HYDRAULIC HOSES Nowadays almost all roadbuilding municipal and

HYDRAULIC HOSES

Nowadays almost all road-building, municipal and other Russian and foreign vehicles have hydraulic transmission. Hydraulic transmission break down rarely, but from time to time it is necessary to change the old details, including hydraulic hoses. We would like to tell about the possibility to replace the foreign hoses to Russian ones. Nowadays Russian specialists use foreign hydraulic transmission, but the European standards are not so much known. It is more convenient to use Russian hoses.

There are 2 types of hydraulic hoses used in industry: skive hoses and spiral hoses. Skive hoses are used in hydraulic transmissions with high pressure – till 25 megapascals and with small radius of flexure. Spiral hoses are used in hydraulic transmissions with the pressure of 3040 megapascals and with constant cycle charge. The European standards for skive hoses are DIN EN 853 and DIN EN 857, and they are almost similar to Russian GOST 6286. These standards are for the hoses which work with hydraulic mineral oils, engine propellant with temperatures from -40 to +100 C, and also for water and oil emulsion with temperatures from -40 to +70 C. These requirements are convenient to Russian hydraulic hoses.

There are 4 types of hoses DIN EN 853: 1 SN and 2 ST – skive hoses 1 SN and 2 SN – the same construction, but thinner external rubber layer. This permits to armour the hoses without preparatory cleaning of external rubber layer. The essential difference between foreign and Russian hoses is DN, which is fixed in inches. It is not always the same as Russian. For instance, the diameter of foreign hose with DN 12 is 12, 7 mm, which is larger than Russian one. At the same time DN 10 and DN 12 are 9, 5 mm and 19 mm and they can allow 11% less liquid than Russian ones.

The testing of Russian hoses on leak resistance and rupture (megapascals): DN Max pressure Leak resistance pressure Rupture pressure 1 ST and 1 SN 2 ST and 2 SN 1 ST and 1 SN 2 ST and 2 SN 5 250 415 500 830 1000 1650 8 225 400 450 800 900 1600 8 215 350 430 700 850 1400 10 180 330 360 660 720 1320 12 160 275 320 550 640 1100 16 130 250 260 500 520 1000 19 105 210 430 420 850 25 88 165 175 325 350 650 31 63 125 150 250 500 38 50 90 100 180 200 360 51 40 80 80 160 32

The marking of the hoses DIN EN 853 is the following: - Producer - Type - Caliber (in inches) - Standard - Nominal diameter - The last 2 figures of the producing year The pressure is not marked, it is determined in the schedule. There are 2 types of DIN EN 857 hoses: 1 SC and 2 SC. Their characteristics are the same as DIN EN 853, but the bend radius is 40% less. There are 4 types of spiral hoses DIN EN 856: - Type 4 SP – 4 -spiral skive hoses for middle-level pressure - Type 4 SH – 4 -spiral skive hoses for high pressure

- Type R 12 – 4 -spiral hose for long work with high temperature and middle-level pressure Type R 13 – 6 -spiral hose for the most hard and long work with very high pressure. Its production is limited. ND Max pressure Leak resistance pressure, bar Rupture pressure, bar 4 SP 4 SH R 12 R 13 16 350 - 276 - 700 - 552 - 1400 - 1104 - 19 350 420 276 345 700 840 552 690 1400 1680 1104 1380 25 280 380 276 345 560 760 552 690 1120 1520 1104 1380 31 210 325 207 345 420 650 414 690 840 1300 828 1380 38 185 290 172 345 370 580 344 690 740 1160 688 1380 51 165 250 172 345 330 500 344 690 660 1000 688 1380

ND, mm Min bend radius, mm 4 SP 4 SH R 12 R 13 6 150 - - - 10 180 - 130 - 12 230 - 180 - 16 250 - 200 - 19 300 280 240 25 340 300 31 460 420 38 560 500 51 660 700 630 830 DIN EN 856 have min temperature -40 C

The characteristics of type 4 SP: Nominal inside diameter Rupture pressure, bar Pressure according GOST The number of cycles with Rmin GOST EN 856 10 1400 1780 340 1000000 12 1360 1660 340 1000000 16 1360 1400 300 800000 19 1200 1400 250 800000 25 1000 1120 250 800000 The hydraulic hoses satisfy the requirements of the customers and can be used both in Russian and foreign machines. The quality and technical control is made during all periods of production. Then the hoses are tested on the testing stand.