Method and apparatus for main fuel pumping system having backup pump

摘要

A pumping system has a main pumping unit (14) and a backup pumping unit (16) mounted in a common housing (4) and adapted to be driven by a drive member (44). The main pumping unit is connected to the drive member by a main drive coupling (68) which incorporates a reduced shear section (76) designed to fail upon a jamming or seizure of the main pumping unit. A backup drive coupling (78) connected to the backup pumping unit is adapted to be axially displaced and threadably connected to the drive member after stoppage of the main pumping unit. An actuation device (18) functions to axially displace the backup drive coupling to establish threaded engagement. When the backup drive coupling is engaged with the drive member, the backup pumping unit will provide flow.