The present invention refers to a hydraulic motor with high torque and low speed particularly adequate for large-sized units in applications that demands potential power and where endurance, reliability and simplicity in the maintenance of the equipment are of real importance. Potential power hydraulic systems are widely used in a large number of applications due, mainly, to the versatility, reli¬ ability and operational characteristics, b) BACKGROUND ART

The hydraulic motors that develop high torque are generally provided with radial pistons (Staffa, Sundstrand and others) and they operate at much higher pressure. Those motors have countless moving components and a great sophis ication to reduce the efficiency loss because of the mechanical fric¬ tion of its components. The complexity of the system brings about a much more care- ful and expensive maintenance. The ver .manufacturing of those motors is rather complex and at high cost so as to garantee acceptable levels, of performance.

Apart from that, there are vane hydraulic motors, such as the ones made by the Norwegian firms Norwinch and Brattvaag which are the more similar ones to the one herein presented. The Norwinch low pressure hydraulic transmission generally works in a closed circuit. The motor itself consists of a cylindrical rotor where eight sliding vanes are placed and linked two by two alternately by means of an also sliding arched spindle (the vanes are not attached to that spindle but just in contact with it).

The case has an approximately elliptical shape including both the oil inlet and outlet. The vanes are always kept in contact with the case and when a vane is contracted (posi- tion in which the rotor and the case are in contact) , it pushes the linking spindle which expels the "opposite" vane, always following the case curve.

The Brattvaag hydraulic motor consists of a cylindrical, square or even dodecagbnal rotor in which the vanes are ra¬ dially placed. The number of vanes varies from 4 to 12 de¬ pending on the motor. In this motor the case has a differ- ^• 5 rent shape depending on the respective rotor. The vanes are always kept in contact with the case walls by means of the pressure of the oil which is sent into the vane chambers through the grooves in the rotor and which tends to expel them. 0 In both cases, the project is highly sophisticated as -w-e .a-s- the piston motors demand a fairly complex manufacturing process and a careful and expensive maintenance. c) DISCLOSURE OF INVENTION Like all hydraulic motors, no matter its kind, the present 5 invention is the traction operating part of a potential power hydraulic motor, which must have a hydraulic pump which will generally be the positive displacement type,with vanes, gearings, axial pistons, etc. This pump is responsi¬ ble for the fluid supply of the hydraulic motor through a 0 hydraulic circuit that may have an oil reservoir, filters, safety and relief valves, outflow regulating valves, direc¬ tional valves, etc.

The hydraulic pump of the system can be operated through any known means (eletric engines, internal combustion en- 5 gines, turbines, etc) as far as it is adequate to its poteri tial power and operation characteristics.

The motor in question has constant displacement and a se¬ ries of constructive characteristics which make it quite - strong, extremely simple and capable of bearing the most 0 severe load conditions in all kinds of equipment. Its con¬ ception allows a fairly smooth and uniform operation at a rotation rate of Ir.p.m. under full load conditions. The operating principle of this motor is fairly simple. The two chambers in the motor are fed by two independent fluid 5 circuits. Each chamber has two opposite oil inlets and out¬ lets, linked to one another by each of the head-shafts. The rotors in the chambers are displaced at 90 .

The sluice-valves are totally devised according to the de¬ sign on figure 3. The fluid coming from the pump fills the volume of the rotor (4) lobule; the case (1), the main cov¬ er (2) and the sluice-valves (7) . The load on the shaft brings about the hydraulic pressure in the chamber. This pressure is limited by the characteristics of the pump and the structural dimension of the motor. As the fluid pres¬ sure acts on the rotor (4) it provides a force component

_* perpendicular to the shaft bringing about the traction torque . Because of the rotation movement of the shaft and the rotor (4) the sluice-valve (7) will be withdrawn at the start of the rotor (4) ascendant curve. At this stage a rabbet on the ro¬ tor (4) or on the case (1) causes a pressure relief in the chamber and the sluice-valve (7) whose main function is that of a reaction plate, acquires free movement in its seat, without lateral pressure effect. The start of the sluice-valve (7) withdrawn in one rotor (4) shows the. start of the other rotor operation, displaced at 90 , whose valves are actioned by the oil pressure on the inlet. In this way, the rotors (4) work alternately assuring the continuity of the movement. The oil ejection takes place si¬ multaneously to its admission, through the rotor (4) lobule, by means of the outlet orifice in the rear part of the valve (7). d) BRIEF DESCRIPTION OF DRAWINGS

The motor is basically formed by a case with two different chambers, each of them with its rotor and separate by an in¬ ternal wall, as shown on the attached figures: Figure 1 - shows an axlewise view of the motor case; Figure 2 - shows a lateral view of the casing lead-shaft; Figure 3 - shows the rotor in its chamber; Figure 4 - shows a cut of the upper part of the set; Figure 5 - shows an expanded view of the motor with its main components in one of the chambers. In figures 4 and 5, we can see the case (1), the main covers (2), the bearing -covers (3), two rotors (4), the head-shaft covers (5), the axle (6), the sluice-valves (7), _t he bearings

(8), the sealing-rings (9) and (10), the stud-bolts (11) for fixing the covers to the case (1) and the bearing cover scre (12), the rabbets (13), the chambers (14) the lateral guides (15) of the sluice-valves (7). e) BEST MODE OF CARRYING OUT THE INVENTION

The following constructive details which identify the concept of the present invention, should be pointed out: The sluice-valves (7) which separate the pressure chambers from the oil chambers run on lateral guides in the case and cover of the motor and have just & seesaw movement. Such a la eral guide arrangement assures a better rigidity of the valve apart from allowing the manufacturing of larger and more dura ble components so that higher torque and more safety for the motor components are achieved. Another peculiar characteristic of this motor are the rabbet on the rotor (4) and/or the case (1) . Such rabbets provide th pressure relief, in one of the chambers together with the re¬ sultant torque decrease which is immediately assured by the other chamber rotor, displaced at 90 . Thus, the sluice-valves (7) when in movement are not laterall actioned by the operation pressure of the motor. This characteristic allows really lower wastage levels of the sluice-valves (7) and of the sliding area of the rotors (4) increasing the endurance of the set. Another characteristic of this motor is that the rotor (4) outline curve is such that the load of one rotor (4) can be transferred to the other with extreme smoothness and really low speed fluctuation. It is clear that the ^' motor shaft is no radially actioned. Therefore, it is not submitted to flexure because the chamber under the same pressure are opposite shaftwise. Apart fro that, the geometry of the rotors enables an easy me¬ chanical balance. It is also understood that the traction torque obtained on the shaft, is a consequence of the geom- etry and size of the motor as well as the pressure differen¬ tial between the pressure and the oil oulet chambers. The efficiency of the set depends mainly on the fairly reduced

mechanical friction as a result of the very low number of ov ing components and on the perfect internal sealing between the zones of high and low pressure which can be obtained through accuracy.in the components grinding. f) INDUSTRIAL APPLICABILITY

The present invention due to its simple conception with low number of components, easy to manufacture and constructive solutions that search for more enduring components, and espe¬ cially adequate for large-sized units for application of high torque and at low speed allowing the research of new fields in the application of high powered hydraulic systems also attending to the utility needs of highly reliable equip¬ ment, low cost manufacturing, simple maintenance, and also capable of replacing conventional actioning systems with effi_ ciency acquisition and therefore less power-consumption.