Definition: Bolt hole pattern describes the number, size, and spacing of mounting holes in a caster top plate.
What it controls: Mounting compatibility, fastener loading, and resistance to loosening or rotation.
Why bolt hole pattern matters
The bolt hole pattern is the mechanical interface between the caster and the equipment frame.
- Ensures correct alignment during installation
- Distributes load evenly into the frame
- Prevents caster rotation under side loads
- Maintains fastener preload over time
Reality: Incorrect bolt patterns cause loose fasteners, cracked plates, and premature failure.
Key elements of a bolt hole pattern
| Element | Why it matters |
|---|---|
| Number of holes | Affects load sharing and resistance to rotation |
| Hole spacing (center-to-center) | Determines compatibility with frames |
| Hole diameter | Matches fastener size and strength |
| Hole type (round vs slotted) | Controls adjustability and movement |
Compatibility and interchangeability
- Standard patterns allow replacement without re-drilling
- Non-standard patterns increase retrofit time and cost
- Slotted holes ease installation but reduce stiffness
- Fastener grade must match hole size and load
Verify both hole spacing and plate size when replacing casters.
Common engineering mistakes
- Assuming similar plate size means compatible patterns
- Oversizing holes to “make it fit”
- Ignoring fastener grade and torque
- Using slotted holes in high side-load applications
Rule: Bolt hole pattern and fastener selection must be treated as a structural system.
FAQs
Are bolt hole patterns standardized?
Some common patterns exist, but many casters use proprietary layouts.
Can I drill new mounting holes?
Drilling can weaken the plate and should be avoided without review.
Are slotted holes acceptable?
They are acceptable for alignment but reduce stiffness under load.
Does bolt pattern affect load rating?
Indirectly. Poor patterns cause uneven loading and reduce service life.