The present invention relates to a pulling hook for pulling caravans, trailers or the like, said pulling hook being provided with locking means for removably fastening the actual hook member to a pulling hook hitching means, which in turn is secured to a pulling vehicle, the actual hook member including a connecting means which is adapted to at least partially overlap the hitching means, whereby the overlapping portions of the hook member and hitching means are provided with abutting faces for limiting the relative movement thereof and also provided is a quick coupling means for bringing the abutting faces of the overlapping portions to press against each other and for bringing the overlapping portions to lock removably relative to each other, said quick coupling means comprising an axle stub, joumalled to be rotatable transversely relative to the common centre axis of the connecting means and hitching means and provided in a certain rotational zone of the quick coupling means with a recess as well as in another rotational zone of the quick coupling means with an eccentric surface whereby, in a certain rotational position of the quick coupling means, the connecting means and hitching means can be threaded in an overlapping position past the quick coupling means whereafter, upon rotating the quick coupling means, the abutting faces of the hook member connecting means and hitching means are pressed against each other for locking said means relative to each other.

The Applicants' earlier Finnish Patent 74657 discloses a disengageable pulling hook which, however, requires relatively strict limitations for manufacturing tolerances and, thus, manufacturing of such pulling hook is relatively expensive. The structural costs in this prior

known solution are also increased by the fact that the moving components of the pulling hook are included in a portion of the pulling hook permanently mounted on a vehicle and this, in turn, requires certain protective precautions for securing the continuous operation of these components .

An object of the invention is to provide a pulling hook, wherein the actual hook member is adapted in a simple and quick fashion - without separate tools - to be uncoupled and coupled and which pulling hook, in order to keep manufacturing costs low, can be produced with relatively loose manufacturing tolerances and which hook also includes all moving parts in the removable portion of the pulling hook and, thus, when the hook is removed and stored e.g. in the trunk of an automobile, said moving parts shall not be subjected to any major stresses nor exposed to mud or other foreign matter.

This object is achieved according to the invention in a manner that and a pulling hook of the invention is characterized in that a quick coupling means is joumalled to a hook member connecting means, that a hitching means is provided with a slot, extending transversely relative to its longitudinal axis and intended for an eccentric surface included in the quick coupling means, said slot preferably comprising a section of a circular cylinder, that the abutting faces of a hook member comprise a conical surface included in the mouth of a hole made in the connecting member for the hitching member and a section of the wall surface of said hole and, respectively, the abutting faces of a hitching means comprise a conical surface provided on the base of a hitching means protrusion extending into the interior of a connecting means and a section of the wall surface of said

protrusion, and that the relative positioning and dimensioning of quick coupling means and slot are arranged in a manner that tightening of the quick coupling means produces on the hook member a force which presses the abutting faces of the hook member respectively against those of the hitching means.

The preferred further developments of the invention are set forth in the sub-claims.

The invention will now be described in more detail with reference made to the accompanying drawings, in which

fig. 1 is a partially sectioned side view, showing the actual hook member of a pulling hook of the invention.

Fig. 2A is a side view, showing a hitching means mounted on a vehicle and included in a pulling hook of the invention.

Fig. 2B is a plan view, showing a hitching means mounted on a vehicle and included in a pulling hook of the invention.

Fig. 2C is a front view, showing a hitching means mounted on a vehicle and included in a pulling hook of the invention.

Fig. 3A is a side view, showing a quick coupling means for a pulling hook of the invention.

Fig. 3B is a section along a line III-III in fig. 3A.

Fig. 4 is a partially sectioned side view of a pulling

hook of the invention with the actual hook member coupled to the hitching means.

Fig. 5 is a plan view, showing a pulling hook of the invention with the actual hook member coupled to the hitching means.

Fig. 6 is a side view, showing a pulling hook of the invention with the actual hook member coupled to the hitching means.

The invention relates to a pulling hook intended for pulling caravans, trailers or the like. In principle, the pulling hook comprises two components: a removable hook member, designated generally with reference numeral 1 in fig. 1, as well as a hitching means, designated generally with reference numeral 2 in fig. 2 and fastened in a conventional manner, e.g. by welding, by its end shown at reference numeral 28 to a pulling vehicle or a support member (not shown) mounted thereon.

A connecting means 21, included in the actual hook member 1 and fastened to the hook member with a welding seam 29, is adapted to at least partially overlap the hitching means 2, as best illustrated in fig. 4. The connecting means 21 is preferably made as a piece of die forging.

The actual hook member 1 and the connecting means 2 are locked relative to each other by means of a quick coupling means 9, said quick coupling means being separately shown in fig. 3.

The quick coupling means 9 comprises an axle stub, joumalled to be rotatable transversely relative to the common centre axis 23 of connecting means 21 and hitching

means 2. The quick coupling means 9 is joumalled in a per se known manner to the connecting means 21 of hook member 1. In alignment with said axis 23 the quick coupling means 9 is provided in a certain rotational zone with a recess 11 as well as with an eccentric surface 12 in another rotational zone of the quick coupling means. In a certain rotational position of quick coupling means 9 (see fig. 1), said connecting means 21 and hitching means 2 can be threaded in an overlapping position past said quick coupling means 9.

Upon rotating the quick coupling means 9 in the direction of an arrow 24 in fig. 4, the eccentric surface 12 engages with hitching means 2 in a groove 13 extending transversely to its longitudinal axis 23, said groove preferably comprising a section of a circular cylinder.

