GB2105679A - Improvements relating to cranes - Google Patents

Abstract

A crane comprises a post (11), a triangular link member (15) pivotally connected to the post at one of its corners (17) and pivotally connected to a jib (12) at another of its corners (18). A ram (14) is pivotally connected (16, 16a) between the post and the jib to cause the jib to be moved angularly, in use. At the third corner of the link member (15) a removable lock pin (19) can be fitted so that the link member moves with the jib (12) as the jib is retracted by the ram to its lowermost operating position, as shown. Thereafter removal of the pin (19) from the third corner allows the jib (12) to be pivotted relative to the link member (15) so that it assumes a parking position substantially parallel to the post (11). The pin (19) can then be passed through aligned holes (20) in the link member (15) and jib (12) to lock the jib to the link member. <IMAGE>

Description

SPECIFICATION Improvements relating to cranes This invention relates generally to cranes and in paricular to cranes having a relatively small lifting capacity, i.e. of the order of 1 ton (approximately 101 6kg). Such cranes can be in the form of a floor crane, which consists of a bedframe on which a crane mechanism is mounted, the bedframe having wheels and castors to give mobility to the crane. An alternative form is a so-called hoist, which consists of a floor socket and a vertical swivel pivot on which the crane mechanism is mounted, enabling it to pivot about a fixed point.

As used herein, the expression "crane" includes both a floor crane and a hoist.

With conventional cranes of this type, an upstanding king post has a jib directly pivoted to the top thereof, the jib being telescopic and being moved angularly about its pivot on the king post by a hydraulic ram pivoted at one end to the jib intermediate its ends and its other end to the bottom of the king post. Such a crane suffers from the disadvantage that by virtue of the jib being directly pivoted to the king post, the jib cannot be broughtto a parked position in which the crane occupies minimum space. In fact with such conventional cranes the jib lies at an appreciable acute angle to the vertical king post when it is in its parked position, and this outward projection of the jib is inconvenient both in use and in storage, as taking up otherwise usable space, and in packaging which becomes bulky and difficult.

Accordingly it is an object of this invention to provide a crane in which the disadvantage referred to is overcome or at least minimised.

According to the present invention a crane comprises an upstanding post, a jib, a ram pivotally connected at one of its ends to the jib and its other end to said post, to move the jib angularly, in use, as the ram is extended or retracted, a link member pivotally connected to said post and having the jib pivotally connected thereto, the jib being pivotable relative to said link member so that it can assume a parking position substantially parallel to said post.

The invention will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a front perspective view of a crane of the present invention, with a jib of the crane in a lowered but unparked position; Figure 2 is a rear perspective view of the crane, with the jib in raised position; Figure 3 is a side view of the crane, showing the jib in its parked position, with the bedframe of the crane not being shown; Figure 4 shows, in perspective, how three of the cranes of the present invention can be stacked once their respective jibs are in the parked position; and Figure 5 shows, in perspective, how two of the cranes can be packaged together.

Figures 1 and 2 show a floor crane constructed in accordance with the present invention.The complete crane comprises a bedframe 10 on which the crane mechanism (Figure 3) is mounted.

As can be seen from Figures 1 and 2 the bedframe is fitted with wheels 1 Oa and/or castors 1 Ob so that the floor crane is mobile.

In an alternative arrangement, the crane is in the form of a hoist comprising a floor socket and swivel pivot on which the crane mechanism shown in Figure 3 is mounted, so that it can pivot about a fixed point. Since the invention is not directly concerned with how the crane mechanism is mounted, it will be appreciated that the invention is equally applicable to floor cranes and hoists.

The crane mechanism shown in Figures 1 to 3 comprises an upstanding king post 1 1, a jib 12 having a hook 13 at one of its ends, a hydraulic cylinder ram 14, and a link member 1 5.

One end of the ram 14 is pivotally connected at 1 6 to the jib intermediate the ends thereof. The other end of the ram 14 is pivoted as at 1 6a to the bottom of the post 11.

The link member 1 5 is in the form of a Ushaped plate, with each of its sides being of substantially triangular form. At its lowermost corner the link member is pivotally connected by a pin 1 7 to the post 11 which is received between the sides of the link member. In a similar manner the end of the jib 12 remote from the hook 13 is received between the sides of the link member 1 5, and at a position slightly spaced from this other end of the jib 12, the jib is pivotally connected to a further corner of the link member 1 5 by a pivot pin 18, as clearly shown in Figures 1 and 2.

As shown in Figure 1 the jib is in its lowermost working position i.e. the position which it assumes when it it ready for operation but with the ram 1 4 fuily retracted. Between the sides of the link member 15 there is provided a welded plate (not shown) which acts as a stop if the jib is raised too much. The plate also serves to strengthen the link member. A lock pin 19 passes through aligned holes in the respective sides of the link member 1 5 at or adjacent the third and uppermost corner thereof in such a position that the outer surface of the jib 12 can bear against it. With this arrangement the end of the jib 12 remote from the hook 13 bears against the lock pin 1 9 due to the weight of the jib and/or load.Thus as the ram extends or retracts the jib 12 moves angularly with the link member 15, which itself moves angularly about its pivot 1 7 on the post 11.

Thus in normal use the jib 12 can move angularly between lower and upper operating positions in conventional manner. Moreover the jib can be, as shown, of telescopic form so that the hooked end of the jib can extend further outwardly. This allows varying weights of loads to be safely carried.

