GB2094917A - Tensioning device - Google Patents

Abstract

In a tensioning device with a screw device consisting of a screw sleeve (2) surrounding a screw spindle, there is a rotation block which has a blocking element (9) permitting unimpeded tensioning of the tensioning device, but preventing undesirable release of the tensioning device by engagement with a groove (8) in the screw sleeve (2). The blocking element (9) is under the action of a spring (15), the force of which has to be overcome, when the tensioning device is released, by actuating an unlocking member (14). <IMAGE>

Description

SPECIFICATION Tensioning device The invention relates to a tensioning device for tensioning lines with at least one screw device which serves for varying the distance between two connection heads and to which belong a screw spindle and a screw sleeve which are both surrounded at least partially by a housing connected in a rotation-proof manner to the screw spindle, and with a rotation block for the screw device, which has a blocking element and a flattened portion assigned to the latter on the outer face of the screw sleeve which is cylindrical outside the flattened portion.

Tensioning devices of the type mentioned above are used, in particular, for lashing articles which are transported on vehicles. Chains, ropes and/or bands are normally used here as tensioning lines, and these are connected to the connection heads by means of shackles, thimbles, loops or the iike.

It has been shown that, in the case of tensioning devices of the type in question, the locking of the tensioning devices in the tensioned state presents problems. Thus, in a known tensioning device (German Patent Specification 580,809) the housing of which is provided with bores for receiving a cotter pin which, in the locking position, is supported by means of part of its periphery against a flattened portion of a screw sleeve belonging to the tensioning device, the flattened portion first has to be brought into a position aligned with the bores, before the cotter pin is introduced. Only after this has been done can the potter pin be introduced and subsequently secured by bending over the cotter-pin ends. It goes without saying that not only the introduction and securing of the cotter pin, but also its subsequent removal are difficult and timeconsuming.Securing by means of a cotter pin proves a particular disadvantage in cases where the tensioning lines have to be re-tensioned after a certain time, since before any re-tensioning the cotter pin has to be removed completely from its receptacle, and there is always the danger that it will be lost.

For the reasons described, other possibilities for locking tensioning devices have been sought.

Although the solutions found (German Offenlegungsschrift 28 02 288 and German Offenlegungsschrift 28 02 293) are easier to handle, they nevertheless still cannot give full satisfaction.

The object on which the invention is based is to provide a tensioning device of the type in question, the rotation block of which is automatically overcome during tensioning, but is automatically transferred, after tensioning, into the tensioning position, from which it can be removed only by actuating an unlocking member.

This object is achieved therein that the flattened portion merges via a shoulder into the cylindrical outer face of the screw sleeve, in that the blocking element is mounted, so as to be movable to and fro between a blocking position and a release position, on the housing and/or on a part connected to the housing, in that the blocking element is pressed by a spring against the flattened portion or the shoulder, and in that, when the screw spindle is screwed into the screw sleeve the blocking element can be pressed out of the blocking position into the release position by the flattened portion or the shoulder, with the force of the spring being overcome, whilst, when the screw spindle is unscrewed from the screw sleeve, the blocking element can be transferred from the blocking position into the release position only by an unlocking member.

The tensioning device according to the invention offers the advantage that it can be handled extremely easily. During tensioning, the user does not need to worry about the rotation block at all, since it acts only in one direction and consequently need to be actuated only when the tensioning device is released. Unlocking of the rotation block is simple and can be carried out quickly without the aid of tools even under unfavourable conditions such as prevail in bad weather and darkness.

Further details and features of the invention emerge from the sub-claims and from the following description of several exemplary embodiments illustrated in the attached drawing in which: Figure 1 shows a perspective view of a tensioning device with the rotation block removed; Figure 2 shows a section through the rotation block installed in the tensioning device according to Figure 1; Figure 3 shows, partially in section, a tensioning device with a modified rotation block; Figure 4 shows a section along the line IV--IV in Figure 3:: Figure 5 shows a plan view of part of a further tensioning device; Figure 6 shows a section along the line VI--VI in Figure 5; Figure 7 shows a section, corresponding to Figure 6, through a tensioning device with a modified rotation block, and Figure 8 shows a section, corresponding to Figure 6, through a tensioning device with a further rotation block.

