US Patent 7506667 Flex stack

A flexible exhaust stack is suitable for use with a vehicle for which relative motion occurs between the cab of the vehicle and exhaust system components mounted to the vehicle frame. The exhaust stack includes a pipe mounted to the cab and having inlet and discharge ends. A collar is secured to an interior portion of the pipe between the inlet end and the discharge end. A flexible hose is at least partially disposed within the pipe, with a discharge end secured to the collar and an inlet end in fluid communication with the frame-mounted exhaust system components. The exhaust stack receives exhaust gases from the frame-mounted exhaust system components and discharges the exhaust gases from the discharge end of the pipe, while the flexible hose allows for relative motion between the cab and the exhaust system.