 The FH77 is powered by a Volvo B20 Auxiliary power unit (APU), which gives the gun a top speed of 7 km/h.The engine is connected to three hydraulic pumps, of which two are linked to the wheels and one is used for a traverse, elevation, ramming and ammunition crane.The fuel tank could hold 40 litres, with two extra 20L jerry-cans as a reserve in front of the gun layer's position.