GB1598795A - Pneumatic lifting devices - Google Patents

Description

(54) PNEUMATIC LIFTING DEVICES (71) We, WINDAK LIMITED, a British Company of Woodside, Poynton, Cheshire SK12 1AH, do 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: The invention concerns lifting devices, and has more particular reference to a method of and a means for the attachment of a lifting device to a drum, container and the like by pneumatic means.

A convenient method of lifting drums is by means of a suction pad which attaches itself to the end of the drum, these pads consisting of a solid section with a flexible or soft seal around the periphery. On many drums, the area of the fact to which the pad can be applied is restricted by plugs or filling connections, so the area exposed to suction is too small to take the required load.

In an alternative arrangement the suction pad seals on the outer lip of the drum, such procedure increasing the effective area of lift and providing for the lifting of full drums. However, difficulty is experienced in forming a satisfactory seal onto the lip because the lip is invariably distorted or damaged by use. A flexible or soft seal can be used to compensate for this distortion or damage but the seal requires to be pressed down with considerable force in order to affect a satisfactory seal round the complete periphery.

The object of the present invention is to provide a means for the attachment of a lifting device to such as a drum, container or the like. hereinafter referred to for convenience as a ' "drum", which avoids the aforementioned problems.

The invention provides a lifting device for use in lifting drums or the like which comprises a primary suction pad for engagement with the surface of the drum, a secondary suction pad in axi-parallel disposition relative to said primary suction pad likewise for engagement with the surface of the drum, the secondary suction pad having an area of intended engagement with the drum substantially greater than that of the primary suction pad, and pneumatic means cooperable with the said primary and secondary suction pads and adapted sequentially to apply a reduced air pressure independently to said primary and thence to said secondary suction pad.

According to a preferred feature the primary and secondary suction pads are arranged in concentric relationship, the secondary suction pad being dimensioned for engagement with the rim of the drum.

According to a further preferred feature, the pneumatic means is common to both suction pads and a valve means is provided whereby such means is isolated from the secondary suction pad during initial engagement of the primary suction pad with the drum.

In some circumstances a plurality of primary suction pads is provided, each such pad being engageable with a respective surface area of the drum and the area engaged by the secondary suction pad substantially exceeding the total area engaged by the plurality of primary suction pads.

The invention will now be described further, by way of example only, with reference to the accompanying drawings illustrating one embodiment thereof and in which: Figure 1 is a diagrammatic section through a lifting device constructed in accordance with the invention, the relative disposition of parts being that appropriate to the initial engagement of a primary suction pad with the drum; and Figure 2 is a view corresponding to Figure 1 but showing a later stage in the attachment of the lifting device to the drum.

Referring now to the drawing, a lifting device 11 for use in lifting a drum 12 and attachable thereto by pneumatic means comprises a rigid plate 13 substantially co-extensive with the end of the drum 12, a lifting arm 14 secured to the said plate at one face thereof, and primary and secondary sealing means 15, 16, respectively, at the other face of the plate.

The primary sealing means 15 comprises a flexible skirt lSa depending from the plate at a position centrally thereof, the upper end of the skirt being in fluid-sealed relationship with the said plate and being downwardly and outwardly directed in relation thereto to form a downwardly open suction chamber 15b arranged in fluid flow connection with a source of reduced pressure via an outlet opening 15c in the plate 13 and a pressure hose 15d coupled thereto.

The secondary sealing means 16 comprises a pad 16a secured to the face of the rigid plate 13 at the periphery thereof, the pad being of an air impermeable, resiliently compressible material and extending continuously about the whole of the periphery of the plate. The axial extent of the secondary sealing means 16 is less than the corresponding dimension of the primary such means 15, and the downwardly-open, annular suction chamber 16b defined by such secondary sealing means is arranged in fluid-flow connection with a source of reduced pressure via an outlet opening 16c in the plate 13 and a pressure hose 16d coupled thereto.

Location guides 17 are provided at the periphery of the plate 13, such guides 17 extending axially of the lifting device 11 beyond the sealing face 16a' of the secondary sealing means 16 and serving to centre the device 11 with respect to the drum 12 before the engagement of the primary sealing means therewith.

