Bonfiglioli RAN series bevel gearbox selection and maintenance guide

Practical Guide for Engineering Selection and Maintenance of Bonfiglioli RAN Series Cone Gearbox

In industrial transmission systems, when power transmission needs to change direction, the bevel gearbox is an indispensable key component. The RAN series bevel gearbox launched by Bonfiglioli provides a reliable right angle transmission solution for applications such as conveying machinery, packaging equipment, lifting platforms, screw jacks, etc., thanks to its compact structure, multiple shaft arrangements, wide torque range, and extremely low maintenance requirements. This article will systematically explain the technical points of the RAN series in practical projects from the dimensions of engineering selection, installation alignment, lubrication and maintenance, and fault diagnosis, to help engineers fully tap into the performance potential of this series of products.

Overview of Product Series and Interpretation of Technical Parameters

The RAN series is a right angle bevel gear transmission unit, designed with quasi double curved or spiral bevel gears, featuring smooth transmission, strong load-bearing capacity, and high efficiency. This series covers a wide range of application scenarios from low power to high torque.

1. Torque and power range

Provides a rated torque range of 2.8 Nm to 3000 Nm, covering 9 machine base specifications (RAN 8 to RAN 48).

At an input speed of 1400 min ⁻¹, the mechanical power range is 0.15 kW to 90 kW, which can be matched with common industrial motor power.

The gear ratio range is 1.0 to 7.7. In addition to the 1:1 straight ratio, multiple reduction ratios are also available (such as the dedicated model with i=3), making it easy to achieve synchronous drive or multi axis speed matching.

2. Axis arrangement and output form

Input shaft: All are solid shaft inputs, providing single axis extension or dual axis extension options (for easy connection to encoders or auxiliary brakes).

Output shaft: Provides a hollow shaft form for key connection, making it convenient to directly fit onto the equipment shaft and saving coupling space; Solid shaft versions can also be provided according to demand (please refer to the ordering code for details).

Axis layout: Supports single-sided output and double-sided output, adapting to different mechanical layout requirements.

3. Thrust bearing capacity

The RAN series emphasizes the rated thrust capacity and is suitable for applications that require bearing axial loads, such as screw conveyors and mixers

RAN 1：50,000 N

RAN 2：80,000 N

RAN 2R：150,000 N

This characteristic gives it significant advantages in working conditions where it is installed vertically or subjected to large axial reaction forces.

4. Special models

The RAN 2R model provides an additional thrust carrying capacity of up to 150000 N, making it particularly suitable for screw jack applications such as lifting platforms, adjustment mechanisms, etc.

The suffix "R" for the model indicates a reinforced thrust design.

Selection calculation and engineering matching principle

The correct selection is the first step to ensure the long-term reliable operation of the bevel gearbox. Engineers need to verify based on actual operating parameters.

1. Determine the required torque and power

Calculate the reduction ratio i=n ₁/n ₂ based on the required torque (T ₂) and speed (n ₂) on the load side, and then deduce the input torque T ₁=T ₂/(i × η). The efficiency η of the RAN series is usually between 0.94 and 0.97 (depending on the speed ratio and lubrication conditions).

When selecting a model, the rated output torque should not be less than the actual load torque, and a safety factor of 1.2-1.5 times should be considered (especially for impact loads or frequent start stop conditions).

2. Verify radial and axial loads

Hollow shaft output is usually used for directly installing drive rollers or spiral shafts. At this time, it is necessary to verify the radial load that the shaft extension can withstand (specific bearing life data of the model needs to be consulted, and if the manual does not provide specific values, technical support can be consulted).

For applications that require significant axial force, such as vertical mixing and spiral extrusion, the RAN 1/2/2R series is preferred, and the corresponding specifications are selected based on the thrust value to ensure that the rated thrust is not exceeded.

3. Thermal power verification

When the ambient temperature is high (over 40 ℃) or the continuous operation time is long, the thermal capacity needs to be checked. The RAN series adopts a cast iron box with good heat dissipation performance, but it is still necessary to consider whether to install forced cooling (such as fans or cooling coils) according to actual working conditions.

4. Installation orientation and lubrication

Different installation orientations (horizontal, vertical, inclined) will affect the selection of lubricating oil level and the position of the vent valve. The manual does not specify all installation methods. In engineering, the installation posture needs to be indicated when ordering, and the manufacturer will provide corresponding oil level indicators and vent plug configurations.

Mechanical installation and alignment process

The installation quality directly determines the noise, vibration, and service life of the gearbox.

1. Installation base and fastening

The bottom of the RAN series enclosure is equipped with installation screw holes, ensuring that the flatness of the installation plane is ≤ 0.05 mm/m. High strength bolts (performance grade 8.8 or above) should be used to tighten according to the specified torque.

For high vibration environments such as crushers and vibrating conveyors, it is recommended to install anti vibration pads or use elastic foundations.

2. Connection between input shaft and motor

The input shaft is a solid cylindrical shaft, usually connected to the motor shaft through an elastic coupling (such as a plum blossom or diaphragm type). It is necessary to strictly ensure coaxiality, and the deviation should be controlled within the allowable range of the coupling (usually radial ≤ 0.05 mm, angle ≤ 0.1 °).

If belt drive is used, it is necessary to ensure that the radial runout and end face runout of the pulley after installation meet the requirements to avoid additional bending moments acting on the input shaft bearing.

