Technical Guides for Automotive Part Identification & Sourcing

1. Housing Geometry & Class Conformity

Under UNECE Regulation 46, European heavy trucks (Mercedes-Benz Actros, MAN TGX, Scania S/R series, Volvo FH) feature designated vision classes that must match exact radius requirements:

• Class II (Main Rear-View Mirror): Requires large-radius curved glass (R1200 or R1800) with motorized tilt adjustment.
• Class IV (Wide-Angle Mirror): Features tighter curvature (R300 or R400) to eliminate wide blind zones on the driver and passenger sides.
• Class V (Close-Proximity Kerb Mirror): Fitted over the passenger-side cab door with high-angle downward pitch.
• Class VI (Front Vision Mirror): Mounted across the windshield header to view pedestrian zones immediately ahead of the cab.

2. Electrical Pinouts, Heating, and Voltage Parameters

Never rely solely on housing appearance. Heavy-duty mirror brackets utilize specific multi-pin sealed connectors that differ by year and accessory level:

Verification Item	Standard Variant	Advanced Option	Impact on Fitment
Operating Voltage	24V Standard Truck	12V Light Commercial	Incorrect voltage causes immediate heater coil failure.
Connector Harness	4-Pin / 5-Pin Basic	8-Pin / 10-Pin Heated + Memory	Mismatched connectors prevent motor control communication.
Temperature Sensor	Without NTC Sensor	Integrated Ambient Probe	Missing probe creates dashboard ECU fault codes.
Mounting Arm Diameter	Ø28 mm Rigid Tube	Ø32 mm Reinforced Bracket	Mismatch causes severe cabin vibration at highway speeds.

3. The Golden Rule of OEM Cross-Referencing

Original equipment manufacturers regularly revise assembly numbers when transitioning between sub-suppliers (e.g., Mekra Lang to alternative tier-1 producers). When sharing enquiries with the Bursa export desk, provide the truck chassis VIN number, photos of the underside multi-pin connector plug, and whether the vehicle is Left-Hand Drive (LHD) or Right-Hand Drive (RHD).

Brake Chamber Sizing Protocols

Chamber sizing follows standardized diaphragm effective surface areas. Type designations (such as Type 20/24, 24/24, or 24/30 Double Diaphragm) directly dictate clamping output force:

• Port Thread Tolerances: Distinguish between metric M16x1.5 or M22x1.5 Voss connectors versus imperial 3/8"-18 NPT fittings used on export models.
• Pushrod Length & Clevis Thread: Verify overall pushrod cut length from chamber mounting base to the center of the clevis pin hole.
• Internal Return Spring Rating: Ensure spring stroke capacity matches drum brake s-cam rotation or disc brake caliper actuation lever requirements.

Automatic Slack Adjuster (ASA) Identification Checklist

• Spline Count & Diameter: Count splines accurately (common configurations: 10 splines Ø1.5", 28 splines Ø1.5", or 37 splines).
• Center-to-Center Arm Length: Measure distance from the camshaft spline center to the clevis pin hole (typical values: 127 mm, 145 mm, 152 mm, or 165 mm).
• Control Arm Offset: Check whether the control arm is straight, angled left, or angled right relative to axle clearance brackets.

Essential Parameters for Replacement Verification

• Top Plate & Piston Bolt Pitch: Measure the exact center-to-center distance between top mounting studs and air inlet port connections.
• Air Inlet Port Specification: Confirm whether the supply port uses standard M12x1.5, M16x1.5, or G 1/4" threaded BSP couplings.
• Maximum Extended Height vs. Compressed Height: An incorrect stroke range can pull internal bump stops or over-extend chassis shocks during axle articulation.
• Piston Material Composition: Specify whether your operational environment requires heavy pressed steel, lightweight glass-fiber composite, or cast aluminum lower pistons.