Hitachi ZX200-3 Hydraulic Pump Adjustment Whole Process

hydraulic pump

The Hitachi excavator brand, with its excellent working performance and durability, has long enjoyed great reputation among consumers in the world. But even for such a tough Iron Man, it still has to face problems after over 10,000 hours of service under various demanding working conditions.

One of those common problems is with the pump. In this article, we offer some tips on how to adjust hydraulic pump flow.

How does it work?

First of all, we must be familiar with the principle of hydraulic pump providing pressure. The main pump is composed of pump 1 and pump 2. The hydraulic pump provides pressure oil to supply hydraulic components such as drive motors and cylinders. The output shaft passes through the hydraulic pump plunger and each pump. The cylinder block is connected. When the output shaft rotates with the cylinder block, the plunger moves in the cylinder block to suck and discharge hydraulic oil.

The increase or decrease of the main pump flow is achieved by changing the inclination angle of the cylinder. In simple terms, the plunger stroke is increased or decreased according to the change in the inclination angle. At the same time, through the operating principle of the servo piston, Move to change the tilt angle of the cylinder.

Hitachi ZX200-3 hydraulic pump adjustment method

1. The adjustment method of the maximum flow rate of the hydraulic pump:

We need to loosen the lock nut 1 of the regulator first, and adjust the screw 2 at the same time. Remember that the direction of adjustment is clockwise to increase the flow, and counterclockwise to decrease the flow. When adjusting the maximum flow rate during the adjustment process, the adjustment screw 2 cannot be more than 2 turns.

2. The method of adjusting the minimum flow rate of the hydraulic pump:

First loosen the regulator lock nut 3 and adjust the screw 4. Remember that the direction of adjustment is clockwise to decrease the flow, and counterclockwise to increase the flow. When adjusting the minimum flow during the adjustment process, it is required to turn the adjustment screw 4 not more than 2 turns.

3. Hydraulic pump torque adjustment method:

Loosen the adjuster lock nut 7 and adjust the screw 8. Clockwise adjustment will increase the torque, and counterclockwise adjustment will decrease the torque. Similarly, loosen the lock nut 9 and adjust the screw 10, the clockwise adjustment torque increases, and the counterclockwise adjustment torque decreases.

At this time, please pay attention: First, the adjustment screw should not turn more than 1 turn; second, the change of the engine power should be observed while turning the adjustment screw, and the lock nut 9 should be tightened after proper adjustment.


After reading the above article, everyone should have an understanding of the flow adjustment process of Hitachi brand excavator hydraulic pump. If your favorite machine happens to be Hitachi brand and the flow is urgently needed to adjust the flow, then you may wish to try to adjust.

Of course, I also want to remind everyone that adjusting the hydraulic pump is not as easy as replacing the maintenance parts. The entire adjustment process must be accurate, so if you don’t have any maintenance experience, it’s best to do it under the guidance of an old driver to avoid mistakes. Operation causes unnecessary malfunction!

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