Mobile Crane Cab and Control Cabin Standards: GB/T 20303.2-2006

GB/T 20303.2-2006 addresses the unique operating environments and usage demands of mobile cranes, providing a dedicated technical specification for the design and manufacturing of their cabs and control stations. The cab of a mobile crane must not only deliver clear sightlines and operator comfort but also perform reliably across two distinct modes: travel and hoisting. This article provides a systematic interpretation of the standard's key technical requirements.

Scope of Application and Cab Types

GB/T 20303.2-2006 applies to two types of operator spaces on mobile cranes. The first is the travel driving cab, used when the crane is driven on public roads and typically sharing design requirements with standard commercial truck cabs. The second is the hoisting operating cab (also referred to as the upper-structure cab), used during lifting operations on site. This can be either an enclosed, fully enclosed cab (common on large all-terrain and crawler cranes) or an open operating platform (typical on smaller truck cranes, featuring only a roof and rollover protection structure). The standard defines detailed requirements for each space, covering dimensions, field of vision, access systems, seating, and environmental conditions.

Travel Driving Cab Requirements

For the travel driving cab, the standard specifies the following:

Dimensional requirements — Where hoisting operations are also performed from the travel driving cab (a common configuration on smaller truck cranes), the cab's interior width must be no less than 850 mm for a single-seat layout or 1,300 mm for an optional two-seat layout. Minimum interior height (from floor to ceiling) must be at least 1,800 mm, including allowance for a safety helmet. The lower edge of the windshield must be no higher than 900 mm above the floor, and the upper edge no lower than 800 mm above the seat reference point, ensuring a clear forward view. Rearview mirrors must provide coverage of at least 30° on each side and to the rear of the machine.

Seating — The driver's seat must comply with GB 15083 and offer fore-and-aft adjustment of ±80 mm, backrest angle adjustment from 90° to 115°, and height adjustment of ±50 mm. The seat must be fitted with a three-point or four-point safety belt, with provisions for a child seat anchorage. In travel mode, seat vibration damping must meet the ISO 7096 requirement for a seat vibration transmissibility of ≤0.7.

Control devices — Steering wheel, pedals, gearshift lever, and other travel controls must follow standard automotive layout conventions. The instrument panel must display essential travel information, including vehicle speed, engine speed, coolant temperature, oil pressure, air pressure (for air-brake models), odometer, and turn signal status. When hoisting operations are carried out from the travel driving cab, the hoisting control levers must be clearly identified and visually or spatially distinguished from the travel controls.

Hoisting Operating Cab Requirements

For the separate hoisting operating cab, the standard imposes more detailed requirements:

Dimensions — The enclosed operating cab must have a minimum interior width of 700 mm and a minimum height of 1,700 mm, with a floor area of at least 0.9 m². The lower edge of the front window must be no more than 800 mm above the floor so that the operator can see the hook and the load area directly from a seated position. The front window area must account for at least 45% of the front wall area. The cab door must have a clear width of no less than 450 mm and a height of no less than 1,500 mm. The door must open outward and be operable with one hand from the operator's position.

Field of vision — From a normal seated position, the operator must have a direct view of: the full hoisting travel of the hook and the load area (directly ahead and below), both sides of the full boom length (with a horizontal viewing angle of at least ±45° on each side), and the slewing platform and outrigger areas (via side windows or video assistance). When the hook is positioned at its closest point directly in front of the operator, the operator must be able to see it with a downward gaze angle of no more than 30°. Where structural obstructions exist, rearview mirrors or camera-based video assistance systems must be provided.

Ventilation and air conditioning — The enclosed operating cab must be equipped with heating and air conditioning, maintaining an interior temperature of no more than 28°C in summer and no less than 14°C in winter. In configurations without air conditioning, the front window must be openable or fitted with a ventilation window providing an effective opening area of at least 0.05 m². Air conditioning outlets must not blow directly onto the operator's hands or face.

Noise — Interior noise levels in the operating cab must not exceed 80 dB(A) at rated engine speed. The engine exhaust silencer must be located at least 1 m from the cab, and the cab wall panels must be lined with sound-absorbing material (minimum 25 mm thick) to effectively reduce engine noise transmission.

Access System and Safety Facilities

The standard sets strict requirements for access and escape facilities on mobile cranes:

Access to the cab — Fixed access systems must be provided from ground level to both the travel driving cab and the hoisting operating cab. The ladder must have a minimum width of 300 mm, with tread spacing between 220 mm and 300 mm, and the first tread must be no more than 400 mm above the ground. Handrails must be installed on both sides of the ladder, with a diameter of 25 to 35 mm. When the ladder inclination exceeds 60°, a safety belt anchorage point must be provided. Tread surfaces must feature anti-skid treatment, such as checkered steel plate or perforated steel plate.

Access System to the Hoisting Operating Cab — Access from ground level to the hoisting operating cab typically runs across the chassis frame, slewing platform, and cab entry. Handrails or guardrails must be provided along the entire route, with a minimum height of 1100 mm. The walkway across the slewing platform to the cab entry must be at least 400 mm wide. Where the cab floor is more than 2 m above ground, intermediate landing platforms must be provided at intervals of no more than 3 m.

Escape Exit — Enclosed operator cabs must be fitted with an escape exit (rear door or escape window) in the rear or side wall, with minimum dimensions of 600 mm × 600 mm. The escape exit must be openable quickly from the inside. Where the cab floor exceeds 3 m above ground, a controlled descent device or escape rope must be provided. The travel driving cab may use its windows as an alternative escape route.

Special Requirements for Rotating Operator Cabs

Large all-terrain and crawler cranes are typically equipped with enclosed operator cabs that rotate with the upper structure. The standard imposes the following additional requirements on such cabs:

The cab's rotation range must provide full visibility for lifting operations with no blind spots. Cables, hydraulic hoses, and air-conditioning lines must have unrestricted movement at the rotating joint, with sufficient slack in all lines. A reliable locking device must prevent unintended rotation when the cab is stopped. Rotation controls must be located inside the cab so the operator can initiate rotation from the seated position. When the cab is rotated away from the travel direction, the travel controls must be automatically shielded or locked to prevent inadvertent activation during lifting operations.

Open-Air Operating Platform (for medium and small truck crane hoisting stations) — A roll-over protective structure (ROPS) must be provided and verified for strength in accordance with ISO 3471. The platform floor must be anti-slip, with toe boards of at least 50 mm in height around the perimeter to prevent tools from sliding off. Guardrails on the operating platform must be no lower than 1100 mm, with an intermediate rail at approximately 550 mm. Kelude Heavy Industry's mobile crane operator spaces are designed in strict compliance with this standard, balancing ride comfort with operational safety.

Mobile Crane Cab Requirements Comparison Table

The comparison table below outlines the core parameter configurations for mobile crane cab requirements, serving as a reference for selection and operational personnel.

Frequently Asked Questions