DGBB Engineer Guide

Use this section when reading deep groove ball bearing results. DGBB is class-first: class and gates decide meaning before score.

How To Read A DGBB Result

1. Confirm the reference bearing was resolved correctly.
2. Read class: DROP_IN, CONDITIONAL, or REJECT.
3. Check gate_report.hard_failures.
4. Check gate_report.conditional_flags.
5. Read differences.rows, missing_info, evidence, and reason_codes.
6. Compare the technical snapshot fields for bore, OD, width, bore type, protection, loads, speed, clearance, chamfer, precision, and snap ring.
7. Decide whether the candidate is a direct candidate, review candidate, or blocked candidate.

Do

• Do treat DROP_IN as the only direct replacement class.
• Do treat CONDITIONAL as an engineering review result, not a procurement-ready result.
• Do treat REJECT as blocked by hard gates.
• Do explain which hard failure or conditional flag drove the class.
• Do use score only to rank candidates inside the same class.
• Do verify clearance, protection, speed, and load ratings when the application is sensitive.

Don’t

• Do not let a high score override REJECT.
• Do not promote CONDITIONAL to DROP_IN.
• Do not ignore unknown speed on sealed/shielded changes.
• Do not ignore snap-ring requirements.
• Do not treat a series mismatch as harmless without review.
• Do not recommend a bearing with lower required load capability.

Status Next Actions

Status	Engineer action
OK	Read class first, then gates, conditional flags, score, and evidence.
AMBIGUOUS_MATCHES	Ask for exact bearing designation, suffixes, dimensions, or protection code.
INPUT_RECHECK_REQUIRED	Resolve conflicting dimensions, suffixes, or bearing identity before using candidates.
NO_REFERENCE	Request part number, ISO designation, dimensions, or datasheet.
ERROR	Treat as no result; retry or escalate.

Tag Next Actions

Tag	What to do next
BEARING_TYPE_MISMATCH	Reject for DGBB substitution unless product family was misclassified.
MISSING_CORE_*	Collect the missing core dimension before deciding.
CORE_DIM_MISMATCH_*	Reject or verify measurement/source if the mismatch looks like bad input.
BORE_TYPE_MISMATCH	Confirm cylindrical/tapered/special bore requirement.
PROTECTION_DOWNGRADE	Do not use without confirming contamination and lubrication requirements.
DYNAMIC_LOAD_DOWNGRADE	Check application load; usually blocks replacement.
STATIC_LOAD_DOWNGRADE	Check static load/shock requirement; usually blocks replacement.
SPEED_INSUFFICIENT	Check operating speed before use.
CLEARANCE_MISMATCH	Confirm required clearance class.
CHAMFER_TOO_SMALL	Check shaft/housing fillet compatibility.
PRECISION_DOWNGRADE	Confirm precision requirement.
SNAP_RING_MISSING	Reject if snap-ring retention is required.
SERIES_MISMATCH	Review envelope, load, speed, and application implications.
SPEED_LIMIT_UNKNOWN	Find speed data before high-speed use.
CLEARANCE_UNKNOWN_REVIEW	Confirm clearance before recommendation.
PRECISION_REVIEW	Confirm precision requirement with engineering.
SNAP_RING_CAVEAT	Check groove/snap-ring details.
SEAL_UPGRADE_UNKNOWN_SPEED	Verify speed impact of seal/shield change.

Example Workflow

When a candidate is CONDITIONAL with SERIES_MISMATCH and SPEED_LIMIT_UNKNOWN:

1. State that geometry may pass, but the candidate is not a direct drop-in.
2. Compare series implications against the installed bearing.
3. Find candidate speed limit data.
4. Escalate or approve only after the unknown speed and series change are accepted.

Never Claim

• Never claim replacement equivalence from bore/OD/width alone.
• Never claim a conditional row is safe without reviewing its flags.
• Never claim a rejected row is usable because its score is close.