B&A Engineering

Stability Analyzer

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Create, save, reopen, duplicate, and manage rack stability analyses.
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Rack Center of Gravity & Tip-Over (Stability) Analysis

Input Method
Standard – Single Table (Stacked)
Uses one table to define equipment at different elevations. Only one piece of equipment can occupy a given elevation, making this mode simpler and easier to use when equipment is primarily stacked within a single mounting plane.
Advanced – Multiple Tables (Free Stack)
Uses a separate table for each mounting plane. This allows multiple pieces of equipment to be located at the same elevation on different mounting planes, providing greater flexibility for complex rack configurations.
Stack Me Up – Drag & Drop
Uses three visual mounting planes. Drag reusable equipment from the Equipment Library onto the Front, Rear, or Rear Exterior plane and position it vertically by rack U.
Note: A Standard configuration can be converted to Advanced at any time without losing information. Converting from Advanced to Standard may result in loss of information where equipment occupies the same elevation on different mounting planes.
A rack stability analysis verifies that a fully integrated rack has adequate resistance to tipping during normal use, movement, transportation, handling, and seismic loading. This calculator determines the combined center of gravity (CG) of the rack, installed equipment, and any additional base mass, and can aid in arranging equipment to satisfy applicable stability requirements.

The calculator evaluates stability in the +X, −X, +Y, and −Y directions using the system CG, caster/wheel spacing, and the specified lateral acceleration requirement. It calculates overturning and resisting moments, stability ratios, minimum required additional base mass, and critical tipping angles for each direction. Equipment may be assigned to the Front, Rear, or Rear Exterior mounting planes to represent the actual rack configuration more accurately.

Equipment height is specified in rack units (U), where 1U = 1.75 in (44.45 mm). The floor defines Z = 0. X = 0 is the rack centerline in the front view, with positive X extending to the right. Y = 0 is the Front Mounting Plane, with positive Y extending toward the rear of the rack.

Integrated Equipment

Enter the installed equipment, its weight, dimensions, mounting plane, and elevation. Use Standard for a single stacked equipment list or Advanced when equipment can occupy the same elevation on different mounting planes.
Recommended Entry Order1 Weight→2 Depth→3 HeightThen enter Width / X Position if needed.
Des. IDWeight (lb)Width (in)Depth (in)Height (U)X Position (in)Mounting PlaneY / Depth Position from Front Plane (in)Bottom Z (U)
Each mounting plane has an independent vertical stack. Drag rows using the ↕ handle to change vertical order. You can also drag equipment between mounting-plane tables; its mounting plane and Bottom Z will update automatically.

Front Mount Equipment

Des. IDWeight (lb)Width (in)Depth (in)Height (U)X Position (in)Mounting PlaneY / Depth Position from Front Plane (in)Bottom Z (U)

Rear Mount Equipment

Des. IDWeight (lb)Width (in)Depth (in)Height (U)X Position (in)Mounting PlaneY / Depth Position from Front Plane (in)Bottom Z (U)

Rear Exterior Mount Equipment

Des. IDWeight (lb)Width (in)Depth (in)Height (U)X Position (in)Mounting PlaneY / Depth Position from Front Plane (in)Bottom Z (U)

Front View (X–Z)

Side View (Y–Z)

Rack Specifications

Select a predefined rack type or choose Custom to enter the rack geometry, empty rack weight, mounting height, and mounting-plane dimensions used in the CG and stability calculations.
Rack width defaults to 19 in and may be adjusted as required. Empty rack weight is modeled as uniformly distributed through the rack boundary. When Rear Exterior Plane is enabled, its depth is used for the rack mass distribution. Rack Overall Height — Ground to Top is graphical only and does not affect CG or stability calculations. The shell begins at the rack base elevation and extends upward only to the entered overall top elevation. Standard and Wide rack presets use 1998 mm overall rack height by default.

Wheel Positioning

Define the rack base and caster/wheel spacing. Wheel locations establish the tipping lines used to calculate resisting moments and tipping angles.
Wheel positions are defined symmetrically about the centroid of the independent rack base plate. The base plate is centered at X = 0. Its Y offset defines the front edge of the base plate relative to the Front Mounting Plane (Y = 0). The wheel rotation axis is parallel to the X axis.

