# Analysis of Dimensional Tolerances on Hydraulic and Acoustic Properties of a New Type of Prototypal
## 1 Introduction
### Development of Gear Unit Design  
The development of a gear unit design tends to desire a reduction of performance pulsation, which may be the reason for: an improper operation of control elements, vibrations, and increased noise of machines and devices with hydrostatic drive. Ear units with an external toothing are characterized by a coefficient of unevenness in efficiency at an average level of approx. 18%. Compared to other positive displacement units, gear pumps have the highest pulsation rates. The most effective method of pulsation reduction is obtained as a result of using the active method, i.e., by mitigating the course of the instantaneous performance function and by reducing the amplitude of the pulsation of efficiency transmitted to the hydraulic system. The second important direction of gear pumps development is the minimization of energy losses and increase of transmitted power; thus, the tendency of any changes is aimed at increasing the energy efficiency of the generator even more.  
The analysis of numerous patents, literary sources, and other currently manufactured gear units could indicate that technical methods have already been exhausted to ensure the optimal internal tightness with maximum operating pressures, minimum efficiency pulsation, and noise emissions [7; 8; 9; 10; 11; 12; 13; 14]. The conducted tests and considerations prevent achieving peak operational parameters by comparisons to modern gear units.  
Therefore, new tasks and goals have been set, one of which is presented and discussed in this article. Two basic goals set in this prototype gear pump research are: to present theoretical possibilities, as well as methods, to reduce performance pulsation and, then, to propose new design solutions to increase working pressures while ensuring high internal tightness. These tasks required solving several technological, design, and manufacturing problems. As a result, innovative design solutions were proposed to reduce the performance pulsation, increase the working pressure, and improve the volumetric and total efficiency, as well as reducing the noise emission to the environment. Eight patents, including copyrights, were filed during this research, with much time having also been devoted to the cognitive aspects. New mathematical models describing, among others, the bearing and gear wheel loads for new methods of compensation of clearance, the determination of presented stresses for compensating elements, relief of sealed space, shaping tooth contours, or performance pulsation modeling. The theoretical considerations carried out were verified by numerous acoustic and hydraulic tests.  
There are many research efforts and production methods concerned with and regarding the design of pump profiles only to be used in gear units. It is instigated mainly by striving for better hydraulic and acoustic properties [15; 16; 17; 18; 19]. This is the next part of the article related to the identification of sensitive dimensions of the importance of measuring points. The tests were carried out for four pump prototype units: 1 PWR, 2 PWR, 3 PWR, and 2 PW-SEW. The results were compared with a conventional pump to determine the impact of the proposed innovative design solutions.  
For example, in the work described in [19], the identification of sensitive control dimensions (value/tolerance) of examined pumps (3 PWR-SE) was determined by means of the multi-valued logic trees.  
In the present work, a neural network is used to analyze the dimensional tolerance and the impact of the performance of prototype 2 PW-SE [15; 20] gear pump components on the overall performance. Optimization then minimized the acoustic noise and vibration. In addition, the theoretical considerations and experimental results presented here open new possibilities for gear pumps.