Description

Overview

The 4mm air brake union connects two matching sections of 4mm metric nylon tube in a straight line. It provides a compact tube-to-tube repair point without changing the line direction or introducing a threaded connection.

Features

• Two push-in ports suit 4mm outside-diameter metric air brake tube.
• Straight double-union configuration maintains the existing tube route.
• Brass body contains the gripping collets and pneumatic seals.
• Each collet can be depressed to release the tube during servicing.

Specifications and Materials

This D.O.T. push-in fitting comes as one complete brass union with equal 4mm connections at both ends. The tube installs directly into the fitting without separate nuts, olives, ferrules or compression sleeves.

Part number: 88-M004-04.

See the manufacturer D.O.T. push-in fitting guide

Compatibility and Fitment

Confirm both air lines measure 4mm across the outside diameter. Do not substitute 5/32in imperial tube solely because it appears close in size, and check that the tube is suitable for the receiving air brake fitting. These cross-references show where this part replaces the part numbers and applications listed. Some installations may need minor changes. MDQ62DOT4, M1862X4, MAQ62-DOT-4, MAQ62DOT4

Related Parts

Check the related size versions below against the air line before ordering.

Compliance and Safety

Depressurise the pneumatic circuit before cutting or disconnecting the air line. Cut each tube end square and remove any scored, crushed, oval or heat-damaged section. Push the tube fully into each port, pull back gently to confirm retention, then restore pressure and leak-test both connections.

Trailer Applications

Workshops use this 4mm air brake union to reconnect a cut or replaced section of small metric pneumatic tube. It suits straight-line repairs in compatible brake control, suspension control and auxiliary air circuits where the original tube route must remain unchanged.

Cross-reference and Suitability

This part cross-references to or suits the following equivalent part numbers and compatible alternatives:

Why Choose ICS Trailers

ICS Trailers supplies metric and imperial push-in fittings for trailer pneumatic repairs. Check the tube outside diameter rather than relying on appearance, particularly when distinguishing 4mm metric tube from nearby imperial sizes.

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