In Figure 1, the housing of a tensioning device, the basic construction of which is known, for example, from German Offenlegungsschrift 2,822,549, is denoted by 1. A screw sleeve 2 carrying a connection head 3 at one end projects from one end of the housing -1. Located at the other end of the housing is a connection head 4 formed by part of a swivel fastener. A screw spindle 5 connected in a rotation-proof manner to the housing 1 projects into the screw sleeve 3 (see Figure 2). The screw sleeve 2 and the screw spindle 5 form a screw device, by means of which the distance between the connection heads 3 and 4 can be varied.

Connected to the housing 1 is an annular part 6 which surrounds the screw sleeve and serves for supporting a rotation block. The screw spindle is provided, in the region of its outer face, with a flattened portion 7 and a shoulder 8. A blocking element 9 formed by a blocking piston interacts with the flattened portion 7 and the shoulder 8.

This blocking element 9 is pressed by a spring 1 5 against a stroke-limiting stop 11 which is formed by a screw pin provided with a hexagon socket 1 2.

An unlocking member 14 designed as an unlocking knob is connected to the blocking element 9 via a rod 13.

A spring 15, one end of which projects into a recess 1 6 of the blocking element 9 and the other end of which is supported against the bottom of a recess 1 7 in the part 6, presses the blocking element 9 against the stroke-limiting stop 11 and the shoulder 8.

When the tensioning device is tensioned, the housing 1 and the screw spindle 5 are rotated synchronously in an anti-clockwise direction, as seen in Figure 2. During each revolution, the blocking element 11 is pushed back once into the recess 1 7 by the shoulder 8 against the action of the spring 1 5. After the tensioning operation, the housing 1 is turned back briefly in a clockwise direction until the blocking element 9 engages into the position shown in Figure 2. Further rotation of the housing out of the position shown, in a clockwise direction, is not possible, but instead is prevented by the blocking element 9 pressing against the flattened portion 7.When it is intended to release the tensioning device, the unlocking member 14 must be actuated, and by means of this the blocking element 9 can be removed to the right, as seen in Figure 2, out of its blocking position, against the action of the spring 1 5.

Whereas, in the exemplary embodiment according to Figure 1, a blocking element 9 which can be displaced essentially tangentially to the screw sleeve 2 is used, a blocking element 18, which is formed by a two-armed lever pivotable about an axle 19, is used in the exemplary embodiment according to Figures 3 and 4. The blocking element 1 8 is provided with a stop face 20, against which presses a ball 21 which is subject to the action of a spring 22. The blocking element 1 8 is pressed automatically by the spring into the position shown in Figure 3. In this position, as may be seen from Figure 4, the blocking element rests against the shoulder 8 of the screw sleeve 2 by means of a side face.The blocking element 1 8 can be transferred from the position shown into the position indicated by dotand-dash lines in Figure 3 by exerting pressure on an actuating projection 36. The blocking element 1 8 is also pressed into the position indicated by dot-and-dash lines when the screw sleeve 2 executes a rotary movement in a clockwise direction, as seen in Figure 4. Such a rotary movement takes place during the tensioning of the tensioning device, and in this case a toggle 23 serves for initiating the rotary movement into the screw sleeve 2.

The tensioning device according to Figure 5 largely corresponds in its basic construction to the tensioning device according to Figure 3. In the last exemplary embodiment, blocking elements 24, 25, 26 of the type indicated in Figures 6 to 8 are used, that is to say blocking elements which are formed by a detent pawl movable to and fro essentially radially to the screw sleeve 2. A curved leaf spring 27 provided with a guide slot 28 serves, in each case, for retaining the blocking elements 24, 25 and 26. One end 29 of the leaf spring 27 is fastened undetachably to the housing 1 , whilst the other end 30 either carries or forms a detent pawl. A spreader element 31 is guided so as to be movable to and fro between the housing 1 and the curved leaf spring 27.The spreader element 31 is connected by means of the guide slot 29 to an unlocking knob 32 which allows the spreader element to be displaced from the end 30 of the leaf spring towards the end 29 of the leaf spring 27.

