Choose a thin section ball bearing’s contact type from the load directions and complete support arrangement. Type A is angular contact and needs an appropriate opposing arrangement. Type C is primarily radial contact. Type X uses four-point contact for combined radial, axial and moment loading. None of these descriptions, by itself, determines the size, installed clearance, friction or acceptable operating speed.
For an enquiry, specify the contact type and full reference code separately from the cross-section series. This guide explains the difference and connects the discussion to published LYDL product entries.
A, C and X answer a different question from KA and KB
Contact type describes the bearing’s internal contact configuration. Cross-section series describes a catalogue family with a particular section envelope. Bore size, seals, clearance, material and accuracy add further requirements.
| Designation element | Question it helps answer |
|---|---|
| Type A, C or X | What contact configuration is being considered? |
| KA, KB or another section family | Which catalogue cross-section family is being referenced? |
| Full part number | Which size and configuration are being requested? |
| Drawing and purchase specification | Which dimensions, tolerances and acceptance conditions control the supply? |
Kaydon’s A/C/X guidance identifies the three contact configurations and relates them to radial, axial and moment loads. It provides technical conventions for comparison; the LYDL supply still requires its own agreed specification. Technical reference: bearing load scenarios
Type A: define the complete opposed arrangement
A Type A angular contact bearing carries axial force in one direction. The reference thin section design is mounted opposed to another bearing to establish the contact arrangement and handle the required thrust directions. Technical reference: Type A construction
The purchasing question is therefore larger than which single bearing to order. State whether the requirement is for an individual component or an agreed set, and identify the orientation and installed preload or clearance.
Include both positions, their spacing and supporting parts in the layout comparison. A single Type X bearing and one member of a Type A pair do not represent equivalent complete support arrangements.
For a new design, request the proposed arrangement and installation method before deciding that an angular contact solution uses too much space or has a particular stiffness.
Type C: begin with radial support, then check the axial task
Type C is intended primarily for radial loading. Applicable designs can accommodate some axial load in either direction, depending on their configuration and installed condition. Technical reference: Type C construction
Include axial force even when it is secondary. Identify which support locates the shaft axially and how the other parts accommodate the required thermal movement.
If the load is applied away from the bearing support plane, include the resulting moment. Calling a force radial does not eliminate the moment created by its position.
Before changing from Type C to another contact type, check the entire arrangement, including clearance, fits, thrust reaction and rotational resistance.
Type X: evaluate combined-load support and rotation together
Type X uses four-point contact geometry and can carry radial, axial and moment loads in a compact bearing position. Technical reference: Type X construction
This makes it a candidate for combined-load layouts, while speed, torque, stiffness and the actual load combination still need evaluation. Separate catalogue capacities should not be read as permission to apply all listed maxima simultaneously. Kaydon’s product tables direct combined-loading questions to a load analysis. Technical reference: Type X product-table notes
Mounting is also part of the decision. Kaydon’s thin section mounting guidance warns against simply placing two Type X bearings on one common shaft. Review the complete support arrangement and applicable instructions. Technical reference: mounting guidance
A combined-load bearing should be selected for the supported duty, rather than assumed to be the lowest-friction choice in every arrangement.
Connect the contact type to a complete model reference
The following entries are taken from LYDL’s published open Type C table and Type X table. They illustrate reference-code and envelope matching, not certified interchangeability.
| Contact type | LYDL table label | Reference code shown | Bore | Outside diameter | Width |
|---|---|---|---|---|---|
| C | LYDL-A040 | KA040CP0 | 101.600 mm | 114.300 mm | 6.350 mm |
| X | LYDL-A040 | KA040XP0 | 101.600 mm | 114.300 mm | 6.350 mm |
| C | LYDL-B040 | KB040CP0 | 101.600 mm | 117.475 mm | 7.938 mm |
| X | LYDL-B040 | KB040XP0 | 101.600 mm | 117.475 mm | 7.938 mm |
Two practical purchasing points follow from this comparison:
- The LYDL table label needs context. LYDL-A040 appears in both contact-type tables. Include the contact type, full reference and drawing rather than relying on the shortened label alone.
- An equal envelope does not define equal behaviour. The KA040 C/X entries share published boundary dimensions, while contact type and load assessment differ. Matching those dimensions is an interface check, not an automatic replacement approval.
Use the stated dimensions as catalogue references and confirm the supplied drawing, including rounding and tolerances. Brand reference codes identify comparison products; they do not imply original-brand supply or affiliation.
Use a three-step selection route
Step 1 — establish the load and support arrangement.
Identify radial and axial forces, reversing thrust, moment loads and their application points. Decide how the shaft or housing is supported and located.
Step 2 — shortlist contact configurations.
Evaluate a Type A arrangement for the required directional thrust and opposing support; Type C for a predominantly radial task with axial conditions checked; or Type X for a suitable compact combined-load position.
Step 3 — compare actual candidates.
Check the full envelope, load/life assessment, installed clearance or preload, displacement, speed, resistance, lubrication and inspection requirements. A contact-type label cannot replace this step.
| Project observation | Additional information needed |
|---|---|
| Thrust reverses | Opposing arrangement or confirmed bidirectional capability |
| A moment governs the design | Force locations and the complete support model |
| Available drive torque is small | Comparable starting/running resistance under stated conditions |
| Thermal movement matters | Shaft location and the planned accommodation of expansion |
| An existing bearing is being replaced | Full reference, drawing, installed arrangement and reason for change |
Turn the selection into a clear enquiry
A useful enquiry can state:
Reference KA040CP0, Type C, open thin section ball bearing. Please confirm the LYDL drawing and configuration against the attached assembly, load table and inspection requirements.
For a Type X reference, state KA040XP0 and Type X explicitly. These are examples of enquiry wording, not complete ordering specifications.
Add the rotating ring, load directions and positions, motion cycle, permissible displacement, seals, lubricant, environment and acceptance requirements. For a Type A arrangement, include the proposed opposing bearing positions and orientation.
Common questions
Does the A in KA mean Type A angular contact?
No. Specify the section family and contact configuration separately; KA040CP0 and KA040XP0 illustrate different contact types within the referenced KA family.
Can a Type X replace a Type C when the dimensions match?
The envelope can match while the load distribution, resistance and installed-condition requirements differ. Review the complete application before approving the change.
Do all three types need to be compared for every project?
Start with the support task. Eliminate unsuitable arrangements, then compare applicable models with equivalent operating requirements.
Discuss the arrangement with LYDL
Explore the LYDL thin section ball bearing range and inch thin section families. Send the full reference, contact type, section drawing and load table.
Contact LYDL about the thin section bearing arrangement so size, contact configuration and acceptance conditions can be reviewed together. A precise reference and defined support task make the technical discussion more useful than a request for a bearing with matching dimensions alone.
