Ball Mill Trunnion Bearing: White Metal (Babbitt) vs Rolling Element, Hydrodynamic Lubrication, and Failure Mode Guide

A ball mill or SAG mill in a cement or mineral processing plant may weigh 1,000–5,000 tonnes when fully charged with grinding media and ore. This entire rotating mass is supported at two points — the trunnion bearings at the feed end and discharge end of the mill. In a large SAG mill, each trunnion bearing may carry a static radial load of 3,000–8,000 kN on a shaft journal diameter of 800–1,800mm. The bearing that supports this load is not a standard rolling element bearing from a catalog — it is a precision-engineered hydrodynamic white metal (Babbitt) bearing, operating on a thin film of pressurised oil that is typically only 50–150 microns thick. When this oil film is intact, the bearing runs indefinitely with virtually zero wear. When the film breaks down — at startup, during oil supply failure, or under overload — metal-to-metal contact occurs within milliseconds, and the soft Babbitt lining sacrifices itself to protect the shaft journal. A single trunnion bearing failure on a large SAG mill can cost $2–5 million in lost production, shaft repair, and bearing remetalling.

This guide provides the complete engineering framework for selecting, specifying, and maintaining ball mill and grinding mill trunnion bearings — covering the fundamental choice between white metal (Babbitt) and rolling element bearings, hydrodynamic lubrication theory and the Sommerfeld number, forced lubrication system design, bearing clearance specification, and the failure modes that result from incorrect specification or lubrication system deficiencies.

Part 1: Trunnion Bearing Types — White Metal vs Rolling Element

1.1 The Fundamental Choice

Two bearing technologies are used for grinding mill trunnion support:

White metal (Babbitt) hydrodynamic bearings — the dominant technology for large mills (shell diameter > 3.0m). The trunnion journal rotates inside a precision-bored bearing shell lined with Babbitt metal. A pressurised oil film separates the journal from the Babbitt surface under normal operating conditions.

Rolling element bearings (spherical roller bearings) — used for smaller mills (shell diameter < 3.0m) and for mills where the simplicity of rolling element bearing maintenance is prioritised over the ultimate load capacity of hydrodynamic bearings.

1.2 White Metal (Babbitt) Bearing Technology

White metal bearings use a layer of Babbitt alloy bonded to a steel or cast iron backing shell. The Babbitt layer — typically 3–12mm thick — forms the actual bearing surface that contacts the oil film.

Babbitt alloy compositions:

For ball mill and SAG mill trunnion bearings, tin-base Babbitt (Grade 2) is the standard specification — it provides the best combination of fatigue strength, corrosion resistance, and embeddability (the ability to absorb small contaminant particles without scoring the shaft journal).

Key properties of Babbitt as a bearing material:

• Sacrificial wear: Babbitt is softer than the shaft journal (typically 20–30 HB vs 200–300 HB for the hardened journal). Under metal-to-metal contact, the Babbitt wears preferentially, protecting the much more expensive shaft journal from damage.

• Embeddability: The soft Babbitt matrix can embed small hard particles (mill scale, dust, wear debris) that enter the bearing, preventing them from scoring the journal surface.

• Conformability: Babbitt can deform slightly under load to conform to minor misalignment between the bearing bore and the journal, distributing load more evenly than a rigid bearing material.

• Fatigue limit: The primary limitation of Babbitt is its fatigue strength — under cyclic loading, the Babbitt layer can crack and delaminate from the backing. The allowable bearing pressure for tin-base Babbitt is typically 3.5–7.0 MPa for continuous operation.

1.3 Rolling Element Bearings for Mill Trunnions

For smaller grinding mills, spherical roller bearings are the standard rolling element bearing for trunnion support. Spherical roller bearings are selected because:

• Their self-aligning capability (up to ±2.5° misalignment) accommodates the shaft deflection and foundation settlement that occurs in grinding mill installations

• Their high radial load capacity relative to bore diameter

• Their ability to carry combined radial and axial loads

The limitation of rolling element bearings for large mill trunnions is the available bore size — standard spherical roller bearings are available up to approximately 1,250mm bore diameter, which limits their application to mills with trunnion journal diameters below approximately 1,100mm. For larger mills, hydrodynamic white metal bearings are the only practical option.

