame to the head portion of the top frame, wherein displacement of the head portion by the hoist actuator relative to the main portion causes displacement of the tail portion relative to the main portion. The linkage may be bidirectional, whereby displacement of the head portion by the hoist actuator from the rearward retracted position to the forward extended position causes displacement of the tail portion from the rearward extended position to the forward retracted position, and displacement of the head portion by the hoist actuator from the forward extended position to the rearward retracted position causes displacement of the tail portion from the forward retracted position to the rearward extended position.

In an embodiment of the invention, a longitudinal displacement distance of the head portion between the rearward retracted position and the forward extended position is greater than a longitudinal displacement distance of the tail portion between the rearward extended position and the forward retracted position. The apparatus may further comprise a forward limit stop preventing the tail portion from traveling forward relative to the main portion beyond the forward retracted position, and a rearward limit stop preventing the tail portion from traveling rearward relative to the main portion beyond the rearward extended position, and the linkage may be configured to couple the head portion and the tail portion together for displacement in unison when the tail portion is between the limit stops, and configured to decouple the head portion from the tail portion for independent displacement of the head portion relative to the main portion when the tail portion is at one of the limit stops.

The linkage may include a connection rod fixed to one of the head portion and the tail portion, wherein the connection rod has an engagement segment, and the linkage may further include a detent mechanism fixed to the other of the head portion and the tail portion, wherein the connection rod is slidably received by the detent mechanism. The detent mechanism may be biased for releasable engagement with the engagement segment of the connection rod to releasably couple the head portion and the tail portion together. For example, the engagement segment of the connection rod may include at least one recess, and the detent mechanism may include at least one ball plunger spring-biased for receipt by the at least one recess. The connection rod may also include a first slide segment and a second slide segment, and the engagement segment may be located between the first and second slide segments.

The invention provides longitudinal displacements of both the head and tail portions relative to the main portion of the top frame using a single actuation stroke, even where the displacement distance of the head portion differs from the displacement distance of the tail portion. Consequently, only a single actuator is required to drive both displacements, thereby reducing cost and complexity, especially if an additional hydraulic actuator is avoided.

DETAILED DESCRIPTION OF THE INVENTION

FIGS. 1-7illustrate a container hoist apparatus10formed in accordance with an embodiment of the present invention. Hoist apparatus10is mountable on a roll-off vehicle V, such as a truck or similar vehicle, and includes a cable hoist mechanism connectable to a container C. As will be apparent from the detailed description that follows, apparatus10is useful for loading and unloading containers of various sizes onto and off of a roll-off vehicle in a safe and efficient manner. InFIGS. 1-7, the forward direction is generally to the left and the rearward direction is generally to the right.

Apparatus10generally comprises a top frame12and a pair of laterally spaced lift actuators14, only one of the lift actuators being visible inFIGS. 1 and 2. Top frame12is mounted on vehicle V to pivot about a transverse hinge axis HA relative to the vehicle. For example, apparatus10may comprise a subframe11adapted to be fixedly attached to the vehicle V, and top frame12may be pivotally mounted on subframe11for pivoting motion about hinge axis HA. In this way, top frame12may be mounted on vehicle V by way of subframe11. As shown inFIGS. 1 and 8, top frame12has a horizontal home position relative to vehicle V. One end of each lift actuator14is pivotally mounted to vehicle V either directly or indirectly through subframe11. The opposite end of each lift actuator14is pivotally mounted to top frame12. Lift actuators14are operable to rearwardly incline top frame12relative to vehicle V by pivoting the top frame about hinge axis HA away from the horizontal home position. For example, lift actuators14may be extended to tilt top frame12as shown inFIG. 29, and may be retracted such that top frame12assumes its horizontal home position as shown inFIGS. 1 and 8. Lift actuators14may be hydraulic actuators. Alternatively, lift actuators14may be electromechanical actuators. While two laterally spaced lift actuators14may be used, it is conceivable to practice the invention using only one lift actuator which may be centrally located for balanced loading.

