NZ237504A - Telescopic lifting device for containers and like objects. - Google Patents

Description

PATENTS FORM NO. 5 Fee No. 4: $260.00 PATENTS ACT COMPLETE SPECIFICATION After Provisional No: 237504 Dated: 20th March 1991 LIFTING DEVICE WE JACK TIDD-ROSS TODD LIMITED, a New Zealand company of 598" Te Rapa Road, Hamilton, New Zealand hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement: / v 1 °CT/993X 23750 4 This invention relates to lifting devices.

In particular but not exclusively, this invention relates to lifting devices for lifting items such as transport containers, structural components for buildings, structures and the like, and buildings.

Conventionally lifting devices such as those for lifting transport containers from a tiuck include cranes, forklifts and hydraulically actuated devices mounted on the truck such as the Palfinger (TM) device. Cranes for this purpose such as straddle carriers and forklifts are able to lift the containers from a truck and transport the container to another site. As such they comprise a motive power unit and wheels which means they are relatively expensive. Forklifts are generally smaller and cheaper than cranes but have lifting limitations due to strength and baNnce restrictions. Mounted lifting devices are cheaper since they can utilize the motive power unit of the vehicle on which they are mounted, however they have the problem of requiring space at the side of the truck to unload the container.

In the construction industry, cranes and jacks are used for lifting components into position or for raising buildings for transport. In certain situations where the load is of large size more than one crane may be required. This ties up the cranes from other uses and increases the construction costs. Also, the capacity of the crane may not be fully utilized since the object is only being held in position during the fixing process and does not need to be moved. When jacks are used the lift of the jacks is generally limited and often packing blocks must be installed during successive lifting stages to facilitate a lift. 2 23 7504 Jacks such as screw thread jacks require a load carrying screw thread which must be of the full length of the lift even though only a small portion is carrying the load at any one time. The components of the jack are therefore used inefficiently. Similarly with rack type jacks the rack must be the length of the lift however only one portion of the rack carries the load.

It is an object of the present invention to provide a lifting device which addresses the above problems and difficulties or at the very least offers a useful choice.

According to the broadest aspect of the present invention there is provided a lifting device comprising a strut assembly, a wheel and a tension member, said strut assembly having a base end provided with a support element and a wheel end provided with bearing elements for rotatably supporting said wheel.

The tension member is disposed on the lifting device such that one end of the tension member is connected by means oi an attachmr at device to a portion of the strut assembly and an intermediate portion passes over the wheel leaving the other end free for connection to an object to be lifted. The invention is characterized in that lifting of the object is effected by an operation whereby the distance between the end of the tension member connected to the object to be lifted and the portion passing over the wheel is reduced, while the base end of the strut assembly is supported on the ground or some solid foundation.

According to another aspect of the present invention the attachment device connecting the end of the tension men: )er to the strut ass etobV °CT 1993$ 3 ►. 23 7504 comprises a take up means whereby the length of the tension member between the take up means and the other end can be effectively reduced or increased.

According to yet another aspect of the present invention the strut assembly may include a hydraulic ram arranged substantially parallel to the longitudinal axis of the strut assembly having a fixed end connected to a portion of the base end of the strut assembly and said bearing means for rotatably supporting said wheel mounted in the other extendible end.

According to even yet another aspect of the present invention said tension member may comprise short tensile members linked together, such as with a chain.

According to a further aspect of the present invention said tension member is made of a flexible construction, such as with a belt.

According to a further aspect of the present invention said strut assembly may include a stabilising support member which bears against the object being lifted thereby distancing the strut assembly relative to the object being lifted.

A lifting device as described above may be preferably constructed with a steel RHS strut assembly having a base plate fixedly or detachably fitted to the base end. In the case of an embodiment wherein the tension member is shortened and lengthened to lift or lower the object, the wheel may be mounted on bearings fitted in the other end of the RHS section. 237504 the wheel may be provided with rect sses to match the links of the chain and thereby ensure even distribution of the load to the wheel. Side faces can also be incorporated in the wheel design to prevent the tension device from coming off the wheel. Flexible tension members such as rope, wire rope, flat belt of "V" belts and the like may be used and in these cases the section of the wheel in contact with the tension member may be shaped so as to ensure even distribution of the load, the wheel is preferably supported on bearings arranged on the central axis of the wheel either inside the wheel with a shaft fixed to the strut assembly of in the strut assembly with an axle fixed to the wheel. However in the case of heavy loads it is also possible to also support the wheel on one or more wheels bearing against a peripheral surface located substantially opposite to the peripheral surface on which the tension member bears.