1.4 Selection Criteria: White Metal vs Rolling Element

Part 2: Hydrodynamic Lubrication Theory — The Foundation of Trunnion Bearing Design

2.1 The Reynolds Equation and Oil Film Formation

The hydrodynamic oil film in a trunnion bearing is generated by the wedge action of the rotating journal. As the journal rotates, it drags oil into the converging gap between the journal surface and the bearing bore. The pressure that builds up in this converging oil wedge supports the journal load — this is hydrodynamic lubrication.

The governing equation for the pressure distribution in the oil film is the Reynolds equation:

Where:

• P = oil film pressure (Pa)

• h = local oil film thickness (m)

• μ = dynamic viscosity of the oil (Pa·s)

• u = journal surface velocity (m/s)

• x = circumferential coordinate

• z = axial coordinate

The key insight from the Reynolds equation is that the oil film pressure — and therefore the load-carrying capacity — is proportional to:

• The oil viscosity μ (higher viscosity → higher film pressure → higher load capacity)

• The journal surface speed u (higher speed → more oil dragged into the wedge → higher film pressure)

• The inverse of the film thickness h⊃3;  (thinner film → higher pressure gradient → higher load capacity, but also higher risk of film breakdown)

2.2 The Sommerfeld Number — The Key Design Parameter

The Sommerfeld number (S) is the dimensionless parameter that characterises the operating condition of a hydrodynamic bearing. It combines the bearing geometry, load, speed, and oil viscosity into a single number that predicts the bearing's lubrication regime:

Where:

• μ = dynamic viscosity of the lubricating oil at operating temperature (Pa·s)

• N = journal rotational speed (rev/s)

• P = bearing unit load =

(Pa), where W is the bearing load (N), L is the bearing length (m), and D is the journal diameter (m)

• R = journal radius (m) =D/2

• C = radial clearance between journal and bearing bore (m)

Interpretation of the Sommerfeld number:

For ball mill and SAG mill trunnion bearings, the design target is S ≥ 0.30 under all normal operating conditions. The Sommerfeld number is most critical at startup (low N) and under peak load conditions.

2.3 Minimum Film Thickness Calculation

The minimum oil film thickness in a hydrodynamic bearing is:

Where ε is the eccentricity ratio (the ratio of journal centre offset to radial clearance). For a well-designed mill trunnion bearing operating in the full hydrodynamic regime:

For a bearing with a radial clearance of C = 0.5mm:

The minimum film thickness must exceed the combined surface roughness of the journal and bearing bore by a safety factor of at least 3–5:

Where Λ is the film thickness ratio (target Λ ≥3) and Ra is the surface roughness (typically 

= 0.4–0.8 μm,

= 0.8–1.6 μm for Babbitt).

For

= 0.4 μm and

= 1.0 μm:

This minimum is easily satisfied by the 150 μm film thickness calculated above — confirming the bearing is operating safely in the full hydrodynamic regime.

2.4 Bearing Clearance Specification

The radial clearance

C between the journal and bearing bore is one of the most critical dimensional parameters in trunnion bearing design:

• Too small: Insufficient clearance restricts oil flow through the bearing, reduces cooling, and increases the risk of thermal seizure under load

• Too large: Excessive clearance reduces the oil film pressure (the wedge action is less effective in a wide gap), increases journal eccentricity, and causes vibration

Recommended radial clearance for mill trunnion bearings:

For a 1,200mm journal diameter:

The clearance must be measured at operating temperature — thermal expansion of the journal (steel, coefficient ≈ 12 × 10⁻⁶/°C) reduces the effective clearance as the mill warms up. For a 1,200mm journal running at 60°C above ambient:

This thermal expansion consumes a significant portion of the cold clearance — the cold clearance must be set large enough to ensure the hot clearance remains within the recommended range.

Part 3: Forced Lubrication System Design

3.1 Why Forced Lubrication Is Essential

White metal trunnion bearings require a forced oil circulation lubrication system — not a simple oil bath or grease lubrication. The reasons are fundamental:

1. Heat removal: The viscous shear of the oil film generates heat. For a large SAG mill trunnion bearing, the heat generation rate can be 20–80 kW per bearing. This heat must be removed by the circulating oil — the oil acts as both lubricant and coolant.

2. Continuous oil supply: The hydrodynamic film must be maintained continuously. Any interruption in oil supply — even for a few seconds under load — causes the film to collapse and metal-to-metal contact to begin.

3. Oil filtration: Contaminants in the oil (wear particles, mill dust, water) must be continuously removed to prevent abrasive damage to the Babbitt surface and journal.