In use, the lifting device 11 is positioned above the upper end of the drum 12 and is lowered into engagement therewith. the device being supported upon the drum via the depending skirt 15a, the annular pad 16a which constitutes the secondary sealing means being in spaced relationship with respect to the rim 12a of the drum 12.

Application of a reduced pressure to the space 15b within the depending skirt 15a has the effect of drawing the lifting device 11 downwards towards the end of the drum, so that the annular pad 16a of the secondary sealing means moves into engagement with the rim 12a of the drum. The pressure contact of the pad 16a with the rim 12a ensuing from the effect of the reduced pressure within the skirt 15a will give an essentially fluid-tight seal between the pad 16a and rim 12a notwithstanding moderate distortion or damage to such rim. Reduction of air pressure within the annular space 16b between the annular pad 16a and depending skirt 15a will urge the annular pad 16a further into contact with the rim thereby to improve the seal thereat.The air pressure within the primary and secondary suction pads is now reduced to a level appropriate to support the weight of the drum, and the same can then be lifted.

Release of the lifting device from the drum is effected simply by venting the suction pads to atmosphere whereupon the annular pad and the skirt separate in succession from the end of the drum.

In the embodiment described and illustrated the two suction chambers have respective pressure hoses connecting the same with the individual sources of low pressure, the secondary suction chamber being connected in fluid flow relationship with its respective source of low pressure in pressure sequence relative to the primary suction chamber, via suitable control means.

Alternatively, the secondary chamber may be connected in fluid flow relationship with its respective source of low pressure whilst the pressure within the primary chamber is being progressively reduced.

The invention is however, not restricted to the use of separate sources of low pressure, since a single, common source can be utilised although in these circumstances a valving arrangement is provided whereby the secondary suction chamber is isolated from the source until such time as the pad relating thereto is in sealed relationship with the rim.

Whilst the invention is described in context of a lifting device for engagement with the rim of a drum, it is by no means essential that the secondary suction pad cooperate with such rim, and arrangements are envisaged wherein the secondary suction pad engages a surface of the drum.

When handling empty drums it may be found sufficient to rely upon the primary suction pad.

WHAT WE CLAIM IS: 1. A lifting device for use in lifting drums or the like which comprises a primary suction pad for engagement with the surface of the drum, a secondary suction pad in axi-parallel disposition relative to said primary suction pad likewise for engagement with the surface of the drum, the secondary suction pad having an area of intended engagement with the drum substantially greater than that of the primary suction pad, and pneumatic means co-operable with the said primary and secondary suction pads and adapted sequentially to apply a reduced air pressure independently to said primary and thence to said secondary suction pad.

2. A lifting device as claimed in claim 1, wherein a plurality of axi-parallel primary

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (11)

