Shijiazhuang Laiye Import& Export Trading Co., Ltd. is one of the leading manufacturers and suppliers of bm3 series heavy-duty gerotor hydraulic motor in China, also supports customized service. If you're going to wholesale high quality bm3 series heavy-duty gerotor hydraulic motor made in China, welcome to get pricelist from our factory.
Products Description
The mechanical reasoning behind the upgrade
In the BM2 series, we used a standard rolling bearing setup. It works fine for most medium-duty jobs. But when you start driving heavy chain sprockets or gears directly off the motor shaft, the radial force on the output bearing increases significantly. That is where the BM3 series heavy-duty gerotor hydraulic motor differs. We fitted it with a double-rolling bearing design. This is not just a larger bearing; it is an entirely different bearing structure that distributes the side-load over a wider surface.
The result you see in the field
With this bearing change, the radial load capacity jumps to 800 Kg, and the axial load capacity reaches 400 Kg. If you are building an auger attachment or a heavy-duty winch, this means you do not have to build an external support bracket for the drive shaft. You can mount the sprocket directly on the motor, as long as the bending force does not exceed the 800 Kg limit. If you are unsure about the weight and chain tension, we recommend verifying the bending force against the limit.
Seal and circuit compatibility
The shaft seal is designed for higher back-pressure, which is important when motors are plumbed in series. In a series circuit, the return flow from one motor feeds the inlet of the next, which increases the pressure on the seal. The BM3 handles this configuration without early seal failure.
Physical Performance
Pressure and torque behavior
The BM3 series is rated for 14 MPa continuous on the 100 and 160 mL/r models. As you go up in displacement, the continuous pressure drops to 12.5 MPa and then to 11 MPa on the largest 400 mL/r model. This is not a manufacturing limitation; it is an engineering choice to protect the larger gerotor set from generating forces that would exceed the shaft's mechanical limits. Even at the lower pressure, the 400 mL/r model still produces 581 N·m of continuous torque.
Speed limitations
The speed drops as displacement increases. The 100 mL/r motor runs at 450 r/min continuous; the 400 mL/r motor runs at 121 r/min. If your application needs speed, you pick a smaller displacement. If you need torque, you look at the larger models. There is no motor that gives you both high speed and high torque.
Output shaft selection
When you order the motor, you have to specify the shaft type. We offer Plain Key shafts in different sizes (like 8x7x28 or 10x8x40) and Rectangular Spline shafts. If you are replacing an existing motor, it is important to measure the existing shaft diameter and keyway width. A rectangular spline is preferred if you are expecting heavy shock loads; the spline distributes the torque more evenly than a single key.
Standard rotation direction
The standard rotation is clockwise when the A port is pressurized, viewed from the shaft end. The motor is fully reversible; swapping the pressure to the B port will reverse the rotation.
Specifications
Main Technical Parameters Table
| Displacement (mL/r) | Rated Flow Cont. (LPM) | Rated Speed Cont. (r/min) | Max Speed Int. (r/min) | Pressure Cont. (MPa) | Pressure Int. (MPa) | Torque Cont. (N·m) | Torque Int. (N·m) |
|---|---|---|---|---|---|---|---|
| 100 | 50 | 450 | 540 | 14 | 16 | 178 | 216 |
| 160 | 50 | 281 | 337 | 12.5 | 14 | 272 | 306 |
| 200 | 50 | 226 | 272 | 12.5 | 14 | 330 | 357 |
| 250 | 50 | 180 | 216 | 12 | 13 | 392 | 424 |
| 315 | 50 | 147 | 177 | 12 | 13 | 499 | 540 |
| 400 | 50 | 121 | 142 | 11 | 12.5 | 581 | 660 |
Installation Notes and Common Pitfalls
Measuring the output shaft correctly
Before you place an order, measure the shaft on your existing motor. The BM3 series heavy-duty gerotor hydraulic motor has several options: a Plain Key shaft with an 8x7x28 keyway, and a Rectangular Spline with a 6D-30x25.4x8 profile. If you select the wrong shaft, it will not fit your coupling or sprocket. Taking a few minutes to measure the diameter, keyway width, and shaft length can save a lot of time later.