3.2 Forced Lubrication System Components

A complete trunnion bearing lubrication system consists of:

Oil reservoir (sump):

• Capacity: Typically 500–3,000 litres for large mill trunnion systems

• Material: Welded steel with internal coating or stainless steel lining

• Features: Oil level sight glass, temperature sensor, low-level alarm, drain valve, access manhole for cleaning

Main oil pump:

• Type: Gear pump (positive displacement) — provides constant flow regardless of system pressure

• Duty: Continuous operation whenever the mill is running

• Standby: A 100% duty standby pump with automatic changeover on main pump failure — mandatory for large mills

High-pressure (jacking) pump:

• Type: Piston pump — provides very high pressure (10–25 MPa) at low flow rate

• Function: Lifts the journal off the Babbitt surface during startup by injecting high-pressure oil directly under the journal through a pocket in the bearing bore. This prevents metal-to-metal contact during the critical startup period before the hydrodynamic film is established.

• Operation: Activated automatically 2–5 minutes before mill start; deactivated when mill reaches operating speed and hydrodynamic film is confirmed by bearing temperature stabilisation

Oil cooler:

• Type: Shell-and-tube or plate heat exchanger, water-cooled

• Duty: Maintain oil supply temperature at 40–50°C (inlet to bearing)

• Control: Thermostatically controlled bypass valve maintains constant oil supply temperature regardless of ambient temperature or mill load

Oil filtration:

• Primary filter: 25–50 micron absolute filtration — removes particles that could score the Babbitt surface

• Secondary (fine) filter: 10 micron absolute — for high-precision bearings

• Magnetic separator: Removes ferrous wear particles from the oil

• Target cleanliness: ISO 4406 Class 16/14/11 or better for mill trunnion bearings

Instrumentation and interlocks:

Critical interlock: If the oil supply pressure drops below the trip setpoint, the mill must be stopped immediately — the bearing cannot survive more than 10–30 seconds of operation without oil supply under full load.

3.3 Oil Selection for Trunnion Bearings

Critical note: Do NOT use oils containing extreme pressure (EP) or anti-wear (AW) additives in white metal trunnion bearings. The sulphur and phosphorus compounds in EP/AW additives react chemically with the tin and lead in Babbitt metal, causing corrosive attack on the bearing surface — a failure mode that is often misdiagnosed as mechanical wear.

3.4 Jacking (High-Pressure) Oil System

The jacking oil system is the most critical protection for the trunnion bearing during startup. During startup from rest:

• The journal is resting on the Babbitt surface (boundary lubrication — metal-to-metal contact)

• The mill must accelerate from 0 to operating speed (typically 0.2–0.5 rpm for large SAG mills)

• The hydrodynamic film cannot establish itself until the journal reaches sufficient speed

Without jacking oil, the startup period involves metal-to-metal contact between the journal and Babbitt for 30–120 seconds — causing measurable Babbitt wear with every start. Over hundreds of starts, this accumulates to significant Babbitt thickness loss and eventual bearing failure.

The jacking oil system injects oil at 10–25 MPa directly under the journal through a dedicated pocket in the bearing bore. This hydraulically lifts the journal off the Babbitt surface before rotation begins, maintaining a full oil film throughout the startup sequence.

Jacking oil system specification:

Part 4: Bearing Clearance, Alignment, and Installation

4.1 Bearing Bore Measurement and Clearance Verification

The radial clearance between the journal and bearing bore must be measured and verified at installation and at each remetalling:

Measurement method — lead wire technique:

1. Place soft lead wires (diameter slightly larger than the expected clearance) at the top and bottom of the bearing bore, parallel to the shaft axis

2. Assemble the bearing housing and tighten to the specified torque

3. Disassemble and measure the compressed lead wire thickness with a micrometer

4. The clearance at the top = lead wire thickness at top; clearance at bottom = lead wire thickness at bottom

5. The diametral clearance = top clearance + bottom clearance

Measurement method — dial gauge:

For installed bearings, the journal lift (the distance the journal can be lifted vertically before contacting the top of the bearing bore) is measured with a dial gauge. This equals the top clearance, which is approximately half the total diametral clearance.

4.2 Shaft Journal Surface Requirements

The shaft journal surface quality is critical for hydrodynamic bearing performance:

A journal surface that is too rough (Ra > 0.8 μm) will abrade the Babbitt surface even under full hydrodynamic lubrication — the asperities on the journal surface periodically penetrate the oil film and contact the Babbitt.

