The rotary hydraulic motors

General properties and description


the Rotary hydraulic motor is a hydraulic machine designed to convert hydraulic energy into mechanical energy due to message working on energy for rotation to less than 360 degrees (typically a maximum of 270 degrees).


In Fig. 1 shows the scheme of a rotary hydraulic motor. It is clearly seen that for it to work you must either create excess pressure in one sector, or area of low pressure in the opposite direction.

History of rotary hydraulic motors connected with the history of hydraulic cylinders. The hydraulic cylinder is the hydraulic motor of the reciprocating action. Installing the RAM on the hinge people do not consciously created the first rotary hydraulic motor (it is possible that it was first pneumatic action).

Given that not all the pivot rotation can be achieved by means of a hydraulic cylinder, the question arose of creating a specialized mechanism.

the Main consumer of first rotary hydraulic motors are construction and agricultural industries. Support – rotating devices have become subsequently essential host any tractor with attachments.





the Main feature of specialized rotary hydraulic motors is that they are not complex (in terms of method of execution of actions) and difficult ( in terms of execution of tasks) job. Essentially making the torque is not a difficult task, choosing the axis of rotation and impart the force on the other end of the lever and all… the business is, but from this moment start to be difficult.

firstly to install specialized rotary hydraulic motors come in instances when there is no possibility to set the cylinder to hinge (usually do not allow dimensions).

In the second setting of the rotary hydraulic motor may require additional evaluation of turning point efforts, depending on the system pressure (usually it changes with the angle of rotation of the hydraulic motor).


individual features could include the use of hydraulic fluid as the energy source in all hydraulic motors. This problem was faced when creating cylinders: when creating a high-pressure fluid begins to seep through the sealing rings (cuff seal) and the cylinder could not complete its task and Vice versa with a high degree of viscosity of the fluid load on the pump and system of pipes carrying liquid from the pump to the cylinder were enormous. It was necessary to compromise, and what were the specific hydraulic fluid, petroleum-based, running along with their main functions is even and lubricating – cooling.

the specific application is the specific mechanism – a rotary hydraulic motor further adds to the complexity of contour seals in the cylinder if it was a cylindrical rubber washer in the swivel mechanism is the typically flat segment of a circle or ring, which should also be a gasket and to provide slide across its surface. Given that different parts of the segment making a large move (closer to the axis of rotation of the linear movement is less than) the work force of the slide will be different, and thus the necessity of lubrication and wear will be different.



Features and their impact


Hydraulic motors with limited angle of rotation is called angular, with differences in piston and vane.

the Piston, as already mentioned above, the simplistic idea of a hydraulic cylinder mounted on a rotating mechanism. Plate of the same rotary hydraulic motor (Fig. 1) is a body formed therein deaf cylindrical hole, inside which is placed a plate, it is called «the Gate», limited to swing at a certain angle, with the supply of hydraulic fluid on opposite sides of the plate to give it time.


Piston rotary hydraulic motors vary in principle the performance of their functions drives the movement. Distinguish lever, rocker, gear and worm transmission and even belt. All these types of transformation are regulated and managed, with mechanisms of protection against overloads, etc., intended for the rotation of the mechanism around a particular axis, but their design (piston-type rotary hydraulic motors) allows you to rotate after a certain displacement of the mechanism (shift to rotate).


Vane rotary hydraulic motors are available with one, two or three plates. Increasing the number of plates you can reduce the angle of rotation of the hydraulic motor without having to modify the design of the camera. So for example the maximum angle of rotation of the two plate of the hydraulic motor will be 60 degrees. Applying trehlistnaya hydraulic motors two plates is further separated working chamber additional «blank» segment, which excludes hydraulic fluid.


Formula to calculate torque on a shaft of the rotary plate of the hydraulic motor represents the following:


M = bz(p1-p2)(r1-r2)(r1+r2)/2


b – length of the plate (scraper)

the z – number plates

p1 and P2 – pressure in the working and idle cavities

r1 the radius of the chamber within which rotates the rotor and plate

r2, the radius of the rotor


Given the complexity of ensuring a healthy state over a long period of time vane rotary hydraulic motors are used only at low pressures of the working fluid.



Analysis of manufacturers


Considering the data provided by the different resources of the Internet leaders in the field of manufacturing of hydraulic cylinders for different purposes (including rotary hydraulic motors) are the following firms: Parker, Denison, Bosch, Rexroth, Vickers. Description and peculiarities of their structures suggests that the basic principle of creating high-quality technique is the use of high precisely made and accurately fitted to each other parts (rolling bearings and sliding seals, pipelines and highways, hydraulic fluid).


Of domestic producers of such prominent representatives as discussed above, the world network was not, however, there are some kind of leaders: the company «GidroMash», the Plant actuators, «Promprivod». More prevalent manufacturers of hydraulic motors and rotary hydraulic motors was not, however, the representatives in question, a more detailed analysis of the nomenclature of the products are not any kind of legislators «fashion» or inventors, but merely continue to produce accumulated since the Soviet Union construction.





Given the specifics of the hydraulic motors check for the maximum force before failure, resistance to increasing loads on the shaft as smoothly varying, and drums, to the ability to work in certain temperature ranges and corrosive environments.


as well and check the various elements of the hydraulic motors, depending on their type. So check the plate on the stability of the blades and shafts, to limit the pressure inside the working chamber and the damper, the durability of the seals. Piston check on the stability of the rod under maximum load, stability and durability of the seals and piston in General. Also checked the rotary mechanisms for limiting torque, gear check for the maximum force on the tooth, to determine the optimal module and number of teeth. Similarly with other types of rotary mechanisms. Determining the marginal value of effort to the failure mechanism and the maximum force on the shaft of the hydraulic motor it is possible to provide fuse (obviously destructible mechanism when the limiting force), which is inoperative will prevent the failure mechanism.



Given the specifics of the test itself and the same hydraulic fluid on its ability of fluidity and compressibility, regardless of the ambient temperature. Another important factor is the viscosity of the hydraulic oil, a well-known fact that with increasing temperature decreases viscosity and little viscous (highly fluid) hydraulic fluid easier to pass through the seals, and accordingly disabling the hydraulic motor. Defining an optimal working temperature of the liquid and the degree of heating in the process, there is a possibility of installation of radiators on the mechanism (rotary actuator) or the tank expanders hydraulic fluid.

potential faults

the Most common failure of hydraulic motors is failure of the seals between the rubbing parts of the plate cylinders and rotary hydraulic motors. However, by itself this fault can not occur, a properly designed mechanism works to violating one of the established characteristics. So an increase in the temperature of the working fluid or excess effort on the shaft or in the hydraulic system will surely lead to failure. Often these or similar reasons are the causes of failure of hydraulic motors, however, the fault can be repaired and beyond repair.

assuming that is out of order only the seal, and lost the hydraulic fluid, changed the gasket and perenapravljat system fluid and continue the work. However, if the mechanism is initially performed in a non remontoprigoden the performance of the slightest malfunction leads to replacement of the entire mechanism. Given the market economic model for manufacturers is the most profitable option.

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