WO1991002179A1

WO1991002179A1 - Rope gripper

Info

Publication number: WO1991002179A1
Application number: PCT/NL1990/000104
Authority: WO
Inventors: Reindert Jan Jansen; Andreas Jacobus Louis Nijsen; Aloisius Henricus Maria Heister
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-07-28
Filing date: 1990-07-26
Publication date: 1991-02-21
Anticipated expiration: 1992-01-28
Also published as: AU6146290A; NL8901958A

Abstract

The invention relates to a rope gripper which mainly comprises a flexible sleeve-like clamping element (7) through which the rope (8) to be gripped can extend. The clamping element can be stretched such that a transversal contraction thereof occurs and the rope (8) to be gripped is gripped by the internal surface of the clamping element (7). Stretching of the clamping element is established by moving apart both ends of the clamping element. In this respect preferably one end of the clamping element is stationary, whereas the other end is movable to and for by means of an actuator element. Preferably the clamping element comprises a spirally braided sleeve (9).

Description

Rope gr pper

The invention relates to a rope gripper. Among others rope grippers are used on sailing boats for attaching sheets of sails or the like. The known rope grippers often have one or several disadvantages. One may mention a low gripping force, such that the rope can slide under high loads, the risk of damaging the rope through extensively high local clamping pressures, or the uncontrolled disengagement of the gripped rope when releasing it.

It is an object of the invention to provide a rope gripper in which these disadvantages have been removed in a simple, but nevertheless effective way.

As a result according to the invention the rope gripper is characterised by a flexible sleeve-like clamping element arranged in a stationary housing, through which clam¬ ping element the rope to be gripped can extend, said clamping element being deformable between a gripping position in which its both ends are distanced such, that the internal surface of the clamping element due to a transversal contraction thereof grippingly engages the outer surface of the rope to be grip¬ ped, and a release position in which both ends are positioned closer such that the internal surface of the clamping element releases the rope for a longitudinal displacement.

When both ends of the flexible sleeve-like clamping element are moved apart, such that the clamping element rea¬ ches its clamping position, this sleeve-like clamping element is narrowed due to a transversal contraction, whereby a rope extending through this clamping element is gripped. This gripping action occurs along nearly the entire length of the clamping element, such that this clamping element should exert oniy a small pressure on the rope for obtaining the high gripping force. Because only low local pressures are exerted on the rope to be gripped this rope will not or hardly be damaged. Further it appears that, when moving the clamping element from its gripping prosition towards its release posi¬ tion, releasing the ^'gripped rope occurs extremely gradually, for example such that this rope may slide through the clamping element in a controlled way. Moreover it appears that the force which is needed to move the clamping element from its gripping position towards its release position is extremely low, also when an extremely high external load is exerted onto the gripped rope.

For obtaining a good gripping action of the flexible sleeve-like clamping element onto a rope to be gripped it is possible, that the clamping element comprises a sleeve of spirally braided threads. Preferably the threads are made of steel.

Further it is preferred if the threads of the sleeve extend left-hand spirally as well as right-hand spirally. Due to this spiral shape the rope gripper according to the inven¬ tion obtains a high gripping force. As a result of moving apart both ends of the clamping element a transversal contrac¬ tion is caused, which in its turn leads to a frictional force exerted onto the sleeve by the rope. Because each thread of the sleeve is wound around the rope to be gripped several times an extremely high force amplification is provided which has as a result that the threads contract the rope even more and that the gripping force is further increased. This means that it is sufficient to provide an initial friction for

obtaining an effective operation of the rope gripper according to the invention.

According to a preferred embodiment of the rope gripper according to the invention one end of the clamping element is positioned stationary in the housing whereas the other end is movable with respect to the housing by means of an actuator element. Moving the clamping element from the release position towards the gripping position and reversed can be realised now in a simple way by moving the movable end of the clamping element relative to the housing using the

- *t actuator element.

In this respect it is favourable if according to a further embodiment of a rope gripper according to the inven¬ tion the actuator element comprises an actuator arm movable with respect to the housing, which actuates the movable end of the clamping element. The housing that is attached to the underground, for example the deck of a sailing boat, then functions as support for the actuator arm.

Further it is advantageous if the actuator element engages the movable end of the clamping element via a spring means. In this respect it is advantageous if the spring means comprises a compression spring which at least partially sur¬ rounds the clamping element and which is prestressed between the actuator element and the movable end of the clamping element. By means of this compression spring a defined force is continuously exerted onto the movable end of the clamping element, such that the rope gripper always engages the rope with a defined initial gripping force. Due to this initial gripping force the clamping element will stretch further. In this respect it is important that the prestressing force of the compression spring is such that this compression spring still has a certain degree of prestressing even in the maximum stretched position of the clamping element.

