Coupling Device

The invention relates to a coupling device comprising two tension members having mutually coacting teeth and a clamping means for keeping the toothed members in mesh with each other.

In lashing containers to the deck of a ship a pair of lashing members is often used. The members (chains or tension bars) are fastened to the deck and a container respectvely, and are tensioned and connected by means of a shroud screw or a lever arm tensioner. Shroud screws are expensive, easily damaged and slow to operate. Lever arm tensioners require high manual strength to tighten and are risky to release. Should the lashing members be tensioned by means of a separate tensioner and then in tensioned condition be coupled by means of a coupling of the type revealed in U.S. Pat. No. 1,652,677, several drawbacks would occur. The U.S. patent reveals a coupling which comprises two connector portions with toothed shanks, the teeth of which are locked in mutual engagement by means of transverse screwed connections extending through the shanks. For example, the teeth can take up a position top-to-top when the screwed connection is tightened, resulting in the risk that the lashing becomes slack or has no effect when loaded.

Before the departure of a vessel, a ship's officer, usually the second mate, must ensure that the lashings are effective, but an inspection of the known coupling devices is time-consuming, since they do not give any clear indication as to whether the teeth are mutually locked in engagement or not.

Furthermore, it takes time and energy to release and tighten the screwed connection.

Another disadvantage is that there have been difficulties in handling couplings of larger sizes/weights in connection with tensioning and releasing lashings.

One object of the invention is therefore to provide a coupling device of the kind mentioned in the introduction, by means of which the disadvantages and difficulties discussed are overcome, and which allows lashings to be more easily and quickly released or tightened.

In accordance with the invention, this object is achieved in a coupling device of the kind given in the introduction in that one flank of the teeth has an angle of between 110.degree. and 91.degree. to the direction of tensional load in the member, that the other flank has an angle of between 30.degree. and 50.degree. to the directional tensional load, that the clamping means is an eccentric clamping collar surrounding the members at their toothed zones and affording clearance between the tooth top planes of the members, which is of the same order of magnitude as the depth of the teeth, that the clamping collar keeps the teeth of the elements in mesh when it is closed, that the clamping collar has an eccentric operating lever, the angular attitude of which indicates whether the collar is open or closed, and that each of the members is provided with means for applying a tensioning apparatus, e.g. a hydrualic tensionor.

The flank angles of the teeth are preferably about 105.degree. and 45.degree.. The flank angle 45.degree. enables mutually relative axial displacement of the members in such a way that the effective length of the coupling device is reduced without any great labor. If this flank inclination were steeper, it would be difficult to axially displace the members for reducing the effective length of the device. Were this angle shallower the pitch of the teeth would become large to the point of clumsiness, since for practical reasons a tooth depth of some millimeters is desired in devices of the type to which the invention relates. The other tooth flank angle (preferably about 105.degree.) should be close to 90.degree., since coacting tooth faces would otherwise exercise a wedging action which would unfavorably affect the eccentric clamping collar. This flank angle should be greater than 95.degree. however, since it would otherwise be difficult and risky to open the coupling device when the lashing is to be released. If the flank angle is 90.degree. or somewhat greater, one would be compelled to work on the coupling device to get the teeth to go free from each other, so that the members could be mutually relatively displaced. With the flank angle preferred in accordance with the invention, it has been found that the members move away from each other in a more controllable way when the clamping collar is opened.

As the clamping means is made as an eccentric clamping collar, special tools for coupling and releasing the members are no longer needed. The reason for this is that the eccentric cam forming a part of the clamping collar is provided with an operating lever which can simply and manually be pivoted to close and open the collar, the angular attitude of the operating lever in relation to the coupling device indicating whether the device is open or closed. A ship's officer with the task of checking lashings can now make a check from a comparatively distant position to see what angular attitude the operating lever has.

Each of the members are suitably provided with a stop at their rear ends in the direction of tensional load, these stops coacting with the clamping collar to prevent the members from leaving the collar. As mentioned, the clamping collar can be formed as a yoke with an eccentric cam on a shaft which is mounted at the free ends of the yoke, the operating lever being connected to the eccentric cam. At their front ends in the direction of tensional load, the members suitably have connecting means, preferably a hook for hooking fast the ring of a chain or the like. A conical disk spring or the like can be mounted between one limb of the yoke and the eccentric cam for providing a certain amount of friction between the eccentric cam and the yoke so that the eccentric cam does not rotate, e.g. under the action of gravity.

The invention is defined in the accompanying patent claims. In the following, the invention will now be described in the form of an example while referring to the accompanying drawing.

FIG. 1 is a side view of a coupling device in accordance with the invention.

FIG. 2 is a horizontal view of the device in Fig. 1, further schematically illustrating a tensioning apparatus for tensioning the device.

FIG. 3 is a detail of the tooth arrangement.

FIG. 4 is a section taken along the line IV-IV in FIG. 1 through the clamping collar in a closed condition.

FIG. 5 shows a section corresponding to that in FIG. 4 but with the clamping means in an open condition.

