If there is high pressure and lower rotation dynamics pumps are inadequate since their productivity decreases in lower speed. In fact after a certain point these pumps will not work.

The rotary pumps are good solution in cases demanding low rotational speed and high pressure.

In an ordinary rotary pump, the liquid volume passed throughout the pump is constant per unit rotation. This volume does not change according to rotational speed. To change the quantity of flow the rotational speed of the pump has to be changed. This causes some difficulties in systems having constant speed. The following rotary system, which we claim to protect it, has a special apparatus to prevent this problem. The flow can be adjusted without any friction inside or outside of the system.

The proposed system has two main differences from ordinary rotary pumps. In the proposed system there is a rotor/cover pair, in contrast to classic rotary systems that have just a simple rotor. In this system, the rotor is placed into a rotor follower cover. The rotor and rotor follower cover rotate circularly around the same axis. The other difference in the proposed system is that there is an additional movement parallel to the axis of principle rotation. An auxiliary apparatus moves the rotor and cover back and forth (Hereafter, this movement will be called as"sliding, or to slide"). This special movement along the axis is only used when the volume needs to change. The rotational speed does not need to change; it stays constant.

Following description explains the system with two rotors and two lobes (See Fig. 1). In the system there are two cylindrical halls partially overlapping (Fig. 2). In center of the each hall there is a shaft (See Fig. 3) [1,2]. The shafts have been connected each other by via cogwheels [3,4]. Each shaft has a stuffing filler [5,10], a rotor [6,9] and a rotor follower cover [7,8], respectively. This order is reverse on the second shaft (See Fig. 4). The rotors have two parts: cylindrical and elliptical parts. The cylindrical part of the rotor is always inside of the filler. The cross section of shafts has polygon shape, and they drive only rotors and covers. The fillers never rotate and they never get away from the related rotor. On the first shaft (drive shaft) the filler is fixed; the rotor can only rotate next to the filler while the cover can rotate and slide. On the second shaft (driven shaft) the cover can only rotate circularly; the rotor can rotate and slide; and the filler can slide together with the rotor. In the other words, in certain conditions the rotor on the second shaft, its filler, and the cover on the first shaft slide altogether. This sliding is not related with the circular rotation of rotors and their covers. Sliding can be performed by means of a special tool. The power and connection elements of the sliding and main rotational movement have not been drafted to keep the figures simple and to diagram the main function of the system. When the system is offthe rotors rotate together fully inside the covers (Fig. 5,7,9 & 11). In this situation even the rotors run, there is no flow since there is no volume between the rotors. There is no common surface between the rotors except that they contact each other on a corner point (Fig. 7). When the rotors have been forced apart from their covers (Fig. 6), a common surface between rotors is taken place (Fig. 8), and a cavity providing flow is created [11] (see Fig 10 & 11). This"sliding"Xlnovement changes the volume of the cavity. The principal rotational movement causes a flow like an ordinary rotary pump. The advance in proposed system is that there is a possibility of changing cavity volume between rotors without any change in rotational movement.