The Time-Delay Relay consists of an operatic coil, a pneumatic timing head, and two sets of contact assemblies.

The four-pole, lower set of double-break solid silver contacts (two normally closed and two normally open) is actuated instantaneously by energizing the 120 V ac operating coil.

The upper pair of contacts (one normally closed and one normally open) opens or closes with a time delay just after the coil has been energized. By turning the adjustment wheel, repeatable (within 15%) time delays from 0.2 s to 60 s can be obtained. The two timing head contacts have the same rating as the lower four main relay contacts.