Carrier For Containers

Abstract

A carrier for the loading and unloading of elongated freight containers includes a U-shaped body consisting of beams forming an inner space corresponding to the size of the container, and hydraulic means gripping and lifting the container. The U-shaped body has four wheels at its corners with hydraulic motors and steering means, an engine and a hydraulic pump driven by the engine and operatively connected with the hydraulic wheel motors, the steering means and the hydraulic gripping and lifting means. The operative connections of the pump include control means.

Parent Case Text

The present application is a continuation-in-part of our co-pending patent application Ser. No. 85,920, filed Nov. 2, 1970, entitled "Side Loader for Containers."

Description

This invention relates to a carrier for containers.

The present invention is particularly concerned with the handling of long freight containers.

The International Organization for Standardization issued an ISO Recommendation R668, dated Feb. 1968 stating the dimensions and ratings of freight containers. The carrier of the present invention is particularly intended for handling containers designated as 1A, 1B and 1C in that Recommendation and having the lengths of 20, 30 and 40 feet or consisting of two longitudinally joined 20 feet containers.

The term "handling" as used herein is intended to include transportation of containers from shipboard to a storage area, transportation from the storage area to shipboard, transportation within the storage area and lifting of containers one upon the other.

An object of the present invention is the provision of a carrier which can be carried along in the ship.

This has the advantage that the ship can use harbors which do not have special equipment for container handling. The carrier is particularly intended for so-called ro-ro vessels having one or several decks which are loaded and unloaded through a tail gate. These container transporting vessels may touch a score of harbors on their route.

Another object is the provision of a carrier which can rapidly load and unload the containers.

This is particularly important for the above-mentioned vessels touching a score of ports. However, in general, rapid loading and unloading results in lower costs and a faster turnaround of the ship.

A further object is the provision of a carrier which will eliminate the need of expensive roll trailers of all types and achieves an 80 to 90 per unit cube utilization of hold space since it can enter practically any place in the vessel and is able to stack containers two high in a head room only inches higher than the carrier.

Yet another object of the present invention is the provision of a carrier the operation of which does not require the necessity of displacing the container laterally to a point outside the carrier.

Prior art carriers which do not have this feature produced the risk of toppling of the side loading carriers as well as a high point load between the wheels on one side of the carrier and the base.

Other objects of the present invention will become apparent in the course of the following specification.

When a carrier according to the present invention is used, the carrier grips the containers by the top corner castings at both ends. The twist-locks enter the corner castings through their vertical openings and not from above, as in the case of a top-lift. Although the overall height of the carrier is small, the lifting height is extremely high, and it is able to stack e.g. 8' .times. 8'6" .times. 40' containers two high. The lifting height without increase in overall height of carrier is 300 mm (approx. 12"). The four wheels of the carrier can be turned 90.degree. in motion and on spot, or locked in any position in between for crab steering of the carrier.

The invention will appear more clearly from the following detailed description when taken in connection with the accompanying drawings showing by way of example only, a preferred embodiment of the inventive idea.

In the drawings:

FIG. 1 shows in perspective the carrier beside containers that have been transported onto shipdeck.

FIG. 2 shows in perspective the carrier and the container to be transported, which is shown as lifted into its upper position with the aid of the lifting gear.

FIG. 3 is the hydraulic driving and braking circuit of the carrier in simplified form.

FIG. 4 illustrates the principle of the carrier's steering gear, including its hydraulic circuit.

According to FIG. 1, the carrier consists of a U-shaped body comprising a first beam 2a, which has the length of the container 1 to be transported (that is, 20', 30' or 40'). To the ends of the first beam 2a are connected second beams 2b, which have a length consistent with the width of the container (e.g. 8'). Consequently, a space having the size of the container to be carried remains inside the body.

The carrier has at each corner of its U-shaped body, one rubber wheel 6 in its fork 7. All wheels 6 are traction wheels and they are steerable, and their direction can be changed by one single operation by 90.degree., when the fundamental travelling direction of the carrier is changed. The carrier has two fundamental directions of travel, indicated in FIG. 1 by arrows A and B. The longitudinal basic direction A of travel of the carrier is used when containers are being transported from the point to another. Thus the carrier is able to move in confined spaces. The requisite width of the corridors for travelling is substantially merely the width of the container 1, increased by the width of the first beam 2a. The container is approached, and withdrawn from, in the fundamental direction of travel B. This enables the loading space to be efficiently utilized in that between the containers to be loaded only a space substantially equal to the width of the second beams 2b is needed. In FIG. 1 the lifting gear for the container 1 is designated by the reference numeral 3 and the gripping device is designated by the numeral 4. These devices 3 and 4 are mounted upon the second beams 2b. The carrier is made to grip the container 1 with the devices 4 by the top corner castings of its shorter end sides, which have been denoted with the numeral 38 in FIG. 1. Only minimal space is then required above the container when one container is placed on top another, for example. Two containers can be placed on top of each other in the hold of the vessel even if the height of the cargo space exceeds the aggregate height of two containers by a few inches only.

