3. HYDRAULIC FRONT AXLE SUSPENSION 3.1 FRONT SUSPENSION CONTROL VALVE 3. When the system is active When the tractor is in motion and the wheels encounter an obstacle, the front axle is pushed upwards. This causes the pressure P2 to increase (the accumulators 6 are compressed) while the pressure P1 decreases (ac- cumulator 3 is decompressed). The pressure balance is thus altered and the system (which is closed) acts to restore the original condition.. / 3 1 ( S max P 2 max S,P 2 t P 1 t shock t damping t D000 2411 10-36 3 ( (2. -0 3(1 3(/ -/ ( -.1 -./ (.1 3.1 ,.0 3./ )(1 ,./ " (./ -1 ,.1 - S min P mi 1 n