Bonfiglioli A-series gearbox selection and maintenance

Bonfiglioli A-series helical bevel gear reducer selection and maintenance engineering guide

In the field of industrial transmission, helical bevel gear reducers have become the preferred choice for many heavy-duty applications due to their high efficiency, high torque density, and flexible installation methods. Bonfiglioli's A-series (Spiral level gearmotors) has undergone years of technological iteration, covering a torque range of 100-14000 Nm with modular design, high-precision gear grinding, and diverse output forms. This article is based on the official technical manual, and systematically elaborates on the practical application points of this series of reducers from the dimensions of engineering selection, mechanical installation, lubrication maintenance, load verification, and fault diagnosis, providing an operable technical reference for on-site engineers.

Overview of Product Series and Interpretation of Technical Parameters

The A series adopts a combination of helical gears and bevel gears for transmission, which can achieve right angle output with input and output shafts perpendicular. Its core advantages lie in:

Torque range: 100~14000 Nm, with a total of 12 machine bases (A 05 to A 90).

Power coverage: At an input speed of 1400 min ⁻¹, the mechanical power reaches 0.22-150 kW.

Speed ratio range: 5.4~1715 (multi-stage combination).

Output form: Foot or flange installation, key bonded hollow shaft, keyless shrink disc, metric/imperial solid shaft, spline hollow shaft (DIN 5480), suitable for various load connections.

Input interfaces: IEC/NEMA motor adapter, servo motor adapter, solid input shaft.

Key points of selection project: Based on the required output torque M ₂ and output speed n ₂ of the load, combined with the input speed n ₁, calculate the reduction ratio i=n ₁/n ₂, and then check the table to select the rated output torque M ₙ ₂ ≥ calculated torque M ꜀ ₂ (M ꜀ ₂=M ₂ × f ₛ, where f ₛ is the service coefficient). The service coefficient needs to be retrieved from the chart based on the load type (uniform, moderate impact, heavy impact), daily operating hours, and start-up frequency.

Selection calculation process and examples

Step 1: Determine the service coefficient f ₛ

Based on the load characteristics (acceleration quality factor K, divided into K1~K3 curves) and the number of starts and stops per hour, combined with the daily operating hours, refer to Table A2 to obtain f ₛ.

Typical values: uniform load, 8 hours per day, with few startups f ₛ ≈ 1.0~1.2; When subjected to heavy impact and frequent start stop, it can reach 2.0 or above.

Step 2: Calculate the required input power P ᵣ₁

Given the output torque M ₂ and output speed n ₂, as well as the dynamic efficiency η₀ (A series 2nd stage about 0.94, 3rd stage about 0.91, 4th stage about 0.89), then:

Pᵣ₁ = (M₂ × n₂) / (9550 × η₀) [kW]

When selecting, it is necessary to ensure that the rated power of the motor P ₙ ≥ P ᵣ₁. If it is a non continuous working system (S2-S8), it can be multiplied by the power enhancement factor f ₘ (refer to Table A7).

Step 3: Select the machine base and speed ratio

Find a model from the selection table (such as A 10, A 20, etc.) that is close to the calculated speed ratio and has a rated torque of ≥ M ꜀ ₂. For example, if an output torque of 800 Nm, an output speed of 20 min ⁻¹, and an input of 1400 min ⁻¹ are required, then i ≈ 70, check the corresponding model of the A 50 series.

Attention: For dual speed motors or special operating conditions (such as lifting or translation), please contact the technical department.

Mechanical installation and alignment specifications

Correct installation is the key to ensuring the lifespan of the gearbox. The manual specifies the following key points:

1. Installation base and fastening

The installation surface must be flat, and the anchor bolts must be tightened with torque (refer to tables B11 and B12). For the A series, different machine bases correspond to different bolt specifications (such as M8, M10, M12, etc.).

If flange installation (B5 or B14) is used, it is necessary to ensure that the flange mating surface is clean and free of paint or burrs.

2. Assembly of output shaft coupling

Hollow shaft fit tolerance: The standard is G7 (hollow shaft) and h6 (equipment shaft). If slight interference is required, j6 can be used.

When outputting with a solid shaft, the inner hole of the coupling or pulley should be machined to ISO H7 tolerance to avoid bearing damage caused by excessive interference.

During installation, it is necessary to use the threaded hole on the shaft end to match the puller, and it is strictly prohibited to strike, otherwise it will damage the gears and bearings.

3. Installation of hollow shaft locking disc (shrink disc)

If a shrink disc (model suffix "US" or "UH") is selected, the bolts should be tightened multiple times according to the manufacturer's recommended torque sequence to ensure even locking force and avoid journal slippage.

4. Ventilation valve and oil level

After installation, the position of the vent valve and oil level plug must be adjusted according to the actual installation orientation (such as horizontal, vertical, inverted). Manual B2 and B3 provide a detailed list of oil plug position numbers (such as C, L, S, T) corresponding to different installation positions (R, D, H, S, VA, VB). Be sure to configure according to the actual installation orientation, otherwise it may cause oil leakage or insufficient lubrication.