GB2198109A

GB2198109A - Lifting device

Info

Publication number: GB2198109A
Application number: GB08628487A
Authority: GB
Inventors: Ola Kristoffer Dalsbo
Original assignee: Individual
Current assignee: Individual
Priority date: 1985-06-06
Filing date: 1986-11-28
Publication date: 1988-06-08
Anticipated expiration: 2006-11-28
Also published as: NO162955C; DK266286D0; NO852275L; GB8628487D0; GB2198109B; DK266286A; SE8602554L; SE8602554D0; NO162955B

Abstract

A crane has a generally vertical, pivoting crane shaft (17) which supports a crane boom (23, 24) which can be raised and lowered by means of a hydraulic cylinder (28). The crane shaft (17) is supported at its lower end by a pivoting arm (20) which is actuated by a power unit (31), the crane shaft (17) being capable of being turned about its own longitudinal axis. Changes in the angle of the boom are reduced by the axis of the crane shaft (17) being tilted at a narrow angle by the supporting arm (20). The rotating movement of the crane shaft (17) is controlled by a link arm (37) which is firmly attached at one end and joined to an arm (36) which protrudes from the side of the crane shaft (17). <IMAGE>

Description

LIFTING DEVICE The invention concerns a lifting device, in particular a crane, of the type described in the introduction to claim 1.

A lifting device of this type can be used for the handling of goods on wharves, onboard vessels or offshore platforms etc. It can also be used on excavators, industrial processing equipment (robots) and other lifting mechanisms. Wellknown small and medium-sized cranes that are available for boats consist of a diagonal boom which can be raised and lowered by cables attached to the free end of the boom. Such cranes require a number of winches making them expensive and complicated. Furthermore, they are plagued by wear and malfunctions. When in use there will be a good deal of slack in the cables whilst the boom pivots. Such equipment also requires a good deal of space.

Another type of crane exists where the boom pivots by means of a hydraulic cylinder. This type of pivoting system unfortunately has a restricted turning angle, usually under 1800. Another system that is known uses a cogged bar to pivot the boom system. This system is complicated to mount and is also exposed to corrosion.

From Norwegian patent specification no. 149 990 it is known a crane boom, which pivots on a vertical axis by means of a hydraulic cylinder. As this crane system is constructed for launching rescue vessels, it is not feasible for use in the handling of goods, or other more general crane applications on vessels or wharves.

The main object of the present invention is to create a simple crane that is not expensive and that is suited for the applications just noted; furthermore , the crane should be compact and reliable. Another object is to create a crane that is able to pivot 1800, where the pivoting motion should be at an approximately even velocity, the torque should be constant and there should be a high degree of accuracy.

According to the invention the main object can be realized by a crane constructed in accordance with the characterizing part of claim 1.

Such a crane can be made very simple and reasonably priced. At the same time, its operative characteristics are satisfactory. Such a crane enables the boom to pivot safely and accurately with minimal power consumption. If this crane is constructed from components which can withstand climatic forces such as icing, corrosion etc., the crane will be manufactured and operated at a reasonable price.

Other advantageous aspects of this invention are described in the subclaims 2-4.

The invention will in the following be explained by means of the drawings where: fig. 1 shows a perspective outline of the crane according to the invention, whilst fig. 2 shows the lower supporting bracket from directly overhead, as well as different pivoting positions for the crane's vertical shaft.

In fig. 1 the crane has a vertical brace 11 which has a hollow square profile that inclines diagonally upwards and forwards from a base which consists of two arms , 12 and 13, respectively, which extend outwards on each side of the front edge of the vertical brace, and a central support arm 14, all of these having hollow square profiles.

At the upper end of the vertical brace 11 there is a protruding bracket 15, which extends in the same direction as the cestral support arm 14, and supports the upper journal bearing 16 for a vertical crane shaft 17.

Against the free end of the central arm 14 on a protruding pivoting trunnion 18 with a bushing 19 there is located a supporting arm 20 on which the lower end of the crane shaft 17 pivots. This supporting arm 20 is also able to pivot the lower end of the crane shaft 17 at a certain angle to all sides of the central position as indicated in fig. 2 and described below. The journal bearing 16 has been constructed so that it can adjust to a certain degree of movement in the longitudinal axis of the crane shaft 17.

At the upper end of the crane shaft 17 there is a supporting bracket 21 with a bearing bolt 22 attached to an inner crane boom 23 which engages an outer crane boom 24 telescopically in a manner already known. At the free end of the outer crane boom 24 there is a pulley 25 for a wire 26 from a winch 27 attached to the upper surface of the inner crane boom 23.