The relative positioning and dimensioning of quick coupling means 9 rotatably joumalled to connecting means 21 and groove 13 included in hitching means 2 are arranged in a manner that tightening of quick coupling means 9 produces between hook member 1 and hitching means 2 a force action substantially parallel to a straight line 25 (fig. 4). Thus, there is produced between pulling hook 1 and hitching means 2 both an axial force, i.e. parallel to axis 23, and a force acting orthogonally thereto.

Said axial force presses a conical surface 7 provided in the mouth of connecting means 21 of hook member 1 against a conical surface 8 provided in the base of a protrusion 22, included in hitching means 2 and extending into the interior of connecting means 21, said surfaces 7, 8 locking the pulling hook and hitching means 2 relative to each other. In order to secure the locking, a radial component force produced by quick coupling means 9 presses

a section of wall surface 6 included in the end of the cylindrical protrusion 22 of hitching means 2 against a wall surface section 5 of a hole included in connecting means 21 for said protrusion 22.

The quick coupling means 9 is fitted with an externally adjustable element, preferably a lever 19 mounted transversely and non-rotatably relative to quick coupling means 9, for setting said quick coupling means 9 in a desired rotational position.

The quick coupling means 9 is fitted with a spring 14 in a manner that, as a result of the spring force, said quick coupling means 9 always tends to rotate to a position in which the eccentric surface 12 of the quick coupling means locks or clamps hitching means 2 and hook member 1 relative to each other. In the exemplary embodiment shown in fig. 5, said spring 14 is adapted to rotate lever 19 in a manner that the quick coupling means 9 always urges towards its locking position.

Lever 19 is mounted on quick coupling means 9 with hook member 1 and hitching means 2 fitted to each other and the quick coupling means rotated to its locking position, whereby said lever 19 is preferably mounted in a manner that, as the pulling hook is in a locking position and secured to a vehicle, lever 19 is horizontal and directed backwards, as shown in figs. 5 and 6. Thus, the quick coupling means 9 is set in an unlocking position by pressing lever 19 downwards. By not effecting the locking of lever 19 to quick coupling means 9 until at the above- mentioned assembly stage, it is possible to acquire a desired position for lever 19 regardless of manufacturing tolerances .

Lever 19 is provided with a locking means 20 for preventing the accidental uncoupling of quick coupling means 9, e.g. in the case of spring 14 being broken. In the solution illustrated in fig. 5, the locking means 20 comprises a member fixed in an axial ly resilient fashion to the end of a rod 17 projecting from connecting means 21 in the direction parallel to quick coupling means 9, said member being adapted in its extended position to secure said lever 19 mounted on the end of quick coupling means 9 and, respectively, in its retracted position to release the same. The locking means 20 is provided with a spring 26 in a manner that said locking means 20 always urges towards its extended position shown in fig. 5. When lever 19 is in the horizontal position shown in figs. 5 and 6 and quick coupling means 9 is in its respective locking position, the locking means 20 extends to a recess 27 provided in the end of lever 19, said recess being of such a shape that the locking means 20 only allows the rotation of lever 19 just slightly above or below the horizontal plane.

In order to prevent the possible failure of quick coupling means 9 from resulting in the disengagement of hook member 1, the overlapping portions of hook member 1 and hitching means 2 are further provided with second abutting faces 15, 16 (see figs. 1, 2 and 4) for limiting the relative movement of elements 1, 2 with the pulling hook in its normal operative position. The abutting faces 15, 16 comprise a grooved surface 16, provided in hitching means 2 and surrounding its circumferential surface, and an abutment surface 15, included in a safety element 17 fixed relative to hook member 1 and capable of engaging said grooved surface upon rotating said hook member 1 relative to hitching means 2.

In the exemplary embodiment shown in the drawings, the safety element 17 comprises a circular rod which is fitted in connecting means 21 orthogonally relative to centre axis 23 in such a manner that the cylindrical envelope surface of said rod extends partially inside the wall section of a hole included in connecting means 21 for hitching means 22. The end of hitching means 2 is provided with a flat bevelling 18 in a manner that, in a certain rotational position, the end of hook member 1 can be pushed on top of hitching means 2 for bringing said second abutting faces 15, 16 against each other.

In the embodiment shown in fig. 4, the connecting means 21 and hitching means 2 of hook member 1 can only be fitted in an overlapping position when the knobbed end of hook member 1 is turned 90° upwards from the plane shown in the figure. In other positions, the safety rod 17 prevents the overlapping insertion of components 21 and 2 or, alternatively, the separation thereof from each other.

In practice, the disengagement of hook member 1 from a vehicle is effected as follows.

The locking means 20 is pressed in to release lever 19, which can be turned down and further below an automobile - with lever 19 turned down, locking means 20 is no longer capable of rising - until said quick coupling means 9 reaches the position shown in fig. 1. At this point, the extraction of pulling hook 1 is still prevented by safety element 17, whose action can be by-passed by turning, in the solution shown in fig. 4, the knobbed end of a pulling hook to point ot the right as seen from behind a vehicle. Thereafter, the hook can be extracted, the action of the force of spring 14 can be allowed to return lever 19 to its locking position, wherein the locking means 20 re-

projects to lock said lever 19, and said hook member 1 can be placed e.g. in the trunk of an automobile.

The hitching of hook member 1 is effected in a substantially identical manner in reversed order.