GB2408038A

GB2408038A - Pivot assembly for a davit or crane

Info

Publication number: GB2408038A
Application number: GB0326279A
Authority: GB
Inventors: Paul Radmall
Original assignee: Reid Lifting Ltd
Current assignee: Reid Lifting Ltd
Priority date: 2003-11-11
Filing date: 2003-11-11
Publication date: 2005-05-18
Anticipated expiration: 2023-11-11
Also published as: GB2408038B; GB0326279D0

Abstract

A pivot assembly for a davit or crane comprises coaxially aligned first and second components 34, 20 constrained within an outer tubular housing 36 to engage one another axially and to rotate relative to one another about said axis. A fastener 44 extends laterally of the housing 36 and the first component 34 to secure both together and to engage the second component 20 to restrain it axially. The pivot assembly may be upright with the second component 20 fixed beneath the first component 34 and the tubular housing 36 and the first component 34 may rotate together about the upright axis. The distal end of the second component 20 may have a spherical bearing surface 10 which extends into a recess within the first component 34 to engage the bearing surface at the base of the recess. The lateral fastener 44 may extend through the first component 34 and a peripheral portion 18 of the recess in the second component 20 to prevent axial separation. A third component 12 may be provided which is axially spaced from the first component 34 and is fixed within the housing and is rotatable relative to the second component 20.

Description

PIVOT ASSEMBLY

This invention relates to a pivot assembly, in particular a pivot assembly for incorporation in an upright structure, such as a davit or crane, to allow the structure to pivot about an upright axis.

A pivot assembly according to the invention comprises coaxially aligned first and second components constrained within an outer tubular housing to engage one another axially and to rotate relative to one another about said axis. Preferably, a fastener extends laterally of the housing and the first component to secure both together, and to engage the second component to restrain it axially, whilst still accommodating rotation of the housing and first component together relative to said second component.

Said pivot assembly is preferably adapted for use with said axis upright. The second component is preferably fixed beneath the first component, and the tubular housing and first component rotate together about said upright axis. The tubular housing may, for example, comprise part of a davit assembly which carries a downward load in use, the first and second components comprising an axially loaded bearing.

In a preferred embodiment, the distal end of the second component has a spherical bearing surface which extends into a recess within the first component to engage a bearing surface on the first component at the base of the recess. The lateral fastener extends through the first component and a peripheral portion of the recess in the second component so as to cooperate with an annular groove in the second component, thereby to prevent axial separation of the first and second components within the housing. Preferably, a pair of fasteners extend laterally, one each side of the second component, and the fasteners cooperate with the annular groove either side of the axis.

Preferably, the bearing surface of the first component is flat, and a bush is provided between the first and second components within the recess to provide lateral support.

Preferably, the first component has an external circumferential profile which at least partially conforms with the internal profile of the housing so that the two are angularly keyed together, but can slide axially relative to one another during assembly, before the lateral fastener or fasteners are inserted.

In a preferred embodiment of the invention, a third component is provided which is axially spaced from the first component, and, like the first component, is fixed within said housing and is rotatable relative to said second component. The third component preferably comprises a cylindrical bearing which gives lateral support to the housing.

The invention will now be described by way of example with reference to the accompanying drawings in which: Figure I is an isometric view of a davit assembly incorporating a pivot assembly according to the invention, and Figure 2 is an isometric exploded view of the davit assembly of Figure 1.

The illustrated davit assembly consists of an upright column 36 of box section which is connected at its upper end to a laterally extending beam 35, also of box section, with a pulley 32 at each end. The column 36 and beam 35 preferably comprise extended metal components. The column 36 is connected to an intermediate point in the length of the beam 35 towards one end so that a short length of the beam 35 overhangs on one side and a longer length of the beam overhangs on the other side. A winch assembly 38 is connected to the column 36 beneath the shorter arm of the beam 35, and a cable (not shown) extends from the winch assembly around the pulley 32 above it and along the length of the beam 35 and over the second pulley 32 to a hook or other fastener at its lower end which is adapted to connect to a load to be lifted.

