Bonfiglioli 3/H series heavy-duty gearbox selection and verification guide

Bonfiglioli 3/H series heavy-duty modular reducer: full analysis of selection process and engineering verification

In heavy industries such as mining, building materials, metallurgy, power, and ports, large conveyors, bucket elevators, ball mills, and mixers have high requirements for the reliability, power density, and adaptability of reducers. Bonfiglioli's 3/H series heavy-duty modular gearbox innovatively combines planetary gear stages (300 series) with spiral bevel gear stages (HDO series) to achieve a rated output torque of up to 1200 kNm, providing an ideal solution for applications with high power density and medium to low speed output. This article will analyze in detail the technical architecture, selection process, thermal power verification, and configuration methods of key components of the 3/H series reducer from the perspective of engineering practice.

Technical architecture and core design features

The 3/H series reducer is the culmination of Bonfiglioli's modular design concept. It combines the high torque density advantage of planetary gear stages with the power splitting advantage of spiral bevel gear stages, forming a unique "planetary+spiral bevel gear" combined transmission structure.

1. Gears and materials

All bevel gears and cylindrical gears are made of alloy steel, which has undergone carburizing, quenching, grinding, and tooth profile modification. This can not only significantly reduce operating noise and optimize smooth transmission of high-speed stages, but also maximize the transferable torque of the final drive.

The input shaft is also treated with carburizing, quenching, and grinding to ensure wear resistance and fatigue strength at high speeds.

2. Modular size

This series offers 10 machine base sizes (11, 13, 15, 16, 17, 18, 19, 21, 23, 25), with rated torque values evenly distributed across the entire speed ratio range, ensuring that engineers can find the best cost-effective solution for each specific application.

3. Compact structure

The compact design of the 3/H series not only saves installation space, but also improves the rigidity of the system. There are multiple optional options for its output shaft configuration, including a hollow shaft (FP) with a shrink disc and a spline hollow shaft (FZP) with an axial locking device, to accommodate different installation methods.

Key requirements for installation and lubrication

1. Installation rules

The reducer must be firmly fixed on the foundation structure to prevent vibration. The manual emphasizes that the machined mating surfaces and the outer edge of the oil seal must be protected before painting to prevent the paint from coming into contact with the rubber seal and causing it to harden and fail.

Fit tolerance: The internal holes of the components installed on the output shaft of the reducer should be machined to ISO H7 tolerance to avoid damage to the gears or bearings during assembly due to over tight fit.

2. Lubrication system

The internal gears of the 3/H series adopt oil bath splash lubrication (oil immersion splash). For operating conditions where the output speed is below 1 rpm or the input speed is above 1800 rpm, it is necessary to consult Bonfiglioli's technical service department.

Key limitation: In the installation position of AB6 (vertical installation, output axis upward), the upper bearing needs to be lubricated through a forced lubrication system with an electric pump (MOP option). This is not optional, but a mandatory requirement.

Factory state: The reducer does not contain lubricating oil when it leaves the factory. Before the user runs it for the first time, they must add the correct amount of oil according to the installation position and the selected oil according to the manual.

Selection process and service coefficient

1. Determine the speed ratio and power demand

Determine the total speed ratio based on the motor speed (n ₁) and the required output speed (n ₂): i=n ₁/n ₂. Then calculate the power demand of the input shaft of the gearbox:

Pr one=Mr two×ntwo nine thousand five hundred and fifty×η[kW]

P r1= 9550×ηM r2×n two [kW]

among which

Mr two

M r2

It is the output torque required by the load,

η is the efficiency of the gearbox (usually requires consulting the manual or consulting the manufacturer).

2. Selection of service coefficient (f ₛ)

The service factor is a numerical value used to quantify the severity of application conditions, taking into account the uniformity of load, start-up frequency, and total operating time.

Load types: divided into three categories: uniform load, moderate impact load, and strong impact load (determined by acceleration coefficient K).

Table lookup method: Select the minimum required f ₛ value from the service coefficient table provided in the manual based on the number of starts per hour (Z) and the number of running hours per day (or total running time).

Selection formula: The rated input power (Pn ₁) of the selected reducer must meet the requirement of Pn ₁ ≥ P_ {r1} × f ₛ.

3. Motor adaptation and speed ratio matching

Confirm the compatibility between the selected motor power and the flange size of the gearbox by referring to the motor adaptation table (IEC or NEMA) in the manual. Attention: If the peak power of the motor far exceeds the rated power of the gearbox, a torque limiter must be installed to prevent overload damage to the gearbox.