This invention relates to a rotatable and lockable bollard for use in winching and securing a rope or hawser, for example to a ship.

To secure a rope or hawser to a ship, it is customary to wind it in a figure of eight around a pair of bollards, the rope being pulled by means of a winch or capstan. On large ships there will be several such ropes each secured to a pair of bollards.

I have devised an improved form of bollard whereby only a single bollard is needed in place of each conventional pair, it is unnecessary to transfer a heavy and tightly heaved rope from a winch to a bollard and which also obviates the need for a dangerous chain stopper in this process, slacking losses in the rope are avoided, a single winch can be used for several bollards, and time, labour and machinery are thus saved in the process of securing ships in port.

According to the present invention I provide a rotatable and lockable bollard for use in winching and securing a rope or hawser, which comprises: an inner cylinder the base of which is securable to a deck or other structure, and an outer concentric cylinder which is adapted to have the rope or hawser wound around its outer surface and to rotate freely on the inner cylinder when pulled by a rope or hawser, and respective gear rings secured to the top or inside of the inner cylinder and the inside of the outer cylinder, and engageable together when the outer cylinder is axially displaced at the termination of the heaving of the rope or hawser.

The gear rings are caused to engage and disengage by axial displacement partly by the rope or hawser pulling on an upper or lower lip of the bollard. The two cylinders fit closely together, separated only by a layer of grease, and the two gear rings are connected by a plurality of flat guide means which are each fixed to one of the rings and movably connected to the other ring so as to allow rise and fall thereof and to lock the two sets of gear teeth together when the bollard is to be locked and the rope secured thereon, whilst keeping the two sets of teeth apart during rotation of the outer cylinder during heaving of the rope.

The invention will be further described with reference to a preferred embodiment thereof as shown in the accompanying drawings, wherein:

Figure 1 is a perspective view from above of a bollard according to the invention and part of a base upon which it is mounted;

Figure 2 is a perspective view from above of the outer rotatable cylinder of the bollard;

Figure 3 is a perspective view from above of the inner stationary cylinder;

Figure 4 is a diagram of the inside of the upper part of a bollard showing the relation of the respective teeth;

Figure 5 is a perspective view, from the lower right hand side, of a guide block;

Figure 6 is a perspective view of a bearing and attached spigot to be used with the guide block of Fig. 5;

Figure 7 is a vertical section through the bollard and through one guide block on line VII-VII of Fig. 5, the guide block being shown spaced away from the remainder of the bollard, the outer cylinder being in its raised position;

Figure 8 is a vertical section similar to that of Fig. 7 but with the outer cylinder in its lower cylinder position and the teeth engaged, and the guide block in its operative position; and

Figure 9 shows a modified form of a lower gear ring as in Figs. 7 and 8.

The base 10 is suitable for mounting upon the deck of a ship, jetty, oil rig or other structure, and it can also have a further bollard mounted thereon, for example a rotatable bollard as described in my Patent Application No. 9214646. Fixed to the base is a stationary inner cylinder 12, to the top of which is welded a gear ring 14 having around its upper edge a row of teeth 16 which are biassed in one direction as shown in Fig. 4. Pairs of lugs 18 are welded to the gear ring below the teeth, for the purpose of attachment of the guide blocks. An alternative form of the gear ring is shown at 21 in Fig. 9; the recessed shape allows stronger welding to the top of the cylinder 12. The bevels 23, 25 allow weld fills.

An outer rotatable cylinder 20 surrounds the inner cylinder, and has an outwardly turned lower lip 22 which extends sufficiently to retain a rope or hawser to be wound around the cylinder. At the top of this outer cylinder is welded a gear ring 24 having at its lower edge a series of gear teeth 26 of a shape to engage with the teeth 16, as also shown particularly in Fig. 4. The inner upper edge of the ring 24 is preferably bevelled as shown at 27 in Fig. 8, to assist its welding to the cylinder 20 by allowing a weld fill.

