working principle
Hydraulic system of domestic QY16 truck crane. The maximum lifting height of the crane is 19m and the lifting capacity is 16t. The hydraulic system is an open, multi pump quantitative system. The hydraulic system consists of outrigger, slewing, telescopic, luffing and lifting hydraulic circuits. Outrigger directional valves 3 ~ 6 are parallel oil circuits, which form a series parallel oil circuit with directional valve 2. Reversing valve for Luffing
1 - hydraulic triplet pump set (pump I, pump port and pump dish); 2 ~ 6,13 ~ 15,17 - directional valve; 7 - check valve; 8 ~ 11 - hydraulic lock; 12 - oil filter;
16 - overflow valve; 18 - five position five way rotary valve; 19 - two position three-way solenoid valve group (including shuttle valve), 20,21 - remote control overflow valve; 22,23 - foot brake
Pump cylinder; 24 - oil makeup valve; 25 - selector valve; 26 - two position ten way hydraulic valve; 27 - pedal hydraulic cylinder; 28 ~ 30 - balance valve; 31 - one way section
Flow valve; 32 - overload valve group; 33,35,36 - brake cylinder; 34 - hydraulic two position three-way brake valve; 37 - rotary hydraulic motor; 38 one stretch
Shrink the hydraulic cylinder; 39 - luffing hydraulic cylinder; 40,41 - hydraulic motor; 42 - outrigger horizontal hydraulic cylinder; 43 - Outrigger
Vertical hydraulic cylinder; 44 - swivel joint; 45 - oil tank; 46 - emergency pump; 47one quick coupler
15 and the telescopic directional valve 14 are parallel oil circuits. In the hydraulic triplet pump set, pump I mainly supplies oil to the outrigger circuit and slewing circuit; Pump II mainly supplies oil to the telescopic and luffing circuits; The pump Ni mainly supplies oil to the lifting circuit.
(1) Outrigger hydraulic circuit
After the oil is supplied by pump I, if the change-over valve 2 is in the middle position, the hydraulic oil can be supplied to the swing circuit. When the swing circuit does not work, the hydraulic oil returns directly to the tank.
When the change-over valves 3 ~ 6 do not work, and only the left and right positions of the change-over valve 2, the hydraulic cylinders (42 and 43) of each outrigger cannot act.
The outrigger horizontal hydraulic cylinder and vertical hydraulic cylinder can be extended or retracted separately only when the change-over valve 2 is in the left and right positions and the change-over valves 3 ~ 6 also act at the same time or separately.
(2) Swing hydraulic circuit
The reversing valve 2 is in the middle position. Operate the reversing valve 13 and the oil from pump I can make the swing hydraulic motor 37 run. At the same time of feeding pressure oil and cooperating with the action of pedal cylinder 27, the hydraulic horse can be realized through overload valve group 32 and hydraulic two-position three-way brake valve 34
Release the brake in time when the brake cylinder 33 (normally closed) is reached.
(3) Telescopic hydraulic circuit
The pressure oil is supplied by pump II, and the telescopic hydraulic cylinder 38 can be extended or retracted through the right or left position of three position six way manual directional valve 14 and balance valve 27.
The hydraulic oil pressure of telescopic hydraulic cylinder is controlled by remote control overflow valve 20 and two position three-way solenoid valve group 19. When the oil circuit pressure exceeds the set value, the pressure relay installed on the oil inlet circuit will energize 19, so as to realize the purpose of pressure oil unloading.
(4) Luffing hydraulic circuit
The luffing hydraulic circuit is composed of pump □, reversing valve 15, remote control overflow valve 20, overload valve group 32, balance valve 28 and luffing hydraulic cylinder 39.
This circuit is also provided with an emergency pump 46. When the pump u cannot supply oil for some reason, the emergency pump 46 and quick connector 47 can ensure the emergency lowering of the boom.
(5) Lifting hydraulic circuit
The lifting hydraulic circuit is composed of pump ID, pump port, five position six way manual directional valve 17 (two positions belong to transition position), remote control overflow valve 21, oil makeup valve 24, selector valve 25, two position ten way hydraulic valve 26, one-way throttle valve 31, balance valve 29 and 30, brake cylinders 35 and 36 and hydraulic motors 40 and 41. The change-over valve 17 operates in different positions to make the lifting hydraulic motor in forward and reverse directions (lifting and lowering).
The different positions of selector valve 25 are used to select the main and auxiliary hoisting mechanisms. The one-way throttle valve 31 is used to release the brake slowly and quickly.
Valve 21 and valve block 19 form a remote overflow unloading.
The remote control port of overflow valve 16 is used to provide hydraulic control operating oil to valves 26 and 31 and operating oil to brake cylinder.
Valve 18 is a five position five way rotary valve. When operated in different positions, the pressure value of hydraulic oil in oil inlet circuits of different circuits can be observed.
When the luffing cylinder of pump u and pump HL does not work, the oil supply can be combined through the middle position of directional valve 15 and check valve 7.