In the exemplary embodiments according to Figures 6 and 7, each screw sleeve has, in either case, only one flattened portion 7 and one shoulder 8. In the exemplary embodiment according to Figure 8, however, the screw sleeve 2 is provided with two flattened portions 7 and two shoulders 8 assigned to each flattened portion 7. To permit unimpeded tensioning in this case also, the blocking element has a slope 33 which, as seen in Figure 8, allows a rotary movement of the screw sleeve in a clockwise direction. 34 and 35 denote detent cams which serve for retaining the spreader element 31.

The foregoing description reveals that, in all the exemplary embodiments described, unimpeded tensioning of the tensioning device is possible as a result of the rotation block, but undesirable slackening is prevented automatically. in other words, the user of the tensioning device according to the invention does not need to actuate any blocking elements after the tensioning operation has been completed. On the contrary, the safety lock takes effect automatically. Only when the tensioning device is to be released does the user have to actuate an actuating member.

Claims (17)

1. A tensioning device for tensioning lines with at least one screw device which serves for varying the distance between two connection heads and to which belong a screw spindle and a screw sleeve which are both surrounded at least partially by a housing connected in a rotation-proof manner to the screw spindle, and with a rotation block for the screw device which has a blocking element and a flattened portion assigned to the latter on the outer face of the screw sleeve which is cylindrical outside the flattened portion, in which the flattened portion merges via a shoulder into the cylindrical outer face of the screw sleeve, and the blocking element is mounted so as to be movable to and fro between a blocking position and a release position on the housing and/or on a part connected to the housing, and in which the blocking element is pressed by a spring against the flattened portion or the shoulder and, when the screw spindle is screwed into the screw sleeve, the blocking element can be pressed out of the blocking position into the release position by the flattened portion or the shoulder with the force of the spring being overcome, whilst, when the screw spindle is unscrewed from the screw sleeve, the blocking element can be transferred from the blocking position into the release position only by an unlocking member.

2. A tensioning device according to claim 1, in which the blocking element is formed by a blocking piston movable to and fro essentially tangentially to the screw sleeve.

3. A tensioning device according to claim 2, in which a stroke-limiting stop is assigned to the blocking piston.

4. A tensioning device according to claim 3, in which the stroke-limiting stop comprises a screw pin arranged parallel to the longitudinal axis of the screw sleeve.

5. A tensioning device according to any one of claims 2 to 4, in which the blocking piston is provided with an unlocking knob projecting beyond the outer face of the housing.

6. A tensioning device according to any one of claims 2 to 5, in which the blocking piston has a recess for receiving part of the spring.

7. A tensioning device according to claim 1, in which the blocking element is formed by a blocking lever movable to and fro essentially radially to the screw sleeve.

8. A tensioning device according to claim 7, in which the blocking lever is provided with a stop face for a ball which is subject to the action of the spring.

9. A tensioning device according to claim 7 or claim 8, in which the blocking lever is provided with an actuating projection.

10. A tensioning device according to claim 1, in which the blocking element is formed by a detent pawl movable to and fro essentially radially to the screw sleeve.

11. A tensioning device according to claim 10, in which the blocking element is located on a leaf spring.

12. A tensioning device according to claim 11, in which one end of the leaf spring is fastened to the housing whilst the detent pawl is located at the other end.

13. A tensioning device according to claim 11 or claim 12, in which a spreader element is guided so as to be movable to and fro between the housing and the leaf spring.

14. A tensioning device according to claim 13, in which the leaf spring is provided with detent cams for retaining the spreader element in different positions.

1 5. A tensioning device according to any one of claims 11 to 14, in which the leaf spring is curved and extends over at least part of the periphery of the housing.

1 6. A tensioning device according to any one of claims 13 to 15, in which the leaf spring is provided with a guide slot for the spreader element and with an unlocking knob connected to the latter.

17. A tensioning device according to any one of claims 1 to 16, in which several flattened portions and shoulders are distributed over the periphery of the screw sleeve.

1 8. A tensioning device substantially as described herein with reference to the accompanying drawings.