AU2017225132A1 - Lifting apparatus and lifting method - Google Patents

Abstract

Abstract A lifting apparatus, comprising: a piston assembly movably disposed in a cylinder for lifting and supporting machinery, the piston assembly comprising an outwardly extending threaded member adapted for movement with the piston assembly; a locking nut adapted for being selectively engaged with the threaded member for limiting axial movement of the piston assembly such that in at least one operable configuration, the locking nut is positioned in a spaced relationship relative to an upper portion of the cylinder to limit downward movement of the threaded member due to failure of the piston assembly. 6070 -45 100 60 r 4 Figure 1

Description

LIFTING APPARATUS AND LIFTING METHOD

TECHNICAL FIELD

This invention relates to a lifting apparatus and to a lifting method. BACKGROUND

The discussion of any prior art documents, techniques, methods or apparatus is not to be taken to constitute any admission or evidence that such prior art forms, or ever formed, part of the common general knowledge.

Fluid based lifting systems especially systems incorporating hydraulic cylinders or hydraulic jacks are routinely used for lifting or lowering large loads including heavy machinery and large equipment, including mining equipment for performing maintenance on the machinery or equipment. Usually in order to lift a large load spanning over a large area, multiple hydraulic cylinders may need to be employed in order to provide the necessary force and balance to lift the load. In order to conduct routine maintenance works, the lifting of large machinery is followed by technicians accessing the machinery from below in order to complete the necessary maintenance tasks, the fluid cylinders may need to lift and support the machinery further while the technician services the machinery from below.

However, during use, carrying out such maintenance works may create a dangerous scenario for the technician because any failure of the fluid cylinders can cause sudden lowering of the load due to a failure in the lifting system. By way of example, the hydraulic cylinder or the hydraulic pump may undergo failure which can cause the lifted machinery to drop all of a sudden. Such a scenario can become even more dangerous, and potentially fatal, for technicians, if the failure of the lifting system occurs whilst technicians are servicing the underside of the machinery. Therefore, there is a need for providing an improved safety mechanism for preventing inadvertent and sudden lowering of the lifting system due to failure.

SUMMARY OF THE INVENTION

In a first aspect, the invention provides a lifting apparatus, comprising: a piston assembly movably disposed in a cylinder for lifting and supporting machinery, the piston assembly comprising an outwardly extending threaded member adapted for movement with the piston assembly; a locking nut adapted for being selectively engaged with the threaded member for limiting axial movement of the piston assembly such that in at least one operable configuration, the locking nut is positioned in a spaced relationship relative to an upper portion of the cylinder to limit downward movement of the threaded member due to failure of the piston assembly.

Preferably, the spacing in between the locking nut and the upper portion of the cylinder determines the extent of downward movement of the threaded member during failure.

Preferably, in at least a second operable configuration, the locking nut is adapted for engagement with an upper portion of the cylinder and preventing downward axial movement of the piston assembly during use.

In an embodiment, the apparatus comprises an actuator assembly for extending and retracting the piston assembly relative to the cylinder such that during failure of the actuator assembly, the locking nut undergoes downward movement in a direction towards the upper portion of cylinder resulting in engagement of the locking nut with the upper portion of the cylinder in the second operable configuration thereby limiting downward axial movement of the piston assembly.

In an embodiment, the apparatus comprises engagement means for selectively engaging the locking nut with the threaded member during use.

In an embodiment, the apparatus may comprise a drive unit, preferably a variable speed drive unit, the drive unit being operable for rotating the locking nut relative to the threading member. Preferably, the drive unit comprises a drive shaft, the drive unit being positioned in a housing, the housing having at least one opening for accommodating the drive shaft and at least another opening for allowing flow of cooling fluid for cooling the drive unit during use.

In an embodiment, the locking nut comprises an outer wall adapted to engage with a pinion driven by the drive unit. Preferably, the outer wall comprises a plurality of teeth adapted for engagement with complementary teeth provided in the pinion, during use.

In an embodiment, one or more controllers for maintaining the spaced relationship between the locking nut and the upper portion of the cylinder. Preferably, said one or more controllers are adapted for varying the position of the locking nut in response to variance in the position of the threaded member of the piston assembly, thereby maintaining the spaced relationship between the locking nut and the upper portion of the cylinder. Furthermore, the controller may comprise a Programmable Logic Controller (PLC) for controlling the position of the locking nut.