Further it is possible that the actuator element and the movable end of the clamping element are interconnected through an element which can take up a tensile force. Like this the rope gripper can be moved to its release position by operating the actuating element. In this respect it is advan¬ tageous if the element comprises a bush engaging around the actuator element or a sleeve attached thereto and further engaging around the movable end of the clamping element or a clamping sleeve attached thereto. When moving the rope gripper to the gripping position this bush has no influence whatsoever. Moreover it is favourable if there is provided a settable abutment for limiting the distance between both ends of the ^lamping element in the gripping position. In a prefer¬ red embodiment thereof the abutment cooperates with the mova¬ ble, end of the clamping element. By means of this abutment it is prevented that as a result of the force amplification the clamping element is stretched to far resulting in rupture, whereas moreover the maximum gripping force^' of the rope grip¬ per can be set.

Finally it is constructively advantageous if the ends of the clamping element each are sandwiched between two tape- ring concentric clamping sleeves. Like this the clamping element can be provided in the stationary housing in a simple way.

Hereinafter the invention will be elucidated by means of the drawing, in which an embodiment of the rope gripper according to the invention is illustrated.

Figure 1 shows an embodiment of the rope gripper according to the invention, partially in section and in a gripping position, Figure 2 shows the rope gripper from figure 1 in its release position,

Figure 3 shows the principle of sandwiching both ends of the clamping element, as applied in the rope gripper accor¬ ding to figure 1 and 2, Figure 4 shows a second embodiment of the rope grip¬ per in a gripping position, and

Figure 5 shows the rope gripper of figure 4 in its release position.

The rope gripper illustrated in figure 1 comprises a housing 1 which> by means of mounting lips 2, 3, is attachable to an underground, for example the deck of a sailing boat. The housing 1 comprises two housing halves 4 and 5 connected to each other at a, mounting partition. Through the house 1 a continuous bore 6 extends in which a flexible sleeve-like clamping element 7 is provided.

It is .noted-here,, that in figure 1 and figure 2 this clamping elementv7 is illustrated in a cut-away vision in its central part for making visible a rope 8 to be gripped exten¬ ding through this clamping element 7. The clamping element 7 mainly comprises a sleeve 9 of left-hand and right-hand spirally braided threads. In a pre¬ ferred embodiment the threads are made of steel.

- In correspondence with the principle shown in figure 3 the ends of sleeve 9 each are sandwiched between two tape- ring concentric clamping sleeves 10 and 11. For sandwiching the ends of the sleeve-9 the inner clamping sleeve 11 is slid into this sleeve 9 via the corresponding end of sleeve 9, until this end is sandwiched between the tapering inner wall of the ociter.jølamping sleeve 10 and the tapering outer wall of the innea? clamping sleeve 11. It is noted that the inner diameter of the inner clamping sleeve 11 has to be such that the rope to be gripped can slide freely through this clamping sleeve 11.

The left-handed end of the clamping element 7 is, via the outer clamping sleeve 10, received in an enlarged section 12 of bore 6 in housing 1. For this the outer clamping sleeve 10 comprises a corresponding collar 13. Due to the cooperation between the collar 13 and the enlarged section 12 the left- handed end of the clamping element 7 is axially stationary mounted in the housing 1.

The opposite movable end 10' of the clamping element is positioned near to an abutment 14 which lets the rope 8 pass and which is positioned in the bore 6 of the housing 1, such that the clamping sleeve 10' is, relative to the housing 1, in axial direction movable to and fro in a limited way.

An actuator arm 15 is pivotable around a pivot axis 16 attached to the housing 1. By means of a slot 17 the actua¬ tor arm 15 engages with its inner end a pin 18 provided on a sleeve 19. It will be directly understood that pivoting the actuator arm 15 around the pivot axis 16 leads to an axial displacement of the respective sleeve 19 relative to the housing 1.

Finally it is visible that a compression spring 20 extends between the clamping sleeve 10' and the sleeve 19, pushing apart these two sleeves 10• and 19.

