Selection and Calculation of Bonfiglioli RAN Right Angle Gearbox

Bonfiglioli RAN series right angle gearbox selection calculation and engineering application guide

Introduction: Engineering Challenges of Right Angle Transmission

In industrial transmission systems, when power transmission requires changing direction between orthogonal axes, the Mitre Gears/Marvel Gears become an indispensable core component. Unlike traditional worm gears or planetary gearboxes, right angle gearboxes need to balance multiple goals such as high efficiency, low backlash, and high load-bearing capacity while achieving 90 ° steering.

The Bonfiglioli RAN series, as a representative of its right angle gearbox product line, covers a wide range of scenarios from small power precision transmission to high thrust heavy-duty lifting applications. From the compact design of RAN 8 to the ultra large axial load capacity of RAN 2R, this series fully embodies Bonfiglioli's over sixty years of technical accumulation in the field of bevel gear transmission. This article will provide engineers with a complete engineering application methodology based on the RAN series technical manual, covering three core dimensions: selection process, load verification, and lubrication strategy.

Three basic parameters before selection

The correct selection begins with precise definitions of three basic parameters: torque, power, and service factor.

1.1 Rated torque and required torque

Rated torque [M ₙ₂]: refers to the torque that can be transmitted at the output end of the gearbox under uniform continuous load, based on the service coefficient f ₛ=1 and a specific input speed [n ₁]. This is the 'nominal capacity' of the gearbox.

Required torque [M ᵣ₂]: The output torque determined by the actual application requirements. When selecting, it is necessary to ensure that M ₙ₂ ≥ M ᵣ₂.

1.2 Input power [P ₙ₁]

The rated power data of the RAN series corresponds to the available input power at a specific input speed [n ₁] and a service factor f ₛ=1. When selecting, engineers need to ensure that the output power of the motor does not exceed this value, or adjust it based on the actual working conditions through a service factor.

1.3 Determination of Service Coefficient [f ₛ]

The service coefficient is a key parameter that quantifies the severity of application conditions. Its determination requires comprehensive consideration of three major factors:

Daily operating hours: The longer the operating time, the more severe the heat dissipation and wear accumulation, and the higher the required service factor.

Hourly startup frequency [Z ᵢ]: Frequent start stop will significantly increase the impact load on gears and bearings.

Quality Acceleration Factor [K]: This is the core link between load properties and selection curves.

K=Jc Jm

among which

J-c: The moment of inertia of the load converted to the motor shaft

J'm: The moment of inertia of the motor

According to the magnitude of the K value, the corresponding load curve can be determined:

K ≤ 0.25: K1 curve - uniform load (such as a continuously running conveyor belt)

0.25<K ≤ 3: K2 curve - moderate impact load (such as agitator, compressor)

3<K ≤ 10: K3 curve - strong impact load (such as crusher, stamping equipment)

When K>10, it is necessary to contact Bonfiglioli Technical Service Center for special verification.

The Four Step Process for Selecting Right Angle Gearboxes

Step 1: Determine the calculated torque

Based on the required output torque [M ᵣ₂] and service factor [f ₛ] for the application, calculate the calculated torque [M ꜀₂] for selection:

Mc two=Mr two×fs 

M c2=M r2×f s 

Step 2: Calculate the speed ratio

Calculate the speed ratio [i] based on the input speed [n ₁] and the required output speed [n ₂]:

i=n one n two

Step 3: Match by looking up the table

In the RAN series performance table, find the gear closest to the calculated speed ratio [i] and confirm whether the rated output torque [M ₙ₂] at that gear satisfies M ₙ₂ ≥ M ꜀.

Step 4: Motor compatibility verification

If direct connection to IEC motors is required, refer to the "Motor Adapter" section in the manual to confirm whether the input interface of the selected gearbox is geometrically compatible with the motor flange (such as B5, B14). For larger machine bases such as RAN 28/38/48, the range of suitable motors needs to be confirmed by Bonfiglioli's technical department.

Load verification: engineering considerations beyond torque

After the selection is completed, engineers must verify the following three types of loads to ensure the reliability and lifespan of the gearbox under actual working conditions.

3.1 Radial load [R] verification

When external transmission components (sprockets, gears, pulleys) are installed on the gearbox shaft, they will generate radial forces acting on the shaft. The calculation formula is:

Rc[N]=two thousand×M[Nm]×Krd[mm]

R c[N]= d[mm]2000×M[Nm]×K r

among which

M: The torque acting on the shaft

d: The pitch diameter of the transmission component

K ᵣ: Transmission type coefficient

K ᵣ=1.0: Chain Drive

K ᵣ=1.25: Gear transmission

K ᵣ=1.5~2.0: Belt drive