Mounting and alignment
The motor uses a 4-bolt flange for mounting. Tighten the bolts evenly in a cross pattern. If the motor shaft and the driven shaft are not aligned, the side-load on the bearings will exceed the 800 Kg limit, even if the motor is not under load. Alignment is not just about the coupling; it is also about the bracket rigidity.
The case drain line
We strongly recommend connecting the T port directly back to the tank. Do not tie it into the main return line. If the return line back-pressure exceeds 5 MPa, the pressure behind the seal will force the lip outward. A direct drain line eliminates this risk.
Cold weather startup
When the machine is operated in sub-zero temperatures, the hydraulic oil becomes thicker. The internal spool valve will shift more slowly during the first few minutes. Let the oil circulate at low speed before applying full load.
Oil condition
The gerotor set relies on clean oil to maintain its efficiency. We recommend keeping the filtration level at 25 microns or better. Contaminated oil will accelerate wear on the gerotor surfaces, and you will notice a gradual reduction in torque output.
Choosing the Right Displacement
The displacement selection is a trade-off between torque and speed.
If your machine needs high torque-above 500 N·m-the 315 or 400 mL/r models are the choices. They run slower but deliver the turning force needed for augers and winches.
If your machine runs at moderate speeds and does not need the extreme torque, the 100 to 200 mL/r models are a good balance. They run more efficiently in the higher pressure range and provide more responsive speed.
When you calculate your torque requirement, if it falls between two models, we recommend selecting the larger displacement to provide some margin for unexpected load spikes.
The Company
How the components are checked
Before the motor goes into assembly, the gerotor set is measured for clearance. That clearance dictates how much oil slips past internally. The bearings are checked for free rotation, and the cast iron housings are inspected for cracks. If any of those checks don't meet the spec, the part goes back to machining. A full performance test is run on the completed motor before it leaves the factory.
Final testing
Before the motor leaves the shop, it runs on a hydraulic test bench. We bring it up to the rated speed and pressure to confirm the torque curve matches the spec sheet. The shaft seal and port faces are checked for any sign of leakage. If we pick up unusual vibration or noise during the run, the motor is pulled aside and opened up for re-inspection.
Customization
We support OEM requests for non-standard output shafts, flange patterns, and port positions. If your machine requires something outside the standard list, send your drawing to our engineering team. We can verify the compatibility with your coupling and bracket before production begins.
FAQ
Q: What is the main difference between the BM2 and BM3 series?
A: The BM3 series uses a double-rolling bearing design, which provides much higher shaft load capacity. The BM3 supports 800 Kg radial load and 400 Kg axial load, compared to 400 Kg and 200 Kg on the BM2 series. The BM3 also offers higher maximum torque output.
Q: What is the maximum back-pressure allowed on the return side?
A: The motor is designed to withstand a maximum back-pressure of 10 MPa. However, we recommend keeping the back-pressure below 5 MPa. If your return line pressure exceeds 5 MPa, install a dedicated case drain line to relieve the pressure behind the shaft seal.
Q: Does the motor require a break-in period before full-load operation?
A: Yes. We recommend running the motor under a low load (below 40% of the working pressure) for about one hour. This allows the internal spool and gerotor surfaces to seat properly. Skipping this step can increase the internal leakage rate over the first few months of operation.
Q: How does the motor perform in very dusty or dirty environments?
A: The motor is designed for outdoor machinery and will perform well in dusty environments, provided the oil is kept clean. The main vulnerability in dirty environments is the shaft seal. If dust accumulates around the rotating shaft, it can abrade the seal lip over time. Periodically wiping the shaft area clean helps extend seal life.
Q: Is it normal for the motor to make a squealing sound during the first few minutes of operation?
A: A brief squealing sound during the first startup after oil change is sometimes caused by air trapped in the motor housing. If the motor has been sitting idle for a while, air can enter the case drain cavity. Once the oil starts circulating, the air will be pushed out through the case drain line. If the squealing noise persists for more than a few minutes, it could indicate that the case drain line is not properly connected or that the oil level in the tank is too low.
Hot Tags: bm3 series heavy-duty gerotor hydraulic motor, China bm3 series heavy-duty gerotor hydraulic motor, manufacturers, suppliers, factory, dc valve in hydraulic, direction flow control valve, directional flow control valve, pilot operated dc valve, sectional valve, solenoid controlled hydraulic valves
