1. Confirm the motor type fits the job

The product page describes the BM4 series as a low-speed, high-torque orbital motor using a gerolor (geroler) gear design, intended for industrial and mobile applications. If your application calls for low-speed, high-torque rotary output, the series is a candidate. If you need high-speed rotation, this description does not support that use, and you should look at other motor types.

2. Check your hydraulic oil conditions against the published limits

The product page lists these operating conditions. Compare them with your system before you compare quotes:

If your machine regularly runs hotter than the normal range, or your filtration cannot meet the stated accuracy and cleanliness level, discuss this with the supplier before you order. Fixing a mismatch later, through extra cooling or filtration, can cost more than the motor itself.

3. Decide on series or parallel connection

The BM4 series is listed as supporting both series and parallel connection, and the page credits its shaft seal design with handling higher pressures in both setups. If you are running hydraulic motors in series, check the return port pressure as well. The parameter table lists "Return Port Pressure: relief required > 10 MPa", so ask the supplier to confirm what relief arrangement your circuit needs.

4. Define the mounting and interface configuration

The series offers a range of customizable flanges, output shafts and oil ports. These choices change the part number, so they are among the main reasons one hydraulic orbital motor price differs from another. Specify the following before asking for a quote:

• Flange type that matches your existing mounting
• Output shaft type that matches your coupling or driven component
• Oil port type that matches your hose and fitting standard

If you are replacing a motor on existing machinery, the original motor's interface dimensions are the most useful reference to send.

5. Plan for load and duty conditions

The page describes a double-rolling bearing design intended to handle significant lateral loads. It also lists an optimal load rate of 1/3 to 2/3 of the rated condition, and recommends a break-in period at 30% of rated pressure for longer life. Two points matter for buyers:

• The page gives no rated pressure or torque figures, so ask for them in order to work out what 1/3 to 2/3 of the rated condition means for your load.
• The parameter table's "High Axial/Radial" load capacity entry is labeled for BM5–BM10, not BM4. Do not assume it applies to the BM4 series without written confirmation.

6. What to include in a quotation request

A complete request helps the supplier quote the correct configuration:

1. Application and machine type
2. Required speed and torque range
3. System pressure and flow
4. Oil temperature range, filtration level and oil viscosity
5. Series or parallel connection, and expected return port pressure
6. Flange, shaft and oil port requirements
7. Lateral or axial load on the shaft
8. Quantity and destination market

Then ask the supplier to confirm price, lead time, any certifications you need, and the rated performance data for the configuration they offer.

When the BM4 series may not be the right choice

• Your oil temperature regularly goes above 60°C, or you cannot keep it below 90°C
• Your filtration cannot reach 10–30 microns and ≤ 19/16 cleanliness
• Your application needs high-speed rather than low-speed, high-torque output
• You need documented ratings or certifications that the supplier cannot provide for your configuration