D.O.T Fittings
What Are DOT Fittings?
DOT fittings are mainly used in the air brake systems of commercial vehicles such as trucks, buses, trailers, and articulated vehicles.
They are used to connect air brake tubing to system components such as brake valves, air reservoirs, and brake chambers, allowing compressed air to be transmitted through the piping system.
Depending on the installation position and piping direction, straight, elbow, tee, or bulkhead types can be selected to meet requirements for line extension, directional changes, branching, and fixed installation.
DOT fittings use a push-in connection structure. The tubing is inserted into the tube connection end to complete the connection.
DOT Fitting Type Classification
DOT fittings can be classified according to fitting shape and connection method into straight and bulkhead types, elbow types, and tee types.
They can be further classified according to the inch or metric outside diameter of the tubing used and whether the fitting has a swivel structure.
| Fitting Type | Inch | Metric | Swivel Inch | Swivel Metric |
|---|---|---|---|---|
| Straight and Bulkhead Types | 68, 82, 62, 66 | M68, M62 | — | — |
| Elbow Types | 54, 65, 69, 70 | M65 | S54, S69, S70 | MS69 |
| Tee Types | 64, 71, 72, 77, 79 | M64, M79 | S71, S72 | MS71, MS72 |
The available tubing outside diameters, thread specifications, and size combinations vary by series. Please confirm the specifications of each product.
DOT Fitting Specifications and Type Selection
DOT fittings should be selected based on tube size, thread, connection type, fitting shape, and whether a swivel structure is required.
The tube connection end should be confirmed according to the outside diameter of the air brake tubing used.
If the fitting has a threaded end, the thread must also match the system port.
| Selection Criteria | Details |
|---|---|
| Tube Size | Select the inch or metric outside diameter according to the air brake tubing used |
| Thread | Select the thread type and size according to the system port |
| Connection Type | Select tube-to-tube, tube-to-male-thread, tube-to-female-thread, or bulkhead mounting according to the connection requirements |
| Fitting Shape | Select straight, 45° elbow, 90° elbow, or tee according to the piping direction and installation position, and confirm whether a swivel model is required |
| Compatible Tubing | Nonmetallic air brake tubing compliant with SAE J844 |
