Overhead Crane Brake Wheel and Brake Disc Runout Tolerances — A Complete Guide by Crane Type

Overhead crane brake reliability is a direct determinant of operational safety. When an overhead crane brake wheel or brake disc is installed with out-of-tolerance runout, the results are predictable: uneven pad wear, reduced braking torque, and in severe cases, brake failure during a lift.

This guide compiles the permissible radial circular runout for brake wheels and face runout for brake discs across the major industrial crane types. The values are drawn from two sources: the type-specific provisions in China’s GB/T crane standards, and the general tolerance grades in GB/T 1184-1996 (Geometrical tolerancing — General tolerances for form and position).

1. General Gantry and Overhead Crane Brake Wheel and Brake Disc

Per GB/T 14405-2011 (General bridge cranes) and GB/T 14406-2011 (General gantry cranes), Clause 5.8.1 — Installation of brake wheels and brake discs.

Table 1 — Brake wheel radial circular runout for general bridge and gantry cranes (source: GB/T 14405-2011, GB/T 14406-2011)

Table 2 — Brake disc face runout for general bridge and gantry cranes (source: GB/T 14405-2011, GB/T 14406-2011)

Key notes:

• Radial circular runout is a composite form-and-position tolerance. It measures the maximum variation of points on a given cross-section from the datum axis. The tolerance zone is a pair of concentric circles perpendicular to the datum axis. This single measurement simultaneously captures coaxiality error (axis offset, tilt, or bow) and cross-section roundness error.
• 1 mm = 1000 μm (e.g., 500 μm = 0.5 mm).
• GB/T 27997-2011 (Shipbuilding gantry cranes) and GB/T 26470-2025 (Bridge erecting machines — General technical conditions) reference the same runout tables above.

Figure 1 — Example of circular runout tolerance marking on a drawing (source: GB/T 1182-2018)

2. Portal Cranes Brake Wheel and Brake Disc

Per GB/T 29560-2013 (Portal cranes), Clause 5.9.1 — Installation of brake wheels and brake discs. GB/T 29561-2013 (Harbour fixed cranes) references the same requirements.

Table 3 — Brake wheel radial circular runout for portal cranes (in mm, source: GB/T 29560-2013)

Table 4 — Brake disc face runout for portal cranes (in mm, source: GB/T 29560-2013)

3. Ship-to-Shore (STS) Container Cranes Brake Wheel and Brake Disc

Per GB/T 15361-2009 (Quayside container cranes), Clause 3.6.2 — Brake wheels (or brake discs) and brakes:

1. For brake wheels mounted directly on a shaft: radial circular runout and face runout shall not be lower than Grade 9 and Grade 10, respectively, as specified in GB/T 1184. See Table 5.
2. For disc brake rotors mounted directly on a shaft: the face runout relative to the shaft shall not exceed 0.2 mm.
3. After assembly, all brake linkage pivot points shall rotate freely. The contact area between the brake lining (or brake shoe) and the brake wheel (or brake disc) shall be no less than 70% of the total friction surface.

Table 5 — Circular runout and face runout tolerance grades (source: GB/T 1184-1996)

Note: Some editions of the standard reference text cite “GB/T 1182” as the source of tolerance grades. This appears to be an editorial error. GB/T 1182-2018 covers geometrical tolerancing symbology and indication — it does not contain tolerance grade numerical values. The correct reference for tolerance grades is GB/T 1184-1996. GB/T 1182-2008 and GB/T 1182-1996 likewise did not include tolerance grade tables.

4. Container Gantry Cranes (Rail-Mounted and Rubber-Tyred) Brake Wheel and Brake Disc

Per GB/T 19683-2025 (Rail-mounted container gantry cranes), Clause 5.6.5, and GB/T 14783-2009 (Rubber-tyred container gantry cranes), Clause 3.6.2 — Brakes and brake wheels (discs):

1. For brake discs mounted directly on a shaft: the axial runout relative to the shaft shall not exceed 0.2 mm.
2. For brake wheels (or discs): the radial circular runout relative to the datum axis shall not be lower than Grade 7 per GB/T 1184-1996. See Table 5.
3. For brake wheels mounted directly on a shaft: the radial circular runout shall not be lower than Grade 9 per GB/T 1184-1996. See Table 5.

5. Brake Shoe-to-Wheel and Shoe-to-Disc Clearance

The recommended clearance values between brake shoes and brake wheels are compiled from JB/T 6406, JB/T 7019, JB/T 7020, JB/T 7685, and industrial brake manufacturer documentation. Use as field reference:

For safety brakes with angular compensation: the rated single-side retraction clearance shall not be less than 1 mm. For other safety brakes: the rated single-side retraction clearance shall not be less than 2 mm.

Standards referenced(Query of Chinese Crane Standards):

• GB/T 14405-2011 General bridge cranes
• GB/T 14406-2011 General gantry cranes
• GB/T 29560-2013 Portal cranes
• GB/T 15361-2009 Quayside container cranes
• GB/T 19683-2025 Rail-mounted container gantry cranes
• GB/T 14783-2009 Rubber-tyred container gantry cranes
• GB/T 27997-2011 Shipbuilding gantry cranes
• GB/T 26470-2025 Bridge erecting machines — General technical conditions
• GB/T 1184-1996 Geometrical tolerancing — General tolerances for form and position
• GB/T 1182-2018 Geometrical tolerancing — Tolerancing of form, orientation, location and run-out
• JB/T 6406-2006 Electro-hydraulic wheel brakes
• JB/T 7019-2013 Industrial brakes — Brake wheels and brake discs
• JB/T 7020-2006 Electro-hydraulic disc brakes
• JB/T 7685-2006 Electromagnetic wheel brakes

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