The 4 Most Commonly Specified Slewing Bearing Types

1. Single-Row Four-Point Contact Ball

The workhorse. If you're ordering for an excavator, small crane, aerial platform, or solar tracker, it's almost certainly this type. Buyers call it "single-row ball slewing ring" or "standard slewing ring."

Application	Commonly Replaced Models
Compact excavators (3–8 ton)	PC30–PC78, 303–308, ZX30–ZX75,
Mid-size excavators (12–25 ton)	PC120–PC220, CAT 312–320, ZX120–ZX210, R140–R210, DX140–DX225, EC140–EC210
Large excavators (30–50 ton)	PC300–PC450, 330–349, ZX330–ZX470
Small truck cranes (< 25 ton)	Custom
Aerial platforms / Solar trackers	Custom light-duty

The mistake: matching the OEM part number without checking the actual load. An excavator running a rock breaker 60% of the time needs a heavy-duty variant—larger balls, deeper raceway hardening—not the standard replacement. Ask: What attachment runs most of the time? Has the machine been modified (extra counterweight, reinforced boom)? Continuous slewing or intermittent?

2. Double-Row Ball

Two rows of balls in roughly the same envelope as a single-row—more load capacity without increasing diameter. Used when a single-row barely passes the load check or when replacing a bearing that failed from overload.

Buyers call it "double-row ball slewing ring" or "heavy-duty slewing ring."

Application	Typical OD
Mid-size truck cranes (25–50 ton)	800–1,400 mm
Crawler cranes	1,000–2,000 mm
Port material handlers	1,200–1,800 mm
Tower cranes (luffing jib)	1,500–2,500 mm
Tunnel boring machines	2,000–4,000+ mm

The mistake: assuming the two rows are identical. They aren't—different pitch circles, different load shares. Grease must reach both rows independently; one nipple won't do it. Ask for individual row load distribution under your specific load case. No answer = reseller, not a manufacturer.

3. Cross Roller

Cylindrical rollers in a 90° alternating pattern. Precision and rigidity matter more than cost here. Buyers call it "cross roller slewing ring" or "precision slewing ring."

Application	Why Cross Roller
CNC rotary tables	Positioning accuracy, low runout
Industrial robots (base/wrist)	High rigidity, compact section
Radar antenna pedestals	Minimal backlash
Medical CT scanners	Precision + quiet
Packaging indexers	Repeatable positioning

The mistake: ignoring runout and sealing. Axial runout should be ≤ 0.05 mm (≤ 0.025 mm for machine tools). Roller-to-raceway contact is a line, not a point—any debris creates stress concentration that spalls the surface in hours. Integrated lip seals on both sides are non-negotiable; felt seals destroy cross roller bearings in months.

4. Three-Row Roller

Three independent roller raceways—axial, overturning moment, and radial each get their own row. Highest load capacity per unit diameter. Buyers call it "three-row roller slewing ring" or "heavy-duty roller bearing."

Application	Typical OD
Mining excavators (100+ ton)	1,800–3,500 mm
Ship-to-shore container cranes	3,000–5,000 mm
Offshore pedestal cranes	2,000–4,000 mm
Bucket wheel reclaimers	3,000–6,000 mm
Wind turbine yaw bearings	2,000–4,500 mm
Steel mill ladle turrets	1,800–3,000 mm

The mistake: ignoring axial clearance and independent grease paths. Overly tight clearance binds under load; overly loose introduces vibration. Ask for the design value and the factory test report. Each row must have its own grease circuit—one manifold feeding all three is a cost-cutting red flag that starves the farthest row.

5. How to Read a Quotation

What the Quote Shows	What It Means
Dimensions and weight only	Reseller or low-end factory. Caution.
+ Load rating + static safety factor	Basic engineering capability. OK for standard jobs.
+ Load curve + raceway hardness + material cert	Real manufacturer. Your minimum threshold.
+ Bolt preload calc + installation tolerance + lube schedule	Engineering-driven supplier. Go with this one.

A quote arriving within 5 minutes for a non-standard application is a red flag—proper selection requires at minimum a load check.

If you need a selection backed by load curve analysis rather than just a matching part number, send the machine model, operating conditions, and attachment details.

Published by Lyhc bearing technical team.