In an embodiment, the controllers are adapted for being connected with the actuator assembly such that any extension or retraction of the piston assembly results in a corresponding movement of the locking nut for maintaining the spaced relationship between the locking nut and the upper portion of the cylinder.

In an embodiment, the actuator assembly comprises: a first port for supplying fluid into a first fluid receiving chamber such that supply of pressurised fluid into the first chamber extends the piston assembly away relative to the cylinder; and a second port for supplying fluid into a second fluid receiving chamber such that supply of pressurised fluid into the second chamber retracts the piston assembly relative to the cylinder.

In an embodiment, the apparatus further comprises a cleaning assembly positioned relative to the locking nut, preferably positioned in a spaced relationship relative to the locking nut. Preferably, the cleaning assembly is adapted for substantially encompassing the threaded member, the cleaning assembly comprising one or more inlets for receiving pressurised fluid and for directing pressurised fluid through one or more fluid outlets in a generally upwardly direction away from the locking nut. More preferably, said one or more outlets are adapted for directing pressured fluid by forming a substantially circular shaped air curtain preventing ingress of dust or other debris into the locking nut.

In an embodiment, the apparatus further comprises a cleaning brush assembly positioned along an upper portion of the locking nut. The cleaning brush assembly is preferably received into a cavity provided on an upper receiving face of the locking nut and comprises a plurality of brush members extending for engagement with the threaded member during use.

In another aspect, the invention provides a method of operating a lifting apparatus, the method comprising: movably disposing a piston assembly in a cylinder, the piston assembly comprising an outwardly extending threaded member adapted for movement with the piston assembly; engaging a locking nut with the threaded member for limiting axial movement of the piston assembly by positioning the locking nut in a spaced relationship relative to an upper portion of the cylinder.

BRIEF DESCRIPTION OF THE DRAWINGS

The Detailed Description is not to be regarded as limiting the scope of the preceding Summary of the Invention in any way. The Detailed Description will make reference to a number of drawings as follows:

Figure 1 is a perspective view of an embodiment of the lifting apparatus 100.

Figure 2 is a side view of the lifting apparatus 100.

Figure 3 is a sectional view of the lifting apparatus 100.

Figure 4 is a top view of the lifting apparatus 100.

Figure 5 is an end view of the lifting apparatus 100.

Figure 6 is an exploded perspective view of a locking nut 10 forming a part of the lifting apparatus 100.

Figure 7 A is a perspective view of the locking nut 10.

Figure 7B is a top view of the locking nut 10.

Figure 7C is a sectional perspective view of the locking nut 10.

Figure 8A is side view of a cleaning brush assembly 19.

Figure 8B is an underside perspective view of the brush assembly 19.

Figure 9A block diagram indicating a system for controlling the lifting apparatus 100.

Figure 9B is a flowchart providing an outline of steps involved for executing a lifting method in accordance with an embodiment of the present invention.

Figure 10 is a block diagram of a lifting system comprising a plurality of lifting apparatus 100.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENT

Figures 1 to 5 illustrate a first embodiment of a lifting apparatus 100 in accordance with an embodiment of the present invention. The lifting apparatus comprises a piston assembly 20 that is movably disposed in a cylinder 30. The piston assembly 20 comprises an outwardly extending threaded member 22 adapted for movement with the piston assembly 20 during use. The lifting apparatus 100 is also provided with a safety mechanism in the form of a locking nut 10 that includes helical grooves 14 for engaging with the threaded member 22 during use for limiting axial movement of the piston assembly 20. Specifically, in at least one lifting configuration, the locking nut 10 is provided in a spaced relationship relative to an upper portion of the cylinder 30. By way of example, in at least some embodiments, the spacing between the locking nut 10 and the upper portion of the cylinder may be pre-set in the range of 1-5mm, more preferably 1-2mm. It should be appreciated the spacing may be varied in accordance with the lifting requirements of the lifting apparatus 100.

