Bonfiglioli AS Series Reducer Installation and Maintenance Guide



Bonfiglioli AS Series Industrial Reducer: A Complete Technical Manual from Installation to Troubleshooting

In the field of industrial transmission, Bonfiglioli's AS Series parallel axis helical gear reducer is known for its high torque density and modular design, and is widely used in harsh working conditions such as metallurgy, lifting, chemical engineering, and material conveying. However, even the most reliable mechanical units can greatly reduce their lifespan and efficiency if there are omissions during installation, commissioning, or maintenance. This article is based on the manufacturer's official technical documentation and combined with frontline service experience to break down the key points of full lifecycle management for AS Series reducers from unboxing to stable operation, helping engineers avoid common pitfalls and solve practical operational pain points.

Key check before installation: the "golden two hours" that cannot be ignored

Before hoisting the heavy gearbox into place, many teams are eager to get started, but often overlook a few fatal details. According to the requirements of Section 4 (INSTALLATION) of the manual, the following steps must be strictly followed:

Triple verification of Nameplate

In addition to confirming that the model is consistent with the order, special attention must be paid to the mounting position code (such as B3, B5, V6, etc., see page 19 of the manual for details). This code determines the position of the Oil Level Plug and Breather Plug, and if installed incorrectly, it will cause the lubrication system to completely fail. At the same time, check the maximum surface temperature on the nameplate, which is the core basis for determining the safety distance of equipment in ATEX explosion-proof environments.

Discharge and flushing of stored oil products

For reducers that have been filled with rust proof oil internally at the factory, if the oil is incompatible with the synthetic oil or mineral oil you plan to use, it must be thoroughly drained and the inner cavity flushed with a special solvent before adding new oil. Warning on page 12 of the manual: Do not allow solvents to come into contact with the seal rings, as this may cause swelling and deformation of the seal lips, leading to early leakage.

Precise fit between output shaft and flange

The AS Series offers two output formats: Solid Shaft and Hollow Shaft with Keyway. On page 20 of the manual, a strict tolerance table is provided: for example, for AS 80 model, the Spigot Diameter tolerance for output shaft positioning is f7 (-0.056 to -0.108 mm), while the fitting tolerance for customer components must be H8 (0 to+0.081 mm). It is strictly prohibited to paint in the sealing area. Only Kluber paste 46 MR 401 and other anti Fretting Corrosion assembly paste should be applied.

Core installation technology analysis: precise docking between hollow shaft and IEC motor

1. The "press fit trap" of hollow output shaft

For AS reducers installed with hollow shafts (commonly seen in conveyor drives), the key is the use of tie bolts and spacers. The illustration on page 15 of the manual emphasizes:

The customer must use their own tension bolts to push the reducer into the main shaft of the equipment, and hammering is strictly prohibited to avoid damaging the bearing cage.

The thrust must act on the spacer ring at the hollow shaft end, not on the shaft itself.

During this process, it is necessary to monitor the axial displacement to ensure that the locking torque of the shrink disc (if any) of the hollow shaft meets the specifications.

2. The "anti leakage art" of installing IEC standard flange motors

When installing motors that comply with the IEC 60072-1 standard (see page 16 for details), bolt locking alone is not enough:

Sealing glue strategy: Loctite 510 flat sealing glue must be evenly applied to the adhesive flange surface of the motor and reducer. After the motor is pressed together, Loctite 5366 (or equivalent performance product) should be applied to the gap at the outer edge of the flange. This is not just for oil protection, but also to comply with ATEX 2D/2G explosion-proof requirements and prevent dust or gas from entering the mating surface and generating friction sparks.

Bolt torque management: The torque table (Tab 1) on page 14 of the manual clearly states that for AS Series aluminum enclosures, it is strictly prohibited to use bolts higher than grade 8.8, otherwise it will cause the threads of the enclosure to slip. For example, M12 bolts have a torque of 87.3 Nm for 8.8 grade and 127 Nm for 10.9 grade, with the latter's high preload force sufficient to crush aluminum flanges.

Lubrication management system: the 'blood' that determines the lifespan of the gearbox

AS Series allows the use of mineral oil, PAO synthetic oil, or PAG polyethylene glycol oil. But on page 17, it is emphasized that once synthetic oil is selected, the first oil change (break in period oil change) must be carried out after the first 500 hours of operation, and the subsequent oil change cycle depends on the oil temperature:

Oil temperature<65 ℃: mineral oil for 8000h, synthetic oil for 25000h.

