## 3 Results  
The laboratory equipment for the evaluation of engine oil filtration was designed to assess the properties of various engine oil filters and their filtration capabilities. Tests on this equipment will shorten the testing time of oil filters, as they are not tied to the operating conditions of the intercity bus, but we will induce the operating conditions by simulation. Tests of suitability for the use of different types of oil filters will be evaluated on the basis of the influence of contaminated working fluids on the change of pressure in the hydraulic circuit and the change of flow rate in the hydraulic circuit of the test equipment. At the same time, we will monitor and evaluate changes in the physical-chemical properties of the assessed motor oils. In the proposed laboratory test equipment, hydraulic elements are used in the reference and test hydraulic circuit: tandem gear hydraulic pump, safety pressure valve, throttle valve with stabilization, three-way valve, filter, heater, tank and measuring devices. and pressure sensors are located behind the throttle valves. There are two oil filters in the primary and secondary circuits, while filter (1) is the filter recommended by the vehicle manufacturer and filter (2) constitutes an alternative use. The direction of the oil to the individual filters is ensured by changing the position on the three-way valve. Circuits A and B consist of a tank in which a heater is included, which we use to reach the operating temperature. Behind the heater is a thermometer and a manometer. Subsequently, the circuit branches off and by means of a three-way valve, the flow is directed to the filters (1) or, if necessary, to filters (2). A three-way valve is re-introduced from the filters at the outlet tube. Behind the three-way valve is a combination of the sensors for digital recording unit Hydac HMG 3110, which is used to sense operating conditions in the hydraulic circuit, temperature, pressure, and flow sensor. Figure 3: Equipment for comparing the flow properties of oil filter materials in the lubrication circuits of internal combustion engines. Legend: **A—**reference measuring circuit; **B—**test measuring circuit; **C—**recording and evaluation circuit; 1, 22—**heaters; 2—**tandem hydraulic pump; 3—**coupler; 4—**rpm sensor; 5—**frequency converter; 6—**electric motor, 7, 23—**tanks; 8, 24—**safety valves; 10, 19, 26, 35—**pressure sensors; 11, 18, 27, 34—**flow sensors; 12, 21, 28, 37—**temperature sensors; 13, 15, 29, 31—**three-way valves; 14, 32—**original filter materials; 16, 30—**testes filter materials; 9, 17, 25, 33—**sampling points; 20, 36—**throttle valves; 38—**computer with software; HG—**tandem hydraulic pump; H\({}_{1}\), H\({}_{2}\)—heaters; N\({}_{1}\), N\({}_{2}\)—tanks; FM—**frequency converter; SP—coupler; SO—**speed sensor; PV\({}_{1}\), PV\({}_{2}\)—**safety valves; Q\({}_{1,1}\), Q\({}_{2,1}\), Q\({}_{2,1}\), Q\({}_{2,2}\)—**flow sensors; p\({}_{1,1}\), P\({}_{1,2}\), P\({}_{2,1}\), P\({}_{2,2}\)—**pressure sensors; t\({}_{1,1}\), t\({}_{2,1}\), t\({}_{2,2}\), t\({}_{2,2}\)—**temperature sensors; F\({}_{1,1}\), F\({}_{1,2}\), F\({}_{2,1}\), F\({}_{2,2}\)—**filters in circuit A and B; TV\({}_{1,1}\), TV\({}_{1,2}\), TV\({}_{2,1}\), TV\({}_{2,2}\)—three-way valves; OV\({}_{1,1}\),OV\({}_{1,2}\),OV\({}_{2,1}\), OV\({}_{2,2}\)—**sampling point; M—**electric motor; SV\({}_{1}\), SV\({}_{2}\)—**throttle valves. The reference measuring circuit A consists of an electric motor 6 connected to a frequency converter 5 for setting and maintaining the required speed of the first Section 2 of the tandem hydraulic pump in the range from the minimum to the maximum. The first Section 2 of the tandem hydraulic pump is connected to the electric motor 6 via a first coupler 3. An rpm sensor 4 is arranged between the electric motor 6 and the first Section 2 of the tandem hydraulic pump and a first safety valve 8 is connected to the output of the first Section 2 of the tandem hydraulic pump.