Base Ballast / Stabilizing Mass

Add optional mass near the rack base to lower the combined CG. Enter the mass directly or define steel plate dimensions and quantity; the calculator determines the equivalent mass and effective height.
The stabilizing mass is centered on the independent rack base plate. Its bottom starts at the rack-base elevation. Default 17 × 8.5 × 0.5 in steel plates use 20.86 lb per plate. For custom plate dimensions, density is assumed to be 0.283 lb/in³ (7,833 kg/m³). Effective height is plate thickness × quantity.
Ballast mass: 0.00 lb • Effective height: 1.00 in

Additional Mass Estimator

Minimum required additional mass: —
Automatically uses the current direct-mass height and checks +X, −X, +Y, and −Y stability requirements.

Stability Requirement

Select the required lateral acceleration the rack must resist. The calculator converts the selected g-level into the horizontal force used for the overturning analysis.
Acting force is calculated from the total system mass and the selected lateral acceleration requirement.
Total System Mass
0.00 lb
Required Acceleration
0.25 g
Acting Lateral Force
0.00 lbf

Stability Analysis

Review the calculated overturning and resisting moments in the +X, −X, +Y, and −Y directions. A Stability Ratio of 1.0 or greater satisfies the selected tipping requirement.

X–Z Plane

Wheel spacing X0.00 in
CG X offset from wheel centroid0.00 in

+X Direction (Left to Right)

Resisting arm to +X wheel line0.00 in
Overturning moment0.00 lbf·in
Resisting moment0.00 lbf·in
Stability Ratio = —

−X Direction (Right to Left)

Resisting arm to −X wheel line0.00 in
Overturning moment0.00 lbf·in
Resisting moment0.00 lbf·in
Stability Ratio = —

Y–Z Plane

Wheel spacing Y0.00 in
CG Y offset from wheel centroid0.00 in

+Y Direction (Front to Back)

Resisting arm to +Y wheel line0.00 in
Overturning moment0.00 lbf·in
Resisting moment0.00 lbf·in
Stability Ratio = —

−Y Direction (Back to Front)

Resisting arm to −Y wheel line0.00 in
Overturning moment0.00 lbf·in
Resisting moment0.00 lbf·in
Stability Ratio = —

Tipping Over Angle

Review the static tilt angle at which the combined CG reaches each wheel tipping line. The angle is calculated independently for all four tipping directions.
+X Direction (Left to Right)
0.00°
Resisting arm 0.00 in • CG height 0.00 in
−X Direction (Right to Left)
0.00°
Resisting arm 0.00 in • CG height 0.00 in
+Y Direction (Front to Back)
0.00°
Resisting arm 0.00 in • CG height 0.00 in
−Y Direction (Back to Front)
0.00°
Resisting arm 0.00 in • CG height 0.00 in

Reporting

Generate a printer-friendly summary of the rack configuration, combined CG, stability results, tipping angles, and graphical views. Use the browser print dialog to save the report as a PDF.
Work in progress — Word formatting may not display correctly.
Rack Stackup Images
Create a proportional rack elevation for each mounting plane. Equipment is positioned by Bottom Z and Height (U), with Component ID and Description automatically wrapped to fit.

X Position is the box center relative to the rack centerline. Y / Depth Position is initially calculated automatically from the selected mounting plane and box depth, but it may be edited manually. Negative Y values are allowed to place equipment partially or fully forward/outside the Front Mounting Plane. Front Mount defaults the box front edge to Y = 0; Rear Mount defaults the rear edge to the Rear Mounting Plane; Rear Exterior Mount defaults the rear edge to the optional Rear Exterior Plane. Physical box Depth remains a positive dimension. Height and Bottom Z remain in U. Box 1 starts at Z = 0, and each following valid box is placed directly on top of the previous valid box.

Total Weight
0.00 lb
CG X
0.00 in
CG Y
0.00 in
CG Z from Floor
0.00 in
CG Z from Rack Base
0.00 U

3D Rack View

Left-drag to rotate • Right-drag to pan • Mouse wheel to zoom • Double-click to reset
Front Mounting Plane Rear Mounting Plane Rear Exterior Plane O = Coordinate Origin for CG (X=0, Y=0, Z=0)
Right-hand coordinates: +X right when viewing the rack from the front, +Y front → rear, +Z up.