WO1995030616A1

WO1995030616A1 - Openable pulley block

Info

Publication number: WO1995030616A1
Application number: PCT/SE1995/000483
Authority: WO
Inventors: Tony Laursen; Olle Fransson
Original assignee: Gnosjo-Dalum Innovation AB
Current assignee: Gnosjo-Dalum Innovation AB
Priority date: 1994-05-05
Filing date: 1995-05-03
Publication date: 1995-11-16
Anticipated expiration: 1996-11-05
Also published as: EP0758302A1; SE502980C2; SE9401556L; AU2458895A; SE9401556D0

Abstract

The invention relates to an openable pulley block, a so-called snatch block, with at least one sheave (4) rotatably journalled on a pin (5) and an attachment means (3) for attaching the block. The block consists of two halves (1, 2) which are pivotable relative to each other. According to the invention, the two halves (1, 2) of the block are joined to each other by means of a pivot shaft (3) extending essentially perpendicular to the pin (5) and spaced a substantial distance therefrom. The pin (5) is only fixed to a first half (1) of the block and the second half (2) is provided with a permanently mounted magnet (8) for interaction with a magnetic portion (7) of the first half (1) when the block is in its closed position.

Description

OPENABLE PULLEY BLOCK

The invention relates to an openable pulley block, a so- called snatch block, with at least one sheave rotatably journalled on a pin and an attachment means for attaching the block, said block consisting of two halves which are pivotable relative to each other.

Openable pulley blocks of the above mentioned type are known in various designs. The great advantage of these blocks is that they can be mounted on a rope or cable without having access to an end thereof. This means that the blocks can be used to change the path of the rope or cable anywhere along the rope or cable even if its ends are not accessible.

Openable pulley blocks known up to now have some type of mechanical latch means in the form of a hook or the like, which requires some form of manipulation before the block can be opened and after the block has been closed. This is a dis¬ advantage since several worksteps must be carried out when mounting the block on the rope or cable or moving the block from the rope or cable. In the known blocks, where the two halves of the block are joined to each other by means of the pin for the sheave, the latch means is often load-bearing. This means that the latch means must be in its correct posi¬ tion, since the load relationships on the block would other- wise be wrong.

The purpose of the present invention is to achieve an open¬ able pulley block of the type described by way of introduc¬ tion, which is of simple construction and is easily mounted on and removed from a rope or cable. This is achieved accord¬ ing to the invention by virtue of the fact that the two halves of the block are joined to each other by means of a pivot shaft extending essentially perpendicular to the pin for the sheave and being spaced a substantial distance there- from, that the pin is fixed only to a first half of the block and that the other half of the block is provided with a per¬ manently mounted magnet for interacting with a magnetic portion of the first half when the block is in its closed position. Advantageous embodiments of the invention are disclosed in the subclaims.

The invention will be described in more detail below with reference to the accompanying drawing, where

Figure 1 is a longitudinal section viewed from the side of an openable pulley block according to one embodiment of the invention,

Figure 2 is a plan view seen from above of the pulley block according to Fig. 1,

Figure 3 is an unsectioned side view corresponding to Fig. 1 but showing the block in its open position, and

Figure 4 is an end view of the pulley block according to the invention, seen from the right in Fig. 1.

The drawing shows an openable pulley block according to one embodiment of the invention. The pulley block consists of a first half 1 and a second half 2. The two halves of the block are joined to each other by means of a pivot shaft 3 which extends through the two halves 1,2 in the vicinity of their one end. This means that the two halves 1,2 can be pivoted relative to each other about the pivot shaft 3, for example to the open position shown in Figure 3.

The first half 1 supports a sheave 4 with the aid of a pin 5, on which the sheave 4 is freely rotatably journalled. The pin 5 is essentially perpendicular to the pivot shaft 3 and is in the form of a screw screwed into a threaded hole 6 in the first half 1 of the block. The pin 5 is provided at its dis¬ tal end with a head 7 located in a corresponding cavity in the sheave 4. In the embodiment shown, the outer surface of the head 7 is essentially coplanar with the outer surface of the sheave 4. The pin 5 or at least the head 7 of the same is made of a magnetic material. The second half 2 of the block is provided with a magnet 4 which is permanently mounted opposite the head 7 of the pin 5. In the embodiment shown, the magnet 8 is arranged in a cavity in the second half 2 of the block and lies essentially coplanar with the surface of the second half 2 facing the sheave 4. The magnet 8 is permanently mounted and when the block is in its closed position, the magnet 8 engages with the head 7 to keep the two halves 1,2 of the block in the closed position shown in Figure 1.

When the block is to be opened, either for mounting on a rope or cable or removal from the same, the two halves 1,2 are pressed apart from the position shown in Figure 1 to the position shown in Figure 3. This must be done with a force which is greater than the magnetic force between the magnet 8 and the head 7. The rope or cable can thereafter be freely removed from or placed onto the sheave 7 through the free space between the halves 1,2. To close the block, the two halves 1,2 need only be moved together and the magnetic force between the head 7 and the magnet 8 will provide a secure closing of the block. There is thereafter no risk that the block will open unintentionally.

The process for opening and closing the block described above means that no mechanical latch means or hooks need to be actuated. All that is required is that one generates a suffi¬ ciently large force to move the two halves 1,2 of the block apart. Such a force can also be achieved by a means fixed at the desired location on the line and when the block passes is inserted between the two halves 1,2. The block can thus be opened automatically to permit passage of means fixed to the rope or cable.

As can be seen in Figure 2 , a portion of the pivot shaft 3 is exposed centrally in the block. This portion of the pivot shaft 3 can be used as an attachment means for attaching the block, for example by means of a shackle (not shown) , a cable, rope or the like. The invention is not limited to the example described above but rather various changes can be made within the scope of the following claims. For example, the magnet 8 can be so arranged that it projects out from the surface of the second half 2 of the block, said surface facing the sheave 4. The magnet 8 can then project into the cavity in the sheave 4 which contains the head 7 of the pin 5. In this manner, it is possible to obtain better guiding of the two halves 1,2 of the block relative to each other. Furthermore, it is also possible to provide the head 7 of the pin 5 with a magnet and make the second half 2 of the block of a magnetic material.

Claims

1. Openable pulley block, a so-called snatch block, with at least one sheave (4) rotatably journalled on a pin (5) and an attachment means (3) for attaching the block, said block con¬ sisting of two halves (1,2), which are pivotable relative to each other, characterized in that the two halves (1,2) of the block are joined to each other by means of a pivot shaft (3) , extending essentially perpendicular to the pin (5) for the sheave (4) and being spaced a substantial distance therefrom, that the pin (5) is fixed only to a first half (1) of the block, and that the second half (2) of the block is provided with a permanently mounted magnet (8) for interaction with a magnetic portion (7) of the first half (1) when the block is in its closed position.

2. Pulley block according to Claim 1, characterized in that the magnet (8) is located directly in front of the pin (5) for the sheave (4) , said pin (5) being at least partially made of magnetic material.

3. Pulley block according to Claim 1 or 2, characterized in that the pin (5) for the sheave (4) is made in the form of a screw (5) extending through the sheave (4) and being screwed into a threaded hole in the first half (1) of the block and being provided with a head (7) which is located in a cavity in the sheave (4) and lying essentially planar with the side of the sheave (4) closest to the second half (2) of the block.

4. Pulley block according to one of Claims 1-3, characterized in that the magnet (8) is at least partially located in a cavity in the second half (2) of the block.

5. Pulley block according to Claim 4, characterized in that the magnet (8) partially extends into the cavity in the sheave (4) .