The lifting apparatus 100 comprises a housing 90 that houses and supports an actuator assembly (e.g., a hydraulic cylinder assembly) comprising the cylinder 30 having an upper portion (including a top end) and a lower portion (including a bottom end) for extending and retracting the piston assembly 20. A longitudinal axis extends between the ends of the cylinder 30. In an embodiment, the cylinder 30 is a dual port hydraulic cylinder. A first port is provided for supplying hydraulic fluid into a first fluid receiving chamber such that supply of hydraulic fluid into the first chamber extends the piston assembly 20 away relative to the cylinder 30. A second port is provided for supplying fluid into a second fluid receiving chamber such that supply of pressurised fluid into the second chamber retracts the piston assembly relative to the cylinder 30.

During periods of operation, the actuator assembly 90 may undergo failure. In the event of a failure, the locking nut 10 which is initially positioned in a spaced relationship relative to the upper portion of the cylinder 30 undergoes a slight downward movement in a direction towards the upper portion of cylinder 30 (due to the downwardly directed weight of the load supported by the piston assembly 20) resulting in engagement of the lower portion of the locking nut 10 with the upper portion of the cylinder 30 in the second operable configuration thereby limiting downward axial movement of the piston assembly 20 during such a failure. The applicants have found that using the locking nut 10 in a spaced relationship, as described above reduces wear and tear on the locking nut 10 by engaging the locking nut with the cylinder only during a failure and not during routine lifting operations.

The housing 90 also supports a variable drive unit 40 for driving the locking nut 10 during use. Specifically, the drive unit 40 comprises a drive shaft 46 that in turn rotates a pinion wheel 42 that incudes teeth that matingly engage an outer wall of the locking nut 10 in order to position the locking nut 10 along a length of the threaded member 22. A programmable logic controller (PLC) system 120 is also provided for controlling the rotational speed of the locking nut 10 relative to the axial movement of the piston assembly 20, specifically, the extension and retraction of the threaded member 22 which is provided by the actuator assembly in order to maintain a spaced relationship in between a bottom portion of the locking nut 10 and an upper portion of the cylinder 30. The PLC system 120 is connected to the actuator assembly and the variable drive unit 40. The PLC system 120 may be programmed such that any signal sent to a hydraulic power unit in the actuator assembly also cause the locking nut 10 to rotate in unison with the movement of the piston assembly 20 thereby maintaining the spaced relationship between the locking nut 10 and the cylinder 30. The use of the PLC 120 may be programmed (as shown in Figure 9) such that any extension or retraction of the piston assembly 20 results in a corresponding movement of the locking nut 20 for maintaining the spaced relationship between the locking nut 10 and the upper portion of the cylinder 30.

The locking nut 10 may be manufactured from a high strength steel, capable of accepting high compressive loads without any deformation. The inside diameter of this nut is machined to have a thread form matching the same thread as the threaded member 22 of the piston assembly 20. The locking nut 10, along its outer walls is provided with a profiled surface having profiled teeth (commonly known as ’spur) extending in a vertical direction relative to the axis of the cylinder 30. The external profiled teeth engage with complementary teeth provided on the pinion 42. The engagement of the pinion 42 with the outer profiled surface of the locking nut 10 causes the locking nut 10 to rotate when the drive unit 40 is activated by sending a signal to the control unit 45 provided for controlling the drive unit 40. The thickness of the nut 10 is determined by the maximum load, the locking nut 10 would be expected to support with a calculated factor of safety-FOS) in the event of a system failure that causes the locking nut 10 to come in contact with the top of the hydraulic cylinder 30. In the preferred embodiment, the length of the profiled teeth on the locking nut 10 is approximately one half of the total vertical length of the nut. The upper half of the locking nut 10 is also provided with a circular cavity 18 that is machined to accept the circular brush 15.