Oil temperature of 65-80 ℃: mineral oil for 4000h, synthetic oil for 15000h.

Oil temperature 80-95 ℃: Mineral oil for 2000h, synthetic oil for 12500h (continuous operation is not recommended in this range).

Practical suggestion: The liquid level of the dipstick or oil sight glass should be checked after operation. For AS 45 and above models, if the LO (with oil) option is selected, the Dummy Plug installed during transportation must be replaced with the included Breather Plug before formal use. In addition, when flushing or changing oil, please be sure to clean the metal powder adsorbed by the magnet on the drain plug, which is the most intuitive basis for judging the degree of gear wear.

Temperature control and vibration acceptance: beyond the practical standards of the manual

1. The "75 ℃ Red Line" for surface temperature rise

On pages 11 and 27 of the manual, it is repeatedly mentioned that the difference between the surface temperature (t_casting) and the ambient temperature (t_ambient) measured at the box closest to the motor joint surface shall not exceed 75 ℃. If the temperature difference approaches or exceeds this value after running at full load for 3 hours, the machine must be stopped immediately.

Typical solution: If the temperature difference is too large, the gearbox should not be suspected of overload immediately. Instead, it should be checked first:

Whether the environmental ventilation is obstructed (especially for outdoor installations with ceilings).

Has it been exposed to external heat source radiation.

Is the viscosity of the oil too high (according to the fault table on page 34 of the manual, high viscosity can cause a sharp increase in operating resistance and temperature).

2. Quantitative determination of noise and vibration

Noise: According to page 24 of the manual, the allowable meshing noise during load operation measured at a distance of 1 meter is 85 dB (A). Any sharp periodic abnormal noise may be a precursor to tooth surface damage or bearing pitting.

Vibration: The acceptance limit for vibration velocity (r.m.s.) depends on the shaft speed. For example, at a speed of 1500 r/min, the boundary of Zone B/C is 5.3 mm/s. If the vibration exceeds the standard, first check the alignment of the coupling, including axial clearance (Gap) and radial misalignment.

Comprehensive troubleshooting: quick investigation of causes and countermeasures

Based on the fault tree on page 34 of the manual (TROUBLESHOOTING), combined with practical cases, we have organized the logical chain of high-frequency faults:

Fault phenomenon 1: Rapid increase in bearing temperature (accompanied by metal friction sound)

Possible reasons: Insufficient lubrication due to low oil level, or fatigue peeling of the bearing itself.

Action plan: If the temperature still rises after refueling, it is necessary to disassemble and inspect the bearings. Remember the suggestion on page 28 of the manual: replace the other bearing on the same shaft to balance the wear cycle.

Fault phenomenon 2: The output shaft does not rotate, but the motor is running

Logical chain: This is almost certainly due to the connection key being cut or the gear tooth breaking.

Root cause analysis: In addition to material fatigue, the actual load torque (Required Torque M2) usually exceeds the design rated torque (Rated Torque Mn2) by more than twice.

Repair Red Line: Page 22 of the manual clearly states that the redesigned transmission system must match the actual load, and simply replacing the gears is ineffective.

Fault phenomenon 3: Normal operating noise, but oil leakage on the joint surface of the box body

Neglected detail: Most oil leaks are not caused by aging sealing rings, but by blockage of breathable plugs leading to excessive pressure inside the box, squeezing oil out of the labyrinth seal.

Quick disposal: Check if the one-way valve of the breathable plug is blocked by oil or paint, and clean or replace it if necessary.

Anti corrosion strategy for long-term shutdown

If the gearbox needs to be shut down for more than a month (such as seasonal production), simply shutting it down is not enough. Warning on page 28 of the manual:

Regular turning: Run at least once a month to re-establish the oil film on the bearings and gears.

Rust prevention protection: If turning is not possible, the box must be filled with new oil of the same model (instead of the normal oil level) to isolate moisture; Alternatively, apply anti rust wax such as Shell Ensis SX to the exposed shaft end on the outside.

Be cautious of condensation water: Changes in temperature can cause water vapor to condense and mix into the oil. On page 30 of the manual, it is required to check for Contaminants, especially water, in the oil every 2000-9000 hours. If the water content exceeds the standard, it must be replaced even before the oil change cycle.