HYDRAULIC SYSTEM - STRUCTURE AND OPERATING PRINCIPLE

2.2.2. IMPLEMENT SECTION

Hydraulic fluid in the implement line flows in the following order: filter (1) → pump (2) → main relief valve (6) → hydraulic block (3), joystick valve (3) → remote hydraulic valve (4) → lift control valve (5). If hydraulic fluid is used in a certain step, it cannot be used in the following step. For example, the remote hydraulic valve and lift cylinder cannot be used at the same time. Therefore, the remote hydraulic valve should be firstly checked if it is properly operated if the lifting arm does not operate.

Hydraulic pressure of the implement line is controlled by the main relief valve, which is installed to the hydraulic block (joystick valve), to 185 kgf/cm² (18,130 kPa / 2,631 psi). Therefore, when pressure in the circuit rises over the relief pressure due to overload for the operation of the remote hydraulic valve and lifting cylinder, the relief valve is open to protect the circuit. When the engine is running at the rated speed (2,600 rpm), the secondary gear pump with the capacity of 26 L/min (6.87 U.S. gal) is operated to supply hydraulic oil to the loader hydraulic block (joystick valve) (3), remote hydraulic valve (4) and lift control valve (5) mainly for tractor work. Hydraulic oil is firstly supplied to the hydraulic block (joystick valve) after passing through the oil filter and secondary gear pump from the transmission case. Then, for loader operation, hydraulic oil is supplied to the loader through the outlet port. Oil returned from the loader cylinder is led back to the transmission case through this port. When the hydraulic block (joystick valve) is not in use, hydraulic oil is supplied to the next component, remote hydraulic valve, through the carryover line in the valve.

The above circuit diagram shows two double acting valves. If any one of two double acting valves is in use, the threepoint hydraulic cylinder behind this step cannot be operated. When the remote hydraulic valve is not in use, hydraulic oil is supplied to the lift control valve through the carryover line to operate the three-point link. When lifting the lift arm, hydraulic oil is supplied to the hydraulic cylinder. When lowering or stopping the lift arm, oil supplied to the valve and drained from the hydraulic cylinder is returned to the transmission case.

2.2.3. MAIN SECTION

HYDRAULIC SYSTEM - STRUCTURE AND OPERATING PRINCIPLE

The pump for the tractor body (primary pump) shares the oil filter (1) and suction line with the secondary pump. The pump (2) supplies oil to the steering unit (3) firstly, then this oil is either returned to the HST (4).

The functions in the main section can be used simultaneously or separately, unlike the implement section. Oil carryovered from the steering unit passes through the HST filter and is delivered to the HST to be used for shuttle shift operation. Oil discharged from the HST motor side is led into the oil cooler to be cooled and returned back to the transmission.