BMK2 500 Hydraulic Motors

BMK2 new series motor adapt the advanced Geroler gear set designed with disc distribution flow and high pressure. The unit can be supplied the individual variant in operating ultifunction in accordance with requirement of applications.
Characteristic featutres:
* Advanced manufacturing devices for the Geroler gear set, which use low pressure of start-up, provide smooth and reliable
operation and high efficiency.
* The output shaft adapts in tapered roller bearings that permit high axial and radial forces. The case can offers capacities of
high pressure and high torque in the wide of applications.
* Advanced design in disc distribution flow, which can automatically compensate in operating with high volume efficiency and
long life , provide smooth and reliable operation.
* The new series motor is suitable for vehicles with greater loads and pressure drop.

BMK2 Hydraulic Orbit Motor

Main Specification 

Type BMK2
Geometric displacement (cm3 /rev.) 65 80 100.9 129.8 156.8 193.4 242.5 304.3 390.8 485
Max.speed(rpm) cont. 835 800 742 576 477 385 308 246 191 153
int. 990 980 924 720 713 577 462 365 287 230
cont. 185 235 295 385 455 540 660 765 775 845
int. 245 345 445 560 570 665 820 885 925 930
cont. 20.5 21 21 21 20.5 20.5 20.5 21 15.5 12
int. 27.5 31 31 31 26 26 26 24 17 14
peak 31 31 31 31 31 31 21 31 20.5 17
cont. 55 65 75 75 75 75 75 75 75 75
int. 65 80 95 95 115 115 115 115 115 115
Weight(kg) 9.2 9.4 9.7 10 10.5 10.5 11 11.5 12 12.4

* Continuous pressure:Max.value of operating motor continuously.
* Intermittent pressure:Max.value of operating motor in 6 seconds per minute .
* Peak pressure:Max.value of operating motor in 0.6 second per minute.


BM Series Orbit hydraulic motor product manual 

1. Matters needing attention

1.1  Output steering  

1.2  The correct use of the motor will directly affect the working life. Therefore, the following basic requirements must be met.

1.2.1  System requirements

  • The system should be equipped with a corresponding oil filter to ensure the cleanliness of the system oil.
  • The hydraulic circuit must be equipped with a cooling system to prevent excessive oil temperature.
  • Pressure gauges and thermometers must be installed in the oil inlet lines.
  • A pressure gauge should be installed in the hydraulic circuit of the hydraulic pump. 

1.2.2  System hydraulic oil requirements

      According to the different ambient temperature and usage, the oil used should have good viscosity-temperature performance, good defoaming properties, anti-oxidation, anti-rust, high flash point, etc. During the operation of the motor, its viscosity is between (25-70)*10-6m2/s, and the water, alkali and mechanical impurities in the oil must not exceed the allowable value.

  • It is recommended to use YB-N46, YB-N68 anti-wear hydraulic oil.
  • The filtration accuracy of the system is better than 20μm.
  • Normal working oil temperature is 25-55℃, short-term working oil temperature is not higher than 65℃.

2. Motor installation

Before installation, check whether the motor is damaged. The motor oil stored for a long time needs to be drained and rinsed to prevent the internal moving parts from sticking.
The motor mounting bracket must have sufficient rigidity to prevent shock and vibration during rotation.
The mounting bolts must be tightened evenly.
Connection method of drain pipe:
The BMR motor has two built-in check valves, and the leaked oil can return to the oil return pipe through the check valve

A) When the oil return pressure is ≤1Mpa, there is no need to connect the drain pipe;
B) When the oil return pressure is greater than 1Mpa, the drain pipe must be connected. (Drain pipe location diagram)

  • The motor is unstable when running at low speed, and can be eliminated by applying back pressure, the back pressure value is not less than 0.2Mpa.
  • This type of motor can not be operated under the pump working conditions, nor can it be used as a pump.
  • The installation surface should be flat.
  • The installation should determine the connection flange, the stop, and the output connection shaft size is accurate.、
  • Ensure that the output shaft and the device connected to the transmission have good concentricity. When the output shaft is installed, it is necessary to prevent the axial thrust of the output shaft and the interlocking device.
    (The cycloidal motor BMR bears a small radial force.)
  • During the installation process, the smoothness and parallelism of the connecting plate part of the oil inlet and outlet are protected to prevent the oil sealing effect caused by the bumps from being bad, resulting in oil leakage.
  • The screws and the rear cover of the rear of the motor must not be hit during installation.
    If you want to tap, please tap the mounting flange.
  • The motor cannot be installed forcefully or twisted.
  • Do not remove the plastic plugs above the pipelines and oil pipes before they are installed.