Top frame12includes a main portion16, a head portion18, and a tail portion20. Head portion18is movably connected to main portion16for longitudinally directed displacement relative to the main portion between a rearward retracted position and forward extended position. For example, main portion16and head portion18may be telescopically adjustable, wherein a pair of longitudinal side rails18A,18B of head portion18are slidably received within hollow longitudinal side rails16A,16B of main portion16. Tail portion20is movably connected to main portion16for longitudinally directed displacement relative to the main portion between a rearward extended position and forward retracted position. Main portion16and tail portion20may be telescopically adjustable, wherein a pair of longitudinal side rails20A,20B of tail portion20are slidably received within hollow longitudinal side rails16A,16B of main portion16.

Main portion16, head portion18, and tail portion20may be steel weldments. In the depicted embodiment, side rails16A,16B include a plurality of support rollers17for supporting opposite sides of container C as the container is displaced along top frame12.

Top frame12also includes a plurality of sheaves including a rear sheave22mounted to main portion16and a front sheave25mounted to head portion18. As best seen inFIG. 4, the plurality of sheaves may further include a first intermediate sheave23mounted to head portion18and a second intermediate sheave24mounted to main portion16. Rear sheave22and second intermediate sheave24may be coaxial as shown inFIG. 4.

A hoist cable26has a fixed end26A coupled to head portion18and a free end26B configured for coupling to a container C. Cable26extends from its fixed end26A to its free end26B by way of the plurality of sheaves. For example, in the illustrative arrangement depicted inFIG. 4, cable26extends from fixed end26A to free end26B by successive engagement with rear sheave22, first intermediate sheave23, second intermediate sheave24, and front sheave25.

Top frame12further includes a hoist actuator28operable to longitudinally displace head portion18relative to main portion16between a rearward retracted position shown inFIG. 30and a forward extended position shown inFIGS. 2 and 9. As may be understood, displacement of head portion18toward the extended position moves first intermediate sheave23and front sheave25away from rear sheave22and second intermediate sheave24, thereby causing free end26B of cable26to be pulled forward toward the front end of top frame12. The diameters of the sheaves may be chosen to provide a mechanical advantage such that displacement of head portion18by hoist actuator28through a given distance results in an even greater displacement of cable end26B toward the front end of top frame12. For example, the sheaves may be sized and arranged to provide a5:1mechanical advantage, i.e. extending head portion18one foot draws cable end26B five feet forward.

In accordance with the present invention, tail portion20of top frame12is connected to head portion18by at least one linkage30, such that displacement of the head portion by hoist actuator28relative to main portion16causes displacement of tail portion20relative to main portion16. In the embodiment described herein, a pair of linkages30are provided, one on each lateral side of frame12, however only one of the linkages is visible inFIGS. 5 and 6. Each linkage30may include a connection rod32cooperating with a detent mechanism34as described in detail below. In the embodiment depicted in the figures, connection rod32is fixed to head portion18, and detent mechanism34is fixed to tail portion20. More specifically, a front end of connection rod32may be fixedly attached to a rear end of a respective longitudinal side rail18A of head portion18by a mounting collar35welded or fastened to side rail18A, and detent mechanism34may be welded or fastened to a front end of a respective longitudinal side rail20A of tail portion20, wherein connection rod32is slidably received by associated detent mechanism34. One skilled in the art will understand that the arrangement of connection rod32and detent mechanism is34may be reversed, i.e. detent mechanism34may be fixed to head portion18and connection rod32may be fixed to tail portion20.

In the present embodiment, connection rod32includes a first slide segment32A and a second slide segment32B separated by an engagement segment32C. Connection rod32may also include a retention flange33at its free end. Detent mechanism34is configured to allow first and second slide segments32A,32B to slide through detent mechanism34without being gripped by the detent mechanism, and detent mechanism34is configured to engage and releasably grip engagement segment32C as the engagement segment passes within the detent mechanism. As shown inFIG. 7, detent mechanism34may include a hollow sleeve36defining a passage38through which connection rod32is slidably received, and one or more spring-biased ball plungers40biased to project radially into passage38through respective holes42in the wall of sleeve36. Each ball plunger40is urged to project into passage38by a corresponding spring44. Engagement segment32C of connection rod32is of enlarged diameter relative to first and second slide segments32A,32B and includes at least one recess37for receiving a protruding ball plunger40upon alignment with the ball plunger. Thus, detent mechanism34is biased for releasable engagement with engagement segment32C of connection rod32to releasably couple head portion18and the tail portion20together.