During use, it is expected that several units of the lifting apparatus 100 (as shown in Figure 10) would need to be positioned for lifting a load. The dual acting cylinders (having the dual port system, as explained in the previous sections) allow the load of a revolving frame to be raised and lowered in a controlled and synchronous manner. The movement of each piston assembly 20 in the several units of the lifting apparatus 100 can be measured with a highly accurate linear displacement instrument (such as a displacement sensor), with the data from each instrument relayed back to the controller (the PLC 120 or another computerised controller) where the movement may also displayed on a visual display means such as a display screen. If any unauthorised or unexpected movement of the piston assembly 20 is recorded or observed (such as due to hydraulic system failure or ground shrinkage), the controller may send a signal to the hydraulic power unit to send more oil to a specific cylinder 30 or several of the cylinders 30 so that full load contact is maintained and the load is maintained on the lifting apparatus 100 in a stable manner. The lifting apparatus 100 may be 'micro adjustable', meaning that cylinder movements of the actuator assembly for each lifting apparatus 100 may be as small as ,13mm (.005") [in comparison the average length of a full stroke of the cylinder may be 1700mm (3foot, 6 inches). Therefore, any movement determined by the linear displacement instruments, on all cylinders or a single specific cylinder, may be automatically adjusted by a computer control system to maintain the designated height of the raised load.

The lifting apparatus 100 is often used in the field where the lifting apparatus 100 may experience harsh environments, such as uneven work base, wind, rain, dust, storms etc. The locking apparatus 100 is adapted for functioning in such harsh environments without excessive use of operating personnel and operating machinery. The drive unit 40 is housed in a drive housing 47 and continuously cooled with pressurised cool air (below atmospheric temperature) entering the bottom of the housing 47 and the heated air is expelled out of the drive housing 47 through an opening provided at a top portion of the drive housing 47. A cleaning assembly 50 that is positioned upwardly relative to the locking nut 10 and in a spaced relationship relative to the locking nut 10 is also provided. The cleaning assembly 50 comprises a circular cleaning collar 55 that substantially encompasses the threaded member 22. Machined orifices are provided along the body of the cleaning collar 55 for directing pressurised air in an upwardly direction, at an upward angle of 30 degrees, away from the locking nut 10 thereby providing a circular curtain of pressurised air for cleaning. The provision of the cleaning collar 55, during use, prevents the ingress of dust or water into the helical threads of the locking nut 10, the threads of the threaded member 22 and the mating teeth of the pinion 42 and the locking nut 10. Pressurised air conveyed through conduits 80 enters the circular cleaning collar 55 through inlets located along the outside diameter of the cleaning collar 55. An air flow controller in the form of a controlling solenoid 60 may be used for controlling the flow of pressurized air. During use, pressurized air enters the collar and flows through a plurality of orifices provided in the collar before being expelled , passing around the annulus, and exits the collar in an upwardly direction as previously discussed. The circular ring 15 is supported on a supporting assembly 70 that comprises three equally spaced support straps bolted to the outside diameter of the cylinder housing. A secondary cleaning assembly in the form of a circular brush assembly 15 is fitted onto a machined cavity 19 provided in a top portion of the locking nut 10. The inner bottom face of the machined cavity 19 is machined at the same angle as the orientation of the helical threads provided on the threaded member 22 of the piston assembly 20. When the circular brush assembly 15 fitted into machined cavity 19, the inwardly directed bristles of the brush assembly are substantially in contact with threaded member 22 continuously wiping the threaded member 22 during use thereby preventing further ingress of dirt, dust and debris into the locking nut 10. The brush assembly 15 is secured into the machined cavity 18 with a locking cap 18 that has a tapered collar 16 that presses on the metal body of the wiper brush assembly 15. The locking cap 18 is secured onto the locking nut 10 by way of fasteners 17.

During use, a plurality of the lifting apparatus 100 (as shown in Figure 10) may be positioned for lifting a heavy load such as heavy earth moving equipment (a heavy excavator in a preferred embodiment) to safely and accurately carry out such a lift. During such a lifting process, the excavator to be serviced is driven (walked) from the work area to another nearby location on the site, commonly referred to as a 'hard stand'. (The hard stand is an area that has been strongly compacted and levelled. The computer control system (with an attached generator and compressor system) hydraulic pumping system and lifting cylinders are delivered to the hard stand and ready to be positioned to lift the excavator revolving frame. When in position, the excavator bucket is lowered onto a 'greased' steel plate and the excavator boom hydraulic cylinders are disconnected from the boom. This arrangement allows the bucket to freely move inwards when the revolving frame is lifted and outward when the revolving frame is lowered.

