Created on:2021-05-22 10:27

Installation of hydraulic pump and motor

Installation of hydraulic pump and motor

As the energy component and the important executive component of the hydraulic system, the correct and reasonable selection, installation and debugging and standardized use and maintenance are one of the important conditions to ensure its long-term performance. Therefore, in the installation and debugging of hydraulic pump and hydraulic motor, we must be familiar with the working condition characteristics, working principle and structure, function and function of each component of the hydraulic system and even the main engine; in use, we should strengthen the daily maintenance and management, in order to ensure its trouble free operation, we must comply with the manufacturer's use and maintenance requirements. Obviously, due to the differences of product models, specifications and working conditions in engineering practice, the precautions for use and maintenance are different. This section will introduce the common problems in the installation, debugging and operation maintenance of hydraulic pump and hydraulic motor.

Installation and commissioning is a series of activities to put new components into operation or put original components into operation again, including acceptance, installation, oil injection, flushing, venting, adjustment and running in. Although the structures of various hydraulic pumps and motors are different, there are many common points in the installation and debugging of the user's site. The general steps and precautions for the installation and commissioning of hydraulic pump and hydraulic motor are as follows.

(1) Acceptance inspection

① Open box acceptance inspection, check whether the arrival content is consistent with the purchase and sales contract and packing list, whether the parts, accessories, random tools and technical documents are complete, and the model and specification of the label should be consistent with the component list; visually check whether there is any damage or pollution during transportation.

② The production date should not be too early, otherwise the internal seal may be aged.

③ The shaft extension of components and the mounting surface of mounting base plate, bracket, flange, etc. shall be flat, the groove shall be free of flash, burr, corner, bump and dent, and the inside of oil port shall be clean.

④ Process hole plug plug or ball should be complete and well connected and sealed.

(2) Installation

① Pay attention to the rotation direction of the transmission shaft when installing.

② Fill the pump or motor with oil as required.

③ The hydraulic pump can be installed inside or outside the oil tank, horizontally (Figure T, figure U) or vertically (Figure V). When the pump is installed horizontally, the pressure port should be installed laterally or upward, and the suction port should be installed laterally or downward. If the working speed of the pump is low, the suction port of the pump should be installed upward, so that it is easy to absorb oil when starting. The drain port should always be installed upward.

When installing the hydraulic pump, it should be below the liquid level of the oil tank as far as possible (Fig. T); for the pump with flow rate less than 160L / min, it can be installed on the oil tank for self-priming (Fig. U). For the piston pump with flow rate ≥ 160L / min, it is recommended not to install it on the oil tank because of the large power of the prime mover, but to use the back filling self-priming (Fig. w).


④ The hydraulic pump and motor can be installed with bracket or flange, and the pump and prime mover should use common base. The support, flange and foundation should be rigid enough to avoid vibration when the pump or motor is running.

⑤ When the vibration of the working environment is small and the prime mover works smoothly (such as the motor), the elastic coupling should be used between the hydraulic pump and the prime mover. The form and installation requirements of the coupling should meet the requirements of the pump manufacturer. The coupling form and installation requirements between the hydraulic motor and the driven device shall meet the requirements of the manufacturer.

If the vibration of the prime mover is large (such as internal combustion engine), it is recommended to use pulley or gear to connect the hydraulic pump and the prime mover (Fig. x). A pile of supports should be added to install the pulley or gear. The coaxiality error between the support and the pump shaft should not be greater than Φ 0.05mm. The mounting bracket of the pump and the base of the prime mover should have enough rigidity to ensure that they are always coaxial during operation. Gear and V-belt drives should be in the best position as shown in Figure y.


After the connection between the hydraulic pump and the prime mover or between the hydraulic motor and the working mechanism is completed, the installation accuracy (coaxiality and perpendicularity) shall be measured with a dial indicator (Fig. z). Generally, the coaxiality and Perpendicularity Error shall not be greater than 0.05 ~ 0.1mm; the inclination angle between the axes shall not be greater than 1 °.


⑥ It is not allowed to install the coupling by knocking to avoid damaging the rotor of the hydraulic pump or motor; the exposed rotating shaft and coupling must be provided with protective cover.

⑦ Piping shall be carried out according to the instruction manual. The connecting pipes of hydraulic pump and hydraulic motor include inlet and outlet connecting pipes and leakage oil pipes. The oil inlet and outlet pipes shall not be connected reversely; the leaking oil pipe of the pump shall be directly connected to the oil tank.

a. The hydraulic pipe should be cleaned strictly before installation, and the general steel pipe should be pickled and neutralized. Cleaning shall be carried out after pipe welding to ensure pipe cleaning. If working in high temperature environment, effective heat dissipation measures should be taken to ensure that the temperature of any exposed part of the pump body does not exceed the specified value. If the temperature exceeds the specified value, a cooling device should be installed for forced cooling (Fig. a).

b. The oil suction pipe of hydraulic pump should be short and thick; avoid too many bends and sudden change of section; the length of oil suction pipe should be l < 2500mm (Figure T), and there should be no more than two pipe elbows; the oil suction height of pump should be no more than 500mm (Figure V) or the self suction vacuum degree should be no more than 0.03mpa; if the oil is supplied by make-up pump, the oil supply pressure should not exceed 0.5MPa; if it exceeds 0.5MPa, the pressure seal should be used.

The oil suction pipeline of the pump must be reliably sealed, and air shall not be inhaled, so as not to affect the performance of the pump. The suction and return pipe orifices of the pump shall be below 200 mm of the lowest liquid level of the oil tank (Fig. V and W).

In order to reduce vibration and noise, it is recommended for high-pressure and large flow hydraulic pump: rubber elastic compensation connecting pipe is set at pump inlet; high-pressure hose is connected at pump outlet; elastic damping pad is set at common base of pump set.

Generally, a coarse filter with nominal flow less than 2 times of the pump flow should be set in the oil suction pipeline (the filtration accuracy is generally 80-180pm). The diameter of the stop valve (Figure T) on the oil suction pipe should be one gear larger than that of the oil suction pipe. The distance from the oil suction pipe end to the side wall of the oil tank H1 ≥ 3D, and the distance from the oil suction pipe end to the bottom of the oil tank h ≥ 2D.

c. For the hydraulic pump with two symmetrical oil leakage ports on the shell, one of them must be directly connected to the oil tank, and the other can be blocked by a screw plug (Fig. w). No matter what kind of installation method is adopted, the oil leakage pipe outside the pump shell shall exceed the center line of the pump bearing to lubricate the pump bearing (Fig. V). The leaking oil pipe must be directly introduced into the oil tank without throttling, and cannot be connected with other oil return pipes. The end of the leaking oil pipe must be below the lowest liquid level of the oil tank, and as far away from the oil suction port as possible, so as to ensure that the oil in the pump shell will not be drained when the pump is stopped. Hot oil mixed with air should be avoided to enter the system circulation. When the pump is immersed in the oil tank for installation, the installation of the leaking oil pipe should be able to form a siphon effect, so as to ensure that the shell is always full of oil. Generally, the pressure of oil drain (shell) shall not exceed 0.2MPa, so as to avoid oil leakage of rubber seal at shaft end caused by too high pressure in shell cavity. Therefore, the length of leaking oil pipe should not exceed 2000mm, the minimum diameter should be selected according to the oil port specification of the pump, and the low-pressure straight through pipe joint with the largest diameter should be selected.

⑧ Mounting parts such as mounting support (flange), coupling and mounting bracket (tripod) and pipe joint can be purchased directly from pump manufacturer.

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