Apparatus10may further comprise a forward limit stop46preventing tail portion20from traveling forward relative to the main portion beyond the forward retracted position and a rearward limit stop48preventing tail portion20from traveling rearward relative to the main portion beyond the rearward extended position. In the depicted embodiment, a flange projecting laterally from each side rail20A,20B of tail portion20acts as forward limit stop46. Forward limit stop46abuts with a corresponding side rail20A,20B when tail portion20reaches its forward retracted position, thereby limiting further insertion of side rails20A,20B into the hollow longitudinal side rails16A,16B of main portion16. Rearward limit stop48may be mounted on a shaft50attached to a cross member51of tail portion20and slidably mated with a sleeve52fixed to a cross-member54of main portion16. Rearward limit stop48abuts with sleeve52when tail portion20reaches its rearward extended position. As a result, a longitudinal displacement distance of tail portion20between its rearward extended position and its forward retracted position is limited to a predefined distance.

The longitudinal displacement distance of head portion18between its rearward retracted position and its forward extended position may be defined by the stroke length of hoist actuator28. In the embodiment described herein, the longitudinal displacement distance of head portion18between its rearward retracted position and its forward extended position is greater than the longitudinal displacement distance of tail portion20between its rearward extended position and forward retracted position. In other words, head portion18has a greater longitudinal travel range than tail portion20.

Linkage30may be configured to couple head portion18and tail portion20together for displacement in unison under the power of hoist actuator28when tail portion20is between the limit stops46,48, and to decouple head portion18from tail portion20for independent displacement of head portion18relative to main portion16when tail portion is at one of the limit stops46,48. Thus, when tail portion20is stopped at forward limit stop46, head portion18can continue to move forward, and when tail portion20is stopped at rearward limit stop48, head portion18can continue to move rearward.

FIGS. 8-32illustrate displacement of head portion18from its forward extended position to its rearward retracted position by hoist actuator28, and the resulting displacement behavior of tail portion20due to linkage30. The displacement of head portion18and tail portion20is shown and described in the context of a process by which container C is unloaded from vehicle V.

In initialFIGS. 8-11depicting container C fully loaded on vehicle V, hoist actuator28is fully extended such that head portion18is in its forward extended position, and tail portion20is in its forward retracted position. As hoist actuator28starts to retract as shown inFIGS. 12-15, head portion18begins to move rearward relative to main portion16and first slide segment32A of connection rod32slides through detent mechanism34; tail portion20remains in its forward retracted position during this initial rearward movement of head portion18. Once engagement segment32C reaches ball plungers40, the ball plungers are urged outward against the bias of springs44until a recess37of engagement segment32C moves into alignment with ball plungers40and the ball plungers40are forced inward by springs44into engagement with recess37. When this occurs, tail portion20becomes coupled to head portion18, such that further retraction of hoist actuator28causes both head portion18and tail portion20to move rearward in unison as depicted inFIGS. 16-20. Continued retraction of hoist actuator28eventually causes tail portion20to reach its rearward extended position, at which point rearward limit stop48abuts with sleeve52to prevent further rearward displacement of tail portion20. This position is shown inFIGS. 21-24. As hoist actuator28retracts further as shown inFIGS. 25-28, rearward displacement of head portion18pushes engagement segment32C through detent mechanism34, and second slide segment32B aligns with detent mechanism34. Finally, as shown inFIGS. 29-32, hoist actuator28is fully retracted and head portion18reaches its rearward retracted position while tail portion20remains in its rearward extended position.

As may be understood, displacement of head portion18from its rearward retracted position to its forward extended position by hoist actuator28, and the resulting displacement behavior of tail portion20due to linkage30, can be understood with reference toFIGS. 8-32taken in stepwise reverse order. Hoist actuator28starts in a fully retracted condition inFIGS. 29-32such that head portion18is in its rearward retracted position and tail portion20is in its rearward extended position. As hoist actuator28starts to extend inFIGS. 25-28, head portion18begins to move forward relative to main portion16and second slide segment32B of connection rod32slides through detent mechanism34while tail portion20remains stationary in its rearward extended position during this initial forward movement of head portion18. Once engagement segment32C reaches ball plungers40, the ball plungers are urged outward against the bias of springs44until a recess37of engagement segment32C moves into alignment with ball plungers40and the ball plungers40are forced inward by springs44into engagement with recess37. When this occurs, tail portion20becomes coupled to head portion18as shown inFIGS. 21-24. Continued extension of hoist actuator28causes head portion18and tail portion20to move together in the forward direction according toFIGS. 16-20. Continued extension of hoist actuator28eventually causes tail portion20to reach its forward retracted position, shown inFIGS. 12-15, at which point forward limit stops46abut with longitudinal side rails16A,16B of main portion16to prevent further forward displacement of tail portion20. As hoist actuator28extends further, forward displacement of head portion18pulls engagement segment32C through detent mechanism34as shown inFIG. 15, and first slide segment32A aligns with detent mechanism34. Finally, as shown inFIGS. 8-11, hoist actuator28is fully extended and head portion18reaches its forward extended position while tail portion20remains in its forward retracted position.

