Hand Hydraulic Pump High And Low Pressure Two Section Oil Speed

Manual hydraulic Pump is a kind of hydraulic pump, its function is to the power machine (such as motor and internal combustion engine, etc.) mechanical energy can be converted into liquid pressure energy. The manual pump is the ladder plunger type two-stage hydraulic pump, it as the hydraulic power source, besides and breaks the tool matching, but also may with other many kinds of tools or the experimental device to use.

Working principle

The cam is driven by the motor. When the cam pushes the plunger upward movement, the sealing volume of the plunger and the cylinder body is reduced, the oil is extruded from the sealed volume and the valve is discharged to the desired place. When the cam rotates to the descending part of the curve, the spring forces the plunger downward to form a certain vacuum degree, and the oil in the tank enters the sealing volume under the action of the atmospheric pressure. The cam keeps the plunger up and down, the sealing volume decreases and increases periodically, and the pump continues to suck oil and drain oil.


1. High and low pressure two sections of the oil speed, the pressure can be maintained in the middle stop, the internal design has high-pressure safety protection hydraulic valve.

2. Manual operation, convenient for application. The pressure gauges can be installed at the same time.

First, in the maintenance of the following three points to find the cause of the failure, and improve the system:

1, check the internal leakage of the movable arm oil cylinder:

The easiest way to do this is to raise the arm to see if there is a noticeable drop in freedom. If the whereabouts are obvious, remove the cylinder check and the seal ring should be replaced if it has been found to be worn.

2, check the control valve:

First cleaning safety valve, check whether the valve core wear, such as wear should be replaced. If the safety valve is not changed after installation, then check the control valve spool wear condition, its clearance use limit is generally 0.06mm, wear seriously should be replaced.

3. Measuring pressure of hydraulic pump:

If the pressure is low, then the adjustment, add pressure is still not up, then the hydraulic pump serious wear.

The main reasons for the failure of the movable arm belt to ascend are:

1, the hydraulic pump serious wear. In the low-speed operation of the pump leakage is serious; High speed operation, pump pressure slightly increased, but because of the pump wear and leakage, volume efficiency significantly reduced, it is difficult to reach the rated pressure. Long-time hydraulic pump work and increased wear, oil temperature rise, resulting in hydraulic components wear and sealing parts of aging, damage, loss of sealing capacity, hydraulic oil deterioration, and finally lead to failure.

2. The selection of hydraulic components is unreasonable. Dynamic ARM cylinder specifications for 70/40 non-standard series, seals are not standard parts, high manufacturing costs and inconvenience of sealing parts replacement. The cylinder diameter of the movable arm oil cylinder is small, which will make the system adjust the pressure high.

3. The design of hydraulic system is unreasonable. Figure 1 shows that the control valve and the full hydraulic steering gear for the single Pump series, the relief valve to adjust the pressure of 16MPa, and the hydraulic pump rated work pressure is 16MPa. Hydraulic pump often in full load or long time overload (high pressure), and the system has a hydraulic impact, long-term oil, hydraulic oil pollution, aggravate the hydraulic pump wear, so that the hydraulic pump shell burst (after the failure of this type).