Chicago Type Universal Air Hose Couplings

Chicago couplings - also sold as universal or claw couplings - are symmetrical two-lug air couplings for compressed-air hose on sites and in workshops. Any two halves of the same pattern connect: the claws are pushed together and turned a quarter turn, and the rubber seal set into each face is compressed to make the joint. There is no male half and no female half.

Tubes International publishes the US pattern with a 41 mm lug distance in zinc-plated cast iron with an oil-resistant NBR seal, at 10 bar working pressure, in hose tails from 10 mm to 25 mm bore and in male and female NPT ends from 3/8 to 1 inch. A silicone seal rated -50 to +140 degrees C is offered where the standard NBR seal, -20 to +100 degrees C, is not suitable.

Lug spacing decides interchange and it is not standardised across markets. The US pattern at 41 mm does not mate with the European DIN 3489 pattern at 42 mm, nor with the 40 mm brass pattern, even though all three look alike at a glance. Check the lug distance before mixing stock from different sources.

These couplings have no positive lock of their own. The claws are drilled for retaining pins, and a pin or safety clip must be fitted to every joint; on compressed-air lines a whip-check restraint should also be fitted across the coupling, because a hose that breaks free under pressure will flail. They are air and water fittings - confirm suitability with the supplier before putting them on any other service.