When a plane takes off do the pilots hit the brakes to stop the wheels from spinning or is there a system that stops the wheels when they are being put in the compartment. Does it even matter if they are stopped? Do they stop fast?
Commercial airliners have a pad in the nose wheel well that contacts the tires to stop their spin when retracted. The main gear hydraulic brake system is designed to stop the wheels upon retraction.
From 737-747 even Airbus, have nose wheel de-spin pad as the NLG goes up the tires touches this pad and wheel de-spins. A B737 MLG likewise has blade seals on the wheel well which does the same purpose, i.e. de-spins the MLG tires. It matters a lot the wheel spinning can be felt as vibrations in the cockpit (for the Nose LG) and cabin for the wheel well. I forgot or don't even remember in my ground engineer's course if brakes can be applied manually by the rudder pedal as I am sure when LD Gears are up both lines (retract extend) are connected to return. I don't recall brakes are still available as it is now flight mode.
On the A320 as soon as gear lever is selected to the up position hydraulic power is applied to the main gear brakes to stop the wheels before retraction. The nose wheel is stopped on a rub strip mounted within the wheel well. To answer your other two questions, yes it does matter that they are stopped as a spinning wheel will act like a gyro. Gyroscopic forces will try to keep the wheel in its original position. If the wheels were not stopped these forces would be felt as the main gear are retracted into the wheel well. The wheels will stop fast as soon as brake pressure is applied.
