MANOR’S TRIO OF BRAKE FLUID RESERVOIRS
At the front of an F1 car, both master cylinders – one is linked to the front brake callipers, the other to the rear callipers – comprise a cylinder and a piston, which operate the related brake circuit when the driver steps on the pedal. Each master cylinder also features a translucent plastic reservoir where brake fluid is stored.
While F1 cars are usually fitted with two reservoirs, the Manor MRT05 has three. Two are connected at the bottom, in a manner similar to communicating vessels. Maybe this is in order to have a bigger reservoir for the front brakes. Indeed, rear brakes can accommodate a smaller reservoir since the disks are supplemented by the MGU-K. This is only a hypothesis though.