The device for tensioning or lengthening the tension member may consist of a winch attached to the strut assembly with a drum around which the tension member is wound or unwound. Alternatively in the case of a chain tension member, the winch may comprise of a sprocket which grips the chain whereby the chain can be moved relative to the sprocket. The winch may be either powered or manually operated. Alternatively any other type of device may be used for shortening and lengthening the tension member.

In the case that the wheel is supported on a strut which extends out of and into the support assembly, the end of the tension member is generally connected directly to the support assembly and the distance between the end of the tension member and the portion passing over the wheel is reduced or increased by moving the wheel relative to the strut member. Preferably this is achieved by mounting a hydrayliS^A^^ V 0\; A A 'OCT 1991 23 7504 between the wheel and the base end of the support assembly. Extension of the ram means that the wheel is moved relative to the base end so that the distance between the fixed end of the tension member and the wheel is increased and consequently the distance between the load end and the wheel is reduced thereby lifting the object by a distance equal to this reduction plus the length of extension of the ram. In this way a mechanical advantage may also be obtained in lifting and by the addition of an upper wheel the load on the chain or tension member is substantially reduced.

Hydraulic pressure for operating the ram may be provided by a hydraulic unit fitted to the lifting device. Alternatively a separate hydraulic supply source which may be provided which may have sufficient capacity to supply hydraulic pressure to operate a number of lifting devices simultaneously. The present invention however is not limited to a hydraulic system, any type of device capable of carrying an axial load and being extended and retracted while under load may ba used to support the wheel and move it relative to the strut. As with the previous embodiment the wheel may be either supported by bearings or the wheel supported on an axle fixed to the end of the strut assembly or on an axle mounted on bearings in the strut assembly or on one or more wheels rotatably mounted on the strut assembly with or without the axial support bearings. However the support system is not limited to this method and any method which provides a means of supporting the tension member under load and allowing relatively low friction movement of the tension member relative to the strut assembly is possible. / 0\ 6 23 75 04 A The lifting device described above has several advantages over conventional methods for lifting and lowering objects particularly in situations where only vertical lifting and lowering is required. For lifting structures during construction several units can be positioned to stably support the structure instead of using expensive cranes and the like. Likewise for lifting containers from a container transporter several units can be positioned to stably carry the weight of the container and the transporter can be driven away from under the container after which the container can be lowered to the ground. Since the units are portable they can be carried with the transporter or container for use in loading and unloading the container. This provides a low cost convenient means for loading and unloading containers compared to conventional lifting means.

The present lifting device using a tension member and wheel system for raising and lowering the load provides a simple construction compared to screw thread type jacks where the screw thread is expensive to manufacture and maintain. Similarly with jack type devices the ratchet system is expensive to manufacture and maintain.

Aspects of the present invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1: is a general layout of lifting device according to a possible embodiment of the present invention, and Figure 2: is an exploded view of the lifting device of Figure 1, and 7 23 75 04 Figure 3: is a side view of a lifting device in accordance with another possible embodiment of the present invention, and Figure 4: is a front view of the lifting device of Figure 3, and Figure 5: is an end view at section A-A of Figure 4.

With respect to Figures 1 and 2 of the drawings there is provided a lifting device generally indicated by arrow 1 comprising a column assembly 2 having a base 3. A movable element 4 is slidably fitted over the outside of the column assembly 2 and a wheel 5 is rotatably supported on an upper end thereof by means of bearings 6 and axle 7. A tension member 8 comprising a belt as shown in Figure 1 and/or a chain as shown in Figure 2 is wrapped over a peripheral surface of the wheel 5 with one end 9 fixed to the column assembly 2 by means of an attachment device 10 and another end 11 fitted with a connector 12 for connection to an object to be lifted. An hydraulic ram generally indicated by arrow 13 is disposed inside the column 2 with a base end 14 supported on the base 3 of the column 2 and an actuator end 15 connected to the movable element 4 by means of a concentric threaded shaft 16 which passes through a hold 17 in an end plate 18 of the movable element 4. The hydraulic ram 13 is supplied with hydraulic fluid from a hydraulic supply unit (not shown) through a connector 19 fitted to the base end 14 and accessed through an opening in the base end of .he column 2. A wedge 20 carried in a holder 21 is provided for holding the movable element 4 in a nutnber of predetermined positions when hydraulic pressure is released, by passing the wedge 20 through one of the slots 22 to thereby rest on the top end of the column 2. {~'0cTI99M 23 7504 A 4 In operation, one or more of the lifting devices is positioned substantially vertically beside an object to be lifted and the connector 12 attached to the object. The wheel 5 and tension member 8 may rest against the object to provide stability. Hydraulic pressure is then supplied to the hydraulic ram 13 thereby extending the ram and moving the movable member 4 upwards. This produces a tension force in the tension member 11 which lifts the objects as the tension member moves freely around the axis of the wheel 5. Once the object has been raised to the desired height the pin 20 may be inserted in the slot 22 and the hydraulic pressure released so that the load is then positively supported independent of the hydraulic ram.

