WO00/26132 PCT/SE99/01991 WINCH TECHNICAL FIELD The present invention relates to a windlass/hoist, preferably to be used in small crafts and vehicles, by sea and land, e.g. sailing boats and the like, which comprises four main components, i.e a drum unit with a rotatable drum cylinder, designed to carry a rope, band, wire, cable or the like, which can be wound on the drum cylinder; a motor unit; a coupling unit with a disconnection element and a reversible driving element; a gear unit with a plurality of gearing steps; as well as a coupling unit with a reversible driving element, the motor unit and the coupling unit being disposed within the drum cylinder and the coupling unit including a disconnection element with a spring-loaded coupling ring having axial heads and spaces between the heads, designed for periferally and axially mounted pins on an outer drum support, which supports the drum cylinder, the coupling ring as well as a coupling cog wheel, said pins being designed to mesh between the heads in the coupling ring, so that the drum cylinder can be driven in two optional directions, and the coupling ring between the lower bottom surface of said heads being designed with guide surfaces, designed to guide the pins, e.g. to a disconnection position. BACKGROUND ART Windlasses are sold, which have disconnection elements WO00/26132 PCT/SE99/01991 2 designed to allow the anchor to be quickly dropped into the water and to the bottom. A few embodiments of such known devices are described in SE B 8103115-5 (426 161) and SE C2 501 244 and SE B 9700720-7. In one of these windlasses a gear is used, which is very satisfactory but which require a molded framing, since it is sensitive to vibrations and other exterior stresses. This framing is very expensive to manufacture and is heavy and unwieldy. BRIEF DISCLOSURE OF THE INVENTION The object of the present invention is to eliminate the above-mentioned drawbacks and inconveniences when using windlasses, primarily mounted on smaller crafts, preferably up to 16 m/52 feet, in order to facilitate the anchoring or the weighing on an anchor, namely the unwinding from and the winding onto the rotatable drum of the windlass of that band, rope, cable or wire, which is fastened to an anchor. One main object of the invention is to build a strong windlass, which is small and compact, has a reliable remote-controlled unwinding and a controlled winding of a band in combination with a coupling, which can be disconnected as well as be driven in both directions in a controlled way. One object of the invention is that the windlass according to the invention is to be used as a hoist. Another object of the invention is to build a windlass, WO00/26132 PCT/SE99/01991 3 which has an automatic, mechanically operated coupling. One object of the invention is to build a windlass, which is reliabel to operate. Another object of the invention is to build a windlass, which is economical to operate. One object of the invention is to build a windlass, which is adjustable as regards the gear change. An additional object of the invention is to build a windlass, which is water resistent and easy to manufacture. Another object of the invention is to build a windlass, which functions in a reliable way. These and other objects are attained according to the invention, when a device described in the introduction is used, provided the coupling unit includes a spring-loaded coupling ring having axial heads and spaces between said heads for periferally and axially mounted pins on an outer drum support, which supports the drum cylinder, the coupling ring as well as a coupling gear wheel, said pins being designed to mesh between said heads in the coupling ring in order to drive the drum cylinder in two optional directions, and between the lower bottom surfaces of said heads the coupling ring being designed with guide surfaces in order to guide said pins into e.g.a disconnection position. According to the inventive idea a windlass is obtained, which it is easy to handle, is ideal for a single-handed WO00/26132 PCT/SE99/01991 4 operation, because it is possible to control the anchoring process from the driver's seat by means of the disconnection function and by means of a radio-control precisely pinpoint the anchoring position, with cm exactitude, and also, if necessary, from ashore. The windlass has a large tractive power, has a variable, adaptable gear change, by which the required rotational speed is obtained, is economic to operate, functions in a noiseless way and has a low weight as well as is compact. Also, the windlass can unwind a substantial band length without trouble, since it has an automatic cable-guide and is water resistent, as well as is safe to operate, since it has a self-activating overload protection, which is released automaticly but is reactivated immediately without any special measures taken by the operator. BRIEF DESCRIPTION OF DRAWINGS Fig. 1 shows a first embodiment of the windlass according to the invention in a longitudinal section; Fig. 2 shows a coupling ring, which is an element of the coupling of the windlass, in a perspective lateral view in a oblique direction; Fig. 3 shows the coupling ring in Fig. 2, seen from above in a horizontal view; Fig. 4 shows the coupling ring in Fig. 3, in a vertical sectional view along section A-A in Fig. 3; Fig. 5 shows in an oblique, lateral view a drum support, which is included in the coupling, for the coupling ring in WO 00/26132 PCT/SE99/01991 5 Fig. 2; Fig. 6 shows in a horizontal view from above the drum support