**WARNING** start of CLMS field may overlap end of DESC **. Referring now to the drawing, a lifting device 11 for use in lifting a drum 12 and attachable thereto by pneumatic means comprises a rigid plate 13 substantially co-extensive with the end of the drum 12, a lifting arm 14 secured to the said plate at one face thereof, and primary and secondary sealing means 15, 16, respectively, at the other face of the plate. The primary sealing means 15 comprises a flexible skirt lSa depending from the plate at a position centrally thereof, the upper end of the skirt being in fluid-sealed relationship with the said plate and being downwardly and outwardly directed in relation thereto to form a downwardly open suction chamber 15b arranged in fluid flow connection with a source of reduced pressure via an outlet opening 15c in the plate 13 and a pressure hose 15d coupled thereto. The secondary sealing means 16 comprises a pad 16a secured to the face of the rigid plate 13 at the periphery thereof, the pad being of an air impermeable, resiliently compressible material and extending continuously about the whole of the periphery of the plate. The axial extent of the secondary sealing means 16 is less than the corresponding dimension of the primary such means 15, and the downwardly-open, annular suction chamber 16b defined by such secondary sealing means is arranged in fluid-flow connection with a source of reduced pressure via an outlet opening 16c in the plate 13 and a pressure hose 16d coupled thereto. Location guides 17 are provided at the periphery of the plate 13, such guides 17 extending axially of the lifting device 11 beyond the sealing face 16a' of the secondary sealing means 16 and serving to centre the device 11 with respect to the drum 12 before the engagement of the primary sealing means therewith. In use, the lifting device 11 is positioned above the upper end of the drum 12 and is lowered into engagement therewith. the device being supported upon the drum via the depending skirt 15a, the annular pad 16a which constitutes the secondary sealing means being in spaced relationship with respect to the rim 12a of the drum 12. Application of a reduced pressure to the space 15b within the depending skirt 15a has the effect of drawing the lifting device 11 downwards towards the end of the drum, so that the annular pad 16a of the secondary sealing means moves into engagement with the rim 12a of the drum. The pressure contact of the pad 16a with the rim 12a ensuing from the effect of the reduced pressure within the skirt 15a will give an essentially fluid-tight seal between the pad 16a and rim 12a notwithstanding moderate distortion or damage to such rim. Reduction of air pressure within the annular space 16b between the annular pad 16a and depending skirt 15a will urge the annular pad 16a further into contact with the rim thereby to improve the seal thereat.The air pressure within the primary and secondary suction pads is now reduced to a level appropriate to support the weight of the drum, and the same can then be lifted. Release of the lifting device from the drum is effected simply by venting the suction pads to atmosphere whereupon the annular pad and the skirt separate in succession from the end of the drum. In the embodiment described and illustrated the two suction chambers have respective pressure hoses connecting the same with the individual sources of low pressure, the secondary suction chamber being connected in fluid flow relationship with its respective source of low pressure in pressure sequence relative to the primary suction chamber, via suitable control means. Alternatively, the secondary chamber may be connected in fluid flow relationship with its respective source of low pressure whilst the pressure within the primary chamber is being progressively reduced. The invention is however, not restricted to the use of separate sources of low pressure, since a single, common source can be utilised although in these circumstances a valving arrangement is provided whereby the secondary suction chamber is isolated from the source until such time as the pad relating thereto is in sealed relationship with the rim. Whilst the invention is described in context of a lifting device for engagement with the rim of a drum, it is by no means essential that the secondary suction pad cooperate with such rim, and arrangements are envisaged wherein the secondary suction pad engages a surface of the drum. When handling empty drums it may be found sufficient to rely upon the primary suction pad. WHAT WE CLAIM IS:

1. A lifting device for use in lifting drums or the like which comprises a primary suction pad for engagement with the surface of the drum, a secondary suction pad in axi-parallel disposition relative to said primary suction pad likewise for engagement with the surface of the drum, the secondary suction pad having an area of intended engagement with the drum substantially greater than that of the primary suction pad, and pneumatic means co-operable with the said primary and secondary suction pads and adapted sequentially to apply a reduced air pressure independently to said primary and thence to said secondary suction pad.

2. A lifting device as claimed in claim 1, wherein a plurality of axi-parallel primary

suction pads is provided, each engageable with a respective surface area of the drum.

3. A lifting device as claimed in claim 1 or 2, wherein the or each primary suction pad comprises a depending skirt engageable with the drum in advance of the engagement of the secondary suction pad with the drum.

4. A lifting device as claimed in claim 1 or in claim 3, when dependent on claim 1.

wherein the primary and secondary suction pads are arranged in coaxial relationship.

5. A lifting device as claimed in any one of claims 1 to 4, wherein the secondary suction pad is dimensioned for engagement with the rim of the drum.

6. A lifting device as claimed in any one of claims 1 to 5, further including a rigid plate supporting the primary and secondary suction pads at its underside, there being a lifting arm connected with such plate at that side thereof remote from the said pads, the said plate being adapted to allow of the independent connection of the pads to a source or to respective sources of low pressure.

7. A lifting device as claimed in claim 6, further including a locator or locators cooperable with the drum for centralising the device relative thereto, the said locator or locators being of such dimension in the axial direction of the device to extend beyond the lower ends of the pads.

8. A lifting device as claimed in any one of claims 1 to 7, wherein a common source of reduced pressure is provided for the suction pads.

9. A lifting device as claimed in claim 8, wherein a valve means is provided for isolating such source from the secondary suction pads during engagement of the primary suction pad or pads with the drum and initial application of reduced air pressure to said primary suction pad.

10. A lifting device substantially as hereinbefore described with reference to and as illustrated in the various figures of the accompanying drawings.

11. The method of lifting a drum which comprises the engagement with the drum of a lifting device in accordance with any one of claims 1 to 10, and raising such drum via the lifting device.