Slewing Ring Bearing

1. Reading the Notation

Two cautions:

1. Φ means through hole; M means threaded hole. They are not interchangeable — a through hole takes a bolt and nut, a threaded hole takes the bolt directly. Misreading this invalidates the whole fastening plan.
2. "Equally spaced" is not optional information. It defines the hole angle as 360° ÷ hole count. If the angle on your part does not match, it is not the same specification.

2. Full Mounting Hole Chart (48 Models)

This table covers mounting holes only. Outside diameter, bore, overall height and gear data are not included — a complete specification is still required to order. Data per the GT product catalogue; where versions differ, the latest revision applies.

3. Grouped by Bolt Pattern: Which Models Share One Bearing

This is the useful part. Merging 48 rows by bolt pattern produces twelve distinct families:

Three conclusions you can use today

One: eleven Doosan models from DH150 to DH225 share one bolt pattern. 36-Φ22 outer, 36-M20×1.5 inner. An operator running DH150, DH215, DH220 and DH225 in the same fleet stocks a single bearing specification. This is the highest-volume, highest spare-parts-efficiency group in the chart.

Two: DH220-3 and DH220-5 are not interchangeable. The inner hole count goes from 30 to 36. The model names differ by one character; the parts share nothing.

Three: DH300 and DH370 are not interchangeable. Both use 35-Φ26 on the outer ring, but the inner changes from 36-M24 to 40-M24. Matching outer rings does not make a bearing fit.

Why "outer ring matches" is not enough

Slewing ring bolts pass through one ring and thread into the other. Two conditions must hold simultaneously:

1. the outer ring through-hole count and diameter suit the bolt;
2. the inner ring threaded-hole count, thread size and angular spacing correspond one-to-one.

Families C and D have identical outer rings (35-Φ26) and differ only on the inner (40-M24 vs 36-M24). Order on the outer ring alone and you discover the mismatch halfway through installation.

4. Three Measurements to Take Before Ordering

The chart gives hole counts. It cannot give pitch circle diameter (PCD), which is the final arbiter of fit. Three steps, ten minutes:

One rule of thumb: hole angle = 360° ÷ hole count. 36 holes is 10°, 40 holes is 9°, 48 holes is 7.5°, 35 holes is 10.286°. If the angle on your part is not that value, the count is wrong or the pattern is not equally spaced.

5. FAQ

Q1: Are DH220-3 and DH220-5 swing bearings interchangeable? A: No. Both have 36-Φ22 outer holes, but the inner threaded holes are 30 on the DH220-3 and 36 on the DH220-5 (both M20×1.5). Order by generation.

Q2: DH300-7 and DH370-9 have the same outer hole count — can they swap? A: No. Both outer rings are 35-Φ26, but the inner is 36-M24 on the DH300-7 and 40-M24 on the DH370-9. A different inner count rules out interchange.

Q3: What is the difference between Φ and M? A: Φ is a through (clearance) hole — the bolt passes through and is secured with a nut. M is a threaded hole — the bolt threads directly into the ring. They are not interchangeable, and confusing them invalidates the entire fastening plan.

Q4: My model is not in the chart. What now? A: Send three things: the full model from the machine plate including suffix, the outer hole count and diameter, and the centre distance between adjacent holes. GT can trace the specification from those.

Q5: Can I reuse the mounting bolts? A: No. High-strength bolts yield once when torqued and cannot hold the specified preload a second time, creating a fatigue fracture risk. They are single-use items.

Q6: Why does this chart only cover mounting holes? A: Mounting holes are the first data needed at the ordering stage and the hardest to find, so they are published separately. For outside diameter, bore, overall height, gear data and clearance, request the specification sheet for your model.

Q7: If two models are in the same family, is the bearing interchangeable? A: Not necessarily. A matching bolt pattern is a necessary condition; outside diameter, bore, overall height, gear data and load rating must also match. Families narrow the search — they do not close it.

Q8: Can the hole count be modified? A: No. Hole count is determined by ring structure and load design. Modifying it compromises ring strength and sealing, and will not match the frame holes anyway.