The column 36 is supported in the upright position by a pivotal assembly, shown in Figure 2, which allows the column to pivot about the upright axis. The pivot assembly consists of an upright pillar 20 which is secured at its base and extends upwards within the lower end of the column 36 to engage a bearing block 34. A steel ball 10 is fixed to the tip of the pillar, for example, by swaying the metal of the pillar around the ball. The tip of the pillar extends into a recess formed in the bearing block 34, and engages a flat bearing surface in the base of the recess. A bush 22, such as a Glacier DX bush, is also provided within the recess in the bearing block 34 and cooperates with the pillar below a groove 18 to provide lateral support for the upper end of the pillar 20. The bearing block 34 is secured within the column 36 by a pair of fasteners 44.

Another bearing block 12, for example, a Delrin block, is located on the pillar 20 so as to be rotatable relative to the pillar and is received within the lower end of the column 36 and secured to it by fasteners 40. Therefore, the two bearing blocks 34, 12 support the column 36 upright on the pillar 20 so that it can pivot about the central upright axis of the pillar.

The bolts 44 which secure the upper bearing block 34 within the column 36, extend through the side walls of the column 36 and through holes 16 in the bearing block, from one side of the assembly to the other, and are held in place by nuts 23. The bearing block 34 has an external profile that closely matches the internal profile of the column 36 so that it can be easily guided into position with the holes 16 in alignment to receive the bolts 44.

The close fit also provides a more rigid assembly. The holes 16 through the bearing block 34 break into the internal recess at axial positions aligned with the annular groove 18 adjacent the distal end of the pillar, and when the bolts 44 are inserted, they engage the groove 18 one each side of the pillar so as to prevent the column 36 from being lifted axially from the pillar. The bolts 44 therefore perform a dual function of securing the bearing block 34 within the column 36, and in retaining the column 36 axially on the pillar.

Claims

Claims 1 A pivot assembly comprising coaxia]ly aligned first and second

components constrained within an outer tubular housing to engage one another axially and to rotate relative to one another about said axis.
2. An assembly as claimed m claim 1 in which a fastener extends laterally of the housing and the first component to secure both together, and to engage the secontl component to restrain it axially, whilst still accommodating rotation of the housing and first component together relative to said second component.
3 An assembly as claimed In claim 2 for use with said axis upright.
4. An assembly as claimed in clang 3 m which the second component is fixed beneath the first component, and the tubular housing anti first component rotate together about said upright axis.
5. An assembly as claimed m claim 4 m whelk the tubular housing cormprscs part of a Davy assembly which carries a downward load in use, the first and second components comprising an axially loaded bearing.
6. An assembly as claimed in any one of the preceding claims in which the distal end of the second component has a spherical bearing surface which extends into a recess within the first component to engage a bearing surface on the first component at the base ol the recess.
7. An assembly as claimed In any one of claim 2 to 6 Itl which the lateral fastener extends through the first component and a peripheral portion of the recess in the second component so as to cooperate with an annular groove in the second component, thereby to prevent axial separation of the first and second components within the housing.
8. An assembly as claimed in claim 7 In which a pair of fasteners extend laterally, one on each side of the second component, and the fasteners cooperate with the annular groove either side of the axis.
). As assembly as claimed In claim 6, car claim 7 or 8 dependent on claim 6, in which the bearing surface of the first component is flat, and a bush is provided between the first and second components within the recess to provide lateral support.
10. An assembly as claimed in any one of' the claims 2 to 9 as dependent on claim 2 In which the first component has an external circumf'erental profile which at least partially conforms with the Internal profile of the housing so that the two are angularly keyed together, but can slide axially relative to one another durmg assembly, before the lateral fastener or fasteners are inserted.
11. An assembly as claimed In any one of the preceding claims comprising a third component which is axially spaced from the first component, and, like the first component Is fixed within said housing and Is rotatable relative to said second component
12. An assembly as claimed in claim 11 m which the third component preferably comprises a cylindrical bearing which gives lateral support to the housing.

13 A pivot assembly substantially as herein described with rel'erence to the accompanying drawings.