The inner crane boom 23 and thereby the outer crane boom 24 can be raised or lowered on the bearing bolt 22 by means of a hydraulic cylinder 28 which is located in a known manner between a bracket 29 at the lower end of the crane shaft 17 and a bracket 30 which protrudes down into the interior of the inner crane boom 23.

The supporting arm 20 can be pivoted by means of a hydraulic cylinder 31 att-ached to one end of the central support arm 14 and extends between a bracket 32 fixed to one end of the side arm 12 by means of a brace plate 33 and an arm 34 connected to the bushing 19 so that the arm 34 extends at about a right angle from the supporting arm 20.

The top end of the trunnion 18 is located into a lower supporting bracket 35, which extends in an L-shape . .

from the end of the central arm 14 in towards the crane shaft 17.

The free end of the lower supporting bracket 35 and a lug 36, which protrudes on the side of the lower end of the crane shaft 17 are joined by a link arm 37. By means of this link arm 37 the crane shaft 17 is forced to rotate about its longitudinal axis when the supporting arm 20 pivots between its outer positions. This is described in more detail below.

Fig. 2 shows the geometry of the movement of the lower end of the crane shaft 17. The solid lines show the lower supporting bracket 35 together with the link arm 37 which reaches the lug 36 on the lower end of the crane shaft 17. The direction of the crane boom 23 in the central position for the crane shaft 17 is indicated by an arrow A. THe figure also shows the corresponding position of the pivot arm 34.

The broken lines indicate the two outer positions for the pivot arm 34 as it is moved by the, hydraulic cylinder 31 (fig. 1). In one position, the pivot arm is indicated by 34', whilst 34' indicates the other position. The corresponding outer positions for the supporting arm 20 are indicated by 20' and 20''. The corresponding directions of the crane boom are denoted by arrows B and C respectively. In the example, arrows B and C point towards each other. this indicates that the crane boom has an angle of pivoting of 1800 The invention enables the operational radius of 0 the crane boom to be extended upto 200 by using a hydraulic cylinder 31 with a relatively short stroke length. The components in the crane in the example can be manufactured without complex machinery and be surface-treated so as to be corrosion-resistant given hostile environments and other forces. Apart from the journal bearing 16, which can easily be sealed, the other parts can be made very simply and robustly with taps and coatings which are resistant to external forces.

A crane of this type can be used for different purposes on boats and platforms, in docks and at fish-farming plants. The equipment required to control the hydraulic cylinders 28 and 31 and operate the winch 27 is not described in more detail as conventional technology can be employed. The crane shown in the example can be mounted to a load-bearing foundation by mounting the arms 12-14.

The crane shaft L7 can also be inclined 100 in a mid-position. The cylinder 31 and its associated arms can also be placed at the upper end of the crane shaft 17. In this case, there must be a fixed bearing below.

In an alternative embodiment the crane shaft is attached to a pivoting support which extends along the length of the shaft and is located onto the crane's support at the top and bottom. If the radial distance between the shaft bearings and the pivoting axis of the movable support differs, one of the shaft bearings will move in a larger arc than the other.

Claims

Claims:

1. Lifting device, in particular a crane, with a shaft which supports a crane boom which preferabLy can be raised and lowered by means of a hydraulic cylinder located between the lifting boom and the shaft, where the shaft can pivot because of the means of attachment at the top and bottom, c h a r a c t e r i z e d in that the shaft at the top and/or bottom is located on an arm which by means of a power unit can pivot horizontally so that the point of location with the end of the lifting boom will pivot in a horizontal arc, and that the shaft's pivoting axis describes a small angle of about 100 from the vertical at the other end, and in addition, that the shaft is linked outside its pivoting axis by an attachment on the support of the lifting device.

2. Lifting device according to claim 1, c h a r a c t e r i z e d in that it includes a pivoting arm (20) at the lower edge of the shaft which is attached to the support of the lifting device and can be pivoted by a hydraulic cylinder

3. Lifting device according to claim 1 or 2, c h a r a c t e r i z e d in that the crane shaft has a rotating movement about its own longitudinal axis that is controlled by a link arm that is attached to the support of the lifting device at one end and a lug which protrudes from the side of the crane shaft at its other end.

4. Lifting device according to claim 1 or 2, c h a r a c t e r i z e d in that the crane shaft at its upper end is located in a bearing which allows a certain degree of tilt in the axis of the crane shaft which passes through the bearing.

5. A lifting device substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.