Using the specifications provided by the excavator manufacturer, the maintenance contractor knows the height from the surface of the hard stand to the underside of the revolving frame. If there is insufficient height for the lifting jacks to be properly installed, the excavator is moved onto hardwood mats to increase the height. The specifications also advises where to locate the lifting jacks under the revolving frame to ensure a stable lift of the revolving frame from the track frame and hold it safely in the elevated position.

With the revolving frame ready to be lifted, the piston assembly 20 in each of the lifting apparatus 100 are extended until contact is made with the underside of the frame. The hydraulic locking device (locks the revolving frame to a special locking plate on the track frame) is released and the load of the revolving frame is now taken on the lifting apparatus 100. The weight sensors (load cells) provided on the lifting apparatus 100 measure the load of the revolving frame and signals it back to the control computer. The program within the computer determines the evenness of the load on all jacks, taking into account any side load factors and calculates the center of gravity.

The control computer may then signal the hydraulic power unit in each of the actuator assembly in the lifting apparatus 100 and adjusts individual lifting apparatus 100 so that the frame is leveled and the load is equally distributed. When the frame is levelled and the load falls within the manufacturer’s specifications, the control computer may be used for activating the actuator assemblies for the lifting apparatus 100 to slowly lift the revolving frame from the track frame and lifts it to the required height.

As the threaded member 22 for each of the lifting apparatus 100 is slowly extending outwardly and away from the stationary cylinder 30, the controller also controls the rotation of the locking nut 10 for each locking apparatus 100 in order to rotate the locking nut 10 at a rotational speed to maintain a pre-set spacing between the upper portion of each cylinder 30 may be set to maintain a spacing of say 1mm between the bottom of locking nut 10 and the upper portion of each cylinder 30. Should there be an unexpected system failure on one or all of the lifting apparatus 100 causing the load (revolving frame) to drop, the load will only drop by 1mm (the distance set between the locking nut 10 and the upper portion of the cylinder 30) before the locking nut 10contacts the top of the cylinder body 30 preventing any further movement. Once the load is taken on the locking nut 10, locking nut 10 is expected to trip out on the controller, or in worst case the drive motor pinion 42 will shear and stop any further driving force on the locking nut 10. When the bottom of the revolving frame reaches the predetermined height, as measured by the linear displacement instrument, the computer shuts down the hydraulic power units for each of the lifting apparatus 100 but leaves the lifting apparatus 100 in an 'immediate use' standby mode. As the lifting cylinders in each of the lifting apparatus 100 are double acting cylinders with dual ports that require the pressurized hydraulic fluid to move the cylinder rod both up and down, the load remains sitting on the top of each of the lifting apparatus 100.

If the load on the loading apparatus 100 increases (vertical or side load), the increase in load is sensed by the loading apparatus and signals containing the new data in relation to the increased load is relayed to the computer controller which in turn signals the hydraulic power unit to send an oil flow to the cylinders 30 for each of the lifting apparatus 100 until the load is moved back to the original prescribed position.

When the maintenance or service work is complete, the revolving frame is slowly lowered on the lifting apparatus 100 until the mating surfaces of the revolving frame and track frame engage. The locking bolts securing the revolving frame to the track frame are engaged and secured. The excavator is then subsequently started and the boom hydraulic cylinders are then reconnected and a full systems check is conducted. Once the system check is completed, the machinery is returned to service.

In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. The term “comprises” and its variations, such as “comprising” and “comprised of is used throughout in an inclusive sense and not to the exclusion of any additional features.

It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect.

The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims appropriately interpreted by those skilled in the art.

Claims (20)

1. A lifting apparatus, comprising: a piston assembly movably disposed in a cylinder for lifting and supporting machinery, the piston assembly comprising an outwardly extending threaded member adapted for movement with the piston assembly; a locking nut adapted for being selectively engaged with the threaded member for limiting axial movement of the piston assembly such that in at least one operable configuration, the locking nut is positioned in a spaced relationship relative to an upper portion of the cylinder to limit downward movement of the threaded member due to failure of the piston assembly.

2. A lifting apparatus in accordance with claim 1 wherein the spacing in between the locking nut and the upper portion of the cylinder determines the extent of downward movement of the threaded member during failure.

