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When specifying ball bearing slides for applications ranging from industrial enclosures and server racks to medical equipment and high-end cabinetry, one critical dimension is often overlooked: the width of the pull-out unit itself. Whether the slides are intended to hold a drawer, door, component, or chassis, the width of the pull-out unit has a large effect on performance.
The primary concern with wider units is racking. Racking occurs when a load applied off-center creates a twisting or parallelogram effect on the slide system, leading to side-to-side movement. If the slide does not have sufficient strength and load capacity corresponding to the drawer’s width, this racking force can cause instability, binding, premature wear, and ultimately, complete drawer failure.
Consider this: a narrow slide rated for a high vertical load might perform perfectly in a 12-inch wide drawer. However, when used in a 30-inch wide drawer, even with the same vertical load, the leverage created by the increased width multiplies the lateral forces. The slide, not designed for this torsional stress, may bind, twist, or fail to operate smoothly.
Key Consideration: Maximum Recommended Width Always consult the manufacturer’s specifications for the maximum recommended drawer width for any slide model you are considering. This specification is crucial because it takes into account the slide’s cross-sectional design, material strength, and ball circuit configuration – all factors that determine its resistance to racking.
The Solution for Wider Drawers: When your application requires drawer widths of 24 inches or greater, relying solely on a standard slide, even one with a high load rating, is often insufficient. The best solution is to upgrade to a slide with a larger cross-section and a correspondingly higher load rating.
- Larger Cross-Section: A deeper or wider slide profile provides greater inherent structural rigidity, significantly improving resistance to twisting forces.
- Higher Load Rating: While the vertical load might not change, a higher-rated slide typically uses larger balls, more ball circuits, or stronger materials, all of which contribute to better performance under racking conditions.
In summary: Don’t just match a slide to your drawer’s length and vertical load capacity. Pay close attention to the drawer’s width. Exceeding the recommended width for a given slide model is a common cause of field failures. For wide drawers (24″+), proactively select a heavy-duty slide designed for enhanced stability. By choosing the right slide based on both length and width, you ensure smooth operation, long service life, and reliable performance for your application.
