Gangway

Catwalks form the walkable working platform behind the cab of tractor units and chassis vehicles. They provide the driver or mechanic with safe, non-slip access to the air couplings, electrical connections and coiled cables between the tractor unit and semi-trailer. On MAN TGA, TGS, TGX and TG3 and Mercedes-Benz Axor, Actros, Arocs and Antos vehicles, catwalks are matched to factors including the chassis configuration, wheelbase, tank layout, exhaust routing, battery box, fifth-wheel mounting bracket and fitted platform supports. A catwalk must therefore always be identified using the vehicle's chassis number. Visual comparison or selection based solely on the model name is never sufficient.

Professional catwalks are generally made from galvanised steel, aluminium or aluminium chequer plate. Steel versions offer high dimensional stability and are suitable for heavy-duty applications, while aluminium platform plates are corrosion-resistant and reduce vehicle weight. The anti-slip profile must retain sufficient grip in rain, snow, hydraulic oil, diesel residue and mud. Depending on the vehicle configuration, central plates, side panels, continuous working platforms, folding sections and plates with cut-outs for line pass-throughs or mounting points are available.

Correct fitment is essential: mounting holes, bend radii, plate thickness, support spacing and height relative to the chassis and fifth wheel must match the original version. A plate that mechanically “more or less fits” may come into contact with air coils, wiring harnesses, AdBlue lines, exhaust components or mudguard brackets when the chassis and cab twist. When replacing it, also check whether the associated support brackets, rubber vibration dampers, mounting bolts and spacers still meet the correct specification. Excessive crevice corrosion between aluminium and steel supports must be prevented using suitable insulating layers and correctly applied corrosion protection.

The most common defects are dented plate sections caused by incorrect stepping, torn bolt holes, cracks at folded edges, detached anti-slip sections and corrosion around mountings. On vehicles used in construction transport or waste collection, stone chips, clay and road salt can accumulate beneath the plate. This retains moisture against chassis supports and fasteners, resulting in seized bolted joints or local material weakening. On aluminium catwalks, white oxidation, fatigue cracks around holes and galvanic corrosion near steel components are important points of attention.

First inspect the platform visually and mechanically. Use a straightedge to measure the flatness of the plate and check that sufficient clearance to the fifth wheel, air hoses and electrical coils is maintained with the tractor-semi-trailer combination fully articulated. Then inspect all support points for cracks, oval mounting holes and missing locking devices. Move the plate by hand: noticeable play often indicates compressed spacers, worn rubber buffers or insufficient preload on the bolted connection. Also check for sharp edges, protruding bolts or raised plate sections; these pose an immediate risk during coupling.

A lightly scratched but flat catwalk with an intact anti-slip profile can generally be cleaned, derusted and protected again. Replacement is the correct solution in the event of permanent deformation, deep corrosion pitting, cracked weld seams, loose reinforcement profiles or damaged mounting areas. Do not simply straighten a deformed plate: cold straightening can locally weaken the material and increase susceptibility to cracking in aluminium.

When replacing the plate, first uncouple the semi-trailer and relieve the load on the working platform. Thoroughly clean the chassis rails and support surfaces, check the dimensions of the brackets and replace corroded fasteners. Install the new plate without stress, using the specified bolt grade, washers and locking devices. Tighten the fasteners in a cross pattern to the vehicle-specific torque specification and, after installation, check the unobstructed routing of electrical and pneumatic connections. A correctly fitting stock catwalk can reduce vehicle downtime, but never at the expense of the original mounting, accessibility and safe anti-slip performance.