4.3 Bearing Alignment

Misalignment between the two trunnion bearings of a grinding mill is one of the primary causes of premature bearing failure. The two bearing centrelines must be co-axial within:

For a 1,200mm journal in a 1,500mm long bearing:

Misalignment causes the journal to run at an angle within the bearing bore, concentrating the load on one end of the bearing and creating a non-uniform pressure distribution across the Babbitt surface. The result is accelerated wear at the loaded end and eventual Babbitt fatigue cracking.

Part 5: Trunnion Bearing Failure Mode Analysis

5.1 Babbitt Fatigue (Cracking and Delamination)

Appearance: Cracks in the Babbitt layer, typically running parallel to the bearing axis or in a network pattern. In advanced cases, sections of Babbitt delaminate from the backing shell and circulate in the oil system (detected by oil analysis or filter inspection).

Root causes:

• Bearing unit pressure exceeding allowable limit (> 7 MPa): Overloading the bearing beyond the Babbitt fatigue limit causes cyclic stress in the Babbitt layer that initiates cracks. Most commonly caused by mill overloading (excessive grinding media charge) or by load redistribution from foundation settlement.

• Babbitt bonding defects: Poor bonding between the Babbitt layer and the backing shell creates stress concentrations at the interface that initiate delamination under cyclic loading. Caused by inadequate surface preparation of the backing shell before remetalling.

• Thermal fatigue: Repeated startup-shutdown cycles create thermal stress in the Babbitt layer (the Babbitt expands and contracts more than the steel backing due to its higher thermal expansion coefficient).

Corrective action:

• Verify mill charge weight does not exceed design — check grinding media level and ore density

• Perform oil analysis and filter inspection to detect Babbitt particles before catastrophic failure

• At next shutdown, inspect Babbitt surface by visual examination and dye penetrant testing (PT)

• If cracking covers > 10% of the bearing surface area, schedule remetalling at the next planned maintenance window

5.2 Journal Scoring (Wiping)

Appearance: Longitudinal scratches or smearing on the journal surface and corresponding damage to the Babbitt surface. In severe cases, the Babbitt is smeared and redistributed along the journal.

Root causes:

• Oil film collapse during operation: Caused by oil supply failure (pump failure, pipe blockage, filter bypass), oil viscosity too low (oil overheating or incorrect grade), or bearing load exceeding the hydrodynamic film capacity.

• Startup without jacking oil: Metal-to-metal contact during startup without the jacking oil system activated causes wiping of the Babbitt surface. Each unprotected start removes a measurable thickness of Babbitt.

• Contaminant ingress: Hard particles (mill scale, silica) in the oil that are larger than the oil film thickness penetrate the film and score both the journal and Babbitt surfaces.

Corrective action:

• Verify jacking oil system is functional and activated before every mill start — this is non-negotiable

• Check oil supply temperature, pressure, and flow rate against design specifications

• Upgrade oil filtration to 10 micron absolute if contamination is suspected

• Inspect journal surface at next shutdown — minor scoring (Ra < 1.6 μm) can be polished in-situ; severe scoring requires journal removal and regrinding

5.3 Corrosive Attack on Babbitt

Appearance: Pitting and etching of the Babbitt surface, often with a dark or discoloured appearance. The pitting is distributed across the bearing surface rather than concentrated at a specific location (distinguishing it from fatigue spalling, which is localised).

Root causes:

• EP/AW additives in the oil: Sulphur and phosphorus compounds in extreme pressure or anti-wear additives react with the tin and lead in Babbitt, causing chemical corrosion of the bearing surface. This is the most common cause of corrosive attack in mill trunnion bearings — it occurs when the oil specification is changed without verifying compatibility with Babbitt.

• Water contamination: Water in the oil (from cooling water leaks or condensation) causes oxidation of the lead component in Babbitt, forming lead oxide that is harder than the Babbitt matrix and causes abrasive wear.

• Acidic oil degradation: Severely degraded oil (high acid number) attacks the Babbitt surface chemically.

Corrective action:

• Immediately change to a pure R&O (rust and oxidation inhibited) mineral oil with no EP or AW additives

• Flush the entire lubrication system with clean oil before refilling

• Check for cooling water leaks in the oil cooler — perform a pressure test on the cooler

• Implement regular oil analysis (quarterly minimum) including acid number, water content, and spectrometric metal analysis

5.4 Bearing Overheating

Appearance: Bearing metal temperature exceeds 80°C (trip setpoint). Oil supply temperature rises. In severe cases, the Babbitt melts locally (Babbitt melting point: tin-base ≈ 240°C; lead-base ≈ 180°C) and the molten metal is expelled from the bearing.