According to FIG. 2, a motor 8 is mounted inside the first beam 2a and drives one or several hydraulic pumps 9, from which the various elements of the carrier obtain their power by pressure pipes. The driving hut 5 of the carrier is placed at the juncture of beams 2a and 2b, which secures the best possible visibility for the driver. The driving hut 5 contains a driver's seat 10 and a steering wheel 11, and governing and control equipment for various functions. These also include a wheel position indicator, by which the position of the wheels 6 may be observed without direct view of the wheels.

In order to achieve the most favorable mobility and best possible steerability, hydraulic motors 12 have been placed in the hub of each wheel 6 which obtain their power from the hydraulic pump 9 through a pipe system and control valves. The hydraulic motors placed in the wheel hub are generally known, and no detailed description of their design is therefore given. The details of the design of the driving, steering and braking hydraulics will be described later on. The hydraulics of the lifting and gripping devices are commonly known, for which reason no detailed description of these is considered necessary.

The operation of the lifting and gripping devices for the container 1, as shown in FIG. 2, will now be described:

The lifting devices consist of four components, namely, the lateral shift beam 19, an inner frame, comprising a horizontal part 18, an intermediate frame, and and outer frame. The lateral shift beam 19 carries gripping devices 4, and the vertical part 20 of the lifting device carries the above-mentioned inner, intermediate and outer frames, which are guided by rolls and sliding surfaces to be vertically movable with reference to each other. These frames are mutually attached by two chains 43 constituting a closed loop; they transfer the vertical forces between the frames both upwardly and downwardly and thereby enable the center of gravity of the container to be displaced so as to be outside of the chain span. The lifting device in its entirety is arranged to run along rails fixed to the beams, supported by rolls.

Lifting is accomplished by power cylinders 13 and 14, which obtain their pressure fluid from the pump 9. The lifting is carried out in two stages: first the power cylinders 13 operate, followed by operation of the power cylinders 14. The first cylinders 13 raise the entire lifting gear, guided by the rails. The second power cylinders 14 rise along with the lifting gear in the described manner; subsequently, when the second power cylinders 14 operate, the chains 43 double the lifting span of the power cylinders 14.

In FIG. 2, the container 1 has been shown as being raised to its upper position, in which the container is at such height that the carrier can be driven into a position in which the raised container 1 may be directly lowered upon another container resting on the transporting base.

At the stage when the container is gripped, it is rather difficult to drive the carrier with one-centimeter accuracy into a position in which all four gripping elements 21 will be exactly positioned with reference to the top corner castings 38 of the container 1. Therefore, in order to facilitate the gripping operation and to provide an exact positioning of the container during lowering, means for lateral and longitudinal displacement have been provided in the lifting and gripping devices. For this purpose, the horizontal beam 18 has a sliding surface on which the lateral shift beam 19 moves, which is moved with reference to the horizontal beam 18 by the lateral shift cylinder 15. The distance of about 1,000 mm outwardly from the center has been found to be a suitable lateral shift range. For longitudinal displacement, a beam 42 has been provided which is movable upon the lateral shift beam 19 longitudinally to the container 1 by the longitudinal shift cylinder 16. The distance of about 150 mm has been found to constitute a suitable total longitudinal shift range. As gripping devices 4, attached to the beam 42, operate dowel-like rods 21, known in prior art, which are turnable about their longitudinal axis through 90 degrees into two different positions, in one of which the rods 21 can be inserted into the corner castings 38 of the container 1, while in the other position the rods 21 are secured in the corner castings 38. The rods 21 of the gripping devices 4 are turned in the manner described by turning cylinders 17.

Furthermore, feeler elements 22 have been provided in connection with the lifting and gripping devices which sense the position of the lateral shift beam 19 with reference to the container 1 on the side, top and end of the container 1. The feeler elements 22 are associated with microswitches, known in prior art, which supply pulses for the control of the lateral, vertical and longitudinal movements. The microswitches are employed to control electrohydraulic valves, which in their turn control the movements of the power cylinders 13, 14, 15, 16 and 17. The gripping of the container 1 and releasing of the container can thus be made to take place automactically, by depressing push bottons marked "Grip" and "Release," respectively, which are to be found in the driving hut 5, whereby the series of movements of the different power cylinders are carried out in succession, controlled by the said microswitches and in accordance with a pre-set program. The gripping and releasing of the container 1 thus cannot be affected by misjudgment on the driver's part.

