TThe Mark 7 Transformer Breathers were introduced to meet the additional robustness necessary for the protection of equipment operating under high mechanical stresses.
The breathers are fabricated from mild steel which is protected with a phosphate and powder coat finish. The construction of these transformer breathers enables them to withstand the bump, vibration and shock parameters found in electric traction and similar vehicles.
These transformer breathers are fitted with oil-seal bowls and are filled with Envirogel desiccant. The only maintenance action required is periodic inspection of the oil level and replacement of the spent desiccant. The beaded desiccant has a much higher dust attrition resistance when compared with the standard granular material previously used.