Root causes:

• Insufficient oil flow rate: Oil flow below design rate reduces both lubrication and cooling. Caused by pump wear, blocked filters, or partially closed isolation valves.

• Oil cooler fouling: Scale buildup on the cooling water side of the oil cooler reduces heat transfer, causing oil supply temperature to rise.

• Excessive bearing clearance: A worn bearing with excessive clearance allows the journal to run at high eccentricity, reducing the oil film thickness and increasing viscous heat generation.

• Mill overloading: Excessive grinding media or ore charge increases bearing load beyond design, increasing heat generation in the oil film.

Corrective action:

• Check oil flow rate against design specification — clean or replace filters, verify pump output

• Clean oil cooler (water side) — descale if necessary

• Measure bearing clearance — if clearance exceeds 1.5× the design value, schedule remetalling

• Verify mill charge weight is within design limits

5.5 Bearing Vibration and Instability (Oil Whirl)

Appearance: Sub-synchronous vibration at approximately 0.4–0.48× the rotational frequency. The vibration amplitude increases with speed and can become self-sustaining (oil whip) at higher speeds.

Root causes:

• Oil whirl: A hydrodynamic instability that occurs when the journal centre orbits around the bearing centre at approximately half the rotational speed. Caused by insufficient bearing load relative to the bearing's load capacity — the journal "floats" in the centre of the bearing rather than being pushed to one side by the load.

• Excessive bearing clearance: Worn bearings with excessive clearance are more susceptible to oil whirl instability.

• Low bearing unit pressure: Lightly loaded bearings (unit pressure < 0.5 MPa) are prone to oil whirl.

Corrective action:

• For mill trunnion bearings, oil whirl is uncommon due to the very high bearing loads — if it occurs, verify that the bearing is actually loaded (check for foundation settlement that may have reduced the load on one bearing)

• Consider a preloaded bearing design or a bearing with a non-circular bore profile (lemon bore, three-lobe bore) that provides inherent stability

• Measure and correct bearing clearance if excessive

Frequently Asked Questions

Q1: What is the difference between white metal (Babbitt) and rolling element bearings for ball mill trunnions?

White metal (Babbitt) hydrodynamic bearings operate on a pressurised oil film that completely separates the journal from the bearing surface — under full hydrodynamic lubrication, there is zero metal-to-metal contact and virtually no wear. They are the standard for large mills (> 3.0m diameter) because they can accommodate very large journal diameters (up to 2,000mm+) with no practical size limit. Rolling element bearings (spherical roller bearings) use rolling contact and are simpler to maintain, but are limited to approximately 1,100mm bore diameter and have lower shock load tolerance. For large SAG and ball mills in mining and cement, white metal hydrodynamic bearings are the only practical choice.

Q2: What Sommerfeld number should a mill trunnion bearing be designed for?

The design target for continuous operation is S ≥ 0.30 — this ensures full hydrodynamic lubrication with no metal-to-metal contact. At S < 0.05, the oil film breaks down and boundary lubrication (metal contact) begins — this is dangerous and must not occur during normal operation. The Sommerfeld number is most critical at startup (low speed N) and under peak load. The jacking oil system is specifically designed to protect the bearing during startup when the Sommerfeld number is below the hydrodynamic threshold.

Q3: Why must EP (extreme pressure) additives be avoided in mill trunnion bearing oil?

EP and AW (anti-wear) additives contain sulphur and phosphorus compounds that react chemically with the tin and lead in Babbitt metal, causing corrosive pitting of the bearing surface. This corrosive attack is often misdiagnosed as mechanical wear. The correct oil specification for white metal trunnion bearings is a pure R&O (rust and oxidation inhibited) mineral oil, ISO VG 100–220 depending on the Sommerfeld number calculation, with no EP or AW additives. Always verify oil compatibility with Babbitt before changing oil brands or grades. 

Q4: How often should the jacking oil system be activated?

The jacking oil system must be activated before every mill start — without exception. Each unprotected start (without jacking oil) causes measurable Babbitt wear from metal-to-metal contact during the startup period. Over hundreds of starts, this accumulates to significant Babbitt thickness loss. The jacking oil system should be activated 2–5 minutes before the mill start command and deactivated automatically when the mill reaches 50–70% of operating speed. Verify jacking oil pressure is within specification (10–25 MPa) before each start.

Q5: What is the correct radial clearance for a ball mill trunnion bearing?

