Australian Trailer Compliance Manual

Australian Trailer Compliance Manual

Bearings • Axles • Suspension • Load Ratings • ADR & VSB1 Requirements

This manual outlines the legally recognised bearing types, axle sizes, suspension systems, and load‑rating requirements for trailers operating in Australia. All information is based on ADR (Australian Design Rules) and Vehicle Standards Bulletin 1 (VSB1).


1. Trailer Bearings — Types & Legal Use

Slimline Bearings

  • Rating: ~750kg per axle
  • Use: Light‑duty domestic trailers
  • Legal Requirements:
  1. Suitable for trailers under 750kg ATM
  2. No brakes required
  3. Must match axle & hub rating

  • Common Use: Box trailers, garden trailers

Standard Bearings (Ford/HT)

  • Rating: ~1000–1500kg per axle
  • Use: Medium‑duty on‑road trailers
  • Legal Requirements:
  1. Brakes required if trailer exceeds 750kg ATM
  2. Must comply with ADR 38 braking rules

  • Common Use: General utility trailers, small equipment carriers

Parallel Bearings

  • Rating: ~1600kg per axle
  • Use: Heavy single‑axle trailers
  • Legal Requirements:
  1. Must match axle rating
  2. Suitable for on‑road and mild off‑road

  • Common Use: Tradesman trailers, enclosed trailers

AL‑KO 2‑Tonne Bearings

  • Rating: 2000kg per axle
  • Use: Heavy‑duty commercial trailers
  • Legal Requirements:
  1. Must be paired with 2T axle
  2. Must use 12\" electric brakes or equivalent
  3. Must comply with ADR 38 braking rules
  4. Common Use: Plant trailers, car carriers, heavy equipment trailers

Dexter Bearings

  • Rating: 1600kg–3000kg depending on model
  • Use: Premium heavy‑load trailers
  • Legal Requirements:
  1. Must comply with ADR 38 braking
  2. Must comply with ADR 62 coupling rules

  • Common Use: Car carriers, imported caravan axles, off‑road trailers

Off‑Road Heavy‑Duty Bearings

  • Rating: 1600kg–2000kg
  • Use: Harsh terrain, corrugations, 4x4 environments
  • Legal Requirements:

    • Must use high‑temperature grease

    • Must use off‑road rated hubs

  • Common Use: Off‑road campers, rural machinery trailers


2. Axle Types & Legal Load Ratings

40mm Square Axle

  • Rating: ~750kg
  • Use: Light trailers
  • Legal Requirements:

    • No brakes required under 750kg ATM

45mm Square Axle

  • Rating: ~1000–1500kg
  • Use: Medium‑duty trailers
  • Legal Requirements:

    • Brakes required over 750kg ATM

50mm Square Axle

  • Rating: ~1600kg
  • Use: Heavy single‑axle trailers
  • Legal Requirements:

    • Electric brakes required over 2000kg ATM

60mm Round Axle

  • Rating: ~2000kg
  • Use: Heavy‑duty and off‑road
  • Legal Requirements:

    • Must match bearing/hub rating

Tandem Axle Combinations

  • Ratings: 1400kg, 2000kg, 3500kg ATM
  • Legal Requirements:

    • Breakaway brakes required over 2000kg ATM

    • Load‑sharing suspension required for 4500kg ATM trailers

Drop Axles

  • Use: Lower deck height
  • Legal Requirements:

    • Must maintain minimum ground clearance (ADR 43)

Off‑Road Axles

  • Use: High clearance, reinforced welds
  • Legal Requirements:

    • Must meet ADR 62 coupling rules

    • Must meet ADR 43 ground clearance rules


3. Suspension Systems & Compliance

On‑Road Suspension

Slipper Springs

  • Rating: Light‑duty
  • Legal Requirements: Must match axle capacity
  • Use: Domestic trailers

Eye‑to‑Eye Springs

  • Rating: Medium‑duty
  • Legal Requirements: Must match axle rating
  • Use: Tradesman trailers, equipment carriers

Rocker Roller Suspension

  • Rating: Heavy tandem
  • Legal Requirements:

    • Required for load‑sharing over 4500kg ATM

  • Use: Car carriers, plant trailers

Off‑Road Suspension

Heavy‑Duty Off‑Road Leaf Springs

  • Use: Corrugations, rough terrain
  • Legal Requirements: Must exceed axle rating

Independent Trailing Arm Suspension

  • Use: Extreme off‑road
  • Legal Requirements: Must comply with ADR 63 stability rules

Coil & Shock Systems

  • Use: Premium off‑road
  • Legal Requirements: Must be engineered to axle load rating

4. Legal Requirements (ADR & VSB1)

Load Ratings

  • Bearings, hubs, axles, wheels, tyres and suspension must all match or exceed ATM.
  • The lowest‑rated component determines the legal limit.

Braking Requirements (ADR 38)

  • 0–750kg ATM: No brakes required
  • 751–2000kg ATM: Brakes required (mechanical or electric)
  • 2001–4500kg ATM: Electric brakes + breakaway system required

Couplings (ADR 62)

  • Must match ATM
  • Off‑road couplings must be ADR‑approved

Ground Clearance (ADR 43)

  • Off‑road axles must maintain legal clearance
  • Drop axles must not reduce clearance below minimum

Lighting (ADR 13)

  • Must include ADR‑approved LED or incandescent lights

Tyres (ADR 23)

  • Must meet load rating and speed rating for ATM


5. Matching Components to Trailer Types

Light‑Duty Trailers

  • Slimline bearings
  • 40mm axle
  • Slipper springs

Medium‑Duty Trailers

  • Standard bearings
  • 45mm or 50mm axle
  • Eye‑to‑eye springs

Heavy‑Duty Commercial Trailers

  • Parallel or AL‑KO 2T bearings
  • 50mm or 60mm axle
  • Rocker roller suspension

Off‑Road Trailers

  • Heavy‑duty parallel or Dexter bearings
  • Off‑road axle
  • Independent or heavy‑duty leaf suspension

6. Compliance Summary

This manual provides a complete overview of legally recognised bearing types, axle sizes, suspension systems, and load‑rating requirements for trailers in Australia. All components must comply with ADR and VSB1, and the lowest‑rated component sets the legal ATM.