# 3119 Dunbier Rolla-Matic Mount 50mm Square | Marine Trailer Part

🔧 Product Description

  

Dunbier Rolla-Matic Universal Mount for 50 × 50mm Cross Member - Part Number: 3119

  

A galvanised universal cross-member mounting plate and U-bolt arrangement for attaching a compatible Dunbier Rolla-Matic support assembly to a 50 × 50mm trailer cross member.

  

⚙️ Key Features

  

• Galvanised mounting plate

• Designed for 50 × 50mm rectangular cross member

• Includes matching U-bolts and mounting hardware as supplied

• Allows Rolla-Matic position adjustment

• Bolt-on installation

  

📏 Specifications

  

• Cross-member application: 50 × 50mm

• Mounting width/adjustment range: Approximately 135-160mm depending assembly

• Supports compatible 20mm or 40mm Rolla-Matic legs through the associated bracket arrangement

  

🔄 Cross Reference & Related Parts

  

• Dunbier: 3119

• 50 × 50mm mount: Dunbier 3119

• 76 × 50mm mount: Dunbier 3120

• 102 × 50mm mount: Dunbier 3121

• Related Rolla-Matic assemblies: Dunbier 3100, 3100SQ, 3102, 3103 and 3110

  

🚤 Trailer Compatibility & Application

  

• Suitable for a structurally sound 50 × 50mm trailer cross member

• U-bolt width and length must fit the actual cross-member dimensions

• Support-leg size must match the Rolla-Matic assembly

  

🔌 Function

  

Clamps the Rolla-Matic support securely to the trailer cross member while allowing its lateral and vertical position to be adjusted.

  

Common signs of wear or replacement:

  

• Plate or U-bolts are bent

• Mount moves on the cross member

• Threads are stretched or corroded

• Cross member is crushed beneath the clamp

• Rolla-Matic leg cannot be retained securely

  

🛠️ Installation & Safety

  

• Install on a clean straight section of cross member

• Tighten U-bolts evenly

• Do not crush thin-wall trailer tube

• Align paired mounts before loading the boat

• Recheck nut torque after initial road and ramp use

  

📦 Condition

  

• Brand new Dunbier Marine Products trailer component

• Supplied as one Rolla-Matic mount kit for a 50 × 50mm cross member

• Supplied in original or equivalent packaging

## Details

- **Price:** 30.5 AUD
- **Vendor:** Dunbier
- **Tags:** Dunbier Boat Trailers | Marine Trailer Parts & Accessories

## Variants

| Variant | Price | Available |
|---------|-------|-----------|
| Default Title | 30.50 AUD | In stock |

## Images

- 3119 Dunbier Rolla-Matic Mount 50mm Square | Marine Trailer Part

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> Source: [Sawley's Auto and Marine](https://www.sawleysautoandmarine.com.au/products/3119-dunbier-rolla-matic-mount-50mm-sq)
> Updated: 2026-08-05