The recommended radial clearance is 0.001 to 0.0015 × journal diameter. For a 1,200mm journal, this gives 1.2–1.8mm radial clearance. The cold clearance must be set larger than the hot clearance target to account for thermal expansion of the journal — for a 1,200mm steel journal running 60°C above ambient, thermal expansion reduces the clearance by approximately 0.86mm. Measure clearance using the lead wire technique at installation and after each remetalling. If the measured clearance exceeds 1.5× the design value, schedule remetalling.

Q6: How do I detect Babbitt fatigue before catastrophic failure?

The most effective early warning methods are: (1) Oil analysis — spectrometric analysis detects tin and lead particles in the oil from Babbitt wear before visible damage occurs; schedule quarterly oil analysis minimum; (2) Filter inspection — inspect the oil filter element at each filter change for metallic particles; Babbitt particles are soft and silvery; (3) Vibration monitoring — accelerometers on the bearing housing detect changes in vibration signature as Babbitt surface condition deteriorates; (4) Bearing temperature trending — a gradual rise in bearing metal temperature over weeks indicates increasing friction from Babbitt surface degradation.

Yile Machinery: Custom Trunnion Bearings and Mill Components

Yile Machinery supplies custom trunnion bearing components, bearing shells, and associated mill hardware for ball mills, SAG mills, rod mills, and rotary kilns in cement, mining, and mineral processing applications.

Our trunnion bearing supply capabilities:

• Babbitt-lined bearing shells: Tin-base Babbitt (Grade 1 and Grade 2) and lead-base Babbitt; shell diameters from 400mm to 2,000mm; precision-bored to ±0.01mm after remetalling

• Bearing backing shells: Cast iron or fabricated steel; precision-machined bore and OD; jacking oil pocket machined to specification

• Trunnion journals (shaft ends): Forged 42CrMo4 alloy steel; ground to Ra ≤ 0.4 μm; hardened to 200–300 HB

• Bearing housings: Cast or fabricated steel; precision-bored; oil inlet/outlet connections; temperature sensor ports

• Remetalling service: Complete Babbitt removal, surface preparation, and re-lining service for worn or damaged bearing shells

• Engineering documentation: Sommerfeld number calculation; minimum film thickness verification; bearing clearance specification; oil system design review

Related products and technical resources:

• Mining & Cement Industry Solutions — complete component supply for ball mills, SAG mills, and rotary kilns

• Rotary Kiln Tyre & Support Roller Guide — Hertz contact stress and alignment methodology for kiln support systems

• Rolling Mill Rolls: Work Roll & Backup Roll Guide — roll neck bearing selection and contact stress for rolling mill applications

• Industrial Helical & Bevel-Helical Gearbox Selection Guide — mill drive gearbox selection and service factor methodology

• Conveyor Pulley Selection Guide — shaft design and bearing specification for conveyor pulleys

• Custom Forgings — Shafts, Gear Blanks & Ring Forgings — forged trunnion journals and bearing components

• Forged vs. Cast Steel Shafts for Crushers — forging process and material selection reference

• Steel & Metal Processing Solutions — mill components for steel plant grinding equipment

To receive a quotation, provide:

• ✅ Mill type (ball mill / SAG mill / rod mill) and mill diameter × length

• ✅ Trunnion journal diameter and length (mm)

• ✅ Bearing load per trunnion (kN) or total mill weight

• ✅ Mill operating speed (rpm)

• ✅ Existing bearing shell dimensions (OD, ID, length) or drawing

• ✅ Babbitt grade required (tin-base Grade 1 / Grade 2 / lead-base)

• ✅ Required bearing clearance (or OEM specification)

• ✅ Quantity and required delivery date

• ✅ Worn or damaged bearing shell available for reverse engineering

Email: jasmine@yileindustry.com

Submit RFQ: www.yilemachinery.com/contactus.html

Sommerfeld number calculation and oil system design review provided with every trunnion bearing order. Remetalling turnaround: 2–4 weeks for standard sizes.

Related Technical Resources

• Rotary Kiln Tyre & Support Roller: Contact Stress, Tyre Migration & Alignment Guide

• Conveyor Idler Roller Selection: CEMA Series, Load Rating & Bearing Life Guide

• Conveyor Pulley Selection: Shaft Design, Belt Tension & Lagging Guide

• Rolling Mill Rolls: Work Roll & Backup Roll Material Selection Guide

• Industrial Helical & Bevel-Helical Gearbox Selection Guide

• Custom Forgings — Gear Blanks, Ring Forgings & Shafts

• Mining & Cement Industry Solutions