3. Installation points of hollow output shaft

The hollow shaft adopts a key connection method, and during installation, the output shaft sleeve needs to be inserted into the equipment shaft and fixed axially using a locking disc (expansion sleeve) or shaft end cover.

Key process: Clean the mating surface and apply anti bite agent before installation; When pushing in, special tools should be used to apply even force to avoid damaging the bearings or gears by knocking.

The locking plate bolts need to be tightened gradually in a staggered order to the specified torque, ensuring even locking force.

4. Ventilation valve and oil level confirmation

After installation, the temporary transportation blockage must be replaced with a working ventilation valve (the appropriate position should be selected according to the installation direction).

Check the oil level through the oil level plug to ensure that the lubricating oil reaches the specified mark. It is recommended to add ISO VG 320 or 460 mineral oil (specific viscosity as recommended in the manual) before the first operation, or synthetic oil can be used to extend the oil change cycle.

Lubrication Management and Maintenance Strategy

The RAN series is designed to be almost maintenance free, but proper lubrication management can significantly extend its service life.

1. Lubricating oil selection

It is recommended to use high-quality extreme pressure gear oil according to the standard, and the viscosity grade should be selected based on the ambient temperature and load. ISO VG 320 is recommended at room temperature (-10 ℃~40 ℃).

For high temperature environments (>40 ℃) or low-speed heavy loads, ISO VG 460 can be selected.

For food grade or special occasions, lubricants certified by NSF H1 should be used.

2. First oil change cycle

After the first 200-300 hours of operation, the first oil change should be carried out to remove metal particles generated during the break in period.

Afterwards, under normal operating conditions, change the oil every 2500-5000 hours or 1 year (whichever comes first). If the environment is harsh (high dust, high humidity), the cycle should be shortened.

3. Oil level inspection and refilling

The oil level should be checked every 500 hours of operation, and the same brand and model of lubricating oil should be used when adding oil to avoid mixing different additives.

If oil emulsification (whitening) or a large amount of metal shavings are found, the cause of seal failure or excessive gear wear should be promptly investigated.

4. Seal maintenance

The shaft end oil seal is a vulnerable component. If oil leakage is found at the shaft end, the oil seal lip should be checked for wear or the shaft neck for damage. When replacing the oil seal, special tools should be used to avoid scratching the surface of the shaft.

Typical application scenarios and configuration recommendations

1. Conveyor line drive

The RAN series hollow shaft is directly fitted onto the drum shaft, eliminating the need for couplings and bearing seats, resulting in a compact structure. Choose a 1:1 ratio for constant speed transmission, or use a reduction ratio to achieve speed matching.

2. Lifting system and screw jack

RAN 2R (Enhanced Thrust Type) is an ideal match for screw jacks, capable of bearing large axial forces and widely used in stage lifts, vehicle lifts, material platforms, etc. It is recommended to choose a dual axis extension input (with one side connected to the motor and the other side connected to the encoder or handwheel).

3. Multi axis synchronous drive

By using dual output shafts or connecting multiple RAN units in series, precise synchronization of multiple shafts can be achieved, such as roller shaft transmission in printing machines and drying cylinder groups in paper machines. At this point, it is important to ensure that the phase and speed ratio between each unit are consistent.

4. Mixing and blending equipment

When installing vertically, it is necessary to confirm the thrust direction. If the mixing blade generates a large axial force, RAN 2 or above specifications should be selected, and the bearing life should be checked.

Common troubleshooting and prevention

Phenomenon 1: Abnormal increase in operating noise

Possible reasons: gear wear, bearing damage, insufficient or contaminated lubricating oil, loose installation bolts.

Troubleshooting steps: Stop the machine to check the oil level and quality, check the torque of the anchor bolts, and use a stethoscope to determine the source of the abnormal noise (such as in the bearing area or meshing area). If it is confirmed that the gear or bearing is damaged, it should be replaced immediately and the root cause should be investigated (such as overload or lubrication failure).

Phenomenon 2: Oil leakage from the output shaft

Commonly seen in oil seal aging or shaft neck scratches during installation. When replacing the oil seal, the surface of the shaft neck should be checked at the same time. If there are grooves, the shaft sleeve should be used to repair or replace the output shaft.

Check if the ventilation valve is blocked (due to increased internal pressure causing oil leakage), and ensure that the ventilation valve is unobstructed.

Phenomenon 3: Excessive temperature rise (over 90 ℃)

Possible reasons: excessive or insufficient lubricating oil, overload, frequent start stop, poor environmental ventilation.

Solution: Check the oil level, verify if the load exceeds the rated torque, and improve the ventilation conditions in the cabinet or surrounding area.

Phenomenon 4: Hollow shaft slipping or axial displacement

Mostly due to the locking plate not being tightened to the required torque or oil stains on the mating surface. Disassemble and clean, tighten the locking bolts in a cross sequence again, and check if the keys and keyways are damaged.

Suggestions for managing installation accessories and spare parts

Standard equipment: Each RAN unit comes with installation nuts, oil seals, vent valves, and oil level plugs.

Spare parts suggestion: Always keep the same type of oil seal, O-ring, and locking plate bolt to prevent sudden shutdown.

Special tools: It is recommended to configure a torque wrench (for locking the disc and installing bolts) and a puller (for disassembling the hollow shaft).