At present, several road sweepers, trenchless drills and airport trolleys are used Cycloid hydraulic motor System used in series. The motor output shaft often leaks oil in the application link. Even if the dynamic seal of the output shaft is replaced, it will not help. This is to select the cycloid Hydraulic motor In addition, the problem of working pressure of casing oil leakage is ignored during series operation. The working pressure of casing oil leakage refers to the large working pressure that the motor shaft seal can bear after the internal structure of the motor is fully lubricated; If the motor is used improperly, the oil in the housing will not be released due to various reasons after the continuous operation of the machine equipment for a period of time. Finally, the working pressure of the housing of the motor will become higher and higher, resulting in the failure of the shaft seal at the beginning. The working pressure of casing oil leakage here is not the bursting pressure of the casing, but the working pressure that the dynamic seal of the motor output shaft can carry. In some manufacturers' motor models, only the back pressure type is mentioned. The actual situation is that the upper back pressure type refers to the working pressure of the motor oil return port, not the working pressure of the casing oil drain. During operation, the regulations on the working pressure of the casing oil drain of the cycloidal hydraulic motor are as follows. Eaton is the earliest manufacturer of cycloidal hydraulic motors in the world. In the field of cycloidal hydraulic motor production and manufacturing in the mainland of China, Ningbo White Hydraulic Technology Co., Ltd. selects the cycloidal hydraulic motor manufactured by Eaton Technology of the United States, and its output shaft dynamic seal has a better pressure bearing capacity, that is, the company's products use a unique internal structure and main oil channel structure design, The internal oil drain not only plays the role of lubricating parts, but also can drain unnecessary oil while maintaining the working pressure of oil drain of the stator housing. Generally, the working pressure of the casing oil drainage of the axial flow distribution motor in mainland China is below 3.0 mpa, the working pressure of the disc flow distribution motor is below 5.0 mpa, while the working pressure of the casing oil drainage of the axial flow distribution motor manufactured by Ningbo White Hydraulic Technology Co., Ltd. is 7.0-10.0 mpa, and the working pressure of the disc flow distribution motor is 7.0 mpa. Such data information is clearly described in the company's motor model. It must be noted that when the working pressure of the motor housing oil drain (internal drain) exceeds its recommended value, the external drain port of the motor housing must be connected to the oil tank, otherwise, the life of the motor shaft seal will be greatly affected, and even the shaft seal will fail, resulting in oil leakage at the output shaft. In practice, it is not recommended that motors be used in series. On the contrary, in order to better ensure the synchronization of several actuators, and at the same time to scientifically and reasonably control costs under the condition of ensuring the quality of structural design, the cycloidal hydraulic horse manufactured by Eaton has greatly improved the pressure bearing capacity of the housing, For example, the working pressure of the case oil leakage of the axial flow distribution motor of the h/s/t series product reached 10.3 mpa, and the working pressure of the case oil leakage of the plate flow distribution motor of the 2000 series product reached 14.0 mpa, which reasonably and effectively improved the ability of the motor to be used in series, provided an improvement plan for the structural design of the machinery and equipment, reduced the total flow of the pump source, and saved the cost of production and manufacturing.

Classification of hydraulic motors:

1. The structure can be divided into gear motor (including external meshing involute gear motor and internal meshing Cycloidal gear motor The gear motor has the advantages of simple structure, small system, low price, safe and reliable application, etc. The disadvantage is that the mechanical energy for operation is low, only 70%~80% of the basic theoretical torque is low. The speed stability is poor, the total flow pulsation of the gear motor is up to, the tightness is poor, and the volume working efficiency is low. Therefore, when the rotation speed is below 50~100 r/min, it will be unstable. The vane motor (single acting and double acting) is small in size and small in inertia moment, so it can operate flexibly, but it has large leakage, and the stability and working efficiency of low-speed gear are still low (better than gear motor). It is used in high-speed rotation, small turning distance and flexible operation places. Plunger motor (including axial plunger and radial plunger).

2. The speed range of safe operation can be divided into high speed and low speed. The rated rotation speed exceeds 50 r/min and is less than 50 r/min, which is called low speed motor. High speed motor includes gear motor, vane motor and axial plunger motor. The advantages are small inertia torque, better operation, reversing and braking system; The axial plunger motor can also achieve stepless speed change. The disadvantages are low mechanical energy for operation and poor stability at low gear. Considering the small output torque of high-speed motor, it is also called high-speed small torque motor. Low speed hydraulic motor includes crankshaft connecting rod motor, ergodic stable balancing motor and internal curve radial piston motor , and its white wire motor, etc. The low-speed hydraulic motor has good low-speed stability and high operating mechanical energy; It can be simply connected with the running structure, greatly simplifying the transmission system of the machine equipment. Generally speaking, the output torque of the low-speed hydraulic motor is relatively large, which can reach thousands of Nm to tens of thousands of Nm High torque hydraulic motor It is widely used in the heavy load and high pressure system. The disadvantage is that the moment of inertia is up to, and the braking system is relatively difficult.

3 Several times of safety action can be divided into single action and multiple action. Single acting hydraulic motor including Gear hydraulic motor , eccentric vane motor, axial plunger motor, crankshaft connecting rod and hydraulic motor with ergodic stable balance. The single acting motor has relatively simple structure and good process performance. The project cost is low. However, under the same technical parameters, it is slightly larger than the multi action motor. The output rotation speed fluctuation is relatively large, and the stability of low gear will be poor. It is difficult to achieve complete hydraulic stability balance, so that the load of rolling bearing increases and the damage of relevant surface layer increases.. The multi acting hydraulic motor includes a traveling vane motor and an internal curve Radial plunger hydraulic motor 。 The structure is relatively complex, and the processing of a few mechanical parts is relatively difficult. Better stainless steel plates are required, so the project cost is high. As long as the final technical parameters are selected scientifically and reasonably, the rotation speed of the hydraulic motor can be free of pulsation, so that the stability performance of the low-speed gear can be good. Considering that the radial force of the rotor can achieve complete stable balance, the operating mechanical energy is high.

4. Whether the displacement of A hydraulic motor can be adjusted can be divided into quantitative and Variable hydraulic motor 。 5. The main forms of structural dynamics are different, which can be divided into basic meshing principle running hydraulic motor, parallel plane structural dynamic running motor, and indoor spatial structural dynamic running motor.