The ABS-1740 Aircraft Passenger Boarding Stair is designed for servicing aircraft with doorsill heights between 1.7m and 4.0m. Stair assembly is mounted on a self-propelled chassis with diesel engine and automatic transmission. Four straight down type stabilizers located at front and rear to provide maximum stability and prevent rocking of front platform. ABS-1740 uses the latest technology with simple electric and hydraulic circuits. Location and accessibility of all components have been designed to reduce maintenance time to a minimum.