A coupling device is shown in FIG. 1, comprising two coupling members which are mutually connectable by means of an eccentric clamping 20. The coupling members are essentially identical and comprise a flat bar 1, 11 with teeth 2, 12 extending across the longitudinal direction of the bar 1, 11. At one end of the bar 1, 11 there is a hooking means 3, 13, in the vicinity of which a pipe length 4, 14 is also rigidly attached to the bar. At the other end of the bar 1, 11 there is a stop 5, 15, preventing the members from being pulled out of the eccentric collar 20. The stops 5, 15 can be so made that they extend from one coupling member over the side portions of the other coupling member to prevent the members from splaying for a skew load in the plane of the teeth 2, 12. These stops 5, 15 can possibly be arranged on both sides of the end of the bar.

The eccentric clamping collar 20 is shown in a closed condition in FIGS. 1 and 2, the teeth 2, 12 meshing accordingly.

A hydraulic tensioning apparatus 30 is shown in chain lines below the coupling device in FIG. 2. The cylinder part of the tensioner is provided with a transverse pin 31, and its ram portion is provided with a pin 32, these pins being disposed for accomodation in the pipe lengths 4, 14 of the coupling device. A pipe 33 is provided for supply and return of hydraulic medium, With the aid of the tensioner 30, the elements can be mutually, axially relatively displaced when the collar 20 is open, so that the hook portions 3, 13 approach each other.

FIG. 3 illustrates the form of the teeth 2, 12. r denotes the respective tensional load direction of the elements, and this is also apparent from FIG. 1. The flanks of a tooth have different slopes. The steeper flank has an angle .alpha. to the load direction which is more than 90.degree. but less than about 110.degree.. The angle .alpha. is preferably between 95.degree. and 110.degree., most expediently about 105.degree.. The more obtuse flank angle .beta. is between 30 and 50.degree. and is preferably about 45.degree..

In a practical embodiment of the illustrated coupling device, where it has a length of about 1.2 m, a breaking load of 30 tons and a weight of about 11 kgs, a tooth depth t of about 3 mms was found to be suitable, and it was also found to be suitable to plane off the tops in the way shown in FIG. 3.

FIG. 4 is a section through the eccentric clamping collar 20. The collar 20 comprises a yoke 21 with a web 25 and two substantially parallel limbs 23 and 24. At the free ends of the limbs 23, 24 a shaft 22 is mounted by means of bearings 28. An eccentric cam 26 is rigidly mounted on the shaft 22. A conical disc spring 27 is arranged between the cam 26 and the limb 24 to stabilize the cam 26 in its set portion. As is apparent from FIGS. 1, 2 and 5, the cam 26 is provided with an operating arm 29 to facilitate its manual setting in the open and closed position.

The collar 20 is shown in its closed position in FIG. 4, the cam 26 maintaining the teeth of the bars 1, 11 in mesh between the yoke and shaft. FIG. 5 shows the collar 20 in an open position. The eccentricity of the cam 26 is such that in the open position it allows the bars, 1, 11 to be moved apart so that there is a clearance s between the tooth top planes of the bars 1, 11, this clearance being of the same order of magnitude as the tooth depth t, i.e. about 3 mms in the embodiment discussed. The tooth angles .alpha., .beta., depth t and clearance s afford substantial advantages. When the coupling members are to be pulled together axially, the flank angle .beta. is such that the teeth easily become unmeshed under the action of the tensioner 30 or a manual tensioning force. The lower value of the angle .beta. is determined by the desire of not having too large a tooth pitch. The flank angle .alpha., locking the members relative to each other against a separating force, allows on the one hand, but because of its small slope, the members are enabled to separate from each other when a loaded coupling (the loading can attain several tons) is released by opening the collar. We have thus found that the angle .alpha., surprisingly enough, affords a substantially automatic, unhindered separation of the members, and unloading of the coupling when the eccentric clamping collar 20 is opened while the coupling is under load. The relation of the clearance s to the tooth depth affords the advantage in connection with the flank angle .alpha. of allowing said separation of the members, but also that the coupling members are actually kept coupled against axial extension when the collar 20 is open and the members are subjected to a tensional load of comparatively small size. Such a load occurs under the action of the weight of a coupling member and the details connected to it, such as chains or the like. The reason for the axial lock with small loads and open collar 20 would appear to be that the members 1, 11 in all probability assume a small angle to each other for small loads. Since the collar 20 only permits the small clearance s in an open condition, the teeth will thus mesh. When the tensioner 30 is connected to the bars 1, 11 and is contracted, the tooth faces with the angle .beta. will ride over each other without disturbing resistance. Since the angle .alpha. is comparatively close to 90.degree., the wedging action against the shaft 22 of the collar 20 of the tooth faces with this angle will be small.

The operating arm 29 of the cam 22, which preferably is disposed so that it is directed perpendicular to the longitudinal direction of the coupling device when the collar 20 is open, and parallel to said direction when the collar is closed, gives a clear visual indication even when observed from a relatively long distance, as to the open or closed state of the collar, an advantage being that the teeth 2, 12 are securely in mesh when the arm 29 indicates the closed condition of the collar 20.