Fig. 1.
Diagram of the device for diagnosing two-line air brake systems of agricultural trailers and towed machines: APS - air preparation station; BA - brake actuator; CH – control coupling head; CR1 and CR2 - calibration reservoirs with volumes of 385± 5 cm3 and 1155 ±15 cm3, respectively (including its coupling head); CU – control unit; DT - displacement transducer (cable encoder); ERV – emergency relay valve; I/O Adapter - input-output adapter; L - line from orifice O up to and including its coupling head CH (having an inner volume of 385 ±5 cm3 under a pressure of 6.5 bar); M - manometer; O - calibrated orifice; PC – computer; PRN – printer; PRV - pressure reducing valve; PTi - ith pressure transducer; R - compressed air tank with a capacity of 30 litres; SH - supply coupling head; SOV - shut-off valve; SV1, SV2, and SV3 – 2/2 electrovalves (NC); SV4 – direct-acting 3/2 electrovalve (NC); and TR - trailer reservoir
Fig. 2.
General algorithm of a computer programme for the diagnosis of braking systems of agricultural machinery and trailers
Fig. 3.
‘Measurement’ window of the ‘Simulator’ program when checking air tank capacity (in Polish)
Fig. 4.
Diagram and view of the dual-line trailer pneumatic system: SH - supply coupling head; CH - control coupling head; LF - line filter; ERV - emergency relay valve combined with a manual brake force regulator; TR - 20 dm3 air reservoir; BA - type 20LS brake chamber
Fig. 5.
The course of the pressure pt in the trailer reservoir during the tightness test of the braking system
Fig. 6.
The course of measured quantities during the response time test: pc - pressure of the simulator control; ps - pressure in the simulator reservoir; pt - pressure in the trailer reservoir; pa - pressure in the brake chamber; L – stroke of the actuator
Tab. 1.
Results of response time tr [s] of the braking system of the tested trailer
| No. | Bialystok University of Technology simulator | Industrial simulator |
|---|---|---|
| 1 | 0.282 | 0.282 |
| 2 | 0.281 | 0.280 |
| 3 | 0.280 | 0.281 |
| 4 | 0.281 | 0.280 |
| 5 | 0.280 | 0.280 |
| 6 | 0.279 | 0.280 |
| 7 | 0.280 | 0.280 |
| 8 | 0.279 | 0.280 |
| 9 | 0.279 | 0.281 |
| 10 | 0.282 | 0.281 |
| 11 | 0.280 | 0.281 |
| 12 | 0.279 | 0.280 |
| 13 | 0.280 | 0.281 |
| 14 | 0.280 | 0.282 |
| 15 | 0.281 | 0.280 |
| Mean | 0.2802±0.0008 | 0.2806±0.0006 |
| Test name | Normality/p-value test results | |
| SDA | H0/0.3756 | H0/0.1406 |
| DLM | H0/0.5722/0.8409 | H0/0.0650/0.2546 |
| DH | H0/0.5855 | H0/0.1037 |
| G | H0/0.7342 | H0/0.0648 |
| Result of the test Welch/p-value | H0/0.2278 | |
| Result of the test MWW/p-value | H0/0.2065 | |
| Response time [6] | 0.3 | 0.3 |
Fig. 7.
The course of measured quantities during checking of the capacity of the air reservoir: pc - control pressure of the simulator; ps - pressures in the simulator reservoir; pt - pressures in the trailer reservoir; and L - stroke of the actuator