GB2163859A - Weight testing apparatus - Google Patents

Abstract

Weight testing apparatus comprises a liquid-impervious bar 12, an outlet 18 at the bottom end of the bag which can be opened and closed, an inlet at the top end of the bag, means for suspending the bag from a support and load supporting means at the bottom end of the bag for suspending a load therefrom. A substantially rigid sleeve 66 is provided at the bottom end of the bag and the load supporting means extends through the sleeve in fluid-sealed relationship therewith. <IMAGE>

Description

SPECIFICATION Weight testing apparatus The present invention relates to weight testing apparatus and particularly, but not exclusively, to apparatus for testing the lifting strength of hoists, winchs, cranes and similar lifting devices.

In our British Patent No. 2047414 we have described apparatus comprising a liquid impervious bag which is surrounded by a plurality of elongate load bearing elements which carry the bag and support it against the burst forces exerted by the weight of liquid contained in the bag. The elongate load bearing elements extend upwardly beyond the open top of the bag to a boss or frame which has means to suspend the bag from a support. A load supporting cable extends through the bag from top to bottom enabling a load to be supported on the cable between the bag without adding any further load to the bag or to the load bearing elements.

The load supporting cable is usually in the form of a wire rope and extends through a plastics sleeve which is joined in a fluid sealed relationship to the bottom of the bag and which extends upwardly to a point adjacent the upper end of the bag. This arrangement has several disadvantages.

The wire rope may fray and then snag on and tear the plastics sleeve so that there is a risk of leakage of fluid out of the bag. A damaged sleeve is also difficult to repair. When the bag is being filled the sleeve wraps around the wire rope rendering the two relatively immovable. This puts a substantial strain on the bag which tends to stretch during filling. It is desirable that the bag is able to be folded or rolled up for storage and the flexible nature of the sleeve allows this to be done. However it also necessitates welding of the sleeve to the bottom of the bag thus complicating the manufacture of the bag and creating an area of potential weakness. A further disadvantage of the sleeve is that it limits the size of the end fitting at the bottom of the bag which can be used.

It is an object of the present invention to provide a through connection for a bag of the type described above to another depending load which overcomes the disadvantages of these known arrangements.

According to the present invention we provide weight testing apparatus comprising a liquid impervious bag, a liquid outlet at the bottom end of the bag which can be opened and closed, an inlet at the top end of the bag, means for suspending the bag from a support and load supporting means at the bottom end of the bag for suspending a load therefrom characterised in that a substantially rigid sleeve is provided at the bottom end of the bag and the load supporting means extends through the sleeve in fluid sealed relationship therewith.

The present invention has the advantage of obviating the need for a flexible tube extending through the bag with all the attendant disadvantages. The sleeve is small enough to permit the bag to be folded and its rigid nature obviates the need for welding to the material of the bag.

Preferably, the load supporting means is moveable lengthwise relative to the sleeve. This feature means that, advantageously, movement is permitted between the load supporting means and the sleeve to allow stretching of the bag during filling with fluid.

In a particular embodiment, the load supporting means comprises a load supporting bar extending through the sleeve so as to have one end located within the bag and the other end located outside and beneath the bag. The load supporting bar may comprise two eye-bolts one of which is threadedly engageable with the other.

A plurality of O-ring seals may be provided within the sleeve to form a fluid tight seal against the load supporting means. The sleeve may include an external collar which is clamped in a fluid sealed relationship to the bag.

A particular embodiment of the present invention will now be described, by way of example, with reference to the accompanying drawings in which: Figure 1 is an elevation of weight testing apparatus according to the present invention; Figure 2 is a plan view of the apparatus shown in Figure 1; Figure 3 is a vertical section through the apparatus of Figures 1 and 2; Figure 4 is a side view partially in cross-section on an enlarged scale of the bottom of the bag of Figures 1-3.

Referring to Figures 1-3, weight testing apparatus according to the present invention is indicated generally at 10 and comprises a flexible bag 12 which is generally pear shaped and which is made from a fluid impervious material such as reinforced polyvinylchloride or neoprene. The bag 12 is suspended from a support shackle 14 and is open topped at 16 and has an outlet 18 at the bottom leading to a flexible outlet tube 20.

The bag 12 is supported by a plurality of supporting straps 22 made of webbing or other similar material. The straps 22 extend from bottom gathering straps, indicated generally at 24 consisting of a system of interwoven straps and buckles, upwardly through sleeves 26 which are attached to the outer surface of the bag 12 and which position the straps 22 in a uniformly spaced manner around the bag 12. Each strap 22 terminates in an eye 28 which is attached to a shackle 30 which in turn is attached to a round sling 32 of polyester covered with a PVC sleeve 34. Each sling 32 is attached to a shac kle 36 which is connected to one of two subsidiary linkage rings 38 and 40 both linked to a master linkage ring 42 connected to the support shackle 14 of the piece of apparatus to be weight tested.

There are three of the straps 22 connected to each of the shackles 30. There are also rubber holding straps 44 fastened to the uppermost part of the bag 12 and attached to the shackles 30. The purpose of the holding straps 44 is to hold up the top of the bag 12, especially during filling of the bag 12 with fluid. There is a generally L-shaped filling inlet 46 secured to the top of the bag 12 to which is attached a length of hose 48. The filling inlet 46 is positioned above the level, indicated by the dotted line 50 in Figure 1, to which the bag 12 is filled with fluid during testing.

The outlet hose 20 is supported by a pulley mechanism of any suitable type indicated schematically at 52 connected to the master linkage ring 42 and is raised and lowered by means of a lanyard 54. Figures 1-3 show the outlet tube 20 supported in an uppermost position as would be used during testing with the free end of the outlet tube 20 well clear of the fluid level 50.

