Mechanical drive system for an accessory gearbox

A mechanical drive system for an accessory gearbox (24) of a gas turbine engine is provided. The gas turbine engine includes a high-pressure drive shaft (12) and a low-pressure drive shaft (14). The mechanical drive system includes a tower shaft (32) and a lay shaft (38). The tower shaft (38) is connected by a first gear arrangement (34) to the low-pressure drive shaft (14) of the gas turbine engine. The lay shaft (38) is connected by a second gear arrangement (36) to the tower shaft (32), and connected to the accessory gearbox (24).