3. A lifting apparatus in accordance with claim 1 or claim 2 wherein in at least a second operable configuration, the locking nut is adapted for engagement with an upper portion of the cylinder and preventing downward axial movement of the piston assembly during use.

4. A lifting apparatus in accordance with any one of the preceding claims further comprising an actuator assembly for extending and retracting the piston assembly relative to the cylinder such that during failure of the actuator assembly, the locking nut undergoes downward movement in a direction towards the upper portion of cylinder resulting in engagement of the locking nut with the upper portion of the cylinder in the second operable configuration thereby limiting downward axial movement of the piston assembly.

5. A lifting apparatus in accordance with any one of the preceding claims further comprises one or more engagement means for selectively engaging the locking nut with the threaded member during use.

6. A lifting apparatus in accordance with any one of the preceding claims further comprising a drive unit, the drive unit being operable for rotating the locking nut relative to the threading member.

7. A lifting apparatus in accordance with claim 5 wherein the drive unit comprises a drive shaft, the drive unit being positioned in a housing, the housing having at least one opening for accommodating the drive shaft and at least another opening for allowing flow of cooling fluid for cooling the drive unit during use.

8. A lifting apparatus in accordance with any one of the preceding claims wherein the locking nut comprises an outer wall adapted to engage with a pinion driven by the drive unit.

9. A lifting apparatus in accordance with claim 8 wherein the outer wall comprises a plurality of teeth adapted for engagement with complementary teeth provided in the pinion, during use.

10. A lifting apparatus in accordance with any one of the preceding claims further comprising one or more controllers for maintaining the spaced relationship between the locking nut and the upper portion of the cylinder.

11. A lifting apparatus in accordance with claim 10 wherein said one or more controllers are adapted for varying the position of the locking nut in response to variance in the position of the threaded member of the piston assembly, thereby maintaining the spaced relationship between the locking nut and the upper portion of the cylinder.

12. A lifting apparatus in accordance with claim 10 or claim 11 wherein the controller comprises a Programmable Logic Controller (PLC) for controlling the position of the locking nut.

13. A lifting apparatus in accordance with claims 10 to 12 when dependent upon claim 4 wherein the controllers are adapted for being connected with the actuator assembly such that any extension or retraction of the piston assembly results in a corresponding movement of the locking nut for maintaining the spaced relationship between the locking nut and the upper portion of the cylinder.

14. A lifting apparatus in accordance with claim 4 or claim 13 wherein the actuator assembly comprises: a first port for supplying fluid into a first fluid receiving chamber such that supply of pressurised fluid into the first chamber extends the piston assembly away relative to the cylinder; and a second port for supplying fluid into a second fluid receiving chamber such that supply of pressurised fluid into the second chamber retracts the piston assembly relative to the cylinder.

15. An apparatus in accordance with any one of the preceding claims further comprising a cleaning assembly positioned relative to the locking nut, preferably positioned in a spaced relationship relative to the locking nut.

16. An apparatus in accordance with claim 15 wherein the cleaning assembly is adapted for substantially encompassing the threaded member, the cleaning assembly comprising one or more inlets for receiving pressurised fluid and for directing pressurised fluid through one or more fluid outlets in a generally upwardly direction away from the locking nut.

17. An apparatus in accordance with claim 16 wherein said one or more outlets are adapted for directing pressured fluid by forming a substantially circular shaped air curtain preventing ingress of dust or other debris into the locking nut.

18. An apparatus in accordance with any one of the preceding claims further comprising a cleaning brush assembly positioned along an upper portion of the locking nut.

19. An apparatus in accordance with claim 18 wherein the cleaning brush assembly is received into a cavity provided on an upper receiving face of the locking nut and comprises a plurality of brush members extending for engagement with the threaded member during use.

20. A method of operating a lifting apparatus, the method comprising: movably disposing a piston assembly in a cylinder, the piston assembly comprising an outwardly extending threaded member adapted for movement with the piston assembly; engaging a locking nut with the threaded member for limiting axial movement of the piston assembly by positioning the locking nut in a spaced relationship relative to an upper portion of the cylinder.