in Fig. 5; Fig. 7 shows in a vertical section the drum support in Fig. 5 along section A-A in Fig. 6; Fig. 8 shows various positions of the windlass according to the invention, in which figure: a) shows an exterior mounting of the windlass with an anchor roller and a housing on a boat deck; b) shows an interior mounting of the windlass with an anchor roller, mounted on a deck; c) shows an interior mounting of the windlass with several pulley wheels and an anchor roller, mounted on a deck; d) shows a mounting of the windlass with pulleys as well as an anchor roller, mounted at the prow, designed to use the windlass in order to hoist a boat onto a trailer; e) shows an interior mounting of the windlass with an anchor roller, mounted through the stem of a boat; f) shows an interior mounting of the windlass with the rope fastened in a buoy to moor the boat; g) shows an interior mounting of the windlass in the kelson and with pulleys as well as an anchor roller mounted on the deck; h) shows an interior mounting of the windlass below the deck with an anchor roller mounted at the prow and with range marks; i) shows an exterior mounting of the windlass with and anchor roller and a housing, mounted on the swimming bridge of a boat; WO 00/26132 PCT/SE99/01991 6 j) shows an interior mounting of the windlass with a pulley and an anchor roller, mounted on the swimming bridge of the boat; k) shows an interior mounting of the windlass in the kelson and with pulley as well as an anchor roller, mounted on the swimming bridge; as well as 1) shows an interior mounting of the windlass with a pulley on the interior side of the stern and with an anchor roller mounted on the swimming bridge. DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION In Fig. 1 a windlass according to the invention is shown in a longitudinal section. This windlass comprises two gables 1,2, constituting the framing, and between the two gables 1,2 a rotatable drum unit 3 with a drum cylinder 4, designed to support a band, rope, wire, cable or the like, which can be wound on the drum cylinder. A motor unit 5 is freely disposed within drum cylinder 4 and fastened by means of a motor support 6 in one of gable ends 1. Motor support 6 is fastened by screws in gable end 1. Motor spindle 7 extends out of gable 8 of drum cylinder 2 and into a central opening 9 in motor support 6 and into gable 1 of the windlass, in which it is mounted in a bearing 12 and extends out of gable 1 of the framing, in which it drives a gear wheel, a sprocket or a cogless wheel 13. Also, in a lower position on the framing a driving spindle 14 is mounted in gables 1,2 gear wheels, sprockets or cogless wheels 15,16 being mounted in the two ends of the driving spindle. Wheel 15 has a much larger diameter than wheel 13 on motor spindle 7 and around these wheels a belt or a chain is placed (not shown in the drawings). The number of revolutions per minute of motor spindle 7, about WO00/26132 PCT/SE99/01991 7 6000 revolutions per minute, will be geared down to 2000 rev./min. on driving spindle 14 (first gearing step). Wheel 16, which is mounted on the other end of driving spindle 14, has a small diameter and has a chain or a belt (not shown in the drawings), which also drives a wheel 17 with a large diameter, which is mounted on an inner drum support 18, fastened in gable end 2 of the framing (second gearing step). On large wheel 17 a smaller gear wheel 19 is axially fastened in the interior of the framing, which gear wheel 19 drives a gear wheel 20 with a larger diameter, which is mounted on driving spindle 14 inside the framing (third gearing step). This gear wheel 20 drives in its turn a gear wheel 22 with a larger diameter, which is mounted on an outer drum support 23, which in its turn is mounted on that portion of inner drum support 18, which is turned towards the drum, and fastened by screws in the drum (fourth gearing step). Four hardened steel pins 24 are mounted on gear wheel 22 around the periphery, designed to interact with a coupling ring 25, mounted on inner drum support 18. Coupling ring 25 is moveable in a lateral direction on outer drum support 18 and an electromagnet 26 is mounted around coupling ring 25 in the form of two windings 27,28, one hold winding 27 and one pull winding 28 and when electromagnet 26 is activated, it pulls drum cylinder 4 and disconnects it, and when the electromagnet is deactivated, coupling ring 25 is released and enters the drum and locks it. Also, a drum brake (not shown in the drawings) is mounted on motor spindle 7 and it is designed to prevent a reversing of the drum.
WO00/26132 PCT/SE99/01991 8 At gable 8 of the drum cylinder a drum bearing 11 is mounted between drum cylinder 4 and motor support 6. Also, on motor support 6 a gear belt wheel 29 is mounted between drum bearing 11 and gable 1 of the windlass. From this gear belt wheel 29 a belt (not shown) is connected to a gear belt wheel 31, mounted on a lead screw 30. Lead screw 30 is mounted in the framing at its one side in gable 1 as well at its other side in a gable flange 32. Also, a guide house 33 is mounted on lead screw 30 and is designed to guide the band or the rope along the entire surface of drum cylinder 4. On the inner casing surface of drum cylinder 4, adjacent gable 2, outer drum support 23 is fastened by screws. Drum support 23 comprises three cylindric parts, 34,35,36, having different sizes. The diameter of cylindric part 34 allows it to be disposed inside drum cylinder 4 immediately below the inner casing surfaces and to be fastened in drum