The upper gear ring 24 also has a channel 28 extending round its circumference, for receiving a roller bearing 32, which is seen in perspective in Fig. 6 and in section in Figs. 7 and 8. Alternatively the bearing can be mounted on an elongated foot which slides in the channel 28, packed in grease. Engaged upon the pairs of lugs 18 are guide blocks 30 as shown in face view in Fig. 5; these are actually slightly curved to fit the curvature of the gear rings to which they are attached, and four such guide blocks will usually be adeguate within a single bollard. Bearing 32 carries a lug or spigot 34, which fits into the sloping elongated slot 50 in the upper part of the guide block 30; this slot is angled at approximately 35° to the horizontal. Holes 36 are provided in the lugs 18 and 34 for the fitting of retaining split pins and washers (not shown) .

All the parts are suitably made of steel, the gearing and gear teeth and roller bearings being of a hardened steel.

A lid 40 is provided at the top and attached (e.g. welded or bolted) to the outer cylinder 20 and gear ring 24, and serves to retain the upper rope or hawser 46 wound around the outside of the bollard. Alternatively this lid can be replaced by an outwardly curved upper lip, similar to the lower lip 22. The two gear rings are of heavy-duty construction and of the same inner diameters, as seen in Figs. 7 and 8.

The gap 42 between the two cylinders is narrow and in use is packed with lubricating grease, so that the respective opposed surfaces of the two cylinders form a bearing surface during the rotation thereof.

Assembly can be as follows. The inner cylinder is secured to the base (it is possible to use. an existing conventional bollard for this purpose if it is in reasonably smooth

condition, the upper part thereof being cut down as necessary and the gear ring welded thereto). The outer cylinder is then lowered onto the inner cylinder, and the respective teeth 16, 26 will mesh together. The roller bearings 32, 34 are then inserted in the channel 28, above each pair of lower lugs 18, and the guide blocks 30 are then fitted and secured by means of heavy-duty split pins. The lid 40 is then if necessary secured on top.

It is important that there is a gap 52 between the lower lip 22 and the base 10, in the raised position as shown in Fig. 7, to allow the outer cylinder to drop and the teeth to engage as shown in Fig. 8, when the lower lip 22 will have dropped to a position four centimetres above the base 10 so as to avoid crushing the toe of a seaman.

To provide power for pulling a rope or hawser, without the need for a conventional large winch, it is possible to provide a power unit like that of a conventional winch which can drive several of the bollards according to the invention by means of a series of shafts from the winch to each bollard, e.g. 3 meters long, the shafts being connected to the bottom of the outer rotatable cylinders 20 by means of suitable mechanical gearing. Alternatively, the main power unit could be hydraulic.

In its raised position the outer cylinder is free to turn continuously. In operation, a nylon rope, e.g. as shown as 44 in Fig. 7 or a wire rope 46, is wound by a seaman several times, e.g. seven to eight turns, around the outer cylinder upon the bottom lip 22 thereof until the top lip is reached. A suitable diameter 53 for a wire rope is 50 mm and the diameter 54 of a nylon rope is 100 mm; the lower lip 22 must be of an appropriate depth. A suitable dimension of the other parts of the bollard can be: thickness of the two cylinders

12, 20, each 15 mm, thickness of the lower gear ring 14=30 mm, thickness of the upper gear ring 24-32 mm, so that the clearance between the tubes 12 and 20 is 2 mm, and total height of the bollard about 80 cms, which would accommodate 8 turns of nylon or polypropylene rope of diameter 10 cm.

Whilst the rope is heaved and taken up on the outer cylinder 20, the two gear rings are held apart because the elongated hole 50 in the guide blocks 30 is at an angle, and the respective spigot 34 of the bearing 32 then slides to the upper end of this slot 50. Wear on the bearing is reduced because the winch being used is a little higher than the bollard and pulls the rope slightly upwards. The guide blocks thus serve to hold the guide bearing while it rolls around the groove 28 as the outer cylinder rotates with its gear ring 24, and it restricts vertical movement of the outer cylinder. The guide blocks take only a little of the force exerted by the rope or hawser, since the pull thereof is substantially horizontal and is taken by the bearing surfaces of the two cylinders.

When heaving is completed, and the rope from the ship to the shore is tight, the operator slackens the rope very slightly, say 20 mm, and that small reverse action causes locking due to the angled elongated holes in the guide blocks, whereupon the respective teeth are pulled together as the outer cylinder is guided to the position shown in Fig. 8, and the cylinders are locked together, and reverse motion is not possible. The ship is secured.

To release the rope, a seaman removes the top four or five layers of rope, whereupon the rope will slip to a slackened position so that the other end thereof can be released, as with a conventional bollard.