Operation of apparatus10to unload a container C from vehicle V will now be described with reference toFIGS. 8, 12, 16, 21, 25, and 29. As shown inFIG. 8, vehicle V is parked with container C fully loaded on vehicle V. Lift actuators14are fully retracted such that top frame12is lowered to its horizontal home position used when transporting container C. Cable end26B is drawn completely forward and is coupled to the front end of container C.

Next, lift actuators14are operated to tilt top frame12as shown inFIG. 12. Hoist actuator28is operated to retract slightly such that head portion18moves away slightly from its forward extended position, and tail portion20remains at its forward retracted position. Cable end26B moves rearward a short distance.

Next, inFIG. 16, hoist actuator28is operated to retract further, causing head portion18to retract further and allowing cable end26B to be pulled rearward by the weight of container C as container C rolls down the inclined top frame12. During this stage, tail portion20starts to extend in the rearward direction by virtue of its linkage with head portion18.

InFIG. 21, hoist actuator is retracted further until the rear end of container C makes contact with the ground. At this stage, tail portion20has reached its rearward extended position limited by rearward limit stop48.

Next, inFIG. 25, lift actuators14are extended to increase the incline of top frame12such that tail portion20makes contact with the ground behind vehicle V. causing cable end26B retracted e

Finally, inFIG. 29, hoist actuator28is retracted fully to allow container C to roll off top frame12and onto the ground.

As may be understood, a reverse process may be followed for loading container C onto vehicle V. Vehicle V is parked with its rear end adjacent to a front end of container C, lift actuators14are extended to rearwardly incline top frame12, and the free end26B of cable26is coupled to a front coupling element provided on container C. At this stage, hoist actuator28is fully retracted such that head portion18is in its rearward retracted position and tail portion20is in its rearward extended position touching the ground.

Hoist actuator28begins to extend while top frame12is fully inclined, thereby starting to displace head portion18forward and draw cable end26B toward the front of top frame12. As a result, the front end of container C is lifted onto top frame12. At this stage, tail portion20is uncoupled from head portion18and remains in contact with the ground.

Next, lift actuators14are retracted enough to lower top frame12to a shallower incline substantially even with an incline of container C, whereby the rear end of tail portion20is lifted away from the ground. During this stage, hoist actuator28is kept at a constant length.

Hoist actuator28continues to extend and displace head portion18forward, thereby pulling cable end26B and container C closer to the front of top frame12. As this occurs, tail portion20becomes coupled to head portion18and moves forward with head portion18. Meanwhile, lift actuators14are kept at a constant length.

Next, hoist actuator28is extended almost fully. Head portion18is close to its forward extended position, and tail portion20has reached its forward retracted position. Cable end26B is almost drawn completely forward to move the front end of container C to the front of top frame12. Lift actuators14are kept at a constant length to maintain the same incline of top frame12relative to vehicle V.

Finally, hoist actuator28is fully extended to bring head portion18to its forward extended position such that cable end26B and container C are pulled to the front of top frame12, and lift actuators14are fully retracted to bring top frame12down to its horizontal home position for transport of container C.

It will be appreciated that hoist actuator28drives the displacement of both head portion18and tail portion20during loading and unloading by virtue of linkage30. Consequently, the present invention avoids the need for an additional actuator dedicated solely to moving tail portion20and related hydraulic and electronic circuitry and controls associated therewith.

While the invention has been described in connection with an exemplary embodiment, the detailed description is not intended to limit the scope of the invention to the particular forms set forth. The invention is intended to cover such alternatives, modifications and equivalents of the described embodiment as may be included within the scope of the invention.