cylinder 4 by means of screws 37. Outer vertical side 38 of cylindric part 34 is provided with four hardened pins 39,40,41 and 42, which are designed to interact with coupling ring 25, which is rotatably mounted on central cylindric part 35. In Fig. 2 it is shown, how coupling ring 25 is designed. It is provided with axial heads 43,44,45,46 having radial sides and into which pins 24 in gear wheel 22 are to be inserted. Pins 24 are mounted on gear wheel 22 and mesh with springloaded coupling ring 25, when the electromagnet, which is controlled by a processor unit, is actuated in the required time intervalls. Between axial heads 43,44,45,46 coupling ring 25 is provided with profiles, which from outer bottom surfaces 47,48 of the heads extend towards the middle of the interspace and to a WO00/26132 PCT/SE99/01991 9 height, which is the same as the height of heads 43,44,45,46. In this way guide surfaces for pins 39,40,41 and 42 are obtained, when they are inserted into the interspace between heads 43,44,45 and 46 in coupling ring 25 and are driving the drum in a certain direction or in the opposite direction, depending on in which direction gear wheel 22 rotates and consequently against which side of heads 43,44,45 and 46 pins 39,40,41 and 42 will make driving contact with. In case gear wheel 22, which is spring-loaded against drum support 23, by means of electromagnet 26 is not in a mesh position, coupling ring 25 will function entirely as a disconnection element and will then easily and smoothly be able to mesh with drum support 23 in order to achieve a controlled driving forwards and backwards. Thus, motor unit 5 and coupling unit 23,25 are mounted in drum cylinder 4 and the four gearing steps are positioned outside drum unit 3. Thus, drum cylinder 4 as well as gables 1 and 2 constitute a housing for motor unit 5 and coupling 23,25, and consequently no special housing for these elements is required. Thanks to the design of the four gearing steps, which results in an efficiency of 90%, the rotational speed of the motor of 6000 rev./min. having been reduced to a rotational speed of the drum cylinder of 52 rev./min., motor unit 5 can be small i.e. smaller than a conventional worm gear having an efficiency of 45%, which is conventional in this connection. The voltage of the motor WO00/26132 PCT/SE99/01991 10 can be 12 or 24V. The driving can be carried out by means of belts or chains. It is suitable to use a driving belt in the first gearing step and chains in the other gearing steps. The wheels suitably are made of polyvinyl. It is easy to alter the gear change consequently also the rotational speed of the drum cylinder by exchanging the gear wheels in the various gearing steps, since these wheels easily can be reached outside the framing. This is a substantial advantage compared to a worm gear, because the latter has fixed gear ratios. This windlass design only needs a motor, which is half as large, and thus, it consumes only half as much energy as motors used in conventional windlasses, which is a substantial advantage, when the windlass is used on sailing boats, which often do not have a large electric currentcapacity. Also, it is light-weight and compact and its tractive force is up to 1000 kg and its weight is only 19 kg and additionally it is able to handle an anchor having a weight of up to 30 kg and using a band, preferably made of polyester, having a length of up to 60 m. The windlass according to the invention facilitates the anchoring of a boat maximally for all the people onboard and is an extraordinary aid during single-handedly carried out excursions, since it is possible to easily and smoothly control the anchoring process from the driver's seat by means of the disconnection function. By means of a radio-control it is possible to make the anchoring very exact, with a cm-precision, by stretching the band or by hoisting the band outwards at a distance WO00/26132 PCT/SE99/01991 11 from the windlass. The rope guide has a centered driving and the coupling allows a controlled and forced driving of the band, which makes it possible to wind all the band on the drum without trouble and this makes the windlass very space-saving. The band, which is made of polyester, is very durable. The breaking point of the band is a s high as 3 tons, i.e. stronger than an 8 cm cable, and the side surfaces of the band allow a brake action in the water, which in its turn allows a positive resilient effect during the anchoring and the mooring. The windlass has an electric current safe-guard, which releases automaticly, if and overload occurs, but which is reactivated immediately. An automatic stop element disconnects the electric current and the anchor reaches a parking position with a crawling speed, in which it is fixed, completely automaticly. A counter indicator is integrated into the windlass, which shows the fed length, which improves the safety during the calling and the removal of the anchor. Also, a buzzer is mounted in the windlass, which emits various sounds during the various working moments of the windlass, e.g. information about the direction of motion of the anchor. The electromagnet, which pulls or holds the coupling ring, is process controlled and it pulls only during e.g. 2 WO00/26132 PCT/SE99/01991 12 seconds, after which it automaticly connects the hold winding. The motor preferably is a PM motor, i.e. a motor with a permanent magnet. It is to be emphasized, that the present invention can be modified within the scope of the inventive idea, which is set forth in the enclosed claims.