The power transfer of the carrier operates according to the hydrostatic principle. The driving and braking circuit, shown in FIG. 3, is now described in greater detail. Hydrostatic pressure is supplied by the pumps 9, connected by means of a driving unit to be driven by the motor 8; two of these pumps are shown in FIG. 3, namely, the variable supply pumps P.sub.1 and P.sub.2, the volumetric supply rate of which is controlled and directed by the aid of electrohydraulic selector valves 24 to 28 to go to the desired functional units. The selector valves 24 to 28 are controlled by the driver from the driving hut 5. The power transfer hydraulics of the travelling motors M.sub.1, M.sub.2, M.sub.3 and M.sub.4 constitute a closed circuit, in which the adjustable axial pumps P.sub.1 and P.sub.2 supply oil to the hydraulic motors 12 in the wheel hubs. The adjustable pumps P.sub.1 and P.sub.2 have been provided with power limiters, which ensure that the engine 8 does not stall if the driver should attempt to overload the pumps.

By means of the hydraulics shown in FIG. 3 both four-wheel traction and two-wheel traction is obtainable, wherein the speeds will be different. For four-wheel traction the selector valves 24, 25 and 26 are in position a, whereby the adjustable pumps P.sub.1 and P.sub.2 supply the travelling motors M.sub.1 to M.sub.4 in parallel. At two-wheel traction the selector valves 24 to 26 are in position b and selector valve 25 is in position a, whereby the adjustable pump P.sub.1 supplies the travelling motor M.sub.2 and adjustable pump P.sub.2 supplies the travelling motor M.sub.3, while travelling motors M.sub.1 and M.sub.4 together constitute a closed circuit. In addition, so-called steering travel can be accomplished, wherein the selector valves 24 and 26 are in position b, whereby the adjustable pump P.sub.1 supplies the travelling motors M.sub.1 and M.sub.2 and adjustable pump P.sub.2 supplies the travelling motors M.sub.3 and M.sub.4. With this steering driving, even very complex routes of travel may be followed.

Braking is accomplished as follows, in accordance with the diagram of FIG. 3. The outputs of pumps P.sub.1 and P.sub.2 are shifted to zero, and similtaneously the selector valve 28 begins to bleed oil from the brake cylinders 23 into the hydraulic fluid tank 39, whereby the brake spring 40 urges the brake shoes into contact. The selector valve 27 for the parking brake has the braking position b. When any one of the selector valves 24 to 26 is in position a, that is when it is energized, the selector valve 27 also obtains its action current, and consequently when any mode of driving has been selected, the parking brake is automatically disengaged, provided that there is pressure in the brake system pipes, that is the carrier is in motion or starting to move. In the opposite case the parking brake is automatically engaged.

FIG. 4 shows the steering system of the carrier with its hydraulic diagram. The system is a four-wheel steering system, wherein the valve 30 (Orbitrol valve) is used to direct the oil over selecctor valves 31 and 32 to steering cylinders 29 provided with a piston rod 41 passing through the cylinder. The piston rods 41 of the steering cylinders 29 actuate the chains 34, which have been attached to sprocket wheels 35 on the upper end of the central post 36 of the wheel fork 7. The chains run over guiding wheels 37. When the piston rods 41 are moved by pressure from the pump 33, the chains 34 also move in such manner that the wheels 6 on the same end of the carrier turn through exactly equal angles. The selector valves 31 and 32 may be used to select different modes of steering as follows: With selector valve 31 in position b and selector valve 32 in its central position, so-called "straddle truck steering" is achieved, with which the carrier tends to run in a circle having its center on one side of the carrier. The turning angles of the wheels are then .+-.20.degree.. At so-called oblique driving the selector valve 31 is in position a and the valve 30 is in its central position. At this mode of driving the turning angles of the wheels may be -20.degree. to 0.degree. to +100.degree..

The following characteristics are typical of the steering system employed in the carrier of the present invention. A controlled amount of pressurized oil passes by the pipes from the steering device to the steering cylinder 29, causing a turning of the wheels 6 which is consistent with the amount by which the steering wheel 11 has been turned. The required steering force is very small under all conditions.

Claims

What is claimed is:

1. A carrier for loading and unloading elongated freight containers, comprising a U-shaped body consisting of an elongated beam and two beams extending at right angles to the first-mentioned beam and connected to the ends thereof, said beams enclosing a space the length of which is substantially equal to the length of the container to be transported and the breadth of which is substantially equal to the width of said container, hydraulic gripping and lifting means carried by said body for gripping said container at its top corners and lifting it into a transporting position and to a height which is at least equal to the height of one container from its base when containers are to be stacked one upon the other, four wheels carried by the corners of said body, separate hydraulic motors connected with said wheels, means connected with said motors and said wheels for steering said wheels and changing their direction to the extent of 90.degree., an engine carried by said body, at least one hydraulic pump driven by said engine means supplying pressure fluid from said pump to said hydraulic motors for the wheels, to said hydraulic gripping and lifting means and to said means steering the wheels and changing their direction, and electrohydraulic control means connected with pressure fluid supplying means for controlling the gripping and releasing of the container, for controlling the lifting and lowering of the container, for accelerating and decelerating the speed of travel of the carrier and changing its direction of travel and for steering the wheels and changing their direction, wherein said gripping means are displaceable relatively to the lifting means longitudinally and laterally to the container.