When the jib 12 reaches the position shown in Figure 1 , on full retraction of the ram 14, it is prevented from moving any further in a clockwise direction by virtue of its engagement against the lock pin 19. Thus in this position the crane mechanism shown suffers from the same disadvantage as conventional floor cranes, in that in its lowermost position the jib extends outwardly from the king post at an appreciable acute angle.

As explained this makes package and storage of the crane difficult and moreover represents a wastage of space, where the crane mechanism is part of a hoist mounted for example on a vehicle.

To overcome this disadvantage the crane of the present invention provides the link member 1 5.

Thus instead of the jib 12 being directed pivoted onto the post 11, it is now as described, pivotally connected to the link member which in turn is itself pivoted on the post 11. In addition, the lock pin 1 9 is removable from the aligned holes it occupies during angular movement of the jib, to allow release of the jib, so that it can be pivoted relative to the link member into a parked position shown in Figure 3, in which it is disposed substantially parallel to the post 11. The link member 1 5 is provided with aligned further holes 20 in its sides respectively at a position substantially between the pivot 18 and the holes occupied by the pin 1 9 during raising and lowering of the crane.When the jib is in its parked position, as shown in Figure 3, the lock pin 1 9 is then placed through the holes 20 and a corresponding hole through the jib to lock the jib to the link member 1 5. As can be seen clearly in Figure 3, the crane mechanism occupies a minimum space when the jib is parked.

Two advantages of this ability of the jib are shown in Figures 4 and 5.

In Figure 4 there is shown an arrangement where three floor cranes, constructed in accordance with the present invention, are stacked together, with the jib of each crane being in its parked position. It can immediately be appreciated that the arrangement of the jib parallel to the post 11 enables the stacking to be accomplished neatly and with much better use of available space than would be the case if the three cranes were to be stacked with their respective jibs extending outwardly at an angle to the king post, as would be the case with conventional cranes.

The Figures show a handle 21 for operating a hydraulic pump which causes extension of the ram. However with a crane in the form of a hoist, a battery and electric motor would be used to power the pump.

Figure 5 shows a further advantage of the present invention, namely how compact a pair of cranes can be packaged with the jib in its parked position.

As can be seen from Figure 5 it is possible for two bedframes to be packed one upon the other, with the upper frame being inverted, and a pair of crane mechanisms having their respective jibs in the parked position, to be stowed within the rectangular frame formed by the two bedframes.

Accordingly the pair of cranes are packaged in a knock-down form in minimum space, and for subsequent assembly only the mounting of a crime assembly on a bedframe is required for the crane to be usable.

In Figure 4 and in Figure 5, it is believed apparent how parking of the jib 12 parallel to the post 11 has made both storage and package of cranes significantly easier than with conventional cranes where the jib is not so parked.

Thus three distinct advantages are possessed by cranes of the present invention. Firstly for lorry mounted hoists, more space is available on the vehicle for goods, when the jib is parked rather than for crane storage, as was previously the case.

Secondly for floor cranes less space is required in storage by distributors, stockists and manufacturers, since the cranes stack conveniently and neatly as shown in Figure 4.

Lastly packaging of a pair of cranes is greatly facilitated as shown in Figure 5, and moreover subsequent assembly of the cranes from their packed form is also very simple.

With conventional cranes it would be extremely difficult and impractical to arrange for the jib to be parked parallel to the king post. For such parking the stroke of the ram would need to be longer.

This could be achieved in three ways. Firstly a telescopic cylinder could be used. However this would be extremely expensive. Secondly the distance between the pivots 1 6a and 1 7 would have to be increased; however this would result in a much higher crane, which would restrict its application. Thirdly if the same length of ram were to be used, it would be necessary to restrict the working arc of the crane. Thus the uppermost position of the ram would be much lower and this again would severly restrict its application.

Thus it is believed that none of the conventional cranes could easily be adapted to gain the advantage of the present invention and accordingly it is believed that the present invention represents a significant advance by solving this problem of the parking of jib.

Claims (6)

1. A crane comprising an upstanding post, a jib.

a ram pivotally connected at one of its ends to the jib and at its other end to said post, to move the jib angularly, in use, as the ram is extended or retracted, a link member pivotally connected to said post and having the jib pivotally connected thereto, the jib being pivotable relative to said link member so that it can assume a parking position substantially parallel to said post.

2. A crane as claimed in claim 1, including means for causing said link member to move with the jib, said means comprising releasable means which allow said jib to pivot relative to said link member.

3. A crane as claimed in claim 2, wherein said link member has a pair of parallel sides between which the jib is pivotally connected and which are themselves pivotally connected to a portion of said post disposed between them.

4. A crane as claimed in claim 3, wherein each of said sides of the link is of substantially triangular form, with the pivot for the jib being at one corner and the pivot on the post being at a second corner thereof, and said releasable means is a removable lock pin which can be passed through respective aligned holes in said sides at or adjacent a third corner thereof, to cause the link to move with the jib as the jib is moved by the ram, and which on removal allows the jib to pivot to said parking position.

5. A crane as claimed in claim 4, wherein said sides of the links have respective further holes aligned with a hole through the jib, so that in its parked position the jib can be locked to the link member by means of said lock pin removed frorn said third corner.

6. A crane substantially as hereinbefore described with reference to and as shown in accompanying drawings.