Referring in particular to Figure 3, a load carrying cable 56 extends through the bag 12 from top to bottom. The upper end of the cable has an eye 58 which is looped around a linkage ring 59 which is connected to a shackle 60 connected to the master linkage ring 42. The lower end of the cable 56 is provided with an eye 61 which is looped around a linkage ring 62 which is secured to a shackle 63 connected to a through connector, indicated generally at 64, for enabling a second bag or other load to be suspended below the first bag 12. The through connector 64 is shown in elevation in Figure 3 and comprises a rigid metal sleeve 66 through which extend two eye-bolts 68 and 70.

Referring to Figure 4 which shows the through connector 64 in more detail, the sleeve 66 is mounted in an aperture in the bottom of the bag 12. The sleeve comprises an integral annular collar 72 which overlies a steel fastening ring 74. The collar 72, the ring 74 and the bag 12 each have a plurality of holes which are aligned to enable a plurality of bolts 76 to be passed therethrough so as to secure the sleeve 66 in the bottom of the bag 12. The collar 72 is continuous thereby preventing any fluid flow out of the bag 12 around the outside of the sleeve 66.

The eye-bolt 68 has a threaded stem 78 engaged in a threaded bore 80 of the eye-bolt 70. Four O- ring seals 82, 84, 86 and 88 are partially housed in grooves on the interior face of the sleeve 66 and serve to maintain a fluid tight seal between the eye-bolts 68 and 70 and the sleeve 66. The seals 82, 84, 86 and 88 permit a degree of sliding movement of the eye-bolts 68 and 70 relative to the sleeve 66.

In practice, the bag 12 is folded flat for storage with the through connector in place. To assemble the weight testing apparatus, the bag 12 is unfolded and the linkage ring 62 of the load carrying cable 56 is shackled to the eye-bolt 68 using the shackle 63. The linkage ring 59 at the other end of the cable 56 is then shackled to the master linkage ring 42 using the shackle 60. The master linkage ring of a second similar empty bag may then be connected to the eye-bolt 70 using a shackle. If the second bag is provided with a through connector 64 then a third bag may be attached to the lowermost eye-bolt of the second bag and so on.

When the desired number of bags 12 have been interconnected, the master linkage 42 of the first bag 12 is attached to the shackle 14 of the piece of apparatus to be tested. A shackle 14 is connected to means for sensing the load applied to the shackle 14, for example, by connection to a dynamometer. The bags are then raised so that the lowermost bag is clear of the ground. Each bag 12 is filled with fluid, usually water, through the hose 48 attached to the inlet tube 46. During filling, the outlet hose 20 is maintained in its uppermost position as shown in Figures 1-3. The holding straps 44 serve to hold up the upper rim of the bag 12 and these are left relatively slack during filling to ensure that no load is transferred to them.

Stretching of the bag 12 during filling is accommodated by movement of the sleeve 66 relative to the eye-bolts 68 and 70 which movement is permitted by the seals 82, 84, 86 and 88.

It can be seen that the entire weight of the lower bag or bags is transmitted to the master linkage ring 42 by the load supporting cable 56 so that no additional strain is placed on the bag 12 by the lower bag or bags. If three or more bags are employed, their weight is borne entirely by the load supporting cables extending through the bags and does not add any additional load to the bags themselves or to their load supporting straps.

When load testing is finished and it is desired to dismantle the weight testing apparatus, each bag 12 is emptied of fluid by relaxing the lanyard 54 to allow the outlet tube 16 of each bag to fall away from the upper end of the bag 12 so that the bag is then emptied under gravity through the outlet 18.

When the bags 12 have been emptied, the master linkage ring 42 of the first bag 12 is detached from the support shackle 14 and the bags 12 are disconnected from one another. The load supporting cable 56 is removed from each bag 12 which is then folded for storage.

It will be understood that depending on the amount of room available and the size of the apparatus being weight tested, as many bags as desired may be suspended in a vertical column using the present invention. The particular shape and construction of the bag itself, the supporting straps and the filling and emptying means may be varied according to requirements.

Claims (9)

1. Weight testing apparatus comprising a liquid impervious bag, a liquid outlet at the bottom end of the bag which can be opened and closed, an inlet at the top end of the bag, means for suspending the bag from a support and load supporting means at the bottom end of the bag for suspending a load therefrom characterised in that a substantially rigid sleeve is provided at the bottom end of the bag and the load supporting means extends through the sleeve in fluid sealed relationship therewith.

2. Weight testing apparatus according to claim 1 or claim 2 characterised in that the load supporting means is moveable lengthwise relative to the sleeve.

3. Weight testing apparatus according to claim 1 characterised in that the load supporting means comprises a load supporting bar extending through the sleeve so as to have one end located within the bag and the other end located outside and beneath the bag.

4. Weight testing apparatus according to any preceding claim characterised in that the load supporting bar comprises two eye-bolts one of which is threadedly engageable with the other.

5. Weight testing apparatus according to any preceding claim characterised in that a plurality of O-ring seals are provided within the sleeve to form a fluid tight seal against the load supporting means.

6. Weight testing apparatus according to any preceding claim characterised in that the sleeve includes an external collar which is clamped in a fluid sealed relationship to the bag.

7. Weight testing apparatus according to any preceding claim wherein the collar is made of metal.

8. Weight testing apparatus according to any of claims 1-6 wherein the collar is made of a plastics material.

9. Weight testing apparatus substantially as herein described and with reference to the accompanying drawings.