With high torque density, low noise, and long life, hydraulic orbital motors have become the core power source for construction machinery, ship deck machinery, agricultural equipment, and other fields. Compared to geared motors, hydraulic orbital motors have a torque density of up to 0.5 kg/kW, a volume reduction of more than 30%, and an operating noise of less than 65 dB, making them the preferred solution for precision hydraulic transmissions.
1. Core components: stator-rotor engagement and volume change
(1) Stator (inner ring)
Fixed inside the shell, forming a continuous closed cavity. The precision of its tooth shape should be controlled within ± 0.005mm to ensure efficient meshing with the rotor.
(2) Rotor (cycloid gear)
The rotor hydraulic orbital motor is the core working part, adopting short-range external cycloid tooth profile design, and the stator to form a less differential internal mesh structure. Under the action of pressure oil, the rotor rotates around its own center at a low speed, and also rotates around the center of the stator at a high speed in the reverse direction to realize the suction and discharge oil continuous flow. Its unique eccentricity design makes the volumetric efficiency as high as more than 90%, and the output torque is amplified by planetary motion, which has the characteristics of low-speed high torque. High surface hardness, wear resistance, with precision machining technology to ensure the accuracy of cycloid tooth shape. This design makes the motor has the advantages of small size, light weight, small inertia and flexible startup.
2. Flow distribution system
(1) Shaft flow distribution type
Principle: The output shaft opens a longitudinal groove to switch the high and low pressure oil circuit by rotation.
Characteristics: simple structure, low cost, but there is a risk of internal leakage (leakage rate of about 5%), applicable to low and medium pressure scenarios (pressure ≤ 14MPa). Excavator slewing mechanism mostly adopts end-face flow distribution motor, with 12% higher efficiency than shaft flow distribution.
(2) End-face flow distribution type
Principle: precision grinding of flow distribution disk and rotor end face, automatic compensation of wear gap through pressure compensation mechanism.
Advantage: volumetric efficiency exceeds 90%, suitable for high pressure working conditions (pressure ≥ 16MPa), such as BM5 motor with pressure compensation disk design, axial clearance automatic adjustment, life expectancy increased by 30%.
3. Bearings and Seals: Durability Guarantee under Compound Load
(1) Bearing design
To withstand the rotor rotation and rotation of the composite load, double angular contact ball bearings (such as BM5 type) can deal with radial and axial forces at the same time.
(2) Sealing technology
Fluoroelastomer is resistant to high-temperature hydraulic oil at 120°C. Hankyu extends seal life to 8,000 hours through low-pressure oil infiltration technology.
4. Maintenance and repair work of the technical points and precautions
(1) The hydraulic orbital motor with slide valve flow distribution requires high precision of oil, so the hydraulic oil filter element and hydraulic oil should be replaced regularly.
(2) hydraulic orbital motor output shaft if you can rotate by hand, indicating that the rotor, stator between the roller wear is serious, the motor shell leakage of oil is large, must be replaced in time, otherwise hydraulic orbital motor is difficult to work properly.
(3) hydraulic orbital motor working pressure on its work has a greater impact, generally in the system allows, the working pressure will be adjusted slightly higher for good.
Only master the hydraulic orbital motor structural characteristics and technical performance, and according to the above warranty technical points for the use of maintenance, in order to give play to its strengths, to avoid its weaknesses, so that it is better for the production services.
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