Another embodiment of the present invention is shown in Figures 3, 4 and 5. In this embodiment elements having a similar function to those of Figures 1 and 2 are indicated with the same reference numbers. The device of this embodiment generally indicated by arrow 30 differs from that of Figures 1 and 2 in that an open link type chain 31 is used instead of the tension members 8 shown in Figures 1 and 2. Furthermore two side plates 32 are attached to the end of the movable element 4 at an angle to the longitudinal axis of the lifting device 30. Two bearings 33 are mounted substantially cent-ally in the side plates 32 and support an axle 34 which is fixed to the wheel 5 thereby enabling the load carrying capacity of the lifting device 30 to be increased. Having the wheel 5 supported by the side plates 32 away from the longitudinal axis of the lifting device 30 offers certain advantages in positioning the lifting device 30 relative to the object lifted. A small wheel 35 is rotatably mounted on an end portion of the side plates 32. This wheel 35 is located so as to bear against the object to be lifted and allow the object being lifted to move relative to the end portion of the side plates 32 with minimum frictj^f^^ ® ^ •/y c\ 9 i« .. 237504 and damage to its surfaces. A fender arm (not shown) with wear strip (which may be adjustable) could be an alternative to the wheel 35. The wheel 35 may have a shaped outer surface which engages with a complimentary portion of the surface of an object to be lifted thereby minimising sideways movement of the object. Pins 36 are provided for supporting hydraulic hoses. Pins (not shown) placed through the side of the movable element 4 may be used for positively carrying the load when hydraulic pressure to the hydraulic ram 13 is reduced.

A valve 38 is also provided for closing and opening the hydraulic supply passage so that hydraulic supply can be isolated for an external supply uni« (not shown). Wear pads 39 (see Figure 5) are provided between inner surfaces of the movable member 4 and the hydraulic ram 13 to allow the movable member 4 to slide freely over the external surface of the ram 13 while providing lateral support to the movable member 4.

As aforesaid the present invention has many applications and advantages. If the lifting devices are used to lift large objects, it is a relatively simple matter to provide means by which individual or groups of the devices can be controlled independently to compensate for uneven terrains, or unevenly weighted loads. If the lifting devices are used to lift large sections of a liquid storage tank the top section of the tank including the majority of the roof structure can be prefabricated. The lifting devices can be positioned inside or outside of the walls of a structure such as a tank and can be used to build or take down existing structures.

In some use applications the lifting device may need to ' ' manually. The addition of handles (not shown) 1 0 237504 detachable will enable each device to be pushed in wheelbarrow fashion with the wheel 35 in contact with the ground.

Aspects of the present invention have been described by way of example only and it will be appreciated that modifications and additions thereto may be made without departing from the scope thereof as defined in the appended claims. 23 758

Claims (6)

WHAT WE CLAIM IS:

1. A lifting device comprising a strut assembly having a base and an upper end which supports a wheel, a tension member which is fixed to the strut assembly whilst an intermediate portion passes over the wheel leaving the other end free for connection to an object to be lifted and a hydraulic ram arranged substantially parallel to the longitudinal axis of the strut assembly for extending a strut to thereby raise or lower the object connected to the free end of said tension member.

2. A lifting device as claimed in claim 1 wherein said tension member is a chain.

3. A lifting device as claimed in claim 1 wherein said tension member is a belt.

4. A lifting device as claimed in any one of claims 1 to 3 including a stabilising support member mounted from the strut so that it can bear against the object being lifted thereby distancing the strut assembly relative to the object.

5. A lifting device as claimed in any one of claims 1 to 4 wherein a strut member is constructed from complimentary inner and outer metal sections and said means for extending the strut is housed within the inner metal section.

6. A lifting device as claimed in claim 4 or claim 5 wherein the wheel is mounted at the free end of the strut by a support whidfe ,mounts both the wheel and stabilising support member. r. 12 23 7 5 0 4 A lifting device substantially as herein described with reference to the accompanying drawings. JACK TIDD-ROSS TODD < LIMITED By its Attorneys JAMES & WELLS 13 'I i'