In the gripping position of the clamping element 7 illustrated in figure 1 the movable clamping sleeve 10' , illustrated at the right-handed side, is positioned so far to the right that the sleeve 9 of the clamping element 7 is contracted due to the axial stretch. As a result the inner surface of this sleeve 9 engages the outer surface of the rope 8 to be gripped which extends through this clamping element 7. Due to the friction between the rope and the inner surface of the sleeve 9 the sleeve 9 is still further stretched by the rope 8 as a result of which the gripping force still increa¬ ses. This effect continues until the right-handed end of the movable clamping sleeve 10' engages the abutment 14. This position of the clamping element 7 is maintained by the rope force and the action of the compression spring 20. In this gripping position the rope 8 is effectively gripped. For releasing the rope 8 the sleeve 10 is displaced towards its position represented in figure 2 by means of the actuator arm 15. As a result of the tensile force exerted onto the clamping sleeve 10' by the spring 20 sleeve 9 is axially compressed which leads to the sleeve 9 widening in trans¬ versal direction, such that the inner surface thereof does no longer engage the outer surface of the rope 8. During this displacement of the respective sleeve 19 to the left the compression spring 20 acts as tensile spring. This means, that this spring is connected to sleeve 19 as well as to clamping sleeve 10'. Thus, for releasing a rope gripped in the rope gripper the actuator arm 15 always has to be operated.

A different embodiment of the rope gripper is shown in figures 4 and 5. -This rope gripper entirely corresponds with the rope gripper described before. The only difference comprises a bush 21 engaging around sleeve 19 and clamping sleeve 10' . When the rope gripper moves from the gripping position according to figure 4 towards the release position according to figure 5 this bush operates in the same way as described in respect to the compression spring 20 operating as tensile spring too. When displacing the sleeve 19 to the left by means of the actuator arm 15 it carries along bush 21, which on its turn carries along clamping sleeve 10' to the left, which results in the sleeve 9 releasing rope 8. In this embodiment the compression spring 20 does not have to operate as tensile spring and can maintain a certain prestressing. Moreover it is not required then that this spring 20 is atta¬ ched to the^* sleeve 19 and/or clamping sleeve 10• .

The bush 21 in no way whatsoever hinders the gripping operation and has no influence when moving the sleeve 19 and the clamping Sleeve 10' to the right. When moving to the left however it takes care for maintaining the prestressing in the spring 20. ^* * ^'*

The invention is not limited to the embodiment des- cribed before,^r which can be varied widely within the scope of the invention.

Claims

1. Rope gripper, characterised by a flexible sleeve¬ like clamping element (7) arranged in a stationary housing

(1) , through which clamping element the rope to be gripped can extend, said clamping element being deformable between a gripping position in which its both ends are distanced such, that the internal surface of the clamping element due to a transversal contraction thereof grippingly engages the outer surface of the rope (8) to be gripped, and a release position in which both ends are positioned closer such that the inter- nal surface of the clamping element releases the rope for a longitudinal displacement.

2. Rope gripper according to claim 1, characterised in that the clamping element (7) comprises a sleeve (9) of spirally braided threads.

3. Rope gripper according to claim 2, characterised in that the threads of the sleeve (9) extend left-hand spiral¬ ly as well as right-hand spirally.

4. Rope gripper according to one of claims 1-3, characterised in that one end of the clamping element (7) is positioned stationary in the housing (1) whereas the other end is movable with respect to the housing by means of an actuator element (15) .

5. Rope gripper according to claim 4, characterised in that the actuator element comprises an actuator arm (15) movable with respect to the housing (1) , which actuates the movable end of the clamping element.

6. Rope gripper according to claim 5, characterised in that the actuator element (15) engages the movable end of the clamping element via a spring means (20) .

7. Rope gripper according to claim 6, characterised in that the spring means comprises a compression spring (20) which at least partially surrounds the clamping element (7) and which is prestressed between the actuator element and the movable end of the clamping element.

8. Rope gripper according to claim 7, characterised in that the actuator element (15) and the movable end of the clamping element are interconnected through an element (21) which can take p a tensile force.

9. Rope gripper according to claim 8, characterised in that the element (21) comprises a bush (21) engaging around the actuator element (15) or a sleeve (19) attached thereto

5 and further engaging around the movable end of the clamping element or a clamping sleeve (18) attached thereto.

10. Roβe gripper according to one of the claims 1-9, characterised in that there is provided a settable abutment (14) for limiting the distance between both ends of the clam-

10 ping element in the gripping position.

11. Rope gripper according to claim 10 and one of the claims 4-9, characterised in that the abutment (14) cooperates with the movable end^'of the clamping element.

12. Rope gripper according to one of the claims 1- 15 11, characterised in that the ends of the clamping element (7) each are sandwiched between two tapering concentric clamping sleeves (10, 11).