3. Use of the motor

3.1   Use of motor

  • The pressure, flow, and output power of the motor must not exceed the specified values.
  • When running for a long time, the oil temperature does not exceed 65℃.
  • Motor limit working temperature: -30℃-70℃.

3.2  Commissioning

  • Before starting, check the motor installation, whether the connection is correct and firm, and the system is correct.
  • Check whether the oil inlet and outlet directions and motor rotation direction meet the requirements of working conditions.
  • The pressure of the relief valve of the oil supply line is adjusted to the lowest value, and gradually adjusted to the required pressure after operation. Tighten the inlet and outlet pipes and the drain pipe.
  • After running the motor under no load for at least 10 minutes, gradually increase the pressure to the working pressure, and observe whether the motor is running normally at any time during the operation.
  • During operation, the working conditions of the motor and system should be checked frequently. If abnormal temperature rise, leakage, vibration and noise or abnormal pulsation of pressure are found, the machine should be stopped immediately to find out the cause.
  • During use, when the temperature of the oil inlet is ≥65 °C, please check whether the cooler works normally. To ensure the normal working temperature of the motor surface.
  • Motor transportation should be equipped with appropriate wooden boxes and cardboard boxes according to the size of the motor, and plastic paper packaging on the surface of the motor to prevent the moisture and moisture from invading the motor and causing the motor to rust and cause motor failure.
  • Avoid placing the motor directly on the ground. No need to apply anti-rust oil for a long time.
  • Motor storage environment: 10-9%RH, -20-65S C.
  • During transportation and storage, the motor should avoid moisture, moisture and any what corrosive gas.

4. Motor troubleshooting

The motor is a precision component, which needs to be installed, commissioned and repaired by professionals. Without our company's consent, it is not allowed to dismantle and repair it by yourself. If the user unit has the conditions for dismantling and inspection with the permission of our company, after reading the instructions carefully, you can dismantle and inspect it yourself, but you must pay attention to the following three points:

  • When disassembling, be careful not to knock the parts and scratch the hair, especially to protect the moving surface and sealing surface of the parts. The disassembled parts are placed in a clean container to avoid collision with each other. It is forbidden to strike with a hammer during disassembly and assembly.
  • The removed parts should be carefully inspected, and the worn parts are basically replaced without repairing by themselves. In principle, all seals are replaced.
  • Before assembling, all parts should be cleaned and dried. Do not use cotton yarn or rags to wipe the parts. The assembly place and the tools used should be clean, and the output shaft should be rotated after assembly. It should be flexible and free of jams.


Serial number Fault phenomenon The Reason Exclude
1 The motor does not rotate Hydraulic pump does not start Turn on the hydraulic pump
Insufficient oil in the tank oil
Directional valve in neutral Open the directional valve
System overflow valve fully open The system pressure is adjusted to the specified value
Motor torque is not enough Replace the motor
2 There is abnormal noise when the motor is running There is air in the hydraulic system Find out the reason for the intake air and discharge the air in the oil
Vacuum Increase fuel supply
Motor failure Replace the motor
Support bearing is broken Replace bearing
3 Motor leakage Damaged seal Replace the seal
Parts have pores, trachoma, cracks, etc. Replacement parts
4 Motor heat Hydraulic oil temperature is too high Increase cooling capacity
Low motor efficiency Replace wearing parts
Abnormal wear Replace the motor
5 Increased oil leakage at the outer drain hole Abnormal wear at the distribution shaft Replacement parts
Wear of the needle column group of the cycloid wheel stator body

5. Motor maintenance and post-processing
Regularly check the accessories in the hydraulic system, the accuracy of pressure gauges, thermometers, etc.

  • Check hydraulic oil regularly:
    It is not allowed to use mixed oils of different types of hydraulic oils, and the period of renewal of new oils varies according to different industries and mines.
  • Under normal circumstances: the hydraulic oil is changed every six months.
  • Disposal of waste oil after motor use:
    Should be sent to a special waste oil treatment unit for centralized treatment of waste oil.
  • If the motor is not used for a long time:
    The cavity should be filled with oil, and the oil ports should be sealed. Grease on the surface of the output shaft should be wrapped with a cloth or sleeve.


The manufacturer is not responsible for the consequences caused by the user not following the above recommendations or using the motor incorrectly.

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