Abstract: The invention provides an improved pneumatically operated circuit for automatically shutting off the flow of high pressure air being introduced into an object to be inflated, such as a tire, when the pressure in the object reaches a preselected maximum pressure significantly below that of the high pressure supply. The air at high pressure is introduced into the object and into a control duct also connected to the object, until pressure in the control duct overcomes the bias of a control valve, at which time the control valve closes to interrupt the flow of high pressure air and allow pressure in the object and the control duct to equilibrate; if the equilibrated pressure does not continue to overcome the bias of a control valve, the control valve again opens to admit additional high pressure air to the object and control duct until the bias of the control valve again is overcome and the control valve closed as previously, repeating the closing cycle.

Abstract: The invention provides a pneumatically operated circuit for automatically shutting off the flow of high pressure air being introduced into an object such as a tire, when the pressure in the object reaches a preselected maximum pressure significantly below the high pressure supply. The air is introduced automatically in timed, high pressure bursts and between the time bursts a safety mechanism gauges the pressure that has built up in the object and interrupts further timed bursts when the latter pressure exceeds the preselected maximum.