AIR SUPPLY CONTROL ARRANGEMENT FOR A HEAVY-DUTY VEHICLE COMPRISING A LIFT AXLE

An air supply control arrangement for a heavy-duty vehicle comprising a lift axle is provided. An electronically controlled brake valve device allows, when open, pressurized air to be passed to the brake chamber of the lift axle. A pressurized air source supplies pressurized air to the electronically controlled brake valve device along a supply passage. A pilot control valve provided between the pressurized air source and the electronically controlled brake valve device can restrict air flow through the supply passage. A pressure-responsive element actuates the pilot control valve when the pressure in the lift bellow is increased so that the lift axle is raised to a lift condition. The pressure-responsive element closes the pilot control valve. When the pressure in the lift bellow is reduced so that the lift axle is lowered to a ride condition then the pressure-responsive element is deactivated to allow opening of the pilot control valve.