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

Thermal power verification (key verification step)

After the mechanical selection is completed, thermal power verification must be carried out. Thermal power (P_TB/P_TFAN) refers to the maximum mechanical power that can be safely transmitted by a gearbox during continuous operation, with the internal temperature not exceeding the damage limit (usually 90 ° C~100 ° C oil temperature). If the input power loss exceeds the natural heat dissipation capacity of the gearbox, the oil temperature will continue to rise, leading to oil degradation and bearing failure.

1. Basic thermal power (P_TB)

The P_TB value in the manual is calculated based on the following standard operating conditions:

Input speed 1800/1500 rpm

Environmental temperature 20/40 ° C

Horizontal installation position (AB3)

Installed in open areas with good air circulation

Use ISO VG 220 mineral oil

If the actual working conditions do not meet the standards, corrections or auxiliary cooling measures need to be taken.

2. Determination of heat capacity

Must satisfy: P_TB ≥ P_ {r1}. If P_TB<P_ {r1}, an auxiliary cooling device needs to be selected:

FAN (forced ventilation): Install a cooling fan on the input shaft, but the efficiency decreases significantly when the input speed is below 900 rpm.

SR (Cooling Coil): Install water-cooled coils in the gearbox oil tank (only for AB3 installation position), using external cooling water to remove heat.

MCRW/MCRA (Independent Cooling Unit): They are water oil coolers and air oil coolers, respectively, suitable for high ambient temperatures or extreme power loss situations. The heat exchange power value can be found in the relevant chapters of the manual.

MOP (forced lubrication pump set): AB6 installation position comes standard, with lubricating oil circulated through an electric pump and filtered to ensure effective lubrication and cooling of the upper bearings.

3. Environmental temperature correction

When the ambient temperature exceeds 40 ° C or falls below 0 ° C, there will be a significant change in thermal power. In high temperature environments, it is necessary to reduce input power or enhance cooling; In low-temperature environments, it should be considered to add an oil heater (HE option) to ensure that the oil temperature reaches the viscosity conditions required for start-up.

Selection and configuration of backstop

For applications that require prevention of load reversal, such as inclined belt conveyors and bucket elevators, a check valve is a crucial safety device.

1. Function of backstop

It ensures that the gearbox can only rotate in one direction, preventing motor reversal and equipment runaway accidents caused by gravity or load reverse torque.

2. Torque limit conditions

When selecting, the following conditions must be strictly followed to ensure that the input shaft torque does not exceed the ultimate bearing capacity of the backstop:

M two η×i≤M one max η×i

M two ≤M 1max

among which

M one max M 1max

The maximum allowable input torque of the backstop corresponding to the machine base number/speed ratio given in the manual. This is a mandatory condition and cannot be exceeded.

3. Rotation direction and installation

When placing an order, it is necessary to specify the free rotation direction of the output shaft (clockwise CW or counterclockwise CCW).

The manual provides detailed installation dimensions and the minimum overspeed speed (n1min). In steady-state operation, it is recommended to maintain the input speed higher than the n1min listed in the table to ensure the normal operation of the centrifugal separation mechanism inside the backstop and avoid wear caused by continuous contact between the rollers and the inclined surface.

Radial/axial load verification

The external transmission components (sprockets, pulleys, gears, etc.) on the output shaft will generate radial force (R_c) and axial force (A_n).

1. Radial load

The manual provides the maximum allowable radial load (R_max) for each machine base number and speed ratio, as well as the displacement coefficient K ₁ at different load application points (distance x from the shaft shoulder). The actual radial load R_c must meet:

R_c ≤ R_n × K₁

Among them, Rn is the allowable radial force of the base, and K ₁ is the displacement correction coefficient of the load application point (the farther the load is from the bearing, the smaller the K ₁ value, and the smaller the allowable radial force).

2. Axial load (thrust)

The allowable axial thrust is: A_n ≤ 0.2 × Rn ₁. If the thrust exceeds this value or axial force dominates, it is necessary to contact Bonfiglioli's technical service department for detailed analysis.

Suggestions for configuring key optional components

1. Sealing system (TK/VS)

TK (Taconite Seal): Used in environments containing abrasive dust, it combines triple protection of oil seal, labyrinth seal, and grease chamber. Regularly add lubricating grease.

VS (Fluororubber Oil Seal): Standard fluororubber seal, resistant to high temperature and chemical corrosion.

2. Sensor (TG/PT100)

Bimetallic thermostat (TG): When the oil temperature exceeds 90 ° C ± 5 ° C, it outputs a switch signal and can be connected to an alarm or shutdown circuit.